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CICG - GENEVA, Switzerland
CICG - GENEVA, Switzerland
Rue de Varembé 17, 1202 Genève
Dimitri Delikaris
(CERN),
Herman ten Kate,
Johan Bremer
(CERN),
Laurent Jean Tavian
(CERN)
Description
We would like to welcome you to the ICEC29/ICMC2024 conference taking place July 22 - 26, 2024 in Geneva, Switzerland. The conference venue is in the city of Geneva in the International Conference Center, while the Welcome Reception will be hosted in the brand new CERN Science Gateway. On the Friday morning visits to different CERN cryogenic installations are foreseen.
Come and join the year's largest cryogenic gathering, talk with colleagues, discuss with the world-wide suppliers, visit CERN’s new flagship for science education and outreach, and enjoy Geneva, it’s lake, it's fountain and much more.
Contact
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11:45
Start of conference CICG
CICG
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12:00
Registration Desk and Publication Office open at conference center
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1
ICEC course 1 "Cryostats for Accelerator Superconducting Devices" Room B
Room B
Speaker: Vittorio Parma (CERN) -
2
ICMC course 1 "Materials selection for cryogenic applications" Room C
Room C
Speaker: Ignacio Aviles Santillana (CERN) -
14:45
Coffee & Tea Break (for course attendees only)
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ICEC course 2: "Cryocooler based cooling options, from principles to performance, to system integration" Room B
Room B
Speaker: Torsten Koettig (CERN) -
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ICMC course 2: "Cryogenic Materials & Magnet Technology for High Energy Physics Detectors" Room C
Room C
Speaker: Herman ten Kate (University of Twente / CERN) -
18:00
Welcome Reception (and Registration) at CERN Science Gateway. Science Gateway, at entrance of CERN (CERN)
Science Gateway, at entrance of CERN
CERN
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11:45
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08:00
Registration Desk and Publication Office open (8:30-18:00)
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08:20
Exhibition open (8:45-18:00) Exhibition area (CICG)
Exhibition area
CICG
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08:45
Conference Opening (8:45)
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Tue-Pl-1: Cryogenics at CERN (plenary 1) Room D
Room D
Convener: Laurent Jean Tavian (CERN)-
5
Low temperature technologies for accelerators and detectors at CERN Salle/Room D
Salle/Room D
The European Strategy for Particle Physics (ESPP) has set new objectives for the future options of accelerators in view of Precision Physics or Frontier’s Discovery machines. All these accelerators imply large scales of technological breakthroughs which performances may be reconsidered in view of the strategic weight of the sustainability and environmental objectives.
Operating accelerator’s systems at higher temperatures for superconducting radiofrequency cavities and for superconducting magnets is one of the highest priorities, giving more visibility and weight to intermediate cryogenic temperatures in the 4.5-50 K domain. As such, the high-Luminosity LHC upgrade was pioneer as technology demonstrator, confirming that the cryogenic aspects shall be part of the overall design of the systems (sc magnets or sc RF cavities), excluding the idea of being a third-party engineering system.
The engineering challenges such as thermo-mechanics, operating temperature range, heat loads extractions, energy efficiency, reliability and Safety and finally integrated M&O (from construction to operation and maintenance) optimisation opens tremendous perspectives to the Cryogenic Engineering in the domains of particle accelerators, keeping their central role in the accelerator and component’s design and offering to the experts, domains of developments in the engineering, systems’ design, M&O at a level which ensure intellectual and scientific competitivity with other industrial applications of Cryogenics, including those of the environmental sustainability.
Thus, without any doubt, Cryogenic domains will remain a central technology of any future accelerator design provided it manages to go through the engineering and sustainability challenges this technology is facing.Speaker: Jose Miguel Jimenez (CERN)
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5
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09:35
Presentation of ICEC Klipping Award (John Weisend) & ICMC Excellence Award (Herman ten Kate)
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Tue-Pl-2: Superconductor Technology (plenary 2) Room D
Room D
Convener: Herman ten Kate (University of Twente / CERN)-
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Advancing Superconductor Technology for High-Field Applications: Current State and Emerging Trends Salle/Room D (CICG)
Salle/Room D
CICG
This presentation aims to provide a comprehensive overview of advancements and future directions in superconductor technology, specifically focusing on high field applications. The Low Temperature Superconductors (LTS) Nb-Ti and Nb3Sn continue to dominate the market, with a large demand driven by Magnetic Resonance Imaging (MRI), Nuclear Magnetic Resonance (NMR) spectroscopy and large-scale science projects. In particular, Nb3Sn is the primary candidate for the accelerator magnets in the CERN’s Future Circular Collider (FCC), a post-LHC collider targeting proton-proton collision energy in the 100 TeV-range. Achieving this milestone necessitates critical current performance beyond state-of-the-art and eventually close to the material’s ultimate limit. On the other hand, High Temperature Superconductors (HTS) are gaining attentions for magnet applications in domains where LTS cannot compete, e.g. for the generation of fields above ~20 T. This includes user magnets operating at 40 T for high-field science, solenoids up to 60 T to reduce muon emittance in future muon colliders, 30 T magnets for ultra-high-resolution NMR spectrometers and 20 T plasma confinement coils for compact fusion devices. These projects benefit from extensive research efforts in material science that have enhanced the properties of REBa2Cu3O7−x (REBCO, RE = Rare Earth) tapes, especially in extremely high magnetic fields. However, it is important to underscore that high transport properties are not the sole requirement for these prospective applications of LTS and HTS; electromechanical and thermo-physical properties also play a critical role. This presentation offers insights into the close synergetic relationship between evolution of the properties of technical superconductors and advancement in superconducting magnet technology, with a focus on recent research contributions from the University of Geneva (UNIGE).
Speaker: Carmine Senatore (UNIGE)
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6
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10:30
Coffee & Tea break Exhibition & Posters area
Exhibition & Posters area
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Tue-Or1: Large Scale Cryogenic Systems 1 Room D
Room D
Convener: Serge Claudet (CERN)-
7
Status of the FCC cryogenics feasibility study (invited)
Capitalising on the cryogenic operation experience of the LHC (Large Hadron Collider) at CERN and thanks to the promising results of the R&D efforts, the first phase of the Future Circular Collider (FCC) study presents in its Conceptual Design Report (CDR) published in January 2019 a clear route to a post-LHC machine, expected to be housed in a new 91km circumference underground tunnel. Regarding the cryogenic system, the CDR is describing the proposed architecture required by the implementation of the staged FCC programme, integrating in sequence a lepton (FCC-ee) then a hadron (FCC-hh) collider in the same tunnel with related cryogenic system upgrades respectively.
As from 2021, the FCC feasibility Study is capitalizing on the work of the Conceptual Design Report to refine its results regarding the architecture of the cryogenic systems of both FCC-ee and -hh machines, aiming at issuing an intermediate Feasibility Report by end of 2023 and a final report by 2025, which shall serve as input for the next European Strategy for Particle Physics (ESPP) update in 2026/2027.
The design of cryogenic systems is taking into consideration all the updates transmitted by stakeholders and impacting its general architecture, from the original ones on the general accelerator layout, to the more recent ongoing work on superconducting RF (SRF) cavities design for the FCC-ee machine.
This paper presents the status of the cryogenics study, emphasizing on the necessary update of the cryogenic processes and heat loads, helium inventory and energy consumption related to the recent modifications of the accelerator general layout, with a distinction made between the SRF systems, the detectors, and the machine-detector interface regions.
An operation mode targeting energy preservation is presented, while ongoing parametric studies on the design of specific components of the SRF cavities and the cryogenic distribution are introduced.
Finally, a preliminary installation strategy is described for surface and underground facilities, covering all operation phases of the machine, and recalling the next objectives to be met to complete the Feasibility Study in 2025.Speaker: Laurent Delprat (CERN) -
8
First-Year Operation Overview of the SLAC LCLS-II Cryoplant
The LCLS-II, an advanced X-Ray light source operated by Stanford University at SLAC for the US Department of Energy (DOE), operates with 37 cryomodules and a 700-meter linear accelerator (Linac) linked to two Cryoplant units, each capable of generating over 4.0 kW at 2.0 K. Commissioned in 2023, the LCLS-II Cryoplant is managed by the SLAC Cryogenic Division. This paper presents a comprehensive review of the first year of Cryoplant operation, encompassing budgetary considerations, staffing dynamics, utility management, availability metrics, performance evaluations, and notable challenges encountered. Insights gleaned from the first year of operation shed light on critical areas for optimization and provide valuable lessons for the sustainable functioning of the LCLS-II facility.
Speaker: Eric Fauve (STANFORD) -
9
LCLS-II LINAC 2.0 K COMMISSIONING
In 2023, SLAC commissioned a continuous-wave superconducting linear accelerator (CW SCRF Linac) to bolster its new Linac Coherent Light Source (LCLS-II). The Linac comprises of 37 cryomodules operating at 2.0 K. Achieving the 2.0 K temperature in the Linac involves reducing the liquid helium saturation pressure to 31 mbar using a series of centrifugal compressors, commonly referred to as cold compressors. This paper presents the commissioning of the Linac at 2.0 K, with a focus on the cryoplant capacity and heatloads at 2.0 K.
Speaker: Akanksha Apte (SLAC) -
10
LCLS-II LINAC Cooldown Automation
The upgrade of the SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) to LCLS-II marks a significant advancement in accelerator technology, incorporating a superconducting linear accelerator enhanced by 37 cryomodules segmented into two LINAC sections. This configuration, with 17 cryomodules upstream and 20 downstream, is uniquely supported by one of two helium refrigeration systems. A pivotal aspect of this upgrade is achieving an average cryomodule cavity quality-factor Q0 of 2.7×10¹⁰, essential for the operational efficiency of LCLS-II. A critical strategy employed to meet this requirement involves cooling the cavities slowly from room temperature and special cooling at a rapid rate of over 10 K/min through the niobium superconducting transition temperature of 9.2 K, aimed at minimizing the remnant magnetic field. This paper presents a detailed account of the first-ever implementation of a fast-cooldown process in a string of cryomodules. It elaborates on the automated functions, sequences, control logic, and machine protections that have been integrated into the system. Furthermore, it provides insights into the design decisions and valuable experiences garnered throughout the process of integration and commissioning, offering a comprehensive overview of this achievement in accelerator science.
Speaker: Swapnil Shrishrimal (SLAC National Accelerator Laboratory) -
11
Cryogenic architecture and heat loads for the High-Luminosity upgrade of the Large Hadron Collider at CERN
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is a major upgrade project of the LHC accelerator, which should allow increasing the peak luminosity by at least a factor of five beyond LHC’s design value. This upgrade will include the replacement of the final focusing superconducting magnets and the implementation of superconducting radiofrequency crab cavities in the long straight sections of the interaction points 1 and 5 of LHC. The cryogenic part of this upgrade consists in the design, specification, procurement, installation, commissioning, and handover to operation of two new cryogenic plants and associated cryogenic distribution lines at the machine interaction points for the high luminosity insertions dedicated to CMS and ATLAS detectors. The two new cryogenic plants, with an equivalent capacity of 14 kW@4.5 K, including 3.25 kW@1.9 K, were defined based on the heat loads of the new superconducting magnets and radiofrequency crab cavities, of the cold powering systems, and of distribution heat loads. This paper presents the details of the static and dynamic heat loads applied to each cryogenic element added for the HL-LHC, the methodology for addressing the maturity of their design, the defined nominal operating modes and finally the required helium refrigerators cooling capacity for each temperature level, considering the effect of luminosity and beam energy.
Speaker: Vanessa Gahier (CERN) -
12
Process design and control strategies of the two large 1.9K Helium refrigeration plants at CERN
In 2022, Linde received the order to deliver two large helium refrigeration systems operating at 4.5 K and 1.9 K for the European Organization for Nuclear Research (CERN) in Geneva, Switzerland. The two identical plants will be installed at opposing points along the circumference of the Large Hadron Collider (LHC). They will facilitate the peak luminosity by a factor of five beyond the LHC’s design value.
Due to the operation of the superconducting magnets at 1.9 K, parts of the cryoplant operate at a very low pressure, down to 15 mbar a. While operating in a steady state, each of the cryoplants delivers up to 14 kW of equivalent power at 4.5 K, including 3.25 kW at 1.9 K (isothermal and non-isothermal),13.5 kW at 60 K to 90 K as well as various loads having 4.5 K supply.
The very low pressure at which the liquid helium is evaporated inside the LHC’s magnets to achieve 1.9 K leads to a high-volume flow of gaseous helium returning from the LHC experiment to the cryoplant. Cold compressors lower the volume flow, which pre-compresses the helium returning from the experiment before it is conveyed to the refrigeration cold box. Due to smaller volume flow, heat exchangers can be designed to be more compact, and the warm screw compressor requires lower capacity.
Since the LHC is located underground, each cryoplant is split into two separate cold boxes. The larger main cold box (refrigerator) is located at the surface, and a second, smaller cold box, which contains mainly the cold compressors, is in the underground cavern close to the experiment.
The combination of floating pressure in all four pressure stages with an integrated 3,500 L LHe phase separator enables rapid adaptation to load changes without using a variable frequency drive for the main compressors. A floating pressure cycle maintains high efficiency even during turndown operation.
The paper covers the process design according to CERN's specification and the control strategies for load adaption.Speaker: Eriks Arajs (Linde Kryotechnik AG) -
13
The consolidation program of the cryogenic systems of the ATLAS and CMS experiments
The CMS and ATLAS experiments and their superconducting magnetic and calorimetric systems, installed in the LHC (Large Hadron Collider) at CERN, have both been equipped with cryogenic installations. The CMS experiment is making use of a large superconducting solenoid magnet, while the ATLAS experiment combines a large superconducting toroid magnetic system, a superconducting solenoid and three liquid argon calorimeters.
The respective and associated cryogenic installations have all been in continuous operation during the LHC physics run started in 2009. Although these systems have been performing with high reliability, specific consolidations have been proposed to improve their reliability. The consolidations have been mainly implemented during the LHC long shutdown periods of 2013-2014 and 2019-2020. For the CMS experiment, hot-spare helium compressors were installed to allow full redundancy in case of failure. For ATLAS one redundant high-pressure helium compressor and two of the booster helium compressors have been upgraded with new and increased capacity units. A unit of 10’000 litres liquid helium storage was integrated into the cooling process of the ATLAS solenoid allowing significantly improved operation autonomy and recovery in case of a resistive transition of the magnetic toroid system. The CMS oil removal system was upgraded to overcome oil problems that were impairing the performance of the helium refrigerator. Finally, for both ATLAS and CMS infrastructure, an upgraded full flow dryer scheme was added in the global process of helium systems.
This paper describes the consolidation program made to these cryogenic systems towards their availability improvement.Speaker: Olivier Pirotte (CERN)
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7
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Tue-Or2: Cryocooler Research Room A
Room A
Convener: Toru Kuriyama (Toshiba)-
14
Development of high-performance cryocoolers capable of operating from 120 K down to 5 mK
This paper presents a review of the recent development of a variety of high-performance cryocoolers developed in the author’s laboratory with the operating temperatures ranging from 120 K down to 5 mK. Above 1.0 K, the refrigeration cycles involves both regenerative and recuperative cycles, and the hybrid cycle composed by the former two as well. For the regenerative cycle, the study is focused on the Stirling-type pulse tube cryocooler (SPTC) because it not only has no moving component at cold end, which eliminates any wear therein and minimizes vibration and EMI, but also is driven by the linear compressor which makes it further realize long life at warm end and achieve high system efficiency. The mature miniature and mid-sized single-stage SPTCs cover 25–120 K while multi-stage ones can achieve 3.3 K with cooling capacities varying from milliwatt levels to tens of watts. These SPTCs are mainly used to provide low-noise cooling for the infrared detectors with short, medium, and long wavelengths and the cold optics systems, and several types of them are developed for space applications. A high-capacity SPTC capable of 1220 W at 77 K has found applications in the high-Tc superconducting power systems such as HTS cables and dynamic synchronous condensers, and several SPTCs with the typical cooling capacity of 100 W at 20 K are used to cool high-Tc superconducting magnets in the controlled nuclear fusion system. The hybrid cryocooler, typically composed of the recuperative JT cryocooler precooled by the regenerative multi-stage SPTC, is developed to achieve the lower temperatures of 1–2 K. With a no-load temperature of 1.36 K and the effective cooling powers at 1.8 K, it is used to cool the superconducting nanowire single photon detector, which often plays an important role in the optical quantum computers. The cryogen-free dilution refrigerator is a rising development focus in the authors’ laboratory, which has a base temperature of 5 mK and the typical cooling powers varying from 400 μW to 1.3 mW at 100 mK, and is expected to provide appropriate cooling for the quantum chips in the superconducting quantum computers. In the latter development, either the multi-stage SPTC with the high cooling capacity at 3.0–4.2 K, or the hybrid cryocooler with the appropriate cooling capacity at 2.0–3.0 K, serves as the critical precooling stage for the dilution refrigerator. The application background, design philosophy and optimization approaches of the above various cryocoolers are described and summarized, and then the performance characteristics of them are presented and discussed.
Acknowledgements:
This work is supported by the National Natural Science Foundation of China (Grant No. 52076210), the Major Project of Science and Technology Commission of Shanghai Municipality (Grant No. 22511100100) and Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01).Speaker: Haizheng Dang (State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciencess) -
15
Experimental investigation of a helium sorption cooler operating below 1 K
With advancements in space exploration and condensed matter physics, the demand for ultra-low temperature (mK) technology is on the rise. Sorption coolers, known for their extended service life, absence of moving parts, low vibration, high reliability, and immunity to electromagnetic interference, stand out as a crucial refrigeration technology for the future. In this study, we successfully developed a prototype single-stage sorption cooler, utilizing helium-4 as the working gas. The gas-gap type heat switch, independently developed by our unit, operates within the temperature range of 4 K to 20 K, exhibiting switch ratio of 1007 at helium-4 fill pressures of 1 bar. Research findings demonstrate that our prototype sorption cooler can achieve a minimum temperature of 870 mK, with a hold time of 10 hours under no load conditions. To meet the demands for prolonged operation, our unit is actively involved in the development of a continuous sorption cooler.
Speaker: Kongkuai Ying (shanghai institute of technical physics Chinese academy of sciences) -
16
Development of a remote cooling system for detector magnet current leads using a single-stage GM cryocooler
The cooling of large superconducting detector magnets used in high-energy physics relies on a continuous supply of liquid cryogen that is provided by large and complex cryogenic plants. An alternative to this is the development of cooling systems based on the use of cryocoolers. Such a solution can be employed to cool a superconducting magnet itself or to intercept heat from other components of the magnet cryostat.
One of the major sources of heat load for detector magnets is current leads. This study aims to develop and test gas-cooled High-Temperature Superconducting current leads for a Low-Temperature Superconducting detector magnet with an operating current of 3kA along with the associated cryogenic assembly. The heat load coming from the room temperature is intercepted at 50K by using helium circulating in the closed loop that consists of a single-stage Gifford-McMahon cryocooler, cold circulator and dedicated heat exchangers. An overview of the design and optimization efforts will be presented. The test setup for the demonstrator is currently under construction and the first experimental results are expected by the end of 2024.Speaker: Weronika Gluchowska (CERN) -
17
Numerical Modeling on a Two-Stage GM Cryocooler
Numerical modeling plays an important role in developing new or improving existing cryocoolers. It enhances design optimization and performance evaluation through the study of physical parameters that are usually impractical to measure. In the current cryogenics industry, cryocooler modeling is primarily conducted using 1D tools, such as Regen 3.3 and Sage. However, there are only a few works applying Computational Fluid Dynamics (CFD), despite CFD being one of the most powerful 3D multiphysics modeling tools available in market and capable of providing more comprehensive data than 1D simulations. More importantly, CFD simulations can represent flow patterns visually allowing engineers to understand complex thermal fluid systems like cryocoolers deeply.
In this work, a two-stage GM cryocooler has been conducted using the commercial software, Ansys-CFX. A robust two-stage model was built by considering a quarter of the axisymmetric 3D cryocooler and set up by taking advantages of advanced Ansys-CFX features, such as dynamic meshing, turbulence options, and porous domain settings. Reliable solutions were obtained over entire 3D domains of the model. From the simulation results, regeneration materials and matrix dimensions were evaluated based on the 2nd stage cooling capacities. The temporal and spatial variations of pressure, temperature and Reynolds Number were also studied. Finally, the results were compared against available experimental data to validate modeling accuracy and provide valuable recommendations for cryocooler design.Speaker: Lydia Shen -
18
Effect of operating parameters on step piston type pulse tube refrigerator
The pulse tube refrigerator, lacking moving components at low temperatures, has the advantages of high reliability, long operational lifespan, low cost, and ease of fabrication, and is widely used in refrigeration medical, semiconductor processing, aerospace and other fields. The improvement of pulse tube refrigerator mainly comes from the improvement of phase shifter. In traditional pulse tube refrigerator, the expansion work at the hot end of the pulse tube is dissipated in the form of heat in the phase shifter, which decrease the intrinsic efficiency. The work recovery type pulse tube refrigerator can recover the expansion work at the hot end of pulse tube while shifting the phase of pressure wave and volume flow at the cold end of the pulse tube, thereby enhancing the performance of the pulse tube refrigerator. The work recovery type pulse tube refrigerator is currently a hotspot. The developed work recovery type pulse tube refrigerator, by recovering the expansion work at the hot end of the pulse tube, has achieved the high cooling efficiency. However, while realizing the function of work recovery, it is often necessary to add additional moving parts or additional cold heads, which makes the structure of the pulse tube refrigerator complicated and loses the inherent advantages of simple structure. The step piston type pulse tube refrigerator (SP-PTR) is a novel work recovery type pulse tube refrigerator which only requires one moving part and one cold head to achieve the work recovery function. SP-PTR consists of a step piston linear compressor and a pulse tube cold head, featuring a simple structure and high intrinsic efficiency in the high-temperature region. At present, the preliminary experimental verification has been carried out. However, further research is needed. In this paper, a thermoacoustic model of SP-PTR is established, and the influence of operating parameters such as frequency, refrigeration temperature, piston displacement, and operating pressure on the phase shifting ability, work recovery ability, and refrigeration performance of SP-PTR is studied. An experimental setup for SP-PTR has been developed to verify this model. The thermoacoustic model and experimental results indicate that for SP-PTR, there exists an optimal operating parameter that maximizes the efficiency. In the test range, the input voltage mainly affects the efficiency of the pulse tube cold head, while the frequency and operating pressure affect the efficiency of both the step piston compressor and the pulse tube cold head.
Acknowledgment
This work was supported by the National Natural Science Foundation of China (No.52076151).Speaker: Sheng Xu (Tongji University) -
19
100 K Cooling Performance of a Modified Collins Cycle Cryocooler for In-space Applications
This paper presents 100 K cooling performance of a Modified Collins cycle cryocooler designed for in-space cooling applications. Descriptions of this lightweight, high efficiency, and power dense cryocooler design are included. Experimental results are shown of a single-stage floating piston design with active control designed to provide 100 W of cooling at temperatures of 100 K. Maintenance of in-space cryogenic propellants (liquid methane, liquid hydrogen, and liquid oxygen) should be possible with this medium-scale, continuous flow architecture.
Speaker: Carl Bunge (MIT) -
20
Development of a high efficiency micro pulse tube cryocooler for 80 K
A miniature Stirling-type pulse tube cryocooler was designed and manufactured. The performance test was carried out with a linear compressor with a piston diameter of 11 mm. The weight of the whole machine was about 1.2 kg. In this study, we utilized SAGE to investigate the impact of parameters such as frequency, transfer line length, and inertance tube length on the refrigeration performance. Through thermodynamic analysis, the energy flow and loss changes in the refrigerator are obtained, and the influence of these parameters on the refrigeration performance is quantified. Finally, the refrigeration characteristics of the cryocooler are tested and the influence of the above parameters on the refrigeration performance is verified by experiments. Through simulation-assisted optimization, experimental tests revealed that the cryocooler achieved a performance of 1.5W@80K at a hot-end temperature of 300K, with a relative Carnot efficiency reaching 10.63 %.
Speaker: Xiaoqin Zhi (Zhejiang University) -
21
Optimal actively cooled shield temperature in vacuum insulated applications with multilayer insulation
Actively cooled shields are used primarily in the temperature range at or below 20 K (e.g. LH2 or LHe) so that the heat load to these low temperatures is as small as possible. This is due to the high energy required to generate such low temperatures and the relatively low latent heat of the corresponding cryogens. Liquid nitrogen (LN2) with a boiling temperature of 77 K at 1 bar is very often used because on the one hand it is very inexpensive and on the other hand it is available everywhere indefinitely.
Even with two-stage cryocoolers, where the first stage is used for a cooling shield, this one is preset to a temperature of approx. 80 K.
Here, the optimal actively cooled shield temperature is calculated depending on the number of super insulation layers between the cold wall and the shield, and between the shield and the warm wall with a view to minimal energy consumption. Depending on the number of layers, these optimal shield temperatures can be far apart. Therefore, the gradient of this function of energy expenditure over the shield temperature is also formed in order to describe the importance of setting this optimal actively cooled shield temperature.
Finally, the energy savings when using an actively cooled shield compared to without an actively cooled shield are also calculated. The results demonstrate the enormous energy savings when using actively cooled shields and also the energy savings when setting the optimal actively cooled shield temperature.Speaker: Holger Neumann (Karlsruhe Instititute of Technology, Institute for Technical Physics; Cryogenics)
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14
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Tue-Or3: Coated Conductors, Films & Bulk Room B+C ( )
Room B+C
Convener: Sonja Schlachter-
22
Correlation between vortex pinning and defect landscape in TLAG -$YBa_2Cu_3O_{7-\delta}$ nanocomposite films
High temperature superconductors (HTS) are one of the most ambitious achievements since the discovery of superconductivity and they have the potential to revolutionize large-scale applications in the form of coated conductors (CC). $REBa_2Cu_3O_{7-\delta}$ (REBCO, RE = Rare Earth) coated conductors which belong to the class of HTS called cuprates are one of the highly studied materials due to their exceptional superconducting properties. However, there are still some scientific and engineering challenges set forth in the fabrication of high-performance CC. The novel growth method developed at ICMAB for the fabrication of REBCO films is an ultrafast (100 - 1000 nm/s) and cost-effective technique which combines Chemical Solution Deposition (CSD) with a non-equilibrium Transient Liquid Assisted Growth (TLAG) method [1,2]. Therefore, TLAG aims to overcome the high cost-performance ratio of the fabrication of REBCO CC.
REBCO successfully covers a wider range of magnetic field - Temperature (H - T) region than any other existing superconducting materials. However, to satisfy the different applications of REBCO coated conductors, one must do a broad characterization on the dependence of critical current density ($J_c$) on magnetic field (H), temperature (T) and the orientation of magnetic field (θ). The final Jc is determined by the vortex pinning mechanism at each H-T region and this is highly correlated to the microstructure of the REBCO films. There have been many efforts in the community to optimize the pinning landscape by nano-engineering the coated conductors and the best way has been the addition of nanoparticles or nanorods to the REBCO films which can enhance Jc in magnetic fields in the so-called nanocomposite CC [3]. Also, to reduce the cost-performance ratio, recently the focus is not only on increasing Jc but also on increasing the growth rates [4]. Therefore, nowadays it is very interesting to study the microstructure and vortex pinning mechanism in TLAG-CSD nanocomposites being a non-equilibrium growth method with ultrafast growth rates [4].
In this work we study different nanocomposites based on the concentration, size and type of nanoparticles by electrical transport measurements to understand the pinning mechanism and with the help of Transmission Electron Microscopy (TEM) and advanced x-ray diffraction we are able to correlate these properties to the microstructure and strain. The nanocomposites used in this study include 6,12,18, and 24% mol $BaZrO_3$ or$BaHfO_3$ preformed nanoparticles with sizes of 5, 7 and 10 nm, and various thickness. All the TLAG nanocomposites shows higher $µ_0H^*$ and nanostrain (ε) and the effective anisotropy factor is reduced down to $γ_{eff}$ = 2-3.5 which in the case of pristine films is 5-7. From the angular dependent transport study, the anisotropic peak around ab-planes is broadened in nanocomposites compared to pristine, signaling an increase of short stacking faults density relevant for vortex pinning at low temperatures and high magnetic fields. These additionally formed stacking faults are also responsible for breaking the twin boundary coherence which prevents vortex channeling at low temperatures. The overall $J_c$ (θ) dependence has been improved in most of the H-T region for TLAG nanocomposites compared to TLAG pristine films. Finally, the effect of nanoparticle concentration and layer thickness will also be discussed.
[1] Soler, L., Jareño, J., Banchewski, J. et al. Ultrafast transient liquid assisted growth of high current density superconducting films. Nat Commun 11, 344 (2020).
[2] Rasi, Silvia, et al. “Kinetic Control of Ultrafast Transient Liquid Assisted Growth of Solution‐Derived YBA 2 Cu 3 O 7 ‐x Superconducting Films.” Advanced Science, vol. 9, no. 32, 2022, p. 2203834.
[3] Vallès, Ferran, et al. “Optimizing vortex pinning in yba2cu3o7-X superconducting films up to high magnetic fields.” Communications Materials, vol. 3, no. 1, 8 July 2022.
[4] Puig, Teresa, et al. “Impact of high growth rates on the microstructure and vortex pinning of high-temperature superconducting coated conductors.” Nature Reviews Physics, vol. 6, no. 2, 4 Dec. 2023, pp. 132–148.Speaker: Aiswarya Kethamkuzhi -
23
Oxygenation under high pressure of EuBCO and GdBCO coated conductors
REBCO (Re=Y, Eu, Gd) coated conductors (CC) based on biaxially textured, thick and homogeneous nanoengineered multilayer structures opened up new application opportunities, such as dissipation-free energy transmission in superconducting grids, highly efficient engines for electrical aviation or compact fusion reactors beyond ITER. However, current carrying capacities of CC could be further improved because they are still far from theoretical limits. Overdoping by oxygen the REBCO structure of CC is one of the possible robust ways to increase current carrying capacity of CC, however overdoping these materials is not easy. Here we report on the high pressure oxygenation results from EuBCO-CC (with the surface Ag layer chemically removed) and GdBCO-CC (coated with 2 microns Ag layer). Oxygen pressure were in the range from 1 - 160 bar and temperatures between 300-800 °C. The layers were characterized by XRD (estimating unit cells parameters), superconducting properties (Tc, Jc (T) and Jc(H, 77K)), and SEM, EDS and quantitative Auger spectroscopy. The highest Jc (77 K, 0 T) of 2.67 MA/cm2 was obtained by GdBCO-CC with c= 1.17310 nm oxygenated at 100 bar O2, 600 oC for 3 h. Its Jc (77 K, 0 T) was 4% higher than that of the initial GdBCO sample with c= 1,17351 nm. The Jc of the initial EuBCO-CC samples decreased after removing the Ag layer (Jc (77 K, 0 T)=1.38 MA/cm2). However, among the high pressure oxygenated EuBCO-CC, the highest Jc(77 K, 0 T)=1.31 MA/cm2 was that treated under 160 bar of O2 at 800 °C for 3 h. The approximate composition of EuBCO matrix phase (estimated after etching of its surface by Ar ions in the chamber of microscope) according to quantitative EDX analysis was EuBa2.06Cu2.89O7.35Ni0.11C1.05 and according to quantitative Auger analysis (which has higher locality than EDS) was EuBa0.57Cu0.25O0.54 The approximate stoichiometry of the matrix phase of EuBCO initial sample was EuBa2.05Cu3O7.97Ni0.12C (EDS) and EuBa0.74Cu0.22O0.72 (Auger). This suggests that high pressure oxygenation of EuBCO may induced anion and cation diffusion. Additional treatments and experiments on charge carrier density are on-going. We also investigated the time degradation process of EuBCO-CC with a chemically removed Ag surface layer when stored in air. It should be noted that the degradation of EuBCO-CC with a chemically removed surface layer after saturation with oxygen at 600 °C under a pressure of 100 bar for 3 h slowed down significantly.
We acknowledge funds from MICIU/AEI/FEDER for SUPERENERTECH (PID2021–127297OB-C21), FUNFUTURE “Severo Ochoa” (CEX2019–000917-S); MUGSUP (UCRAN20088) project from CSIC scientific cooperation with Ukraine; Catalan Government 2021 SGR 00440; NAS of Ukraine Project III-7-22 (0785).
Speaker: Tetiana Prikhna -
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PLD-grown (Y,Gd)BCO superconducting thin films: Jc enhancement by mixed phase REBCO and oxygen annealing
Within the last decades, researchers from all over the world have been demonstrating the fascinating abilities of RE Ba2Cu3O7-δ (Rare Earth=RE) coated conductors (CC) to improve our day-to-day lives. However, among all large-scale applications, the prospect of acquiring energy from fusion power plants may well be the most breath-taking one. The main characteristic of RE BCO CC, which allows such wonders, is the ability to carry large amount of currents. Therefore, in order to acquire the best characteristics of such technologies and most compact designs, it is of utmost importance for material scientists to understand how the highest critical current density (Jc) of RE BCO superconducting layer may be achieved.
In RE BCO-based superconducting thin films Jc strongly depends on the interaction of vortices with defects present and, therefore, over the years the main strategy for enhancing Jc was implementation of additional nano-sized defects by various techniques. The most prominent among those is the introduction of artificial pinning centres (APC). In our recent work on the oxygen annealing of PLD-grown GdBa2Cu3O7-δ (GdBCO) superconducting thin films [1], we have shown that the defect morphology may be tailored via either decomposing Gd2O3 nanoparticles (NP) or stacking faults (SF) by varying the annealing temperature (Tann) and the oxygen pressure (P O2). Therefore, as a next step of pushing Jc we are combining two approaches: usage of mixed phase Y0.5Gd0.5Ba2Cu3O7-δ (YGdBCO) thin films and oxygen annealing. To do so, first the deposition conditions for PLD-grown YGdBCO thin films will be optimized. Secondly, YGdBCO thin films will be annealed in a tubular furnace at various Tann and P O2, similarly to GdBCO thin films from our previous work [1]. Structural and transport properties of YGdBCO superconducting thin films will be discussed compared to pristine GdBCO thin films. The similarities and differences of in-field Jc, anisotropy of Jc, and the defect morphology will be discussed.References:
[1] Popov, R. “Influence of oxygen annealing on structural and transport properties of pristine and BaHfO3 nanocomposite GdBa2Cu3O7−δ films”. PhD thesis. Karlsruhe Institut für Technologie (KIT), 2023. 157 pp.Speaker: Ruslan Popov (Institute for Technical Physics, Karlsruhe Institute of Technology) -
25
Effect of metamaterial engineering on the superconductive properties of ultrathin layers of NbTiN
The electronic transport and optical properties of high quality multilayers of NbTiN/AlN with ultrathin NbTiN layers were characterized. The anisotropy of the dielectric function of the multilayers confirmed their hyperbolic metamaterial properties. The superconductive transition temperature, Tc, of these engineered superconductors was enhanced up to 32% compared to the Tc of a single ultrathin NbTiN layer while the resistivity per NbTiN layer remained unchanged. We have demonstrated that this Tc increase can be attributed to enhanced electron-electron interaction in superconducting hyperbolic metamaterials. The measured critical fields are high and have anomalous temperature dependence in the perpendicular to the magnetic field direction. These results demonstrate that the metamaterial engineering approach can be used to enhance Hc2.
Speaker: Vera Smolyaninova (Towson University) -
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Signs of pressure-triggered decomposition of the REBCO layer in Coated Conductors subjected to thermomechanical stress
A robust technology for producing superconducting joints between Coated Conductors (CCs) is crucial for those applications in which closed-loops coils working in persistent current mode are required, such as Nuclear Magnetic Resonance (NMR). The preparation of these joints involves applying both temperature and a transverse compressive load simultaneously to produce the bonding of two adjacent REB2Cu3O7-x (REBCO, RE = rare earth) layers. We carried out experiments to simulate this process, subjecting samples from commercial CCs to various combinations of pressure (50 to 80 MPa) and temperature (600 to 850 °C). The goal was to understand the impact of thermomechanical cycles on the critical current (Ic) of the CCs and find out the upper limit for the achievable current in a superconducting joint between CCs. Across the studied parameter range, we observed a degradation in Ic performance. For example, the average reduction in Ic, measured at 77 K in self-field, is approximately 45% for samples subjected to simultaneous heating at 820°C and pressing at 60-70 MPa compared to samples heated at the same temperature without applied pressure. In this work, tests have been performed on CCs with different RE elements in the REBCO layer and varying not only the temperature and external pressure, but also the time at maximum temperature, the heating ramp and the oxygen partial pressure. Electrical transport measurements combined with microstructural analysis by means of TEM, SEM, and EDX served to determine a possible correlation between Ic degradation and variations in the REBCO microstructure caused by changes in these parameters. Our analyses suggest that the concurrent application of temperature and pressure eases the decomposition of the REBCO phase. EDX data indicates that decomposition products correspond to a melting process of the REBCO occurring at lower temperatures, accelerated by the presence of external pressure and as expected, taking place earlier when the RE in the REBCO compound leads to a lower peritectic point. The larger time at maximum temperature, the shorter the heating ramps or the lower oxygen partial pressure also speed up the decomposition of the REBCO phase. The observed early decomposition occurs in localized areas of the REBCO layer, reducing the available cross-section for current flow and thus decreasing the critical current.
Speaker: Pablo Cayado Llosa -
27
Superior RE123 bulks with small RE211 particles in-situ self-formed at temperature above Tp
The refinement of RE2BaCuO5 (RE211) particles is a matter of significant importance in fabricating high-performance REBa2Cu3O7- (RE123) superconductor bulks by top-seeded melt growth (TSMG). However, RE211 coarsening and RE123 peritectic decomposition naturally promote a continuous growth of the pre-existing RE211 during the heating up to the maximum processing temperature (Tmax), causing an unwanted size enlargement.
Here, we report a novel TSMG approach in which with absence of RE211, modified precursor powders (MPP, RE2O3, and Ba-Cu-Ox) were employed to fabricate RE123 bulks (RE= Y, Sm in this work). As a result, there is neither RE211 in the beginning nor related enlargement behaviour in the heating stage. Upon exceeding peritectic temperature (Tp), a peritectic solidification of RE2O3 + Ba-Cu-Ox → RE211 instantaneously and simultaneously occurs, characterized by nucleation catastrophe. That is to say, spontaneously, the massive small sized RE211 in-situ formed at Tmax, ultimately yielding fine and evenly distributed RE211 particles in the grown RE123 bulks. Consequently, the MPP-processed superior RE123 bulks with superior properties were achieved.Speaker: Simin Huang -
28
Designing high Cr-alloy Eurofer with advanced properties by cryogenic processing for fusion
Improving known materials and exploring new alternatives for applications in challenging energy environments, such as fusion, has been a priority in recent years in material science. A unique combination of corrosion resistance, toughness, strength, machinability, and wear resistance is required for materials used in energy sector applications. In recent years, a process called cryogenic processing (a cost-effective and environmentally friendly technology) has emerged as an additional step in the heat treatment of various ferrous and non-ferrous alloys, offering improvements in various properties which, despite its long history, has only recently begun to develop actively. Cryogenic processing involves subjecting materials to temperatures below 273 K. There are 3 known cryogenic processing technologies conventional (CT in the range 273-193 K), shallow (SCT in the range 193-113 K), and deep (DCT below 113 K). For most applications of cryogenic processing liquid nitrogen is usually used (77 K). Cryogenic processing technology fundamentally changes material´s properties (hardness, toughness, strength, ductility, corrosive and wear resistance, etc.) through the leading mechanisms of improved austenite transformation into martensite and increased carbide precipitation. In our study, we attempt to achieve the optimised microstructure, modified residual stress state, corrosion resistance, modified magnetic and surface properties of Eurofer in combination with DCT in response to the increasing demand for material improvement in fusion applications. In conclusion, this study shows that DCT is an effective microstructural modification tool, but its influence on the final mechanical properties is strongly correlated with the alloying dynamic (in-situ SPEM observations), initial microstructure, and heat treatment parameters of Eurofer.
Speaker: Patricia Jovicevic-Klug (Max-Planck-Institut für Eisenforschung) -
29
Behaviour of superconducting coils inside the sub-cooled water ice
The helium bath cooling becomes more and more expensive and limited and therefore cooling alternatives e.g. conduction cooling or other cryogens have to be used. In the past years, liquid hydrogen or sub-cooled solid nitrogen (at ~ 20 K) were used for superconducting devices. But, liquid H2 needs a special safety conditions and solid N2 may sublimate easily and lost the cooling efficiency. Therefore, behaviour of several MgB2 coils inside the water ice cooled by cryocooler down up to 10 K were studied [1-3]. In addition, I-V characteristics and critical currents versus temperature and external field for coils wound of different wires (Bi-2223, REBCO and Nb3Sn) were measured [4]. Stable and safety behavior of superconducting coils inside sub-cooled water ice have been observed under high DC or pulse currents. The effect of unpleasant volume expansion in water is compensated by double-walls container. Consequently, sub-cooled water ice is promising, cheap and safe cooling medium applicable for He-free systems at temperatures above 10 K.
[1] M. Búran et al Sup Sci and Technology 34 (2022) 105004
[2] P. Kováč et al Sup Sci and Technology 34 (2022) 055001
[3] P. Kováč et al Sup Sci and Technology 34 (2022) 095007
[4] M. Búran et al Supercond. Sci. Technol. 36 (2023) 105013Speaker: Pavol Kovac (Institute of Electrical Engineering, Slovak Academy of Sciences)
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Tue-Po-1.1: Large Scale Cryogenic Systems 2 Poster area
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Convener: Laurent Jean Tavian (CERN)-
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A thermodynamic analysis of a coupled LAES system for recycling liquid ethylene cold energy
Liquid air energy storage (LAES) is an emerging energy storage technology with significant potential for development, owing to its geographical flexibility and superior ability to integrate external energy sources. However, the efficiency of conventional LAES systems is hindered by the shortage of internal cold energy, necessitating the incorporation of external cold energy to improve system performance. Given the substantial amount of unutilized cold energy in the liquid ethylene (LE) regasification process, effective methods for recovering LE cold energy are required. This study proposes an innovative LAES-LE coupled system for the recycling of LE cold energy, using an intermediate cold-storage medium. The regasification cold energy of LE is employed in the low-temperature compression of air and subsequent cooling processes. In addition, Additionally, waste heat of approximately 245°C is introduced to provide the heat for air expansion. This study establishes a composite thermodynamic model of the LAES-LE system and examines the impact of LE pressure, the temperature in low-temperature compression, and the number of low-temperature compression stages on system performance.
Speaker: Yihong Li (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
31
An economic analysis of a coupled LAES system utilizing the regasification cold energy of liquid ethylene
Liquid air energy storage (LAES), characterized by high energy storage density, large-scale storage capacity, and rapid response time, emerges as a novel energy storage technology applicable to grid peaking and renewable energy saving. However, LAES lags behind other energy storage technologies in terms of system efficiency, primarily due to the internal cold energy deficit. To enhance system efficiency, the integration of external cold energy is crucial. Considering the significant waste of cold energy in the liquid ethylene (LE) regasification process, effective strategies for LE cold energy utilization are imperative. This study introduces an LAES-LE coupled system that utilizes LE cold energy: the storage and utilization of LE cold energy are facilitated by an intermediate cold-storage medium, and is used in the low-temperature compression of air and the following cooling process. Besides, waste heat is incorporated to provide the heat for air expansion. This study develops an economical model of the coupled LAES-LE system and investigates the influence of various parameters on the system’s economic performance, including the temperature of the waste heat, the mass flow of the LE, and the varying peak-valley electricity prices.
Speaker: Yihong Li (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
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Carbon Footprint of the Helium Recovery System at the ISIS Neutron and Muon Source
ISIS Neutron and Muon source is a scientific facility which welcomes over 3000 scientific and industrial users per year to carry out experiments across a range of scientific disciplines. Approximately 500 experiments per year require some form of cryogenic sample environment equipment for cooling the sample, and a significant proportion of these use ‘wet’ cryostat or magnet systems consisting of a liquid helium bath.
Helium is a global finite resource, which is becoming vitally important to recover and reuse as it continually diminishes. ISIS has a helium recovery and liquefaction system which allows for recycling of 96% the helium used in the facility for cryogenic applications. The Helium recovery and liquefaction process is well known and incorporates plant which consumes significant amounts of power, thus contributing to a facility’s already large carbon footprint. The drive to reduce carbon footprint, and therefore lessen the impact of climate change, is gathering momentum. UK Research and Innovation, the parent body of Science and Technology Facilities council, is Committed to reaching net zero CO2 emissions by 2040.
In this work we have assessed the CO2 produced per liquid litre of Helium processed by the ISIS helium recovery facility. The main components have been taken into consideration, including high pressure compressors, instrumentation, Linde KryoTechnik TCF20 cold box, screw compressor, building infrastructure and safety systems. We also compare this carbon footprint for in-house liquid helium production with that of the supply from gas companies. To do this we have explored the liquefaction process of both liquified natural gas and helium, the methods of transportation that are employed, the time taken to transport and the liquid boil off rates during the delivery process. This allows us to comment on the contribution helium recovery can make in the pursuit of net zero.
Speaker: Alexander Jones (Science and Technology Facilities Council) -
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Conceptual design of the cryogenic distribution system for the Shenzhen superconducting soft X-ray free electron laser
The Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL) accelera-tor is based on the TESLA type superconducting RF cavity technology. It consists of 26 1.3 GHz cryomodules and 2 3.9 GHz cryomodules, which can produce 2.5GeV free electron laser and operate in continuous wave mode. Three cryogen-ic systems, namely Test Facility CryoPlant (TFCP), Prototype Accelarator Cry-oPlant (PACP) and Accelarator CryoPlant (ACCP) will be constructed to support the S3FEL. This paper will mainly introduce the preliminary design of these three cryogenic distribution systems.
Speaker: Guang Long Cui (Institute of Advanced Science Facilities, Shenzhen) -
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Enhancing liquid air energy storage efficiency through integration with LNG: comparative analysis of cold energy recovery methods
Liquid air energy storage (LAES) technology is characterized by its high energy storage density, geographical independence, and ease of integration with other systems. The LAES integrates and offsets the intermittency and volatility of renewable energy sources. However, air compression and liquefaction processes significantly impact the round-trip efficiency of the entire LAES system. This study proposes the integration of an external cold source with the LAES system to recover cold energy and enhance the system’s energy efficiency. Liquefied Natural Gas (LNG) serves as an effective external cold source when coupled with LAES. The coupling of LNG and the LAES is achieved by providing cold energy to the system in two ways: reducing the system’s compression work and supplementing cold energy to assist in liquefaction. This paper compares and analyzes these two methods to enhance system performance, serving as a reference for research on the integrated system of LNG and LAES.
Speaker: Junxian Li (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
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Failure analysis for liquid helium leaking to the vacuum envelope of the cryogenic distribution system of the ESS superconducting linac
The European Spallation Source (ESS) is going to provide long-pulsed cold and thermal neutron fluxes at very high brightness. It is one of the largest science and technology infrastructure project being built on outskirt of Lund, in Sweden. Protons at 2 GeV (with a normal current of 62.5 mA) are delivered by a superconducting linear proton accelerator and are injected on a rotatory tungsten target at pulsed repetition rate of 14 Hz. The Accelerator Cryogenic Plant (ACCP) is designed to deliver the cooling power to 21 high-beta, 9 medium-beta and 13 spoke cryomodules through the Cryogenic Distribution System (CDS). In the CDS, supercritical at a temperature of 4.5 K and thermal shield gaseous helium at a temperature of 40 K are provided, while the thermal shield flow and the vapor low pressure (VLP) from the 2 K cavities are returned. The CDS consists of the three main parts: Cryogenic Transfer Line (CTL), Cryogenic Distribution Line (CDL) comprising the 30 valve boxes for the high- and medium-beta cryomodules and that for the 13 spoke cryomodules. The CDS have a total length of 385 m and a vacuum volume of 326.22 m3.
The most severe failure for the CDS is considered to be a liquid helium leak to the CDS vacuum envelope through a crack formed on a bellow. An analysis was conducted on the released flow rate from a vacuum safety device of the CDS to the accelerator tunnel. The Authors have already developed an analysis code that predicts pressure and temperature changes in the hydrogen transfer line for the ESS Cryogenic Moderator System (CMS) and its vacuum envelope. In this analysis, the helium leak from the VLP, which has the maximum inventory, to the vacuum envelope was considered and the pressure rises in the VLP and vacuum envelope were analyzed using the code. The heat load to the vacuum envelope was calculated by natural convection heat transfer and that to the process line was estimated based on CFD analysis results. The crack size (length and width) of the bellows has been determined based on the fatigue test results of the bellows.
For the small crack size, the CDS vacuum pressures did not increase up to the set point of the vacuum safety device (1.05 bar) and all the helium was discharged through a rupture disk on the process line, because of the considerable vacuum volume. For large crack size, the leaked helium is discharged into the accelerator tunnel. Due to the substantial vacuum volume, it takes 54 seconds for individuals accessing the accelerator tunnel to move away from the leak source. Consequently, continuous monitoring of the CDS vacuum pressure is essential to interlock helium supply valves from the cryoplant.Speaker: Hideki Tatsumoto (European Spallation Source ERIC (ESS)) -
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Optimizing pre-cooling methods for liquid air energy storage power stations: A focus on cooling of tanks
Liquid Air Energy Storage (LAES), characterized by its large-scale energy storage capacity and geographical flexibility, represents a promising solution to address the intermittency and volatility of renewable energy. In the construction phase of a LAES power station, the pre-cooling procedure for the cold energy storage fluid and its corresponding tank assumes critical significance, as it profoundly impacts both the round-trip efficiency and the overall economic viability of the station. Traditionally, the liquid-phase cold energy storage method employs a methanol-water solution and propane as the cold energy storage fluid. However, direct injection of the low-temperature cold energy storage fluid into the tank can lead to excessive stress, potentially compromising the tank's integrity. Hence, it is crucial to pre-cool the methanol-water solution tanks, propane tanks, liquid air tanks, and their associated pipelines to the appropriate temperatures prior to fluid injection. This paper proposes the use of liquid nitrogen spraying for tank cooling and evaluates the impact of various cooling rates on tank stress levels. A tank pre-cooling calculation model is subsequently developed to analyze the effects of ambient temperature, external wind speed, and pre-cooling rate on liquid nitrogen consumption. Taking into account the influence of cooling rate on thermal stress and liquid nitrogen usage, the paper provides a recommended pre-cooling rate range for storage tanks.
Speaker: Zhikang Wang (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China) -
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Simulation of the JT-60SA supercritical helium cooling loops during magnet integrated commissioning using Simcryogenics
The JT-60SA tokamak fusion experiment is under final commissioning at Naka, Japan. The magnetic confinement of this fusion facility is performed by superconducting magnets cooled around 4.5 K. The JT-60SA magnet system is composed of toroidal field (TF) magnets, central solenoid (CS), and equilibrium field (EF) magnets. There are 18 TF magnets (Nb-Ti conductor, max field at conductor 5.65 T), which, along with their structures, represent a mass of 420 tons. There are 6 EF magnets (Nb-Ti conductor, peak field 6.2 T) weighing 178 tons. The CS consists of 4 modules (Nb3Sn conductor, peak field 8.9 T) and weighs 100 tons.
These magnets are kept in their superconducting state by a forced-flow circulation of supercritical helium (SHe) ensured by two separated cooling loops. The SHe flows into these loops by the means of cryogenic circulators and ensure a temperature of around 4.5 K to the magnets inlet. The first loop (mass flow rate circulating 900 g/s) is cooling in parallel the TF magnets and in series, their structures, and the CS structures. The second loop (mass flow rate circulating 1 kg/s) is cooling in parallel the CS and EF magnets. The heat deposited in or created by the magnets and their structures is removed through the SHe loops by the cryogenic plant able to extract about 9 kW equivalent at 4.5 K.
This work presents the thermal-hydraulic model of the SHe cooling loops and the superconducting magnets circuits to predict their behavior, particularly in the event of a fast safety discharge (FSD). The comparison of the modeling and FSD experimental measurements provide inputs to ensure that the loops and the refrigerator can cope with a FSD of magnets without endangering the facility. The modeling of the loops is developed using Simcryogenics, a cryogenic simulation tool developed by CEA/DSBT. The modeling of the loops is a step towards the complete modeling of the whole cryomagnetic system of JT-60SA to improve the control of key variables for a more reliable operation.Speaker: Francois Bonne (Univ. Grenoble Alpes, CEA IRIG-DSBT,Grenoble 38000 France) -
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Simulation of thermal compensation of the ESS cryogenic moderator system caused by a transient heat load change when the proton beams are turns on or off
The European Spallation Source ERIC (ESS) will provide long-pulsed cold and thermal neutron fluxes at very high brightness to the research community. Spallation neutrons are produced by a linear proton accelerator with an average beam power of ultimately 5 MW. These neutrons are moderated to cold and thermal energies by the moderators. Initially, the ESS will install two hydrogen moderators above the target wheel. The nuclear heating is estimated to be 6.7 kW. The ESS cryogenic moderator system (CMS) plays a role in circulating subcooled liquid hydrogen at a temperature of 17 K and a pressure of 1 MPa with a flow rate of 0.5 kg/s to remove the nuclear heating at the moderators. The heat load will be efficiently removed through a plate-fine type He-H2 heat exchanger (HX11) located in the CMS cold box by a large-scale 20 K helium refrigeration system, which is called the Target Moderator Cryoplant (TMCP), with the cooling capacity of 30.3 kW at 15 K. High-pressure helium streams, operating at a temperature of 16 K, are transported from the TMCP cold box to a valve box called the Jumper spool box (JSB) through a 300 m-vacuum insulated cryogenic helium transfer line (CTL). The return temperature is maintained at 21.2 K by warm helium streams via a mixing valve in the JSB in order to apply no thermal disturbance to the TMCP cold box.
When the proton beams are injected, an immerse heat load is suddenly applied to the CMS. The feed helium flow rate to the heat exchanger is adjusted by the feed control valve in the JSB to compensate for the heat load, while the JSB bypass valve is automatically adjusted to maintain a pressure drop through the bypass line. This allows the available cooling capacity to be regulated without applying any thermal disturbance to the TMCP cold box. The hydrogen temperature supplied to the moderators remains consistently at 17.5 K.
In this study, a one-dimensional simulation model of the heat exchanger was developed to comprehend the propagation of the thermal fluctuations when the return hydrogen temperature was rapidly changed due to proton beam injection or trip event. The thermal propagations through the heat exchanger were analyzed by varying the speed of ramping up the feed helium flow rate and the timing to initiate the ramp-up mode. The operational parameters can be optimized to mitigate the fluctuation of the hydrogen supply temperature within ±0.1 K.Speaker: Hideki Tatsumoto (European Spallation Source ERIC (ESS)) -
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Study of the influence of the plate-fin heat exchanger pressure drop on the performance of liquid air energy storage
Wei Ji1, Jiyun Liu1, Zi Lin1, Lingwei Cui1, Liubiao Chen2, 3, Junjie Wang1, 2, 4, *
1 Zhonglv Zhongke Energy Storage Technology Co., Ltd., 18 Lishi Hutong, Dongcheng District, Beijing, P. R. China;
2 Chinese Academy of Sciences Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, 29 Zhongguancun East Road, Haidian District, Beijing, P. R. China;
3 Institute of Optical Physics and Engineering Technology, Qilu Zhongke, Jinan, P. R. China;
4 University of Chinese Academy of Sciences, No.19(A) Yuquan Road, Shijingshan District, Beijing, P. R. China;
*Corresponding author: wangjunjie@mail.ipc.ac.cnABSTRACT: Liquid air energy storage is a very promising energy storage technology, which has the advantages of large capacity, long time, long life and no geographical restrictions. In order to improve the efficiency and economy of the liquid air energy storage system, the optimization design of the heat exchanger is the focus of the research, especially the low-temperature plate-fin heat exchanger employed in the process of air liquefaction. The key design parameters of heat exchanger include heat transfer temperature difference and pressure drop. However, most of the current studies only focus on the heat transfer temperature difference of the heat exchanger. Reducing heat transfer temperature difference can improve the system efficiency, but significantly increase the cost of the heat exchanger. Therefore, this paper mainly studies the influence of the pressure drop of plate-fin heat exchanger on system performance. Thermodynamic analysis based on steady-state mathematical model was employed to evaluate the system efficiency. The results show that a moderate increase of pressure drop can significantly reduce the cost of the plate-fin heat exchanger, while the system efficiency decreases slightly.
KEYWORDS: liquid air energy storage; plate-fin heat exchanger; pressure drop
Speaker: Wei Ji -
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Study on in situ measurement of heat leak into transfer line
In fusion experimental devices and accelerators, superconducting magnets and cavities are cooled by cryogen supplied through transfer lines from helium liquefier/refrigerators. Since those devices have become larger recently and are operated continuously for a long time, the heat leak into transfer lines has a large influence on the cooling capacity of the helium liquefier/refrigerators. Therefore, it is essential to evaluate the heat leak accurately. Nevertheless, it is difficult to measure the heat leak in situ after installation, although the heat leak is just estimated by numerical analysis or measured by mock experiment before installation. Generally, the heat leak is evaluated by measuring evaporation rate of cryogenic liquid or enthalpy difference between inlet and outlet of flowing cryogenic gas through a tube. In the device after installation, however, the measurements using existing instruments to be necessary for operation are required, and therefore the instruments are not optimized for the location and the working range to be measured. In the present study, an alternative method to measure heat leak into transfer lines by using existing pressure gauges and thermometers, which are relatively installed at many points, is proposed. In the proposed measuring method, the inlet and outlet valves of a transfer line, the pressure gauge and the thermometer within the transfer line are used. After the temperature of the target transfer line is equalized with cryogenic helium gas, the valves at both ends of the line are closed. Then, the pressure increases over time, while the mean density of the confined helium gas keeps constant because the mass of that keeps constant. Since the initial enthalpy and density of the helium gas can be calculated by HEPAK® from the initial pressure and temperature, the increase of the enthalpy can be calculated from the pressure rise and the density. The heat leak into the transfer line is determined from the increase of the enthalpy, the mass of the helium gas and the confinement time. In the present paper, results of the demonstration on the in situ measurement of a transfer line in the cooling system for the superconducting magnets of the Large Helical Device at National Institute for Fusion Science are reported. The transfer line is a vacuum insulated tube and has six inner tubes wrapped with multi-layer insulations and an 80 K shield, which are housed in a 68 m long outer tube with a diameter of 660 mm. The measured tube is a supply line of supercritical helium that is one of the inner tubes. Although the heat leak into the tube was evaluated by numerical analyses and short sample tests before installation, the heat leak had never been measured after installation. As the results that the heat leak was measured using the above method, the heat leak of 58 W was obtained for the first time after installation and the amount of the measured heat leak was relatively consistent with that of the evaluated heat leak before installation. Consequently, the proposed method was confirmed to be effective.
Speaker: Shinji Hamaguchi (National Institute for Fusion Science) -
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Thermodynamic analysis of an efficient liquefaction unit with high-grade cold storage in liquid air energy storage systems
Liquid air energy storage (LAES) technology stands out as a promising large-scale energy storage solution owing to its inherent advantages such as high storage density, geographical flexibility, and scalability. The liquefaction unit, being a pivotal element of the LAES system, significantly influences its overall performance. However, existing research on the liquefaction unit within the LAES system remains incomplete. These technologies encounter challenges, including low efficiency, safety concerns, and substantial investment requirements, thereby impeding the widespread adoption of LAES in the energy storage market. In response to these challenges, this study proposes an efficient liquefaction unit tailored for high-grade cold storage in the LAES system. The suggested liquefaction unit utilizes a solid-phase medium for cold storage, demonstrating commendable cold storage performance. The study establishes relevant thermodynamic models and conducts a thorough thermodynamic analysis, exploring the impact of key design parameters on system performance. Results indicate that the innovative liquefaction unit effectively addresses current technological challenges, achieving a liquefaction rate exceeding 80% while ensuring safety and cost-effectiveness. This research contributes valuable insights to the LAES community and aims to drive the commercialization process of LAES technology.
Speaker: Xiaoyu Fan (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
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Thermodynamic analysis of liquid air energy storage systems based on different liquefaction cycles
Liquid air energy storage (LAES) is a large-scale, long-duration energy storage technology that stores electricity in the form of liquid air. Air liquefaction is the core process of a LAES system, determining the conversion rate between electricity and liquid air and affecting the system efficiency. Conventional LAES systems are often based on a single liquefaction cycle, such as the Linde-Hampson cycle, and thermodynamic comparisons of LAES based on different liquefaction cycles still need to be further investigated. The LAES systems based on the Linde-Hampson throttling liquefaction cycle, as well as combined liquefaction cycles represented by the Claude cycle, the Heylandt cycle, and the Kapitza cycle are presented and compared in this paper. Characterized by parameters such as energy consumption per unit of liquefied air, liquefaction rate and round-trip efficiency, the system performance of different liquefaction cycles was compared. The operating parameters of the LAES system based on different cycles were optimized. The sensitivity effects of typical operating parameters of the system on the system performance was evaluated. Considering the practical engineering feasibility and economy, the preferred liquefaction process and critical operating parameters of the liquefaction were determined.
Speaker: Zhaozhao Gao (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences)
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Tue-Po-1.2: Cryocoolers, Dilution Refrigerators & Magnetic coolers Poster area
Poster area
Convener: Patricia Tavares Coutinho Borges De Sousa (CERN)-
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Computational Fluid Dynamic Studies of Miniature Pulse Tube Cryocoolers
Conventionally cryocoolers are defined as devices that are capable of reaching temperatures of 120 K or below. Among various types of cryocoolers, pulse tube cryocoolers (PTCC) have developed rapidly over the past decades. PTCC are advantageous due to the absence of moving parts at the cold end, and their miniaturization aspects. Computational fluid dynamic (CFD) studies are nowadays necessary to capture the multi-dimensional effects and complex transport phenomena occurring in PTCC. The current work focuses on the miniaturization aspects of PTCC with increasing frequencies. A distributed parameter model is developed for PTCC and validated against the published result from the open literature. The discrepancy in the obtained results is attributed to the use of different thermophysical properties of the fluid and solid used in the simulation. Further, the governing equations are non-dimensionalized to generalize the simulation results. Furthermore, some parametric studies on the aspect ratio and high-frequency operations of PTCC are carried out.
Acknowledgement: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB 1527/1 – project-ID 454252029.
Speaker: Rajendra Kumar (Karlsruhe Institute of Technology) -
44
Cryogenic thermoelectric coolers with different passive branches
Cryogenic thermoelectric coolers can be widely used in aerospace industry for satellite cooling systems. However, the commercialization of thermoelectric cooling technology has been built on the Bi2Te3 alloys, which have been aimed at room temperatures. Therefore, suitable materials for cryogenic thermoelectric coolers are needed. In this paper, four thermoelectric coolers have been fabricated from active elements (polycrystalline Bi85Sb15) and different passive elements (Bi-2212 bars, Bi-2223 tapes, high purity copper bars and EuBCO tapes). The maximal temperature drops between the hot and cold sides are measured at both room temperatures and cryogenic temperatures (80K, 100K and 120K) without a magnetic field. The results show the possibility of fabricating thermoelectric coolers for cryogenic temperatures.
Speaker: Hongwei Zhang (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
45
Design methodology of a Mixed Refrigerant Joule-Thomson (MRJT) cryocooler
Joule Thomson (JT) cryocoolers are emerging as an alternative choice for cooling temperatures upto 100 K. This is enabled by using refrigerants instead of single/pure refrigerant as a working fluid. Such cryocoolers are also referred to as Mixed Refrigerants Joule-Thomson (MRJT) cryocoolers. By using mixed refrigerants, the pressure ratio in the cryocooler is reduced from an order of 100s to around 8-10. As a result, off the shelf air conditioning compressors can be used for MRJT cryocoolers. In addition to this, the MRJT cryocoolers also have an efficiency that is of order magnitude higher than that of a JT cryocooler operating with a single refrigerant. However, a clear and systematic methodology for designing an MRJT cryocooler for a given evaporator temperature and refrigeration load is not available. The present work focuses on a detailed design methodology for designing an MRJT cryocooler for a given capacity and cooling temperature. Major components that need to be designed for an MRJT cryocooler are compressor, aftercooler, recuperative heat exchanger, expansion device and evaporator.
Before going into the detailed design of the individual components, it is essential to carry out the theoretical design of the MRJT cryocooler cycle. The first step in designing an MRJT cryocooler is the identification of the cryocooler operating parameters. In the present work, the operating parameters are determined by carrying out theoretical optimization of the MRJT cycle. Commercial softwares are available for optimization; however, an inhouse solver is also developed to determine the cryocooler theoretical performance. For optimum results, it is recommended that the exergy efficiency of the cryocooler be used as the objective function.
As described earlier, air conditioning compressors are used in MRJT cryocoolers. The selection of the compressors is carried out by matching its swept volume with the volume flow rate required at the suction side of the compressor. For cases where two stage compression process is required, a mathematical model is developed to select the compressors of the subsequent stages. The aftercooler of the compressor is similar to the condenser of a conventional air conditioning unit. The aftercooler is designed based on the heat generation during the compression process. The recuperative heat exchanger is the most critical component of the MRJT cryocooler. In the present work, a numerical model is developed in order to determine the heat transfer area leading to the heat exchanger dimensions.
Capillary tubes are used as an expansion device for MRJT cryocoolers as they do not contain any moving parts and, hence, do not require sealing arrangements at low temperatures. A one dimensional mathematical model, already published by authors, is used to select the capillary tube size (diameter and length). In MRJT cryocoolers, the heat load may range from a few watts to several kilo watts, thus, an evaporator based on the refrigeration effect and the end application may be designed. The design of individual components is combined to form an MRJT design methodology. The design methodology, so developed, is validated by comparing the results with experimental results obtained in our laboratory.Speakers: Darshit Parmar, M D Atrey -
46
Development of a 2 kW Class Two-Stage Cascade Type Mixed Refrigerant Joule-Thomson Refrigerator for Semiconductor Etching Process with Cooling Temperature Below -100℃
A mixed refrigerant (MR) Joule-Thomson (J-T) refrigerator has been developed for application in the semiconductor etching process. The designed refrigerator operates on a 2-stage cascade-type MR J-T refrigeration cycle. For pre-cooling, a vapor compression cycle utilizing R1234yf, a low global warming potential refrigerant, is employed. The main cooling cycle utilizes a mixture of argon (Ar), tetrafluoromethane (R14), trifluoromethane (R23), and octafluoropropane (R218). The target temperature of the MR J-T refrigerator is below -100℃. To facilitate its application in semiconductor etching, an indirect cooling method using coolant (HFE77200) is introduced. The paper provides a detailed description of the component selection process, including the compressor and heat exchanger, based on the design results. Additionally, numerical analysis of the coefficient of performance of the designed refrigeration cycle is presented, along with experimental results.
Speaker: Cheonkyu Lee (Korea Institute of Industrial Technology) -
47
Development of the 4 K G-M assisted J-T cooler with off-the-shelf mini compressor
A 4 K J-T cooler is developed to provide sufficient cooling capacity for SNSPD (superconducting nanowire single photon detector) or other quantum information devices. The system is designed for a nominal cooling capacity of 10 mW at 4 K and is conceived to retain sufficient operating flexibility so to properly tune the operating condition. To that extent the design facilitates additional compressor capacity respect to nominal value. The cooling system consists of a compressor, a series of three recuperative heat exchangers and a commercial G-M cryocooler to pre-cool the compressed helium gas before the J-T expansion valve, the J-T valve and an evaporator. For the compressor, a series of small commercial units originally made for R-134a working fluid and a commercial oil removal system are utilized. It is tested with helium gas instead of R-134a. Compression ratio above 9 and with power consumption lower than 100 W can be achieved. In addition, the commercial oil removal system is utilized to prevent oil from reaching the J-T circuit. The three recuperators are adopted in the J-T system to exploit the cooling capacity of the returning cold gases, reducing the load on the compressor. The optimized recuperators are specifically designed in consideration of the load map of the two-stage cryocooler according to the principle of entropy generation minimization. Especially, the coldest heat exchanger is designed to have minimal volume and mass to maximize the available space for the user scientific package and to reduce cooling time after startup. Furthermore, the performance of the J-T cooler with a novel heat exchanger design is assessed and compared with that of more conventional solutions.
Speaker: Giorgio Ghilardi (Korean Institute of Science and Technology) -
48
Experimental and numerical study of a modified condensation-driven dilution refrigerator
Dilution refrigerators are widely used in the fields of condensed matter physics and quantum technology. The condensation-driven dilution refrigerator uses a condenser operating at temperatures below that of the Still to liquefy the 3He vapor and achieve the circulation of the 3He, which has the advantages of compact structure, lightweight, low cost, and low vibration. Due to these characteristics, the CDR can meet the requirements of specific applications, such as the forthcoming generation of Cosmic Microwave Background observatories and astrophysics balloon missions. The published research primarily focuses on the system architecture and performance, and in-depth thermodynamics analyses are lacking. In 2023, we built a condensation-driven dilution refrigerator with a lowest no-load temperature 68 mK, and the cooling performances need to be further improved. In this paper, the condensation-driven dilution refrigerator will be modified, optimizations will be made to the heat exchanger of the previous prototype. Experimentally studied and corresponding numerical simulations will be performed, and the results of experiments and simulations will be compared and analyzed. In the experiments, the lower cooling temperature and higher cooling power of the system could be expected. With the help of simulations, the internal dynamic and thermodynamic characteristics of the experimental system during operation will be clarified, which provide guidance for further optimizations.
Speaker: Weijun Cheng (University of Chinese Academy of Sciences) -
49
Experimental and theoretical investigation to study pressure drop in regenerators
Stirling type Cryocoolers are required to cool the I-R detectors and have become essential in military and space-based applications due to its efficiency and compactness. At the core of a cryocooler lies the regenerator, a crucial component acting as a heat exchanger. This heat exchanger plays a vital role in the operation of the cryocooler due to its efficient heat transfer resulting in cooling of the working fluid. Optimum design of heat exchanger is the critical requirement for the cryocooler. This optimization primarily focusses at minimizing pressure drop within the regenerator and maximizing the heat transfer. As the cryocooler reaches steady state performance, less energy is expended due to reduced friction and pressure drop as the fluid moves through the regenerator. As a result, the overall cooling performance of the cryocooler improves.
The present study is aimed at experimental and numerical investigation to assess the pressure drop characteristics of the regenerator which uses meshes of stainless steel, such as SS 400 and SS 200 meshes, under varying ambient and cryogenic temperatures. Ansys Fluent software is used for numerical simulations to derive hydrodynamic parameters, such as mass flow rate, Darcy permeability and Forchheimer coefficient, which capture both viscous and inertial resistance. The mass flow rate represents the rate at which fluid flows through the regenerator, while the Darcy permeability characterizes the ability of the porous medium (the stainless steel meshes in this case) to allow fluid to pass through under the influence of a pressure gradient. The Forchheimer coefficient accounts for additional resistance due to inertial effects within the flow. These parameters are integrated into the momentum equation, which represents the balance of forces within the regenerator. By incorporating the volume-averaged hydrodynamic resistance, the momentum equation calculates the overall pressure drop across the regenerator.
A numerical model is developed and validated with the experimental data reported in the literature. An experimental set up is developed in our laboratory to measure the pressure drop across the regenerator. The setup is similar to a pulse tube cryocooler configuration, incorporating a pressure wave generator, an aftercooler for heat dissipation due to compression, a regenerator, an inertance tube as phase-shift mechanism, and a buffer volume to stabilize gas flow and pressure. Cold end and hot end heat exchangers are omitted. Experiments are conducted for various charge pressures and input powers at ambient conditions. Pressure transducers are used to measure the pressure drop across the regenerator, mounted at the inlet and outlet of the regenerator. Upon obtaining experimental results for the pressure drop across the regenerator, the hydrodynamic parameters specific to the regenerator in this setup are calculated using the developed numerical model. Investigation is carried out to predict pressure drop for cryogenic temperatures and for different charge pressures using these parameters. Experimental work is further carried out to study and compare the predictions with the actual experimental results.Speakers: Parikshit Badhe (IIT Bombay), Praveen Topagi (IIT Bombay) -
50
Experimental Study of a Coupled Stirling Generator-Pulse Tube Cryocooler System Driven by a Stirling Engine
Cold end temperature of Stirling generator needs to be increased to reduce the heat sink radiator area which is limited due to the payload capacity of rocket in space application. However, the cold end temperature increase leads to the linear alternator’s overtemperature and failure consequently. A coupled Stirling Generator-Pulse Tube Cryocooler system driven by a Stirling Engine was proposed in this work to solve the high temperature failure problem of the linear alternator for space usage. In the system, the Stirling Engine converts heat from hot source to PV power first. Then the PV power actuates the linear alternator for electricity generation and the Pulse Tube Cryocooler for refrigeration simultaneously, where the later one pumps heat from the former to cold end of the Stirling generator. The linear alternator temperature can be controlled by the PV power allocation between it and Pulse Tube Cryocooler system, which avoids the high temperature failure problem in the space condition. A prototype was built to validate the feasibility of this proposal, where the Pulse Tube Cryocooler system was connected with the compression space of the Stirling Generator. It shows that, with 300W heat input and 532℃ at hot end temperature, the Stirling Generator system can output 43.9W electricity and Pulse Tube Cooler system can reach 61K without heating load.
Speaker: yanjie Liu -
51
Experimental study of a Dilution Refrigeration Unit for space applications
Multiple space X-ray missions in China are under preparation in recent years including HUBS and DIXE. The demand for the Sub-Kelvin space refrigeration technology becomes urgent. The space dilution refrigerator with the advantages of continuous cooling power, little magnetic interference, and light weight has application prospects for space detection missions in future. A dilution refrigeration unit for the space application is designed to study the start-up process and dilution process in space. The unit starts successfully and obtains 162 mK. Based on the experimental results, the influencing factors including the circulation concentration, the viscosity dissipation, the single-phase extraction are carefully discussed for the performance and optimization.
Speakers: Zijie Pan (Key Laboratory of Technology on Space Energy Conversion, Technical Institute of Physics and Chemistry, CAS), Lingjiao Wei (Technical Institute of Physics and Chemistry, CAS), Ziyao Liu (Technical Institute of Physics and Chemistry, CAS) -
52
Experimental study of a single-stage adiabatic demagnetization refrigerator
The adiabatic demagnetization refrigerator (ADR), based on the principle of magnetocaloric effect, is a solid-state cooling device. One of its key advantages is the ability to operate under microgravity conditions while offering high thermodynamic efficiency and modular design. Moreover, it stands out as one of the few coolers capable of achieving sub-Kelvin temperatures. As a result, it is gaining significant attention in space applications requiring extremely low temperatures. This study presents the design and experimental performance of a single-stage adiabatic demagnetization refrigerator. The ADR incorporates a superfluid helium bath, providing a precooling temperature of approximately 1.2 K. The magnetocaloric material chosen for this setup is a paramagnetic salt (CPA). A superconducting magnet supplies a magnetic field of 2 T. Experimental measurements show that, under adiabatic conditions, this single-stage ADR can obtain a minimum temperature of 73.58 mK upon completely removing the magnetic field.
Speaker: Lingjiao Wei (中国科学院理化技术研究所) -
53
Experimental study on a 1.3 W@4.2 K GM type pulse tube cryocooler
GM pulse tube cryocoolers with large cooling capacity at liquid helium temperature are widely used due to the advantages of low vibration, long life and high reliability in some fields, including quantum computing, condensed matter physics research and others. Our research team previously developed a cold head of the GM type pulse tube cryocooler based on the American compressor CPA1110, which achieved a minimum temperature of 3.1 K and can provide 0.8 W cooling capacity at 4.2 K. This paper focuses on the matching test and coupling research between this cold head and the domestic commercial compressors LAVROCK 60 and LAVROCK 100. Finally, the optimized GM type pulse tube cryocooler achieves a minimum temperature of 2.5 K and can simultaneously provide 1.3 W at 4.2 K and 20 W at 45 K.
Speakers: Xuming Liu (Southern University of Science and Technology), Changzhao Pan (Shenzhen International Quantum Academy) -
54
Investigation and optimization of the continuous and discrete heat exchangers in the mK dilution refrigerator for cooling superconducting quantum chips
The recent decade has witnessed the rapid development of superconducting quantum computing for its ultra-fast execution speed. The quantum chips should operate at a temperature below 20 mK, which poses a significant challenge for the suitable cryogenic system. The dilution refrigerator which can not only operate continuously and stably but also features with the merits of low vibration and electromagnetic interference has become an indispensable cryogenic technology for it. Unlike other refrigerators in ultra-low temperatures, there are two types of heat exchangers in the dilution refrigerator due to the effect of Kapitza resistance, including the continuous and discrete heat exchangers. Both of them are decisive factors because their flow and heat transfer characteristics play an important role in determining the cooling performance. In this paper, a numerical model of both the continuous and discrete heat exchanger is established, based on which the effects of working conditions (inlet pressure, temperature, etc.) and structure parameters (tube diameter, length, particle size, etc.) on the heat transfer coefficient are simulated. In addition, the coupling between each stage of the heat exchanger is also investigated to optimize the cooling performance of the dilution refrigerator. The theoretical analysis and simulation results will be discussed in detail, and the effect of the coupling relationship on the performance of the dilution refrigerator will be presented. It is indicated that the designed heat exchangers are quite helpful for optimizing the cooling performance of dilution refrigerators.
Speaker: Yujia Zhai -
55
Magnetocaloric alloys for active magnetic regenerative refrigeration
In response to the escalating demand for energy-efficient refrigeration, active magnetic refrigeration (AMR) has emerged as a promising solution, with researchers focusing on identifying environmentally friendly solid-state refrigerants. Among various candidates, including Gd and Heusler alloys, the evaluation criteria typically revolve around parameters such as isothermal magnetic entropy change (ΔSM) and adiabatic temperature change (ΔTad). However, the complexities of AMR systems demand a broader assessment, considering factors like thermal conductivity, corrosion resistance, and heat transfer coefficients.
To address this, an in-house AMR system has been developed specifically for testing different magnetic refrigerants. This system is being utilized to evaluate MnxFe5−xSi3 compounds with varying compositions to identify the optimal blend for room-temperature refrigeration. By aligning experimental methodologies with real-world application requirements, this study aims to advance the development of efficient magnetic refrigeration technologies.
Speaker: Eunjeong Kim (lawrence livermore national laboratory) -
56
Numerical and experimental study of a single-loop cryogenic pulsating heat pipe
A Pulsating Heat Pipe (PHP) is an energy-efficient heat transfer device that operates using the processes of evaporation and condensation to effectively transport heat across long distances. Notably, room-temperature PHPs find crucial applications in cooling electronic components, such as CPU chips. In cryogenic environments, superconducting magnets that are cooled using cryocoolers require efficient conduction cooling to maintain the magnets in their superconducting state. Traditional heat conduction via copper straps becomes less effective when the distance between the cryocooler and the magnet is substantial. To address such challenges, the straightforward design of a PHP with its exceptional heat transport capabilities is a highly suitable alternative. The experimental studies on cryogenic PHP mainly focus on the heat transfer potential of the PHP. Understanding the complex two-phase flow behaviour and the transient nature of the temperature and pressure field inside the PHP is crucial. In the present study, a novel two-dimensional CFD model for a cryogenic pulsating heat pipe has been developed in ANSYS Fluent. The PHP is configured in a vertical heating mode, featuring the evaporator positioned at the bottom and the condenser at the top. The orientation of the PHP has been set in vertical heating mode, with the evaporator at the bottom and the condenser at the top. The PHP is a two-channel single loop with an inner diameter of 1.8 mm and an outer diameter of 3.16 mm. Nitrogen serves as the working fluid, and the tube structure material is chosen to be stainless steel. The total length of the PHP is 120 mm, with each of the three sections equal to 40 mm. The evaporator section is subjected to a constant heat flux boundary condition, while the condenser section is set at a constant temperature of 77 K. The Volume of Fluid (VOF) model has been chosen as the multi-phase Eulerian model, and the Lee model has taken care of the phase interaction between the liquid and vapour. A User Defined Functions (UDF) code is written to solve the mass transfer between the two phases and the corresponding heat transfer due to evaporation and condensation. The thermal physical properties of liquid and vapour nitrogen have been set as polynomial functions with temperature except for vapour density, which obeys the ideal gas law. Moreover, the saturation temperature and the latent heat follow a polynomial variation with pressure. The system is initialized with a FR of 50 % and has been tested at different thermal loads. The CFD model helps to understand the transient behaviour of temperature and pressure inside the PHP and the evolution of flow patterns with time. The evaporator temperature and pressure of the system initially rise as the evaporator is supplied with heat load and then reaches a quasi-steady state. However, the condenser temperature does not change significantly during the operation. The fluid under operation eventually distributes itself as liquid slugs and vapour plugs under gravity and surface tension combined. The thermal efficiency of the single-loop PHP has been assessed at varying heat loads by determining the effective thermal conductivity parameter. An increase in the thermal conductivity of the PHP has been observed as the heat loads rise.
Furthermore, an experimental setup of a single-loop PHP has been constructed with stainless steel (SS) as the tube material with geometric configurations, as stated above. The condenser section of the PHP is contained inside a condenser shell filled with liquid nitrogen. The entire PHP is kept inside a vacuum dewar to avoid undesirable heat leakage. Temperature sensors are attached to the evaporator side to measure the evaporator temperature. Two additional sensors are fed inside the adiabatic section to measure the transient behaviour of the fluid temperature inside the adiabatic section.Speaker: Abhinav Singh (Cryogenic Engineering Centre, Indian Institute of Technology Kharagpur) -
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Optimizing of regenerator materials for a high-frequency pulse tube cryocooler working below 3 K
Limited by insufficient cold storage capacity of regenerator materials, especially operating below 10 K, it is challenging for a high-frequency pulse tube cryocooler to obtain a low temperature down to liquid helium temperature. In this study, the influence of different regenerator materials on the refrigeration performance of a high-frequency regenerator working in the liquid-hydrogen to liquid-helium temperature ranges was investigated primarily by detailed numerical simulation. Besides, the design and optimization direction of the low-temperature regenerator was outlined. Based on simulation results, a three-stage high-frequency pulse tube cryocooler with composite thermal-coupled and gas-coupled refrigeration process was designed, built, and tested. Using 4He as the working gas, a no-load temperature below 3 K was experimentally obtained, and a cooling power of around 20 mW at 4 K can be provided.
Speaker: Biao Yang (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
58
Pulse tube refrigerator with shared inertance tube
Due to the absence of moving parts at cold end, Stirling type pulse tube cryocoolers (SPTCs) possess the benefits of low vibration, long maintenance intervals and high reliability. SPTCs have been widely used in the fields of superconductors, aerospace, industrial gas liquefaction etc.
Currently, single-stage SPTCs operating at liquid nitrogen temperatures have been successfully developed and commercialized. However, the development of highly efficient and reliable multi-stage SPTCs for space applications operating below 20K is still ongoing.
The novel concept of the shared inertance tube SPTC has been developed. In this structure, a multi-stage refrigeration system is driven by a step piston compressor, with the shared inertance tube connecting the hot ends of the pulse tubes. This structure enables the redistribution of work at the hot end of the pulse tube, thereby enhancing the refrigeration capacity of the low-temperature stage and ultimately improving the overall efficiency of the multi-stage SPTC.
Before conducting research on the 2-stage shared inertance tube SPTC, numerical and experimental investigations will be carried out on a single-stage shared inertance tube SPTC with two cold heads in this paper.
In the single-stage shared inertance tube SPTC, two identical cold heads are driven by two identical compressors. A mutual inertance tube connects two same cold heads at the hot ends of the pulse tube. The cold head consists of the aftercooler, the regenerator, the cold heat exchanger, the distributor, and the pulse tube. Fluids in both cold heads flow into a mutual inertance tube to get phase shift. The impedance of two cold heads is the same，so in ideal condition, at the hot end of the pulse tubes, phase angle, pressure amplitude and mass flow rate should be the same.
A comparison is made between a single-stage SPTC with a single cold head utilizing an inertance tube and a shared inertance tube SPTC with double cold heads utilizing an inertance tube whose cross area is doubled. Under the same operating conditions, the phase-shifting angle at the inlet of the inertance tube increases with the diameter of the tube according to thermoacoustic theory. When using an inertance tube to connect two identical cold heads, if helium flows from the inertance tube into the hot end of the pulse tube, the mass flow rate is halved. However, the phase angle at the hot end of the cold head pulse tube remains unchanged from that at the inlet of the inertance tube. Therefore, using a shared inertance tube instead of two separate inertance tubes can achieve greater phase-shifting capability, especially in situations where the cooling capacity is limited and the inertance tube phase-shifting capability is poor. The numerical simulation results are presented, which are consistent with the findings of the thermoacoustic analysis. The inertance tube in the shared inertance tube SPTC has larger phase shift ability than that in a single-stage SPTC with a single cold head.
Preliminary experiments is conducting to verify the feasibility of the shared inertance tube pulse tube refrigerator.
Acknowledgment
This work was supported by the National Natural Science Foundation of China (No.52076151) and National Key Research and Development Program of China (No.2022YFB4002802).Speaker: Shurui Zhang (Tongji university) -
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Thermodynamic analysis of a high cooling capacity dilution refrigerator under the critical velocity limitation of the dilute phase
The rapid development of superconducting quantum computing technology has stimulated the demand for cryogen-free dilution refrigerators with high cooling capacity. The method of increasing the mass flow rate to obtain a high cooling capacity is limited by the critical velocity of the dilute phase. This study delves into the operation of a high cooling capacity dilution refrigeration system, analyzing the enthalpy change from 0.7 K to 10 mK under the assumption of equal chemical potential of superfluid 4He, and subsequently establishes a thermodynamic analysis model. Through this model, the critical velocity limitation of the dilute phase is considered, and the effects of the dilution unit structures on the performance of a high cooling capacity dilution refrigerator are studied. Additionally, leveraging the real physical properties of 3He and 3He-4He mixtures, a comprehensive analysis is conducted on the pressure drop and viscous heating in the heat exchanger, particularly under critical velocity. This thermodynamic model furnishes robust support for designing and optimizing high cooling capacity dilution refrigerators.
Speaker: Shiguang Wu (State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciencess)
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Tue-Po-1.3: Electronics, Sensors & Detectors Poster area
Poster area
Convener: Goncalo Tomas-
60
A helium isotope separation device with flow visualization unit
Distillation, adsorption, and thermal diffusion are commonly employed methods for separating helium-3 and helium-4 isotopes. However, due to the exceptionally low concentration of helium-3 present in natural gas or natural helium, an initial enrichment of helium-3 is necessary to reach the minimum concentration required for traditional separation methods. Entropy filter, a porous element, offers a straightforward and effective method for the preliminary separation of helium-3 and helium-4. This paper introduces a new quantum separation device that employs a GM cryocooler as the cold source and incorporates optical windows for precise real-time flow detection. The main focus of this paper is on the rational design of the 2K cryostat structure and the improvement of the heating method to ensure precise heating of the fluid at the entropy filter outlet. Additionally, a thorough analysis of heat leakage was conducted to ensure that the integration of optical windows would not affect the cryogenic separation process.
Speaker: Qianxi Qu (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
61
Conceptual design of a high intensity liquid ortho-deuterium moderator for the European Spallation Source
The European Spallation Source (ESS) in Lund, Sweden, is designed to become the most powerful accelerator driven spallation neutron source in the world. ESS is currently under construction, first beam on target is planned for 2025, with first user operation expected to start in 2026. As a key component of the neutron production, the cryogenic moderator slows down high-energy neutrons released from the spallation target. In the framework of an European funded research project (HighNESS) the next generation of ESS cold moderators were investigated. The first, already built, cryogenic moderator for ESS was designed for high brightness, using para-hydrogen as a moderator material. For future developments of ESS an additional cryogenic moderator is foreseen. In contrast to the first moderator, the new moderator is optimized for high neutron intensity, which is why liquid ortho-deuterium was chosen as a moderator material. The intensity of the presented liquid ortho-deuterium moderator is about 3-4 times higher than the existing low dimension para-hydrogen moderator. This opens up the possibility of providing significantly more neutrons to the users within the existing infrastructure, resulting into better research results. This paper describes the conceptual design of such a liquid ortho-deuterium moderator system for ESS including mechanical design, manufacturability verification, definition of fluid parameters, cooling process concept design and integrability verification.
Speaker: Yannick Beßler (Forschungszentrum Juelich GmbH, Central Institute of Engineering, Electronics and Analytics – Engineering and Technology (ZEA-1)) -
62
Design and construction at CERN of an enhanced thermal conductivity measurement setup in the temperature range of 1.8 K to 50 K
Within the goals of the High-Field Magnet (HFM) program at CERN, ongoing research focuses on achieving magnetic flux densities of up to 16 T using superconducting coils. Understanding the thermal properties of composite materials used as impregnation resins or insulation layers in superconducting magnets is crucial for the design of effective cooling methods. To this end, a new test stand was built at CERN in the Cryogenic Laboratory, to extend the investigation of thermal properties to a lower temperature range compared to the conventional cryocooler-based set-ups stopping at around 3 K, by linking a closed He II circuit to this system. This circuit enables to pre-cool helium gas, then gets it condensed by expansion through a Joule-Thomson valve before it gets pumped continuously via a roots pump, allowing to extend the measurement capabilities down to 1.8 K. The He II circuit is coupled to the cryocooler’s cold head via a gas-gap heat switch, enabling the He circuit to be thermally decoupled from the warmer cryocooler head for measurements at the lowest temperature. By varying base temperatures of the experimental platform, provided the cooling power either by the cryocooler or by the He circuit, a steady-state heat flux measurements can be ensured from 1.8 K up to 50 K. This work details the design and construction of this new innovative test stand for thermal conductivity measurements at a lower temperature range, and its validation by measuring a reference sample.
Speaker: Maha Rhandi (CERN) -
63
Experimental research on heat transfer performance of low temperature support structure
The design of the support structure of high vacuum and low temperature adiabatic vessel should not only meet the mechanical design requirements such as strength, but also meet the thermodynamic requirements such as low leakage heat. A cylindrical dry calorimeter based on two-stage G-M refrigerator was designed and built, and the heat transfer performance of the support structure was tested. The support structure under test has three fixed temperature ends, which are 300 K at the room temperature end, 80 K at the cold screen connection end and 10 K at the inner Dua connection end. The test results and heat leakage analysis when meeting the temperature requirements show that the heat leakage power Q1 of the support structure in the temperature zone of 300 K~77 K is 3.308 W and the heat leakage power Q2 in the temperature zone of 80 K~10 K is 0.247 W.
Speaker: Tiantian Xiao -
64
Fabrication of Intrinsic Josephson Junction Devices using Hydrogen-Atmosphere Treatment
Using a hydrogen annealing process, we have successfully fabricated intrinsic Josephson junction (IJJ) tunneling devices in Bi2Sr2CaCu2Oy (Bi-2212) high-temperature superconductor. To flow electrical current along c-axis direction, a Bi-2212 single crystal was annealed in a hydrogen atmosphere at 300-500℃ for 15-60 minutes. By the annealing, an electrical property of the Bi-2212 single crystal between electrodes was deteriorated. Therefore, a current pathway was changed from ab-plane direction to c-axis direction. The annealed Bi-2212 single crystal showed clear voltage jumps in current-voltage characteristics.
To investigate how the intrinsic Josephson junction tunneling device is formed by the new process, we carried out X-ray photoemission spectroscopy. From Cu 2p XPS spectra obtained at Bi-2212 single crystals annealed in hydrogen-nitrogen mixed gas, we found that Cu ions in a new region were reduced. The new region does not show a superconducting property in R-T characteristics because of the high resistivity. Therefore, it is expected that the new region changes a current pathway. The change of a current pathway probably leads to an attainment of IJJ tunneling devices. Our process is expected to have great advantages in its technical simplicity.Speaker: Hiromi Tanaka (National Institute of Technology, Yonago College) -
65
GFK-Cryostat for a Cryogenic Current Comparator
A large volume glass-fibre liquid helium cryostat with beam tube was developed for a Cryogenic Current Comparator (CCC). Cryogenic Current Comparators are used for beam diagnostics in accelerators and storage rings.
Measurement problem
Cryogenic Current Comparators (CCC) have been developed for electrical metrology to compare ratios of two electrical currents with the highest precision [1]. This is needed, for example, for high precision measurements of resistances, non-contact measuring of tiny currents or the amplification of small currents.
Intensities of beam currents in particle accelerators or storage rings need to be measurable. A major problem arises if the following requirements must be met:
• the beam has to be (energetically) unaffected
• very small beam currents have to be measured
• reduction of measurements to national standards must be achieved.
In accelerator research, the monitoring and non-destructive measurement of very small beam intensities is a major challenge. The beam currents to be measured are generated by charged particles such as ions, protons or antiprotons. The production of anti-particles is particularly complex and the yield is low.
A solution to this problem is the detection of the magnetic field generated by the moving charged particles using a non-destructive beam monitoring system based on the CCC-principle.
The CCC consists of a superconducting low-temperature SQUID (Superconducting Quantum Interference Device), a superconducting ring-shaped pickup coil and a highly effective meandering superconducting shield. This device enables the measurement of continuous (DC) and pulsed beam currents.
A current resolution of 6 - 65 pA Hz-1/2 depending on the frequency range should be achieved, allowing measurement of ion beams with intensities down to 107 particles per second with high accuracy.
To measure such tiny currents, the CCCs are using dc-SQUID recording techniques, which require cooling with liquid helium (4.2K), i.e. cryostats.
Up to now these cryostats for CCC were made from metallic material. To prevent disturbing currents due to electromagnetical noise they used an essential circuit breaker located in the 4.2K area. Supracon AG innovative design transfers the circuit breaker to an ambient temperature area of the cryostat. An obvious solution is a cryostat made from glass-fibre enforced epoxy. A new approach allows Supracon AG to manufacture the first cryostat for a CCC from epoxy enforced materials such as glass-fibre.Solution: glass-fibre liquid helium cryostat with beam tube
Our cryostat contains two containers with a high vacuum in-between to insulate the inner container, which is filled with liquid Helium (4.2K). Vapor-cooled radiation shields and super insulation reduce the boil-off rate substantially. The super isolation is placed between the inner and the outer container as well as between the radiation shields.
A beam tube (cold one) is mounted in the inner dewar on the “cold” side. Furthermore, a smaller beam tube (warm side) is mounted inside the first one and is vacuum-tight connected with the outer container. Between the cold and warm beam tube super isolation and radiation shields are located. A special design of the thermal insulation prevents electromagnetic induced currents along the beam tube.
The super isolation and radiation shields are mounted on the inner container. The radiation shields are fixed at the neck. Between each radiation shield, several layers of isolation are wrapped using super isolation foil, aluminium tape, tulle and Kevlar.Results
Our cryostat covers the following specifications:
Height: 900mm
Diameter: 488mm
Overall diameter: 540mm
Neck diameter: 120mm
Beam tube diameter: 50mm
Helium reservoir: 70lRepetitive thermal tests confirmed the following thermal performance data of the cryostat (including coil, SQUIDs and cables):
Boil-off rate: about 5 l/d
Holding time: up to 14 dOutlook
The GSI Helmholtz Centre for Heavy Ion Research in Darmstadt is now subjecting the CCC built in Jena to a series of tests to prepare the device for a future continuous running.References
[1] I. K. Harvey, “A precise low temperature dc ratio transformer”, Rev. Sci. Instrum. Vol. 43, 1972.Speaker: Hannes Nowak -
66
Machine Learning Framework for Anomaly Detection and Maintenance Optimization in Large-Scale Cryogenic Systems
Abstract:
CERN, home of the 27 km long LHC (Large Hadron Collider) particle accelerator, operates and maintains the world’s largest cryogenic infrastructure. This complex system is essential to the LHC’s functionality, reliability, and availability. Big data analytics and machine learning are promising techniques to extract descriptive and predictive models in complex systems for operation support, early identification of failures, and prescriptive maintenance.
We propose a machine learning framework for the anomaly detection and prescriptive maintenance of the LHC helium compression system. The initial proof of concept has been based on data acquired from 20 motor-compressor systems (12 low-pressure and 8 high-pressure) custom-made by Aerzen™ to meet CERN’s cryogenic system requirements. Since their commissioning, all the principal operational parameters have been tracked and saved in a proprietary database owned by CERN. Furthermore, since 2016, these compressors have been subject to close monitoring via periodic analysis of vibrational data obtained using specific triaxial accelerometers. Measurements are manually taken at four points: two on the female rotor and two on the male rotor, and subsequently stored in a dedicated database. By using all those data, the proposed framework is designed with the aim of automatically detecting anomalies and estimating the RUL (Remaining Useful Life) of the compressor systems and their components. The objective is to ensure a longer lifespan for all the compressors, leading to savings in maintenance and operational costs.
The initial version of the framework, leveraging autoencoder (AE) architecture, renowned for its capacity to learn condensed representations of signals and subsequently reconstruct them, has been trained using data representing typical operational conditions. By learning to reconstruct the normal signal, any disparity between the AE's reconstruction and the actual collected signal in the test phase served as an indicator for measuring signal abnormalities. This approach has showcased encouraging results in systematically and consistently identifying anomalies and their underlying causes. Furthermore, the integration of a system capable of identifying and tracking potential issues with the aim of safely extending the service life becomes crucial as the motor-compressor systems will approach the 40,000 hours recommended maximal usage window before the next long shutdown and the planned major overhauling in manufacturer’s premises.
Considering future applications, the algorithm has been engineered to be computationally efficient. This effort seeks to facilitate the integration of the developed model into compact, energy efficient IoT devices that can be used directly on-site to acquire and process data in real-time. Furthermore, this design paves the way for the integration of federated learning, an innovative privacy-preserving approach to machine learning that, through the aggregation of on-site generated models, allows for the continuous improvement of anomaly detection accuracy and reliability.
The proposed framework can potentially be extended to other cryogenic facilities given the large amount of data available and the secure and privacy-preserving federated learning platform available at CERN, to allow several IoT devices to share the model parameters to improve the global model robustness and accuracy for the use of all participating facilities.Speaker: Paolo Cacace (Sapienza Universita e INFN, Roma I (IT)) -
67
Mixed-refrigerant cooled 10 kA current leads for superconducting applications
Current leads for superconducting magnets or power cables contribute significantly to the cryogenic heat load of the otherwise well isolated system. The thermodynamic optimization of current leads requires cooling not only at the cold end, but along their entire length. For larger scale systems, cooling with boil-off nitrogen or helium gas is well established. For compact or stand-alone applications, however, a liquid nitrogen or liquid helium infrastructure is usually not available to realize a closed-cycle cooling system with vapor-cooled current leads.
For the latter applications, a novel type of cryogenic mixed-refrigerant cooled current leads (CMRC-CC) offer a highly compact and efficient closed-cycle solution. In this case, the current leads fulfil both their electrical, as well as the thermal purpose as internal heat exchangers in a Linde-Hampson cycle operated with a wide-boiling refrigerant mixture. We present the prototype design of such 10 kA micro-structured current leads, which will be tested in our new test facility COMPASS. The paper gives an overview on the design process and presents the results of numerical studies on the current lead design and operation in different load scenarios.
Speaker: Jonas Arnsberg (Karlsruhe Institute of Technology) -
68
Monte Carlo simulation of the thermal radiation heat load to the cryogenic mirror and vacuum system of the Einstein Telescope
A third-generation underground gravitational wave (GW) observatory, known as the Einstein Telescope (ET), will be developed by European countries together. It is designed as an equilateral triangle with 10 km long arms 200 to 300 meters underneath the ground and with detectors being located in each corner. Any two adjacent arms comprise two independent interferometers, and one interferometer will detect low-frequency gravitational wave signals (ET-LF), while the other will be optimized for operation at higher frequencies.
The most distinguishing and important feature of ET is that the frequency band of ET-LF will be expanded to lower frequencies compared to the current advanced gravitational wave detectors (Virgo, LIGO). In order to reduce seismic noise, thermal noise and other systematic noise, the beamline pipes require ultra-high or high vacuum conditions. In addition, the mirrors of ET-LF will be cooled to cryogenic temperatures below 20 K. Obviously, at this temperature the mirror will adsorb gases as a frost layer, degrading its optical properties. It is a challenging task to develop the vacuum pumping systems, based on cryopumps, to fulfil the requirements regarding pressure and frost mitigation aspects.
Basically, there are three different Monte Carlo based simulation approaches to simulate the thermal heat loads, i.e., the view factor method, the radiation exchange factor method and the direct ray trace method, and each has its own pros and cons. In this paper, the radiation exchange factor method is used, which results in a model framework where the temperatures of the components are external parameters that can be modified systematically. For this purpose a Test Particle Monte Carlo model has been established with the KIT in-house code ProVac3D, to allow for a systematic analysis of the thermal radiation heat load to the cryogenic and vacuum systems of the ET-LF. Several virtual surfaces are implemented in the simulation model to divide the physically very huge vacuum system into several domains in order to check particle conservation. Finally, a 55 x 55 matrix of radiation exchange factors with high precision is obtained and the heat loads to every surface are calculated. It was found that the resulting heat load is in an acceptable range.
Additionally, the heat load to the mirror has been systematically investigated by changing the temperature of the thermal baffles inside the cryopumps which are exchanging thermal radiation with the mirror, and the mirror emissivity. With these results an appropriate and justified design of a cryogenic vacuum pumping system of ET-LF can be developed in detail, a first concept of which will be proposed.Speaker: Xueli Luo (Karlsruhe Institute of Technology) -
69
Numerical investigations on pressure wave refrigerators for sizing the dump tank and studying its effect on the operating frequency at first peak efficiency
Pressure Wave Refrigerators (PWRs), in principle, work with thermal separation through shock waves. The fundamental flow dynamics within a PWR closely resemble those in a shock tube. The sudden release of high-pressure gas in a tube or channel produces shock waves that move through the driven gas, and the associated rarefied waves reduce the pressure of the driver gas. A PWR typically comprises a rotating gas distributor that periodically injects high-pressure gas into one or more stationary receiving tubes. The produced shock wave heats the residual gas towards the dead end, while the rarefied waves produce refrigeration in the driver gas at the nozzle end. Upon connection to the outlet port, the refrigerated gas flows out of the receiving tube into a receiver. PWRs have several advantages, such as simple design, low cost, high reliability, low rotational speed, and high efficiency comparable to conventional turbo-expanders. PWRs are effectively used in applications such as gas separation, cryogenic grinding, and cryogenic refrigeration.
The performance of a PWR is influenced by several key factors, such as tube length, operating frequency, pressure ratio, damping of reflected shock waves, and heat generation through shock wave compression. Some works have reported the effects of these variables or issues. Reflected shock waves from the dead end of the receiving tube of a PWR may heat the fluid inside the tube and seriously affect the performance. A damping unit in the form of a large cylindrical tank, i.e. a dump tank, is usually fitted at the end of the receiving tube so that the reflected shock waves are attenuated and retained within the tank. However, very little information is available in the literature on the sizing of the dump tank.
Reported studies indicate that for a given system and other operating conditions, there are peaks in isentropic efficiency at some operating cycle frequencies. The frequency for the first peak efficiency is important in terms of the minimum speed requirement of the rotor. It also depends on the size of the dump tank. Therefore, in this work, we have also determined the first peak frequency under varying sizes of the dump tank.
The present simulation involves the solution of mass, momentum, and energy conservation equations by using a finite volume formulation in Ansys FluentTM platform. Realizable k-ε turbulent equations are solved in a 2-D model. The effects of the size of the dump tank in terms of the volume of the stationary receiving tube are studied for different tube lengths and pressure ratios. The model is validated with experimental data from existing literature. The studies indicate that with the size of the dump tank, initially, the performance of the PWR increases upto a limit and then decreases. For example, as the volume of the dump tank is increased from 5 times to 20 times the volume of the receiving tube, the isentropic efficiency increases from 65% to 74% for a stationary receiving tube length of 1.5 m and operating pressure ratio of 2. The studies also show that there is a strong relation between the first peak in efficiency and the size of the dump tank. For instance, the occurrence of the first peak reduces from 90 Hz to 80 Hz as the volume of the dump tank is increased from 5 times to 20 times the volume of the receiving tube. The results of this research are expected to be useful for the design and operation of a PWR.
Speaker: Shariq Zafar (Indian Institute of Technology Kharagpur) -
70
Overview of collaborative research between UNICAMP in Brazil and Fermilab in cryogenics.
Abstract. The Long-Baseline Neutrino Facility (LBNF) situated at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, serves as the host for the Deep Underground Neutrino Experiment (DUNE), employing cryostats with nearly 70,000 metric tons of high purity liquid argon (LAr). The integrity of LAr quality is pivotal in determining the electron lifetime within DUNE, directly impacting its signal-to-noise ratio. Specifically, Far Detector 1 (FD-1) in cryostat 1 requires an electron lifetime over 3 ms within its 3.5 m drift, corresponding to less than 100 parts-per-trillion (ppt) Oxygen equivalent contamination. Far Detector 2 (FD-2) in cryostat 2 demands over 6 ms electron lifetime within its 6.0 m drift, corresponding to less than 50 ppt Oxygen equivalent contamination. Nitrogen (N2) absorption of LAr scintillation light, known as quenching, necessitates N2 contamination in LAr to remain below 1 ppm to minimize photon loss and enhance energy reconstruction. Studies indicate that at 1 ppm N2, approximately 20% of scintillation light is lost, highlighting the importance of minimizing N2 contamination.
Brazil State University of Campinas's (UNICAMP) contribution to LBNF focuses on developing argon purification and regeneration for DUNE FD-1 and FD-2.
To that effect, they constructed a test facility to perform studies on LAr purification at a smaller scale, the Purification Liquid Argon Cryostat (PuLArC) with approximately 90 liters of LAr. One of the filtration materials was considered and tested Li-FAU molecular sieve.
Value engineering on argon purification media was conducted, leading to the identification of Li-FAU zeolite's ability to effectively capture N2 impurities during LAr circulation. Testing at UNICAMP's PuLArC facility demonstrated that 1 kg of Li-FAU is capable of reducing N2 contamination from 20-50 ppm to 0.1-1.0 ppm within 1-2 hours of circulation.
In October 2023, testing at the Iceberg cryostat in Fermilab's Noble Liquid Test Facility (NLTF), with approximately 2,625 liters of LAr, confirmed the efficacy of 3 kg of Li-FAU in reducing N2 contamination from ~ 5 ppm of injected N2 down to less than 1 ppm over 96-hour cycles, showcasing its potential for larger-scale LAr cryostats. Further tests are planned to validate Li-FAU's use as a possible alternative to Molecular Sieve 4A in LBNF-DUNE and related liquid argon experiments.
This contribution will describe how the research was performed and present the test setups and results in detail.
This advancement not only has the potential to enhance DUNE's precision but also to elevate liquid argon experiments globally, showcasing the power of international scientific collaboration.
Speaker: Roza Doubnik (Fermi National Accelerator Laboratory, PO Box 500, Batavia IL 60510, United States.) -
71
Performance analysis of a cryogenic liquid air energy storage system coupled with LNG cold utilization and ORC
Abstract：
Cryogenic liquid air energy storage (LAES) is a physical energy storage technology with significant development. However, conventional systems suffer from problems such as high air liquefaction throttling loss, insufficient utilization of heat storage capacity, and low efficiency of system electrical to electrical conversion. Therefore, a liquid air energy storage systemcoupled with LNG cold utilization and waste heat type ORC (LAES-LNG-ORC) is proposed, which further improves the overall performance of LAES from the perspective of port LNG cold energy recovery and LAES system waste heat reuse. Analyzed the impact of energy storage pressure and heat storage temperature on system indicators. The research results show that the cycle efficiency of the optimized LAES-LNG-ORC system can reach 95.6%, which is about 40% higher than the benchmark LAES system; The heat utilization efficiency can reach 96.2%; The additional energy increment of the ORC system can achieve an electrical to electrical conversion efficiency of 82.0%, which is approximately 42.8% higher than the benchmark LAES system. The research results can provide certain technical references for the theoretical research and application of cryogenic liquid air energy storage.Acknowledge：
This research is supported by the National Natural Science Foundation of China (No. 52206032 & 21978308), and Special Fund for Central Guiding Local Science and Technology Development (ZYYD2022B11 & 2022ZY0048). We also thank Changsha Borui Power Technology Co., Ltd. for its technical support.Speaker: Jiahao Hao (Technical Institute of Physics and Chemistry, CAS) -
72
Preliminary development of near-feild radiative heat transfer measurement system for high-temperature superconductor
With the miniaturisation and high efficiency of electronic devices, near-field (NF) radiation has become a key factor in the study of thermal radiation control in electronic devices. NF radiative heat transfer (RHT) is several orders of magnitude greater than far-field (FF) radiation in the vacuum state, while it has been found that NF radiation decreases significantly as the sample passes from the normal state to the superconducting state. To investigate the mechanism of superconducting transitions on thermal radiation modulation, we have designed a cryogenic device to study NF radiation from high-temperature superconducting materials in different states (superconducting or normal state). The samples consist of concentric discs, and the spacing is controlled and measured using a nanoscale displacement device with adjustable spacing ranging from 10-1000 μm. Capacitance sensors are positioned at each of the four corners of the emitter and absorber to measure parallelism between the two samples with an accuracy of up to nanometer level. This device utilises a thermopile heat flow meter to transfer heat to the liquid nitrogen bath. The required measurement accuracy is 0.1 μV/W/m2.
Speaker: Bixi Li (Technical Institute of Physics and Chemistry) -
73
The development and validation of a multi-purpose cryostat for cryogenic pellet experiments
In fusion devices cryogenic has a crucial role, not only in superconductive magnet cooling, but also in the formation of cryogenic pellets. These pellets are used for fueling and other solidified matter injection of fusion reactors. At the HUN-REN Centre for Energy Research Fusion Plasma Physics Department, a support laboratory has been set up to study pellet production, launch and shattering of cryogenic protium, deuterium, neon, and neon-protium mixture pellets.
The development of an efficient cryogenic system is essential for the success of this pellet production research, thus a new cryostat has been designed. The purpose of this cryostat is to test new types of equipment, to make simplified modelling and measurement of the pellet formation and other cryogenic tests related to fusion devices. For this reason, the cryostat has multiple ports, a reconfigurable structure and large viewports, thus even in-depth visual inspection is achievable.
In this contribution, we introduce the cryogenic pellet formation process in fusion devices and discuss the results of the development and validation of this cryostat. In that cryostat highly relevant parameters of desublimation of protium were studied.
Speaker: Richard Csiszar (HUN-REN Centre for Energy Research) -
74
Ultra low temperature noise thermometry and its applications at ISIS Neutron and Muon Source
The ISIS Neutron and Muon Source undertakes approximately 100 experiments per year at temperatures below 1K. At these temperatures there is a clear need for accurate, precise, and well-calibrated thermometry, which is resilient to the challenging sample environments found in large science facilities. Commonly used resistive thermometers, whilst offering convenience and operational simplicity, struggle under conditions involving radiation flux and magnetic fields. Additionally, they can be prone to self-heating and have a relatively high cost when bought fully calibrated.
The magnetic field fluctuation noise thermometer (MFFT-1) from Magnicon can be utilised to overcome these difficulties. It operates through the Johnson-Nyquist noise theorem to link thermodynamic temperature to thermal fluctuations of voltage in a metal, allowing it to function as a primary thermometer. Through the use of a superconducting quantum interference device (SQUID), it can read precise temperatures in the mK range.
In this work we look to improve the use of low temperature resistive sensors in the high-throughput environment of an operational large-scale facility. Firstly, by installing the MFFT-1 into a dilution refrigerator we were able to create a methodology and mounting solution for the rapid calibration of cheap commercial resistors, thus enabling the creation of our own low-cost resistive thermometers able to measure down to mK temperatures. Secondly, this provision enables us to characterise the behaviour of both SQUID and resistance based thermometers in the extreme environments found at neutron and muon sources. This incorporates the behaviour of our sensors under radiation, whilst also including a scheme to operate the MFFT-1 in moderate magnetic fields, allowing calibration of the magnetoresistance effect in our resistive sensors. Lastly, we use these tools to understand the effect of ‘beam heating’ upon samples placed in our neutron instruments. This has been historically enigmatic due to the poor understanding of radiation on resistive sensors, coupled with the large variety of potential materials and neutron energies that are used.
We wish to share our experiences implementing ultra-low temperature noise thermometry at a large-scale facility and discuss possibilities for further developments.
Speaker: Lucy Bain (ISIS Neutron and Muon Source)
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60
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Tue-Po-1.4: Material Properties of Conductors, Insulation, Resins & Steel Poster area
Poster area
Convener: Kirtana Puthran (KIT - Karlsruhe Institute of Technology (DE))-
75
Adhesion analysis of resin impregnation systems in superconducting magnets
The mechanical properties of Nb3Sn coils are strongly influenced by the adhesion between the impregnation resin and the coil constituents, which may significantly impact the magnets’ performance. To improve the understanding of the parameters governing the adhesion in such superconducting magnets, a study was conducted on the adhesion of several impregnation systems with respect to different coil parts, including copper, stainless steel, aluminium, and glass fibre. The study evaluated the adhesive strength in various test configurations, considering the influence of substrate surface conditions. The effect of cryogenic environment on the adhesion strength of the most commonly used epoxy resin was also studied. The contact angles and surface energies of substrates were measured under varying conditions and wetting analysis was carried out. Additionally, the surface tension of the resins was measured, and an adhesion analysis was performed. The experimental adhesion results were found to be in accordance with the theoretical predictions of the adhesion analysis. The obtained results provide insights into potential modifications of the epoxy resin formulation and surface treatment methods to achieve specific wetting properties on the surfaces. This, in turn will impact the adhesion between the impregnation resin and the coil constituents thereby potentially impacting the magnet’s performance. Furthermore, these results will facilitate the development of predictive models for adhesion in superconducting magnets.
Speaker: Roland Piccin (CERN) -
76
Advanced Composite Insulation Systems for Niobium-Tin Superconducting Magnets: Electrical Characterization of Laminates at Cryogenic Temperatures
The electrical insulation system in wind-and-react niobium-tin (Nb3Sn) superconducting magnets must be robust, such that it can sustain the mechanical stresses, high radiation doses, and thermal cycles involved in the operation of the magnets. The chosen cable insulation material, currently a thin layer of braided S2-glass, must also withstand a high-temperature heat treatment in an inert atmosphere, required to develop the superconducting phase in the cable. To be braided, these fibres require sizing; however, the presence of organic components on the fibre surface can lead to the formation of conductive residue during the Nb3Sn heat treatment.
In this study, the electrical properties of different glass fibre reinforced composite systems have been characterized by measuring dielectric strength, resistivity, permittivity, and dielectric loss. Techniques for fibre desizing have also been employed and compared for their suitability to the wind-and-react manufacturing process by using thermal analysis. The results of these tests are presented and compared in this paper, providing an indication of how the design of composite insulation systems can be adapted to achieve improvements in magnet performance.Speaker: Javier Osuna (CERN) -
77
Carbon fiber composites with cryogenic hydrogen-barrier property for liquid hydrogen storage tanks
Liquid hydrogen, characterized by its low mass density and high volumetric energy, is actively promoted as an ideal spacecraft fuel. However, due to its cryogenic storage temperature and the risk of leakage, it imposes extremely high demands on the tank structure and material property. Currently, most liquid hydrogen storage tanks are made of metal materials such as aluminum alloys and titanium alloys, which are heavy and difficult to process. In addition, reducing the weight of the tank is beneficial for improving the spacecraft's range and response capability, while also allocating more weight to the payload. Under the same strength requirements, all-carbon fiber composite tanks (type V tanks) reduce the weight by approximately 40% compared to aluminum alloy tanks, making them a transformative technology that overturns traditional cryogenic hydrogen storage equipment.
In the current study, by adding multiple layers of polyethylene films between carbon fiber layers, the leakage mode of liquid hydrogen was shifted from microcrack leakage to diffusion, resulting in an exponential decrease in fuel permeation. Moreover, the impact of film crystal structure on the diffusion of hydrogen molecules was studied. By inducing the formation of spherulites within the polyethylene film, the hydrogen-barrier properties of the film could be enhanced. Furthermore, a multilayered progressive barrier structure was constructed to enable the permeation of liquid hydrogen through the composite to be controlled. Ultimately, the issue of poor hydrogen-barrier property in carbon fiber composite was addressed.
During the experiment, the carbon fiber composites were subjected to 10,000 cycles of cyclic loading under cryogenic conditions (77 K), followed by testing the gas permeation coefficient of the samples using the pressure difference method. The research results indicate that when the crystal structure transforms from lamella structure to spherulite structure, the gas permeation coefficient of polyethylene film decreases from 17.0×10^(-15) mol/(m·s·Pa) to 7.3×10^(-15) mol/(m·s·Pa), representing a decrease of 57.3%. This reduction is attributed to the relatively open structure of lamella structure, which possess larger crystal voids and defects, resulting in a relatively higher gas permeation rate. Conversely, the surface and internal structure of spherulites are relatively dense. The spherulites create tortuous pathways for the permeation of hydrogen, thereby increasing the diffusion resistance of hydrogen molecules and enhancing the hydrogen-barrier property of the film. The gas permeation coefficient of the composite decreases with an increase in the number of film layers. When three layers of polyethylene film are added, the gas permeation coefficients of the carbon fiber composites at room temperature and cryogenic temperature are 1.0×10^(-15) mol/(m·s·Pa) and 0.6×10^(-15) mol/(m·s·Pa), respectively, both meeting the usage requirements. Therefore, the composites with cryogenic hydrogen-barrier properties can be used to fabricate Type V hydrogen storage tanks, promoting the application of liquid hydrogen propulsion technology in the aerospace field.
Acknowledge:
This work was supported by the National Key R&D Program of China (2023YFC3010301), Project of Emission Peak and Carbon Neutrality of Jiangsu Province, China (grant number BE2022001-2).Speaker: Jiaqiao Zhang (Southeast University) -
78
Characterization of XM-19 forge products at 4K for their use in fusion energy devices.
Driven by the electrification of industries and economic development in emerging economies, the global demand for electricity is anticipated to surge in the coming decades. It is in this framework that a growing interest in fusion energy devices as a sustainable energy solution emerges. Among the different concepts, SPARC stands out as one of the most promising ones: a compact high – field tokamak built with high temperature superconductors (HTS) with the ambitious goal of being the world’s first confined net energy fusion system (Q>1). In this quest, Commonwealth Fusion Systems (CFS) has developed groundbreaking HTS magnets that enable for significantly stronger magnetic fields in the plasma that permit for a much smaller device size. However, when adopting these technical solutions, a critical need arises for structural materials capable of withstanding significantly higher stresses to counteract the increasing Lorentz forces in smaller sections. Under these extreme conditions, XM-19 austenitic stainless steel, known for its exceptional strength and corrosion resistance, has emerged as a promising candidate for structural components within these compact devices.
XM-19, a nitrogen-strengthened austenitic stainless steel, exhibits a promising combination of mechanical properties at cryogenic temperature, but it necessitates precise forging techniques for its full utilization in large scale components. Through extensive cryogenic material characterization at 4 K, including tensile testing and fracture toughness assessment, this study provides critical insights into the behaviour at low-temperature of XM-19. Additionally, microstructural analysis, identification of secondary phases, chemical composition analysis, and assessment of magnetic permeability contribute to a comprehensive understanding of XM-19's properties and its potential as structural component for high field tokamaks. These findings deepen our comprehension of this high strength austenitic stainless-steel grade, crucial for fusion energy applications.This work was supported by Commonwealth Fusion Systems
Speaker: Enrique Rodriguez Castro (University Carlos III (ES)) -
79
Design of a multipurpose test facility (MTF) for HTS cables
Abstract: The High Field Magnet (HFM) program foresees, among others, the systematic measurement and assessment of mechanical, thermal, and electrical properties of HTS cables. These measurements are a key factor to characterize the conductor, verify its performances and control the production quality. These values are also necessary inputs to size the prototype magnets that will use HTS windings.
Cable and coil properties must be measured at room temperature, in liquid nitrogen, in helium gas at 20 K – 30 K and in liquid helium at about 5 K. Cable samples and small coils are tested at different temperatures, under a given force or deformations. The mechanical and electrical loads can be applied simultaneously or in different combinations. The output data span over a large range of signals: strain measured by strain gages, optical fibers or digital correlation techniques, critical currents, displacements, and structural deformations.
At the moment any property can be measured individually. The proposed multipurpose test facility is a testing station capable of simultaneous measurements to facilitate the development of correlation laws: for example, by powering a small HTS coil at 20 K while measuring its deformation via digital image correlation; or measuring the critical current in a sample under a given mechanical pressure or after a certain amount of load cycles.
Another important requirement is the flexibility and the short turnaround time to test samples.
This note describes the multipurpose test facility designed at CERN and under construction in this moment. Some examples of possible measurements are given as well.Speaker: Diego Perini (CERN) -
80
Dielectric and thermal performance of insulation systems for quench heaters for the protection of superconducting magnets
Quench heaters for the active protection of superconducting magnets are large flexible circuits that are produced in a photolithographic process. The quench heater base material is a lamination of a thin steel foil from which the circuits are produced by chemical etching, and an insulating film which provides electrical insulation between the quench heater circuit and the magnet coil. The insulating film should have highest possible breakdown voltage under operating conditions to prevent short circuits between coil and heater. On the other hand, the thermal conductivity of the film should be as high as possible to limit the coil hot spot temperature in case of a magnet quench. Another requirement of the quench heater insulation system is that it needs to withstand the mechanical stresses exerted during assembly, thermal cycles and operation of the magnet. To improve the performance of quench heaters for future superconducting magnets in the present study we have characterised the dielectric properties, the thermal conductivity, and the mechanical properties of different 50 um thick insulating films made of polyimide and PEEK. We present an overview of these results and discuss potential improvements in terms of breakdown voltage, hot spot temperature and robustness of the heater to coil insulation system.
Speaker: Javier Osuna (CERN) -
81
Effect of irradiation in ambient air and in liquid helium on the mechanical properties of SLA and FDM 3D printed high performance polymers
3D printing of high-performance polymers enables the production of functional components with complex geometries that cannot easily be obtained by conventional manufacturing methods. A concern is the possible degradation of the materials properties of the 3D printed polymers under the irradiation conditions in particle accelerators and detectors. In the present study we have characterised the mechanical properties of different high-performance SLA and FDM 3D printed polymers for potential use in superconducting magnets before and after gamma and 24 GeV proton irradiation up to 10 MGy Since in superconducting accelerator magnets irradiation occurs at low temperature in inert atmosphere, at the CERN IRRAD facility we have irradiated the 3D printed polymer samples immersed in liquid helium in a cryostat, and simultaneously identical samples have been irradiated by the same proton beam in ambient air, outside the cryostat. Based on the results obtained by Dynamic Mechanical Analysis (DMA) and static and dynamic mechanical tests of non-irradiated and irradiated materials we discuss the effect of irradiation temperature. The effect of irradiation on the mechanical anisotropy of FDM printed polymers is addressed too.
Reference:
D. M. Parragh, C. Scheuerlein, N. Martin, R. Piccin, F. Ravotti, G. Pezzullo, T. Koettig, D. Lellinger, “Effect of irradiation environment and temperature on aging of epoxy resins for superconducting magnets”, Polymers 2024, 16, 407Speaker: Christian Scheuerlein (CERN) -
82
Exploring 19 years of operating a superconducting wiggler at the Canadian Light Source
Canadian Light Source, a 2.9 GeV 3rd generation synchrotron located in Saskatoon Saskatchewan Canada, has had a superconducting wiggler since 2005. Commissioned in July 2005, the wiggler and associated systems have been serviced and upgraded throughout the years. I will look at system design, operations use and upgrades. A look at the quench count and some contributing factors for the excessive high number. What is CLS doing to reduce the frequent quenches and how this could affect operations?
Speaker: Denis Beauregard (Canadian Light Source (CLS)) -
83
Fatigue strength properties of SS304 at cryogenic temperatures
Prior information of physical and mechanical properties of materials is very crucial in design and development of a mechanical system. In the normal course, sufficient data is available at around room temperature. However, data of these properties are not easily available at cryogenic temperatures. At the same time, the available data cannot be extrapolated down to cryogenic temperature since the properties suddenly change at low temperatures like ductile to brittle transition for carbon steels, etc. Wide varieties of materials are used for low temperature applications and obtaining information of the low temperature properties becomes a case to case study. Knowledge of fatigue strength is very essential for materials which are subjected to continuous cyclical stresses e.g. springs. Fatigue is a progressive, localised and permanent structural change that occurs in materials subjected to fluctuating stresses and strains that may result in cracks or fracture after sufficient number of stress cycles. Cyclic stresses induce micro cracks within the material which tend to grow with time. These cracks initiate and propagate in regions where strain is very severe. Since most of the engineering materials contain internal defects, fatigue cracks mainly initiate and grow from these structural defects. Inadequate fatigue strengths can lead to premature failure of mechanical components resulting in entire collapse of the system. In view of this critical background, a rotating beam fatigue testing machine for cryogenic temperature zone has been designed and developed. This machine can be used to obtain the data of fatigue properties of any specified material from room temperature down to cryogenic temperature. The cryogenic temperature environment is produced by circulating controlled quantity of liquid nitrogen (LN2) around the test specimen. In this experimental work, fatigue properties of stainless steel (SS304) are determined both at room and cryogenic temperature. The test results are compared and analysed.
Keywords: Liquid nitrogen, Fatigue strength, Stress, Strain, S-N curve, Cryotreatment
Speaker: D.S. Nadig -
84
Isothermal Discharge Current and Trap Characteristics of Epoxy Resin at Low Temperature
Epoxy resin has been commonly used as a supporting and insulating material in superconducting systems that operate at low temperatures and high electric fields. However, it has diverse and complex internal defects. The traps within epoxy resin can capture space charges, especially under factors like radiation and Schottky injection. This can affect the material's performance in terms of mechanical and breakdown strength. In this study, a Corona injection was performed using a needle-plate electrode. The isothermal discharge current method (IDC) was used to test a bisphenol F epoxy resin sample (using DETD as a curing agent) with a thickness of 0.2 mm. The migration characteristics of space charges were investigated at both 77 K and room temperature, and the trap characteristics at different temperatures were obtained. The results indicate that temperature has a negative effect on the intrinsic conductance current, dipole polarization current, and de-trapping current. This suggests that the trap properties of epoxy resins are strongly influenced by temperature.
Speaker: Jixiang Yan (TIPC) -
85
Measurement of critical current irreversibility limits on ReBCO tapes for mechanical axial tensile and compressive strain
High magnetic fields of up to 20 T in tokamak-type fusion devices, such as in Central Solenoids of European DEMO and the Chinese BEST fusion reactors, require High-Temperature Superconductors (HTS) and a promising candidate is ReBCO tape. The large Lorentz forces occurring under these operating conditions may locally generate high mechanical stresses, which can irreversibly degrade the critical current of the superconductor. For the design of these cables, knowledge is required about the mechanical limits of the tapes. Detailed structural finite element analysis (FEA) based on accurate material electromagnetic and mechanical properties under relevant electromagnetic load levels is needed for reliable and optimal operation. Knowledge of the axial tensile and compressive strain irreversibility limits for the critical current of ReBCO tapes is imperative.
For this purpose, the existing TARSIS facility at the University of Twente for axial tensile stress–strain measurements, has been upgraded for testing of ReBCO tapes with critical current measurements at 77 K. In addition, a method has been utilized to test the effect of compressive strain imposed by winding tapes on different core diameters with different angles. The evolution of the critical current and n-value were measured at 77 K in self field for various loading conditions on some first results are presented.Acknowledgment:
Part of the funding is provided by the EUROfusion Consortium, funded by the European Union (Grant Agreement No 101052200 — EUROfusion). Views and opinions expressed are however those of the author(s) only. The tapes have been provided for free by involved manufacturers.Speaker: Simon Otten (UTwente SuperACT) -
86
Mechanical and physical properties of AlMgSc-alloy developed for cryogenic temperature applications
Aluminum alloys, by virtue of their lightweight, good formability, and good corrosion resistance, are widely used in aerospace, construction, and automotive applications. The recently introduced AlMgSc-alloy, namely Scalmalloy® CX by APWORKS, processed by Selective Laser Melting (SLM) with high specific strength and a lightweight structure with minimal design constraints has enormous application possibilities, particularly at cryogenic temperatures. This alloy exhibits the highest yield strength (YS), ultimate tensile strength (UTS), and elongation among the aluminum alloys manufactured by SLM. These advantages have prompted research at the Karlsruhe Institute of Technology (KIT) on the mechanical and physical characteristics for the purpose of prospective applications at cryogenic temperatures. Tensile and fracture measurements conducted at various temperatures demonstrated the novel alloy’s higher fracture toughness when compared to conventional Scalmalloy®. The developed cryogenic version showed a rise in fracture toughness to 13.4, 20, and 43 MPa√m at 20K, 77K, and room temperature, compared to the standard version's 9.5, 10.8, and 28 MPa√m. This improvement in fracture toughness comes at the expense of ultimate tensile strength although the reduced UTS value is still within the range of high strength aluminum alloys. Microstructural and microhardness observation depicted the direct influence of distribution and size of precipitations as well as their volume fraction on the mechanical properties.
Speaker: Zahra Abbasi (Karlsruhe Institute of Technology, Institute for Technical Physics) -
87
Mechanical strength and stability of bulk insulation materials: A study on hollow glass microspheres and expanded perlite.
Bulk insulation materials such as expanded perlite are widely used in double-walled cryogenic insulation systems and well known to the industry. However, expanded perlite is also known to be very fragile. Mechanical stress e.g. due to thermal cycling or vibrations can result in material degradation over time and limit its application.
In contrast, hollow glass microspheres which are engineered and well-defined bulk insulation materials are reported to not only exceed the thermal insulation performance of perlite but also stand out with their higher robustness. In the field application of a spherical liquid hydrogen tank 3M’s K1 Glass Bubbles have been shown to reduce LH2 boil-off by 46% versus perlite with no decline of the insulation performance over three full thermal cycles within six years.
Emerging applications for storage and transport of liquid hydrogen and other cryogenic liquids require more and more strong and robust insulation materials.
This paper presents a lab study on the uniaxial compression behavior of hollow glass microspheres (3M Glass Bubbles) comparing it to commercial cryo-insulation grade expanded perlite.
Stress-compression data of bulk hollow glass microspheres was generated in a proprietary test setup and correlated with true density measured in a gas pycnometer. Consequently, the macroscopic uniaxial compression data can be interpreted with respect to mechanical damage of the Glass Bubbles on the microscopic scale. This allows engineers to assess if the respective insulation material meets their requirements. The paper presents the stress-compression behavior of various commercial grades highlighting the potential to also serve demanding applications.
A cyclic testing mode was implemented allowing the simulation of application conditions such as thermal cycling. Data shows that the Glass Bubbles remain undamaged even after undergoing a 1000x cycle test if the maximum stress is appropriately chosen. This information can help to select suitable Glass Bubbles grades based on anticipated stresses or dimensional changes.
To put the data on hollow glass microspheres into perspective, commercially available cryo-insulation grade perlite was analyzed in the same setup for comparison.Speaker: Friedrich Wolff (3M Germany) -
88
Synthesis of graphene blended activated carbon adsorbents for cryo-adsorption vacuum pump application and their thermal conductivity evaluation at 80 K
Adsorbents are an integral part of a cryo-adsorption vacuum pump. Activated carbon is the most efficient adsorbent material for such applications for a multitude of reasons like high surface area, versatile pore structure, chemical stability, and regenerative capacity. However, activated carbon does possess an inherent limitation of having low thermal conductivity, which is an essential vital factor that can enhance the pumping performance of a cryo-adsorption vacuum pump. Conductive adsorbents can enhance heat transfer within the adsorbent bed while cooling down to operational cryogenic temperatures and heating up during the regenerative process. This enhanced heat transfer capability ensures uniform and rapid adsorption-desorption processes, thereby optimizing overall pumping performance. Incorporating conductive metals such as copper, silver, or gold into activated carbon can enhance the thermal conductivity of the adsorbent bed but, this enhancement comes at the expense of reducing active adsorption sites of activated carbon. In this scenario, graphene can be the best candidate material as filler for thermal conductivity enhancement as it has high thermal conductivity
along with adsorption complementing features like large surface area, high strength, and chemical stability.
The work reports the synthesis of graphene blended activated carbon by agglomeration and incipient wetness method, and their thermal conductivity evaluation at 80 K. The agglomeration technique utilized carboxymethyl cellulose (CMC), a water-soluble binder, to bind graphene onto activated carbon. Specifically, it employed coconut shell-derived 60 CTC-carbon powder (SURSORB 60 Carbon, from Suracsh Filters Pvt. Ltd.) and graphene in the form of platelets, stacked in a few layers (Grafino RG, from CUMI Murugappa). In contrast, the incipient wetness method utilized 50 CTC-activated carbon pellets (SURSORB 50 ACP,from Suracsh Filters Pvt. Ltd.) along with a water-soluble graphene dispersion (Grafino dispersion, from CUMI Murugappa) as the graphene source. Samples with graphene to activated carbon weight percentages of 0.5% and 1% were prepared using both methods. In the agglomeration method, the samples were shaped into 3mm pellets, while in the incipient wetness method, 4mm pellets were formed. The synthesized samples underwent thermal conductivity testing at 80 K using a Liquid Nitrogen (LN2) based dip experiment setup. Results revealed that samples prepared via the agglomeration method displayed thermal conductivity enhancements of 62% and 92% for 0.5% and 1% graphene to activated carbon weight percentages, respectively. Conversely, the sample prepared through the incipient wetness method with 0.5% graphene to activated carbon weight percentage, exhibited negligible thermal conductivity improvements, while the one with 1% graphene to activated carbon weight percentage showcased a 69% enhancement.Acknowledgement
The authors gratefully acknowledge Suracsh Filters Pvt Ltd for providing the activated carbon samples utilized in this study. Additionally, we extend our appreciation to CUMI Murugappa for supplying the graphene samples. Their contributions were instrumental in the synthesis of graphene-blended activated carbon, which serves as a high thermal conductivity adsorbent material for cryo-adsorption vacuum pump applications.Speakers: Abdul Nazer K H (Department of Instrumentation, CUSAT), Pankaj Sagar (Cochin University of Science and Technology) -
89
The effects of cryogenic treatment on the performance and microstructure of austenitic stainless steel weldments
The metallurgical changes and micro defects after welding can influence the mechanical property, corrosion resistance and dimensional stability of the stainless steel wielding joints. It is necessary to explore an effective post-welded method to improve the service performance for stainless steel welding joints. Furthermore, the essential mechanism between microstructure changes and macro-property variation during this process needs deep reveal. Therefore, this paper aims at investigating the effects of different post-weld treatments including naturally aging, artificial aging and cryogenic treatment on the residual stress and mechanical properties of 304 stainless steel weldments. The microstructure evolution was also studied to reveal and establish the microstructure-performance relationship. Considering the application of austenitic stainless steel in aerospace industry, mechanical properties at low temperature is also tested and compared with room temperature condition. This work verifies cryogenic treatment as a prospective post treatment for improving the welding performance of stainless steel welding joint, without prolonging the implementation period and damaging the microstructure when compared with naturally and artificial aging treatments.
Speaker: Zeju Weng (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
90
Thermal Properties and Microstructural Assessment of Glass Composites with Epoxy Matrix for Cryogenic Applications
Thermal properties of materials, especially their thermal conductivity and emissivity, are extremely important in the efficient design of terrestrial cryogenic equipment, such as Dewars and cryostats. It is widely known that composite materials based on epoxy resin and glass reinforcement are good candidates for applications in extreme temperature conditions due to their high stiffness together with low thermal conductivity. The aim of the work is to investigate the effect of several resin matrix on thermal conductivity in the range from 4.5 K to 300 K and total hemispherical emissivity. Additionally, as part of this study, an analysis of the microstructure of composite materials was conducted to detect changes in the structure caused by low temperatures. A discussion was conducted and compared with other science data. Simulation of a single-layer composite material in the ANSYS environment is considered.
Speaker: Anna Krzak (Silesian University of Technology) -
91
Relevance of Atomic Diffusion Additive Manufacturing (ADAM) in cryogenics and vacuum applications
Atomic Diffusion Additive Manufacturing (ADAM) represents cutting-edge technology in the field of cost-effective additive manufacturing. This study investigates the viability of utilizing ADAM for producing components intended for cryogenic heat transfer, heat exchanger etc. in vacuum environments.
The emergence of ADAM presents a promising alternative to traditional metal printing technologies, offering notable cost efficiencies. However, concerns arise regarding the suitability of ADAM-produced parts for these extreme cryogenic temperatures and vacuum tightness due to the possible imperfection of the powder bonding after the thermal sintering and binder removal. To address this, an experimental evaluation was conducted, focusing on the heat transfer performance of ADAM-produced parts under cryogenic conditions.Speaker: Erik Walcz (Centre for Energy Research)
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75
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Tue-Po-1.5: Expanders, Pumps, Compressors, Regenerators & other devices Poster area
Poster area
Convener: Xiujuan Xie (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences)-
92
Design and Development of Cryogenic Dewar
Abstract:
Types of Cryogenic storage vessels may vary from low-performance containers, insulated with rigid foam or fibrous insulation to high-performance containers having multilayer insulation along with high vacuum in the annular space of the double-walled vessel. Thermal insulation is the most vital factor in the design of any cryogenic system to prevent the following possible modes of heat leak resulting in low evaporation loss of cryogen. Sources of heat leakage into inner vessels are due to neck and inner vessel support conduction, the existence of residual gas in the vacuum interspace leading to both conduction and convection, radiation through walls etc. The mouth opening and closing for the use of cryogen may also lead to direct gas convection and radiation. Provision should also be made for easy repeated evacuation service for removing slow evolution of gas from inner metal surfaces and/or repairs as and when needed. Minimum weight and maximum strength of the structure, ease of assembling, handling and transport, noncorrosive, indigenous availability, reasonable cost of materials for fabrication etc are the other design considerations.
Various types of small cryogenic vessels, especially liquid nitrogen containers, with body shells fabricated from aluminium and necks made from glass fibre-impregnated epoxy resin tubes, pressure joined to aluminium bodies with imported Sycast/ Ecobond cement, are being manufactured under foreign know-how by different industrial organisations. A unique design of a cryo container of 3-litre capacity, made from austenitic stainless steel of 304 grade with neck indigenously made from glass fibre impregnated epoxy resin of comparable weight, strength and efficiency to aluminium vessels, serviceability, long life and good appearance, especially suitable for the laboratory use and transport of LN2 frozen bull semen to rural areas for animal husbandry purposes, LO2 for health services and metal fabrication work and LCH4 for supplying a high-grade non-pollutant fuel, has been designed and constructed. Details of the design, fabrication and material of construction for a 3-litre liquid nitrogen container using a stainless steel body and glass fibre-reinforced plastic as its neck are discussed in the paper. The indigenously built container is tested by filling it with liquid nitrogen and noting the evaporation loss. The results are encouraging for laboratory-scale use as well as for small-scale application.
Keywords: Glass fibre tube, cryogenic, Radiation, Conduction, convection. Multi-layer InsulationSpeaker: Prof Swapan Chandra Sarkar (CENTRE FOR RURAL & CRYOGENIC TECHNOLOGIES, JADAVPUR UNIVERSITIES, KOLKATA-700032,INDIA) -
93
Dynamic temperature variation of insulation materials for solid-phase cold storage tank of liquid air energy storage
The regenerator is a vital component within the liquid air energy storage system, enabling the transfer of cold energy between the processes of air liquefaction and gasification. Solid-phase cold storage, distinguished by its lack of operating temperature constraints, environmental friendliness, and cost-effectiveness, stands out as a highly promising method for cold storage in liquid air energy storage systems. The solid-phase regenerator undergoes periodic cycles of heating and cooling during the processes of air liquefaction and gasification. To explore the dynamic temperature variations in the external insulation material of the solid-phase regenerator and improve the insulation performance of the solid-phase cold storage tank, this study developed a dynamic computational model for the tank's insulation system. It simulated the temperature distribution and dynamic changes of the insulation material in both the first-stage (173~300 K) and second-stage (98~175 K) cold storage tanks under periodic temperature fluctuations within the tanks. The dynamic temperature changes of the insulation material were examined with a focus on the effects of insulation material type, thickness, and the rate of temperature increase and decrease inside the storage tank.
Speaker: Yihan Tian (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
94
Evaluation on the operational state of turboexpanders in a helium refrigerator for nuclear fusion experimental devices using principal component analysis
In a nuclear fusion experimental device using superconducting magnets, it is necessary to continuously supply liquid helium to the magnets. Therefore, the stable operation of a helium refrigerator is required during the plasma experiments. Turboexpanders, which are core equipment of the helium refrigerator, contain many parameters to be monitored constantly. During the operation of the helium refrigerator, the parameters of the turboexpanders are being evaluated by experienced operators of the helium refrigerator. In this study, we propose the application of a machine learning technique to the operational state evaluation of the turboexpanders. Using the machine learning technique, not only manpower saving but also objective evaluation is expected for the refrigerator operation.
To develop the evaluation model of the turboexpanders, the operational data of the cryogenic system in the large helical device (LHD) were used. The helium refrigerator in the cryogenic system is equipped with seven helium turboexpanders. Regarding the machine learning technique for the evaluation model, the principal component analysis which is one of unsupervised learning techniques was applied. This paper describes the details of the evaluation model and the evaluation results of the helium refrigerator in the LHD cryogenic system.Speaker: Tetsuhiro Obana (NIFS) -
95
Experimental characterization of a compact centrifugal pump for liquid helium transfer
A compact submersible centrifugal pump has been developed to transfer liquid helium with flow rates up to 20 liters per minute between dewar vessels against the pressure loss of the transfer line. The pump is equipped with a cold motor and ball bearings. The authors report on the latest test results and performance characteristics.
Speaker: Johannes Doll (TU Dresden) -
96
Experimental study of the thermo-hydraulic performance of 3-stream plate-fin heat exchanger
The performance of a 3-stream plate-fin heat exchanger in a helium refrigerator plant having a modified Claude cycle is crucial to achieve required refrigeration power. This heat exchanger is placed between 2 warmer turbines of the helium refrigerator plant, which is being developed at IPR, Gandhinagar, India. This 3-stream plate-fin heat exchanger has been designed using serrated fins of Al-alloy (Al3003) for 2 hot helium streams of flow rates ~13 g/s and ~17 g/s and cold helium stream of 30 g/s with cold end at ~15 K and hot end at ~27 K. The fabricated 3-stream heat exchanger has been tested down to 80 K in a test bed before using it in the plant. In this test bed, a helium circulator and LN2-precooling heat exchanger along with this 3-stream heat exchanger were used. In the 3-stream heat exchanger, the temperature at the cold end was ~80 K and at the hot end, ~300 K. A simple test set-up has been made without a vacuum chamber and using insulation like nitrile rubber and MLI. In this test setup, thermo-hydraulic performances were measured successfully and found to be quite close to the designed value. The thermo-hydraulic performances have been compared with that of Aspentech software results and design results. The test setup and results will be discussed in detail in this paper.
Keyword: 3-stream, plate-fin, heat exchanger, Helium, Cryogenics, Test setup
Speaker: Parthasarathi Ghosh (IIT Kharagpur India) -
97
Investigation on multi-stage centrifugal cold compressors in superfluid helium cryogenic system
The centrifugal cold compressors are the pressurizing device commonly used in large-capacity superfluid helium systems to connect the 2 K helium tank to the room-temperature screw compressors. In order to provide a large pressure ratio, the cold compressors are connected in the form of multi-stage series, which would result in the stable operating region that is reduced to a certain extent. Therefore, this paper models the multi-stage cold compressors and piping system, also decouples and analyses the system using different actuators to study the characteristics of the system under steady and dynamic load conditions, and uses bypass valves to regulate the compressor under surge conditions.
Speaker: Jihao Wu (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
98
Investigation on the dynamic response of aerostatic bearings-rotor system with different bearing gas
Aerostatic bearings, due to their low friction and long lifespan, are widely used in high speed cryogenic turbo expanders. In various refrigeration cycles, it is essential for the bearing gas to be compatible with the working fluid gas to prevent contamination of the whole process. Due to variations in bearing gas viscosity, density and other properties, the static and dynamic characteristics of bearings differ. In this study, the fluid-structure coupled model of the bearing-rotor system is established, then the transient Reynolds equation and rotor motion equation are solved by finite difference method and direct integration method synchronously, the nonlinear dynamic response of the system is obtained. Ultimately, the study analyzes the effects of different bearing gases on dynamic characteristics, indicating that low-viscosity gases can improve system stability, which offers valuable guidance for optimizing the performance of bearing-rotor systems.
Speaker: Liqiang Liu (Technical institute of physics and Chemistry,CAS) -
99
Numerical and Experimental Study on Dynamic characteristics of gas spring resonant system
The compressibility of the gas is used to produce elastic recovery force, provide the axial stiffness of the reciprocating movement of the piston, which effectively avoids the problems of stress concentration and large dynamic mass of the plate spring. The gas spring is a new development direction of the compressor and the free piston Stirling engine, it is important to clarify its dynamic characteristics while applying in the power machine. The gas spring resonance system is taken as the research object, a numerical model was established considering the dynamic processes such as gas flow at the gap seal. Driven by a linear motor, the dynamic characteristics such as piston displacement and working medium pressure change in the cavity were obtained. The numerical results were in good agreement with the experimental results, which verified the accuracy of the numerical model. The equivalent stiffness and damping of the gas spring system are measured indirectly by using the resonance principle of the system. It provides reference for the design of gas spring generator.
Speaker: Ziyao Liu (Technical Institute of Physics and Chemistry, CAS) -
100
Numerical and parametric analysis of Regenerator used in miniature Stirling cryocooler based on SWaP-C objectives for HOT IR technology
Miniature Stirling cryocoolers based on SWaP-C (Size, Weight, Power Consumption, and Cost) objectives for HOT IR technology are prioritize size, weight, and power at a low cost and have grown their importance in the industries of defense, aerospace, medical devices and small scale cryogenic systems. The significance of a miniature Stirling cryocooler for HOT IR technology based on SWaP-C objectives lies in its potential to address the specific requirements and challenges of HOT IR systems compactly and efficiently. The regenerator is one of the most essential component of the miniature Stirling cryocoolers, and effective geometrical and thermal design of the regenerator plays a major role in the overall cooling performance of a small scale miniature Stirling cryocooler based on SWaP-C configuration, therefore, enhancements in the geometrical design and thermal performance of the regenerator have been imperative aspects in upgrading the cryocooler's efficiency. When optimizing the regenerator design for a miniature rotary Stirling cryocooler in a SWaP-C configuration, several factors should be considered. The regenerator must be designed with a compact geometry that minimizes dead volumes and reduces clearance spaces. A tight fit between the displacer and the cylinder walls helps minimize gas bypass and improves efficiency. The appropriate length and porosity of the regenerator must be determined to maximize heat transfer while minimizing pressure drop and dead volumes. The regenerator materials with high thermal conductivity must be selected to enhance heat transfer within the regenerator matrix. Besides the material selection, the proper implementation of strategy is necessary to reduce thermal dispersion within the regenerator material, such as using thin foils or woven wire meshes. This helps maintain a temperature gradient across the regenerator, enhancing the heat transfer process. In the current research, numerical and parametric evaluations of a cryogenic regenerator are carried out by using ANSYS Fluent and REGEN3.3 to optimize the geometrical and thermal design of regenerator for a miniature Stirling Cryocooler based on SWaP-C configuration. The effects of geometrical design and flow variables are explored, on the temperature swing, pressure drop, regenerator losses, thermal in-effectiveness and COP of the regenerator for a variety of regenerator length and diameter and for a wide range of velocities/massflow rates, porosities, frequencies, and cold end phase angles and temperatures. The analyses revealed that the calculated outcomes for both ANSYS Fluent and REGEN3.3 strategies are generally in accord with one another and most interestingly by optimizing the geometrical and thermal design of the regenerator, a miniature rotary Stirling cryocooler can achieve enhanced SWaP-C characteristics and improved efficiency.
Speaker: Dr. Zhang Xiaoqing -
101
Porous-medium modelling for CFD simulation of perforated plate heat exchangers for cryogenic applications
Perforated plate heat exchangers (PPHEs) are made of alternately arranged high thermal conductivity plates with an insulating spacer in between. While the plates help in inter-fluid heat exchange in the lateral direction, the spacer minimizes the axial conduction losses. They, being very compact and efficient, find use in applications in many places including space, 2K helium cryogenic and other low temperature heat transfer applications.
Performance predictions of PPHEs are usually done numerically through CFD simulations. However, a major issue in CFD modelling is the meshing of a large number of plates with fine pores (pore diameter typically 0.5 to 0.8 mm) involving a substantial increase in the number of computational cells and inviting challenges in computation procedure and time. One of the effective ways of numerical modelling of PPHEs is that the perforated plates are considered to be an anisotropic porous medium with unidirectional permeability. However, certain aspects or issues need to be resolved while using the porous medium method in modelling a PPHE. In this paper, these issues under varying geometrical orientations and dimensions are resolved and presented.
Porous medium modelling of a PPHE using a finite volume method such as Ansys FluentTM requires inputs such as viscous resistance, inertia resistance and porosity of the body. Thermal simulation can be done using either local thermal equilibrium (LTE) or local thermal non-equilibrium (LTNE) approach. As reported, the thermal non-equilibrium approach provides better results, hence, in the present case, we consider this approach. For LTNE model we require the local heat transfer coefficient data. The correlations for the Colburn factor are available in the literature for the Reynolds number 10<Re<1000. In some applications where pressure drop is not a critical criterion, a smaller flow area is preferred which may lead to a Reynolds number (Re) greater than 1000. Numerically obtained correlations for Colburn factor and friction factor for 1000<Re<4000 as functions of geometrical parameters are presented in the paper.
For calculating pressure drop across the stack of perforated plates and spacers Darcy-Forchheimer equation has been used. To calculate the viscous and inertial resistance, permeability and Forchheimer coefficient have been calculated by using correlations from the Bae & Kim and the Li models. Many researchers have worked on a single perforated plate to calculate the pressure drop across it, but very little work has been reported on the pressure drop across a perforated plate heat exchanger. In a perforated plate heat exchanger, plates are arranged either in an aligned hole (inline) manner or shifted-holes manner. In the case of inline-holes arrangement, because of the small spacer thickness, we consider interconnected pores where inertia loss is taken zero. For shifted-holes arrangement, the magnitude of velocity and direction change significantly in between the plates and, hence, the inertia loss is accounted for in the Darcy-Forchheimer equation. Steady, pressure-based, incompressible flow has been used for the study. The numerical simulations consider various parameters such as plate porosity, thickness of the plates, pore diameter, plate material, fluid properties to comprehensively investigate the flow friction behaviour.
For validation of the proposed model, PPHEs, for which experimental data are available, have been modelled under similar operating conditions using the porous medium method. The results compare well within the acceptable limit. Some corrective measures for further improvements are also in consideration. This model can be effectively used for performance prediction of PPHE covering a wide range of geometrical parameters and Reynolds number.Speaker: TAPAS KUMAR NANDI (INDIAN INSTITUTE OF TECHNOLOGY KHARAGPUR) -
102
Study on motion characteristics of check valve in reciprocating liquid hydrogen pumps
Reciprocating liquid hydrogen pump is the key equipment for the liquid hydrogen transport technology in the hydrogen energy industry. The check valve, serving as a vital component in the pump, regulates the flow of liquid hydrogen into and out of the pump chamber during each stroke of the reciprocating motion. This paper simulates the check valve motion based on the mechanical equilibrium equation and the fluid continuity equation. By using Runge-Kutta method to solve the model, the cylinder pressure, valve lift and velocity are obtained and discussed. Furthermore, influences of discharge pressure, spring stiffness and spool-head angle of the valve cone on the valve motion are studied by altering structural parameters of the check valve and working condition of the pump. The results demonstrate that the discharge pressure directly affects the initial speed of the valve and then has a greater impact on the valve movement. This work would contribute to understanding the valve motion mechanism of reciprocating liquid hydrogen pumps and further investigation is encouraged.
Speaker: Shaoqi Yang -
103
The experimental investigation of gas-coupled free piston Stirling generators
Space free piston Stirling generator technology is an important thermoelectric conversion technology in space reactor energy system. In order to realize the high reliability and low vibration characteristics of the space reactor energy system, the dual gas-coupled opposing Stirling generator is proposed in this paper, and its cooperative operation mechanism will also be investigated. Firstly, a numerical model of five degree of freedom dual gas-coupled opposing Stirling generator with coupling thermodynamics, dynamics, linear motor and vibration transmission is established. Then the model is used to analyze the adaptive process from start-up to stable operation of the dual gas-coupled opposing Stirling generator and the influence of the dual-gas connecting pipe and key parameters on the cooperative operation of Stirling generator. Finally, an experimental system for the cooperative operation of dual gas-coupled opposing Stirling generator is set up and experimental investigation is carried out. The results of experimental investigation and theoretical simulation are compared and analyzed, then the theoretical model is modified.
Speaker: Ziyao Liu (Technical Institute of Physics and Chemistry, CAS) -
104
The Influence of Filling Ratio and Number of Turns on Heat Transfer Performance of Nitrogen Pulsating Heat Pipe
ABSTRACT:Pulsating heat pipes (PHPs) are promising high-efficiency heat transfer devices with high cost-effectiveness and flexibility. To investigate the heat transfer performance of cryogenic PHP with a long heat transfer distance, a 0.6 m long nitrogen PHP was tested in this paper. The PHP was made by a stainless-steel capillary tube with an inner diameter of 1 mm and an outer diameter of 1/16 inch in a serpentine arrangement. The lengths of the condenser, adiabatic, and evaporator sections were 50 mm, 500 mm, and 50 mm, respectively. Stepwise heat load tests were conducted at various filling ratios ranging from 15% to 95% to explore the effect of the filling ratio on the heat transfer performance of the PHP. In addition, 6-turn and 12-turn PHP prototypes with identical operating conditions and geometric parameters were tested to investigate the effect of the number of turns on the heat transfer performance. Experimental results showed that the 6-turn PHP exhibited optimal characteristics at filling ratios of 30~50%. At the filling ratio of 33.1%, the PHP achieved a maximum effective thermal conductivity of 138.4 kW/(m·K) under a heat load of 10 W, which is 3 orders of magnitude higher than that of oxygen-free high conductivity copper (OFHC) in the same temperature region. Additionally, increasing the number of turns significantly decreased the temperature difference between the condenser and evaporator, but slightly reduced the thermal conductivity.
Keywords: Nitrogen Pulsating Heat Pipe, Filling Ratio, Number of turns, Heat Transfer Performance.Speaker: Jixiang Yan (TIPC) -
105
Thermal characterization of a three-fluid cryogenic heat exchanger
Magnetic refrigeration, a well-established technique employed to attain temperatures below the Kelvin scale, is currently gaining prominence for its application at temperatures corresponding to liquid helium and liquid hydrogen. This surge in interest is attributable to the elevated Carnot efficiency associated with magnetic refrigeration in such temperature ranges. A test stand has been developed for evaluating heat transfer coefficients of magnetocaloric materials using the single-blow transient test technique. The system involves a hermetic helium gas circuit cooled to cryogenic temperatures, flowing through a packed bed of magnetocaloric material. A three-fluid heat exchanger is used to cool down the helium gas flowing through the magnetocaloric packed bed. This paper presents the test setup, experimental performance results and the analysis of the three-fluid heat exchanger in the 4.2 K–290 K temperature range. The recorded measurements are juxtaposed against numerical predictions across various mass flow rates and fluid stream pressures. Under nominal operational conditions with helium gas, a maximum average effectiveness of 99.9% is attained, accompanied by a combined pressure drop of merely 15 mbar. The study also entails the evaluation of static losses and a comprehensive examination of the numerical model in alignment with experimental observations. Furthermore, recommendations for enhancing the design are proposed based on the findings.
Speaker: Carlos Hernando (CYCLOMED TECHNOLOGIES) -
106
Cryopumps applied to Fusion Energy - MAST-U Enhancements Double Beam Box System
The MAST-U – Mega-amp Spherical Tokomak – is undergoing enhancements which will position it at the forefront of fusion energy research. The enhancements will allow the reactor to run at elevated temperatures, provide more flexibility with studying plasma physics exhaust and increase our understanding of the underlying physics of tokomaks. It will also be essential to validate models when designing future fusion demonstrator reactors, making it a crucial part of fusion energy research.
The double neutral beam injection system (or Double Beam Box -DBB) is one of the main components of this enhancement as it will increase the heat injection power into the tokomak. A bespoke cryopump will be installed within the double beam box to create a high/ultra-high vacuum during standby operations and pump a high gas throughput during a pulse. This will allow it to extract impurities and reduce the re-ionisation of the neutral beam before it enters the tokomak.
We are currently at the latter end of the design and manufacture of the double beam box cryopump. The poster will show the developments and requirements with design and analysis, the challenges, and considerations with the final stages of design and manufacture, a literature review drawing on experiences of the already existing JET – (Joint European Torus*) cryopump, and a look ahead into future completion of the MAST-U DBB cryopump.
*JET was operating regularly on UKAEA Culham site until recently shutting down. It has its own neutral beam injection system with a working cryopump that was running for over 60 years.
Speaker: Kiyana Patel (UK Atomic Energy Authority)
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92
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Tue-Po-1.6: H2 & LNG 1 Poster area
Poster area
Convener: Hendrie Derking (Cryoworld BV)-
107
A review on determining the equilibrium ortho-parahydrogen ratio
Exact knowledge of the equilibrium ortho-parahydrogen ratio is of crucial importance for most engineering applications related to liquid hydrogen. It is usually determined using the Boltzmann distribution rooted in statistical thermodynamics. This distribution requires some assumptions regarding the modeling of the rotational energy levels related to the different rotational states of the hydrogen molecule. It was found that the assumptions related to these energy levels reported in literature differ in a way that causes significant deviations. This leads to potentially large problems with accuracy and comparability of calculations and measurement results.
This work presents a review on the calculation of the equilibrium ortho-parahydrogen ratio. A comparison of several reported assumptions and constants is provided, and a reference calculation method is proposed.Speaker: Sebastian Eisenhut -
108
A study on the scheme of cold energy recovery for compensating liquefaction in liquid hydrogen energy storage
As a recognized low-carbon clean energy, hydrogen energy is an important part of the global energy transformation. In the vigorously developed hydrogen energy industry chain of production-storage-transportation-use, cryogenic liquid hydrogen has gradually become an effective means to realize large-scale application of hydrogen energy and long-distance, large-capacity and long-term energy storage, with the advantages of high storage density, low transportation cost and low working pressure. From the perspective of thermodynamics, low temperature energy storage technology has higher energy quality. However, in the application of pressurization and gasification, a large amount of high-quality cold energy is wasted, so its recovery and utilization must be considered. In this paper, the technical route of cold energy recovery and compensation back to precooling or other temperature zones in the liquefier by cold storage is put forward, and the significant improvement of system efficiency and economy is analyzed. The contribution to several different liquefaction devices and the different recovery methods of sensible heat and latent heat are compared. At the same time, the operation strategy coupled with renewable energy hydrogen production is planned, in order to match and stabilize the fluctuation, cut the peak and fill the valley more reasonably in time and space. It provides more new idea for a more perfect, diversified and efficient hydrogen energy utilization industry chain.
Speaker: Bingming Wang -
109
ANN-CFD synergistic approach for improved predictions of pressure evolution in non-venting self-pressurized liquid hydrogen tanks
Self-pressurization phenomenon due to heat leakage into liquid hydrogen (LH2) tanks, is considered the primary challenge and dominating factor for its long-term storage and safe operation. Until now, there is still a difficulty in accurately predicting the pressure evolution in such tanks. Despite the wide-spread use of CFD as a mature-developed non-equilibrium modeling approach, intrinsic complex nonlinear phenomena are still hindering its applicability to real practical situations due to assumptions and limitations. In light of this, artificial neural network (ANN) as an intelligent modeling approach is first hybridized with CFD model to provide a new synergistic approach called (ANN-CFD) hybrid model for the sake of improving the predictions of the single CFD model. This hybridization has been implemented through integrating the CFD model with distributed neural networks for improving the CFD model outputs. The hybrid synergistic approach has been applied to the multi-purpose hydrogen test bed (MHTB) as one of the most important LH2 test facility available from literature work. Here, the ullage pressure would be predicted as a response to the hold time under given operating conditions of heat flux, initial filling ratio and initial operating pressure. Compared to experimental results, the predictions of the pressure evolution from the hybrid synergistic model has been proven to be desirable in its accuracy with an average error of 0.5 % and a maximum error of 1 % better than the CFD model solely which presented a significant deviation. The present work has revealed the strong capability of the new synergistic ANN-CFD hybrid model in improving the predictions of CFD model significantly with robust, accurate and consistent results.
Speaker: Anas A. Rahman (Assistant Professor of Mechanical Engineering) -
110
Cryo-Compressed Hydrogen Economic Analysis
Hydrogen energy holds significant potential as a novel and clean alternative energy source. Due to its low density under ambient conditions, hydrogen faces challenges in storage and transportation. Consequently, various high-density hydrogen storage and transportation methods have emerged in recent years, including compressed gaseous hydrogen, liquid hydrogen, and cryo-compressed hydrogen.
Nevertheless, the cost comparison among the three methods remains unclear. This has resulted in an unclear delineation of application scenarios for cryo-compressed hydrogen storage, impeding the practical implementation of this technology.
Therefore, this paper compares and analyzes distinct production processes among the three hydrogen storage and transportation methods, followed by an economic analysis of these diverse transportation approaches. A cost calculation model was developed, including the establishment of economic calculation boundaries, identification of factors influencing costs, formulation of calculation assumptions, and results analysis. Analyzed factors influencing the cost, including initial equipment investment, operational energy consumption, and transportation labor costs.
The primary influencing factor for compressed gaseous hydrogen storage and transportation is the labor cost of transportation. For liquid hydrogen storage and transportation, the main influencing factors are initial equipment investment and operational energy consumption. The various influencing factors for the cost of cryo-compressed hydrogen are relatively balanced. With the increase in transportation distance, the costs of all three methods also increase. Compressed gaseous hydrogen, liquid hydrogen, and cryo-compressed hydrogen have respective advantages in the ranges of less than 100 km, greater than 1000 km, and 100-1000 km. At 800 km, the cost of low-temperature and high-pressure hydrogen is 92% of that of liquid hydrogen.
This provides a reference for the applicable range of the cryo-compressed hydrogen storage and transportation mode.Speaker: Le Fang (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
111
Dynamic modelling of catalyzed vapor cooled shield for accelerated chill down of a liquid hydrogen tank during refilling.
Liquid hydrogen is a promising vector for long distance clean energy distribution through shipping. The rapid onloading and offloading times necessary for liquid hydrogen export and the need for regular tank inspections require tanks to be warmed up and chilled down quickly and efficiently. For large tanks utilizing evacuated powder insulation, this can be a slow process due to the low thermal diffusivity of insulation materials [1, 2]. Concepts for vapour cooled shields (VCS) have been proposed in the literature for reducing steady state heat transfer for cryogenic storage in the order of 30 to 70% [3, 4]. However, a VCS could serve to provide a faster chill-down of the tank by passing vapour through channels in the tank annulus. Furthermore, coupling of the VCS with a para-orthohydrogen converter could enhance this process by utilizing the endothermic nature of the spin-isomer catalysis.
This study investigates the transient chill down performance of a proof-of-concept liquid hydrogen storage tank using a VCS. A reduced order heat transfer model was developed in Matlab coupled with a kinetic model for para-orthohydrogen conversion. The rate of tank chill down and the resulting boil-off losses were quantified to assess the feasibility of utilizing a VCS for accelerated liquid hydrogen refilling. The results help frame the path to advance VCS design and optimization for rapid chill down and minimal boil off liquid hydrogen tank refilling.
- Liebenberg, D.H. and E. Murley, Initial Warmup of 500,000-Gallon Liquid Hydrogen Dewar. 1967, Los Alamos Scientific Laboratory.
- Liebenberg, D.H., R.W. Stokes, and F.J. Edeskuty. Chilldown and Storage Losses of Large Liquid Hydrogen Storage Dewars. in Advances in Cryogenic Engineering. 1966. Boston, MA: Springer US.
- Liggett, M.W., Space-based LH2 propellant storage system: subscale ground testing results. Cryogenics, 1993. 33(4): p. 438-442.
- Shi, C., et al., Performance analysis of vapor-cooled shield insulation integrated with para-ortho hydrogen conversion for liquid hydrogen tanks. International Journal of Hydrogen Energy, 2023. 48(8): p. 3078-3090.
Speaker: Liam Turner (Monash University) -
112
Modeling and dynamic simulation of liquid hydrogen-based low/high pressure hydrogen supply system using EcosimPro
Currently, several hydrogen liquefaction plants are being built in Korea, and the distribution of liquid hydrogen to society is only a few years away. One of the major sources of liquid hydrogen demand is liquid hydrogen-based charging stations. These stations serve as pivotal hubs, utilizing liquid hydrogen as a storage medium, employing a pump for pressurization, and delivering low-pressure and high-pressure gaseous hydrogen to consumers. The Korea Institute of Machinery and Materials (KIMM) is actively engaged in a project aimed at localizing and demonstrating this system in Korea. This study focuses on the modeling and dynamic simulation of a liquid hydrogen-based low/high pressure gaseous hydrogen supply system using EcosimPro. The dynamic simulation validates the robustness of the system design and identify potential operational deficiencies. Through the application of EcosimPro, the soundness of the system design is verified, and checks are conducted to rectify operational shortcomings.
Speaker: Byeongchang Byeon (Korea Institute of Machinery & Materials) -
113
Numerical modelling of tank motion on heat and mass transfer in liquid hydrogen storage
The rate of self-pressurization in partially filled cryogenic tanks is dependent on vapour-liquid heat transfer and the ability of the liquid to transfer heat from the surface. This heat transfer may be enhanced by tank motion, such as during transport, which can lead to different pressurisation profiles depending on the mode of liquid sloshing within the tank. In pressurized liquid hydrogen fuel tanks, sloshing may cause a drop in vapour pressure and affect the fuel flow. During the transport of liquid hydrogen, this may extend the period of lossless storage but affect the subsequent rate of boil-off. Existing studies in this area have included empirical correlations for heat transfer based on lab-scale tank data [1]. This study aims to extend this work by investigating the effect of lateral and rotational motion in partially filled pressurized tanks. A CFD model was developed in ANSYS FLUENT and was validated against experimental data for a spherical tank. A parametric investigation was conducted across a range of sizes and fill levels. The effect of baffles as a method for reducing pressure drop was also investigated. Limitations of the VOF method for multiphase flow and interface capturing were encountered and will be discussed.
- Ludwig, C., M.E. Dreyer, and E.J. Hopfinger, Pressure variations in a cryogenic liquid storage tank subjected to periodic excitations. International Journal of Heat and Mass Transfer, 2013. 66: p. 223-234.
Speaker: James Wang (Monash University) -
114
Numerical Simulation of the Protective Effect of Air Walls on Liquid Hydrogen Leakage
Hydrogen is increasingly recognized as an ideal clean energy source, with its use in industry proliferating. Among various storage and transportation methods, liquid hydrogen storage stands out for its high efficiency. However, the risk of accidental leaks leading to the formation of hydrogen clouds poses safety concerns due to hydrogen's high explosion potential and low ignition energy. Understanding and mitigating the consequences of such leaks is crucial for safely utilizing liquid hydrogen. To address this challenge, a research project has been carried out to develop a 3D numerical model by using the open-source computational fluid dynamics (CFD) code, OpenFOAM. This model aims to simulate the complex multiphase flow phenomena involved in the accidental leakage of liquid hydrogen, encompassing processes such as evaporation, condensation, heat exchange, diffusion, convection, multi-component, and radiation. The accuracy of the numerical simulations has been validated by comparing the results with experiments conducted by NASA.
An innovative approach known as the "air wall" has been proposed to enhance safety measures as an alternative to traditional fencing systems. The air wall consists of a series of upward air outlets placed to intercept the lateral diffusion of low-temperature, high-density hydrogen. These traditional walls could initially block the hydrogen. But as the temperature rises and the wind acts on it, the density of the hydrogen decreases, and the hydrogen climbs over the wall and continues to diffuse. The hydrogen moves to a certain distance on the ground along the wind direction until the density decreases significantly and the hydrogen leaves the ground. However, the air wall redirects the trajectory of hydrogen, increasing convection and diffusion rates and effectively reducing the hazardous range of hydrogen dispersion.
The protective efficacy of the air wall has been verified through numerical simulations. The geometric model is derived from modifications to the fencing design based on NASA experiments. The VOF multiphase flow model, the Lee evaporation condensation model, and the standard K-epsilon turbulence model have been used, and the details of other numerical models are described in the paper. Detailed descriptions of boundary conditions, settings, and simulation parameters are also provided in the paper. Comparative analysis between the traditional enclosure wall and the innovative air wall demonstrates significant differences in the trajectory of hydrogen dispersion. Employing the air wall results in substantially reduced lateral movement of hydrogen near the ground and increased vertical displacement compared to the enclosure wall. Overall, the findings suggest that the air wall offers a safer alternative for mitigating the consequences of liquid hydrogen leaks.
Speaker: Liqiang LIU (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
115
Numerical study on evaporation characteristics of LH2 tank during transportation under typical driving conditions
Liquid hydrogen (LH$_2$) is believed as the top-rising storage method for long-distance and massive bulk transportation of hydrogen. However, LH$_2$ is easy to vaporize, and also flammable and explosive. It’s necessary to release the boil-off gas for pressure reduction after the safe pressure limit of the container. An improper release time or frequency would pose a safety threat to the surroundings, leading to a dilemma between hydrogen's extensive application and its utility safety.
This paper applied the volume of fluid (VOF) method to establish a computational fluid dynamics (CFD) model for the phase change of liquid hydrogen. The evaporation characteristics of a 40-ft ISO LH$_2$ tank under the road transportation environment were studied, with reference to China’s heavy-duty vehicle driving cycle standard (CHTC-TT). It aims at providing guidance and suggestions for the boil-off gas release device and active release strategy while transporting.
Linked by the glass-fiber-made supporting members, the shell and cylinder of the tank were made of 16MnDR and 316 steel, respectively. Multiple layers were adapted as the isolation method. Pipes, valves, and other attachments or structures were simplified. The tank was assumed to be exposed in the atmosphere of 293K at 1 atm. Liquid hydrogen of 20.3K and a 50% filling rate was set in the cylinder. The physical feature of hydrogen was obtained from the NIST database.
Four working conditions of normal or 1000 times higher heat leakage, and street or expressway transportation were simulated. Specifically, the case of street transportation experienced four driving cycles spanning 1800 seconds, while the other cases experienced two driving cycles adding up to 1600 seconds on the highway. The line charts of temperature and pressure, and the radar chart of pressure changes were given.
The results show that under the normal heat leakage condition, the pressure growth rate of the container on the expressway is 34.41% lower than the urban road scenario, and 0.19% lower than the static condition studied before. In addition, there are sudden pressure increments in those two conditions. A corollary for the aforementioned phenomenon is that the internal energy of the liquid is increased by violent driving with speed changes, fostering the untypical evaporation and a corresponding ullage pressure growth. Under the high heat leakage, the evaporation rates of LH$_2$ are almost consistent, and reach the gas-release criteria of 1.0 MPa at about 1250th second and 1350th second, respectively. This implies that the external heat leakage becomes the main heat source, and the effect of speed change behavior on pressure is negligible.
Therefore, it’s suggested that drivers should give priority to the road with less major acceleration and deceleration, to reduce the irreversible sudden increment of pressure in the tank. When the vacuum status is lost or there is a fire, drivers have about 20 minutes of safe time to drive to a safety zone and finish the rescue operation.Speaker: Shihao Li (Southeast University) -
116
Optimized Para Fraction of Liquid Hydrogen for Efficient Liquefaction and Storage
A thermodynamic investigation is performed to determine the optimal para fraction of liquid hydrogen for efficient liquefaction and storage. Ortho-to-para (OP) conversion is required in hydrogen liquefaction process, because any residual ortho-hydrogen in cryogenic liquid would eventually result in a boil-off loss due to the conversion heat. On the other hand, a liquefier should be capable of more liquid production, if no or less conversion is involved in the liquefaction process. Since the OP transformation is a slow process in the absence of catalyst, the production of larger quantity of liquid with lower para fraction could provide more hydrogen to the final user, especially in case of short-term storage. A rigorous thermodynamic model is developed to predict the capacity of a practical liquefier, where four different levels of para fraction can be selected by the optional bypass of three-staged catalytic converters. A process simulator (Aspen HYSYS) is used with the real thermodynamic properties of fluids (REFPROP). By incorporating a kinetic model for the OP transformation in storage tank, it is revealed that there exists an optimal para fraction for efficient liquefaction and storage, depending on the length of storage period. Full details of analytic results are presented and discussed towards the practical application to upcoming hydrogen value chains.
Speaker: Ho-Myung Chang -
117
Performance parameters of a compact cryogenic hydrogen test platform
Currently, there is a great need for test facilities for material samples and components for later LH2 applications. This includes low temperature compatibility at 20 K, H2 compatibility and potential degradation or permeation effects. A versatile test apparatus has been developed without the need of an external LH2 supply. A limited LH2 quantity of typically 2–3 L is generated directly on site by simple condensation. Hydrogen is taken from an external reservoir (high pressure cylinders) and condensed by means of a two-stage cryocooler (115 W @ 80 K, 18 W @ 20 K). Pre-cooling is done by the 80 K stage, final cooling and liquefaction by the 20 K stage. A cylindrical pressure vessel with an inner diameter of d = 109 mm and a length of 1000 mm is attached. It is designed for a working pressure of 0.1 MPa up to max. 2.1 MPa. The cryocooler and the pressure vessel (sample chamber) are installed in a common vacuum cryostat and are thermally coupled at the two temperature levels. At the 20 K flange, thermal coupling is achieved by a sophisticated thermosiphon arrangement. This contribution discusses the main performance parameters of this test platform, including the cool-down and warm-up procedure, as well as the measurement of the real liquefaction rate and the maximum heat input in stationary operation.
Speaker: Maximilian Grabowski (TUD Dresden University of Technology) -
118
Simulation of cryo-adsorptive hydrogen storage performance of type III hydrogen storage tank in a wide pressure range
Hydrogen is an important green energy source, but its low density and low boiling point bring problems for large-scale storage and transportation. Presently, liquid hydrogen storage and high-pressure gaseous hydrogen storage are two main hydrogen storage technologies. However, Liquid hydrogen storage has the problems of ortho-para hydrogen conversion and high liquefaction energy consumption; high-pressure gaseous hydrogen storage has a low hydrogen storage density which is only around 5 wt% at 70 MPa. Cryo-compressed hydrogen storage can effectively enhance hydrogen storage density, achieving liquid hydrogen density at 80 K and 48.52 MPa, but still faces issues of high hydrogen storage pressure and relatively high energy consumption. Adsorption-based hydrogen storage holds promise for improving current hydrogen storage technologies. For instance, MOF-210 exhibits a material-based gravimetric hydrogen storage density of 15 wt% at 77 K and 8 MPa. Combining porous adsorbent materials with cryo-compressed hydrogen storage for cryo-adsorptive hydrogen storage offers a new approach to achieve higher hydrogen storage density at relatively lower hydrogen storage pressures.
However, current researches on cryo-adsorptive hydrogen storage primarily focus on the synthesis of new porous materials and the measurement of their own hydrogen storage capabilities. The experiments and simulations predominantly concentrated in the low-pressure range (below 10 MPa). There is still a lack of research on low-temperature and high-pressure adsorptive hydrogen storage systems. Therefore, we establish a Type III hydrogen storage tank model by using finite element analysis software COMSOL Multiphysics. Activated carbon AX-21, metal-organic frameworks MOF-177, MOF-5, compacted MOF-5, Cu3(BTC)2 and MIL-101 are added to the Type III hydrogen storage tank, respectively. The modified Dubinin-Astakhov (D-A) model is used to simulate hydrogen adsorption isotherms, and the reliability of the model is validated. Subsequently, we simulate and predict the gravimetric/volumetric hydrogen storage density of the Type III hydrogen storage tank with different adsorbent materials at 77 K and pressures ranging from 1 to 50 MPa, and then study the effect of filling ratio on the overall gravimetric/volumetric hydrogen storage density.
The results show that at 77 K, activated carbon AX-21 and compacted MOF-5 achieve a gravimetric hydrogen storage density of 5.5 wt% at 41.4 MPa and 42.7 MPa, respectively, reaching the hydrogen storage target set by the U.S. Department of Energy for 2025. Additionally, compacted MOF-5 exhibits a volumetric hydrogen storage density comparable to liquid hydrogen at 77 K and 28.5 MPa, demonstrating excellent hydrogen storage performance and promising application prospects.Speaker: Linlin Gao (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
119
Structural design and optimization of cryo-compressed hydrogen storage vessels
Safe, compact, lightweight, and cost-effective hydrogen storage technology is key to the comprehensive development of hydrogen energy. Cryo-compressed hydrogen storage refers to the use of adiabatic, pressure-resistant vessels to store hydrogen in a supercritical state under the cryogenic temperature and high-pressure. Compared with other hydrogen storage methods, it has significant advantages in terms of hydrogen storage density, storage cost, safety, and non-destructive storage time. However, the two extreme conditions of cryogenic temperature and high pressure impose high demands on the performance of hydrogen storage vessels. As the main ultimate bearing parts of vessels, the composite material layer generates stress concentration phenomenon under cryogenic temperature and high pressure. This leads to damage such as fiber fractures, matrix microcracks, and fiber-matrix debonding, affecting the ultimate bearing capacity and fatigue life of the vessels. In order to ensure the safety of hydrogen storage vessels under cryogenic temperature, it is necessary to study its cryogenic mechanical properties and optimize structure.
For the mechanical properties of cryo-compressed hydrogen storage vessels, the composite winding layer is designed based on the grid theory. Numerical simulation to analyze the stress distribution of the metallic liner and the winding layer under operating conditions. The maximum stress criterion is used to determine the ultimate bearing capacity of the vessels. The effects of winding angle, autofrettage pressure and stacking sequence on the cryogenic mechanical properties and fatigue life of the vessel are further investigated, and the results are used in the optimization of the vessel structure. The study focuses on a vessel with a volume of 20 liters, operating at 20 MPa and 80K. The results show that the stress level of the hoop winding layer increases by at least 90% compared with that of the helical winding layer, and the stress is uniformly distributed in the cylinder section, with a decreasing trend near the head. When the winding angle increases, the maximum stress at the cylinder section of the winding layer decreases, while the maximum stress at the head section first decreases and then increases. When the autofrettage pressure is increased from 29 MPa to 37 MPa, the average stress of the metal liner at working pressure decreases by 43.2%, which is conducive to increasing its fatigue life. Instead of concentrating all the hoop winding layers in the inner or outer of the layers, alternating between hoop winding and helical winding is more favorable to improve the comprehensive performance of the composite. Further, based on the results of each sub-study, the structural design and optimization of vessels is supported.Speaker: Kexin Li (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
120
Thermodynamic modeling of mobile cryogenic tanks with a liquid-cooled thermal shield
Mobile cryogenic tanks are used to transport liquefied process gases in large quantities. To increase the possible distances and minimize the product loss due to evaporation, the tanks can be additionally equipped with a liquid-cooled thermal shield. The known vapor-cooled shields use the boil-off gas of the main product by feeding it through the pipe wound on the outside of the container to use its sensible heat before venting it into the environment [1,2]. In contrast, the liquid-cooled shield utilizes the vaporization of an initially liquid coolant to reduce heat leak from the environment into the main product tank. The lower the heat leak, the longer it takes for the main product to warm up and reach the maximum allowable pressure before some must be vented. The travel distance and time that the main product can be transported without loss are used to characterize the performance of mobile cryogenic tanks.
This contribution presents a dynamic simulation to describe the mobile cryogenic tank system that consists of an outer vessel, a multi-layer insulation, a coolant tank, a liquid-cooled shield, and an inner product tank. Both the main product and coolant may exist either in a single phase, or as a two-phase mixture of liquid and vapor. The model considers unsteady mass and heat transfer in both tanks and shield. All fluids are treated as real fluids.
A coupled differential-algebraic equation (DAE) system for the coolant tank, the liquid-cooled shield, the main product fluid tank, and the multi-layer insulation was implemented in MATLAB. The non-equilibrium system is described using implicit model formulation [3]. The equation system adapts dynamically depending on the fluid state and the operation mode. Required fluid properties were taken from the REFPROP reference database.
The presented model offers insights into the time-resolved behavior of a liquid-cooled cryogenic tank. The assumptions of unsteady flows and real fluids allow for a more precise representation of coupled thermodynamic processes in the system. The results allow for performance analysis and venting time prediction of mobile cryogenic tanks.[1] W. Jiang., P. Sun, P. Li, Z. Zuo, Y. Huang, Y., Transient thermal behavior of multi-layer insulation coupled with vapor cooled shield used for liquid hydrogen storage tank, Energy 231 (2021) 120859. https://doi.org/10.1016/j.energy.2021.120859.
[2] D. Kang, S. Yun, B.-k. Kim, Review of the Liquid Hydrogen Storage Tank and Insulation System for the High-Power Locomotive, Energies 15 (2022) 4357. https://doi.org/10.3390/en15124357
[3] J. Hamacher, A. Stary, L. Stops, D. Siebe, M. Kapp, S. Rehfeldt, H. Klein, Modeling the thermodynamic behavior of cryo-compressed hydrogen tanks for trucks, Cryogenics 135 (2023) 103743. https://doi.org/10.1016/j.cryogenics.2023.103743Speaker: Valeryia Sidarava (Technical University of Munich, TUM School of Engineering and Design) -
121
Thermodynamic modelling of liquid hydrogen tank warm-up at low fill levels
The export of liquid hydrogen (LH2) offers a carbon neutral replacement for liquefied natural gas (LNG). However, among the key challenges in the storage and transport LH2 is the requirement for significantly insulated tanks due to the low storage temperatures required when compared to LNG. During the return voyage, tanks may carry a small amount of liquid (heel) to maintain low temperatures in the tank, as a warm tank may lead to excessive vapour generation during loading, which must be handled by the terminal. However, a higher fill level during the return voyage reduces the effectively carrying capacity of the carrier. To evaluate the effect of fill level on boil-off losses and tank heat gain, a lumped-mass analytical liquid-vapour model was developed in Matlab with a discretized 2D axisymmetric tank and insulation model. The effects of insulation type, wall material and fill level within the vessel were considered, and different methods for tank chill-down during the voyage were assessed across different storage durations. The model points to frequent intermittent spraying of the tank walls as a preferable option, highlighting key differences with the operation of large LH2 carriers compared to existing LNG transport procedures.
Speaker: James Wang (Monash University)
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107
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Doing Business with CERN (Reserved for participants from Industry only) Room B+C
Room B+C
Convener: Alvaro Lecinana Soldevilla (CERN) -
15:30
Coffee &Tea break Exhibition & Posters Area (CICG)
Exhibition & Posters Area
CICG
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Tue-Or4: Large Magnet Systems Room D
Room D
Convener: Ignacio Aviles Santillana (CERN)-
122
Qualification of the first MgB2 and REBCO based Cold Powering System for HL-LHC
The powering of the High Luminosity LHC (HL-LHC) magnets will rely on eight Cold Powering Systems incorporating Superconducting Links (SC Links) based on MgB2 cables. These cables are housed in compact and flexible vacuum-insulated pipes and transfer, via multiple cable configurations feeding circuits rated at currents ranging from 0.6 to 18 kA, total DC currents of about 120 kA at up to 25 K. The length of the SC Links reaches 120 m. Cryogenic cooling is with helium gas generated inside the systems. Two cryostats, located at each extremity of the SC Links, are part of each Cold Powering Systems. They provide, at one side, the connection at 4.5 K to Nb-Ti bus bar going to the magnets and, at the other side, a transition via REBCO cables to the resistive part of the current leads. The REBCO cables operate at up to 50 K. A Cold Powering System comprises up to nineteen HTS current leads, which are cooled by forced flow of helium gas transferred by the SC Link. The current leads are arranged in a compact configuration.
Following a development phase, which enabled qualification of individual system components, a first full-scale Cold Powering System has been constructed and tested at CERN. It contains all instrumentation needed for cryogenic operation and for protection of the superconducting circuits. To reproduce the configuration in the LHC underground, the system features a vertical path of about 5 meters. After a number of convolutions on the ground, the SC Link rises upward, supported by a cable chain, before being lowered, in a vertical configuration, inside the cryostat that contains the Nb-Ti bus-bar.
This paper reports on the results of the tests performed on the first HL-LHC Cold Powering System operated in nominal conditions and under various transient scenarios.Speaker: Amalia Ballarino (CERN) -
123
Design and test of a 10 MJ hybrid high-temperature superconducting magnetic energy storage module
The high-temperature superconducting magnetic energy storage device can realize the rapid support of the grid voltage and frequency, and has a good application prospect in the new energy grid. In order to reduce the leakage magnetic field of the energy storage magnet, the large superconducting energy storage magnet can adopt a toroidal magnet structure. At the same time, in order to improve the utilization rate of superconducting materials, different types of superconducting materials or the same type of superconducting materials with different parameters can also be used at different magnetic field positions. A 10 MJ superconducting energy storage magnet is presented, which operates in the 20 K temperature region and consists of a toroidal superconducting magnet structure composed of 16 D-type coils. A YBCO superconducting coil is used in the inner high-field area of a single D-type coil, and a low-cost MgB2 superconducting coil is used in the outer low-magnetic field. In order to reduce the inductance of the superconducting coil, both YBCO and MgB2 superconducting cable are used to make the superconducting coil with a maximum operating current of 1.6 kA and a maximum operating voltage of 10 kV. We have fabricated and tested one D-type coil with a maximum steady-state operating current of 1.6 kA and a maximum DC withstand voltage of 15 kV.
Speaker: Tao Ma (Beijing Jiaotong University) -
124
A thermal hydraulic evaluation method of toroidal field superconducting magnet for China’s next generation fusion reactor
With the increasing requirements of the operating parameter of DEMO fusion devices to realize power generation, the Toroidal Field (TF) magnet is required to withstand a substantial thermal load. BEST (Burning Plasma Experimental Superconducting Tokamak), a novel Tokamak machine in China, has been developed to achieve Deuterium-Tritium fusion. The maximum fusion power is 130MW and the nuclear heat within a TF magnet amounts to 160 kW. The TF magnet is cooled by supercritical helium with temperature of 4.2 K. To ensure a steady operation of TF magnet, an thermal hydraulic analysis is urgent. The conductors with the highest magnetic field and maximum nuclear heat are taken as the analysis object. Firstly, an electromagnetic analysis is carried out to obtain the magnetic field distribution of the conductors. Subsequently, the nuclear heat is calculated to gain the thermal load on TFCC (TF coil case) and WP (winding pack). Then, the steady thermal analysis is conducted to gain the thermal conduction from TFCC to WP. Finally, thermal hydraulic analysis is undertaken. To solve the technical challenges associated with high fusion power operation, where the temperature rise of superconducting conductors varies significantly over time and space under various thermal loads, making it difficult to determine the minimum temperature margin, the project team has developed a multi-heat source loading program integration and it can achieve precise dynamic thermal load loading and obtain efficient evaluation of the minimum temperature margin under non-steady-state conditions. The results indicate that the temperature margin of conductor is over 1.7 K.
Speaker: Jinxing Zheng (Institute of plasma physics, Chinese Academy of Sciences) -
125
Cryogenic options for future accelerators: case study for the Muon Collider ring
Future, multi-km particle accelerator projects will be under heavy scrutiny to be energetically sustainable. Compared to previous accelerators, these machines must sustain increasingly high beam-induced, static and dynamic heat loads per meter length. These features make the cryogenic infrastructure required for superconducting magnet operation a major cost and energy driver. The choice of a general cooling scheme and associated superconductor temperature operating window that optimizes both is essential. With cost-effectiveness, simplicity, and a lessening of the reliance on cryogen availability and market volatility in mind, the virtues of having magnets that would incorporate conduction cooling, thus avoiding full immersion in helium, and that operate at increasingly higher temperatures are examined.
This study presents an overview of cooling options for collider-type magnets, discussed in the context of the collider ring of the Muon Collider. The main drivers when choosing a cryogenic system for future accelerators are identified, and guidelines for magnet thermal design are established. A conceptual study of cooling schemes that fulfil these guidelines is presented and compared to present and past choices for accelerator magnet cooling.Speaker: Patricia Tavares Coutinho Borges De Sousa (CERN) -
126
The Cryogenic Distribution System for the High Luminosity LHC upgrade at CERN
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will require the replacement of the final focusing superconducting magnets, the implementation of new superconducting links to power the magnets and the implementation of new superconducting radio-frequency (SRF) crab cavities, totalizing a length of about 150 m on both sides of the collision points of the ATLAS (P1) and of the CMS (P5) experiments in the LHC accelerator. To cooldown the new and reconfigured cryogenic devices, a new Cryogenic Distribution System will replace the LHC existing cryogenic distribution line on each side of the experiments. Two multi-header cryo-distribution lines (QXL) for each of P1 and P5 will transfer helium at different temperature levels, pressures, and mass flows between the HL-LHC machine components and the connection to a new helium refrigerator located underground in a cavern next to the LHC tunnel. The QXL system, manufactured and installed by industry based on a CERN detailed specification, will have a total length of approximately 1.5 km and will be implemented in two phases, respectively, in the underground service galleries and in the LHC tunnel.
This paper first describes the cryogenic configuration of the new equipment of the HL-LHC machine and the main functional requirements of the QXL. The cryogenic parameters for the different circuits and operation modes are presented. The paper emphasizes on the architecture of the cryogenic distribution system, the conceptual design of its main components and its integration in the HL-LHC environment.Speaker: Michele Sisti (CERN) -
127
Commissioning of the cryogenic system of the HL-LHC Inner Triplet String test bench
For the High Luminosity LHC (HL-LHC) project, the final focusing Inner Triplet (IT) superconducting magnets of the LHC will be replaced by a new 60 m-long set of higher performance Nb3Sn magnets that will operate at 1.9 K in pressurised He II. A test facility, the HL-LHC IT String, is currently being built to validate the collective behaviour of these new magnets and of the related systems. A dedicated cryogenic system was recently installed to provide the specific cryogenic functionalities required for the planned test program. The system includes a refrigerator with helium liquefaction capacity of around 25 g/s, a 100 m-long cryogenic multi-header distribution system, and a low-pressure pumping system equipped with a cold compressor with a capacity of 18 g/s at 10 mbar. This article reports on the first cooldown and commissioning of this cryogenic system in a standalone mode without magnets. The test program and a staged cooldown plan for the first cryogenic commissioning were defined with the goal to assess the functionality of the system, to determine its performance and to validate its individual components. The cryogenic commissioning was performed under conditions representative of the cooldown of the IT magnets in the future HL-LHC. Different cooldown modes were tested, and the performance of the system was evaluated for the conditions that are required for nominal operation at 1.9 K with heat loads up to 300 W. The pressure drop and heat loads on the cryogenic distribution system were measured at several temperature levels and compared to the expected design values. The presented results are demonstrating that the cryogenic system can provide the operating conditions required to accomplish the complete test program of the HL-LHC IT String test bench.
Speaker: Aleksandra Onufrena (CERN) -
128
SIS100 By-pass line - from the sketch into the tunnel
In Darmstadt, Germany, the Facility for Antiproton and Ion Research (FAIR) is presently under construction. One of the most complex machines is the SIS100, a synchrotron with a circumference of 1100 metres. The magnets for SIS100 are superconducting magnets, using an internally cooled superconducting cable.
Since the accelerating structures for heavy ions are normal conducting and have to be operated at room temperature a cryogenic by-pass line is required to bypass these warm components.
The by-pass line provides continuity around the synchrotron for liquid helium and houses the superconducting busbars for the electric current.
This 300m long by-pass line has been developed in close collaboration between GSI and the Wrocław University of Science and Technology (WUST). The design must fulfil both the mechanical requirements of the overall system in respect of interfaces to other components and the demanding requirements for the arrangement of the busbars.
SIS100 will be a fast-ramped from a few amps to almost 14 kA within 0.5 second. The busbars must therefore be both stable against electromechanical forces and flexible to compensate for thermal shrinkage.
After a phase of intensive design, the production was placed to industry and the development team was expanded by Kriosystem. After the production of the first prototype, the complete series of 27 diverse by-pass line modules, consisting of 5 main layout, was finalised.
This article summarises some of the challenges during design and production phase, tests which were successfully carried out and, last but not least, the installation in the tunnel. Furthermore, an outlook is given on the upcoming final assembly and connection to the magnets.Speaker: Marion Kauschke
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122
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Tue-Or5: Thermal Properties & Numerical Studies Room A
Room A
Convener: Milind Atrey-
129
Numerical study on transient heat transfer in forced flow of superfluid helium
ABSTRACT:
Superfluid helium (He II) offers unique challenges and opportunities in heat and mass transfer phenomena due to its exceptional thermal conductivity and peculiar flow characteristics. These properties make superfluid helium an indispensable medium in cooling applications, particularly in high-energy physics where maintaining the operational stability of superconducting cavities is critical. A key issue is the prevention of quenching—a sudden loss of superconductivity caused by inadequate heat removal in forced flow He II, which can lead to significant operational disruptions and damage to the equipment.
This study presents a two-dimensional(2D) numerical investigation of the transient heat transfer in forced flow superfluid helium, utilizing Landau's two-fluid model in conjunction with Vinen's vortex density equation. Our program nicely reproduced the temperature variations during the heat transfer process as observed in Fuzier's experiments. In the 2D cases, the result illustrates a unique phenomenon where superfluid helium exhibits a radial velocity near the heater, creating a "nozzle" effect that leads to the contraction and subsequent expansion of the flow. This effect is accompanied by the generation of vortices in the normal fluid component near the heater. Upon cessation of heating, both the "nozzle" effect and the vortices detach from the heater and dissipate downstream with the heat flow. As the inlet velocity increases, the axial motion intensifies, leading to a reduction in vortex size near the heater walls and a decrease in overall thermal contraction, yet the vortices and "nozzle" effect persist downstream post-heating. Furthermore, in line with previous predictions, the mechanism of counterflow remains active even under conditions of forced flow. Following the input of heat, there is a noticeable decrease in velocity at the upstream locations of the heater, whereas the velocity and temperature downstream are significantly enhanced. Specifically, at an inlet velocity of 2 m/s and a heating power of 9.9 W/cm2, the velocity of the normal fluid upstream was reduced by 15%, while it increased by 79% downstream. For the superfluid component, the trend is reversed, aligning with momentum conservation principles. Notably, as the inlet velocity increases, the influence of thermal counterflow diminishes, leading to smaller variations in velocity differences. This study aims at our understanding of the complex dynamics in transient heat transfer of forced flow He II, providing valuable insights for engineering applications, particularly in managing heat dissipation in superconducting accelerators during quench events.
KEYWORDS: Superfluid Helium, Forced flow, Transient heat transfer.Speaker: Yingxuan Hu (Zhejiang University, Institute of Refrigeration and Cryogenics) -
130
Solubility of hydrogen in liquid helium - development of a measurement apparatus
The solubility of hydrogen in liquid helium seems to be unknown. One potential explanation for this could be the exceedingly low solubility limit, making this phenomenon irrelevant for the vast majority of applications. In cryogenics, however, this effect is crucial. Traces of hydrogen in liquid helium and in the liquid helium supply systems result in a malfunction of liquid helium flow cryostats and throttle devices.
The project HyLiqHe (granted by DFG) aims to quantify the solubility limits by measurement. Two specialized disciplines must come together for success. On the one hand, cryogenic expertise is required, as the solubility process takes place at liquid helium temperature. On the other hand, the hydrogen contents to be quantified range from hundreds to tens of ppb (parts per billion). This stands for challenges in analytics.
An experimental setup is presented that allows the preparation, analysis, and condensation of helium/hydrogen mixtures. The saturation pressure is adjustable and the presence of precipitated hydrogen particles can be detected. The current status of work and preliminary investigations will be presented.
Speaker: Julian Will -
131
Supercomputing of Cryogenic Fine Solid Nitrogen Particle Production Using Laval Nozzle for Physical Photo Resist Removal-Cleaning Technology
The high thermal-fluid mechanical functionality of cryogenic fine solid particles of micron to nanometer size has been noted in ultrahigh heat flux cooling technology, which is applied to high thermal emission devices and nonaqueous physical nanodevice cleaning technologies.
To effectively use the high performance of such cryogenic solid particles in advanced nanotechnology, our laboratory has developed a new physical semiconductor cleaning method that employs cryogenic spraying.
In particular, given recent progress in developing high-aspect-ratio and fine-cantilever nanostructures in semiconductors, there is a strong expectation of an ultimate cleaning method that avoids physical damage. Because of the capillary force due to the surface tension of water that remains in the structure in the drying process, the fine structure is deformed, finally causing collapse or adhesions.
We have developed a new nonaqueous physical semiconductor-photoresist removal and cleaning method that employs cryogenic fine particulate spraying.
Cryogenic high-speed spraying of fine-solid nitrogen ($\mathrm{SN_2}$) in a nonaqueous resist removal and ultracleaning system for semiconductor wafers is investigated by an integrated supercomputational and experimental approach.
The fundamental characteristics of the cryogenic single-component fine $\mathrm{SN_2}$ particle production using a superadiabatic de\,Laval nozzle and an $\mathrm{SN_2}$ particulate spray for the physical photoresist removal and cleaning technology are investigated utilizing a new technique that couples measurements and computation.
The present study shows that high-speed ultrafine $\mathrm{SN_2}$ particles are generated continuously by the solidification of liquid nitrogen droplets induced by rapid adiabatic expansion of transonic subcooled two-phase nitrogen flow passing through the de\,Laval nozzle. Also clarified is the interactive effect of the ultrahigh heat flux cooling and impingement behavior of the $\mathrm{SN_2}$ particles on the resist removal performance.
We also investigate computationally the microscopic cryogenic particle heat transfer mechanism (which is difficult to obtain by conventional measurements) and the ultrahigh heat flux cooling characteristics and impingement behavior of a cryogenic fine-$\mathrm{SN_2}$ particle on a heated wafer substrate.
Furthermore, we use laser optical measurements and particle--structure--interaction computing to investigate how the $\mathrm{SN_2}$ particle diameter, injection velocity, and impact angle affect the wafer substrate regarding the resist removal and cleaning performance.
Finally, we use scanning electron microscopy to analyze the microscopic condition of the resist-removed cleaned wafer surface and a new type of integrated time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) measurement to analyze the impurity removal characteristics.
According to this research, the resist removal characteristics associated with the impingement and cooling behavior of a single cryogenic fine-$\mathrm{SN_2}$) particle on a heated wafer substrate were investigated computationally and experimentally in a microscopic approach.
The findings of this research are summarized as follows.
1. We conducted a new computationally assisted study of single-component cryogenic fine-particle production using mixed flow through a superadiabatic de\,Laval nozzle (converging--diverging nozzle).
This method continuously produces single-component fine solid nitrogen particles without helium refrigerant. Furthermore, almost spherical particles and a homogeneous particle diameter distribution can be obtained.
2. From the PIA measurement results, $\mathrm{SN_2}$ particles can be atomized to the order of several microns by using the present de\,Laval-nozzle-type fine-$\mathrm{SN_2}$ spray production system. Especially in the dense spray core region, $\mathrm{SN_2}$ particle atomization is enhanced by the shear stress acting on the particles from the transonic high-speed axial spray velocity component. Therefore, finer particles are produced and have a high probability of being in that region.
3. It was found numerically and experimentally that the hybrid interactive effects of the fluid dynamic force by impingement of a fine-$\mathrm{SN_2}$ particle and the thermomechanical effect of the resist due to the ultrahigh heat transfer characteristics contribute to the resist removal and cleaning process.
Also, the effect of ultrasonic atomization of the fine-$\mathrm{SN_2}$ particulate flow on the ultraclean performance of the semiconductor wafer was found for the first time.Speaker: Jun Ishimoto (Institute of Fluid Science, Tohoku University) -
132
Mesoscopic Numerical Study of Cryogenic Bubble Generation and Liquid-Vapor Interface Movement in Microgravity
Liquid oxygen, a potential spacecraft fuel, exhibits distinct behaviors under varying gravitational conditions, particularly at the liquid-vapor interface. While this interface remains static under standard gravity, it shifts significantly in microgravity environments. Accurately predicting this movement is essential for designing spacecraft fuel tanks to ensure uninterrupted fuel supply, a challenge compounded in saturated liquid boiling scenarios due to experimental constraints in simulating gravity variations. This study addresses the gap through a mesoscopic numerical approach, focusing on cryogenic bubble generation and liquid-vapor interface dynamics in microgravity conditions.
The Lattice Boltzmann Method (LBM) has emerged as a powerful computational tool for simulating boiling phenomena, offering a unique mesoscopic approach that bridges the gap between the microscopic interactions and macroscopic fluid behavior. Distinguished by its simplicity, parallelizability, and versatility in handling complex boundaries and interfaces, LBM excels in modeling the intricate dynamics of vapor-liquid phase transitions inherent in boiling processes. By employing various models, such as the pseudo-potential, free-energy, and phase-field models, LBM provides insights into multiphase flow dynamics, making it indispensable for optimizing industrial applications and advancing theoretical understanding of boiling phenomena.
This research utilizes the pseudopotential LBM, integrated with the Peng-Robinson equation of state to accurately model oxygen properties. Temperature variations within the computational domain are determined using a finite difference scheme, and a slip boundary condition is applied to mimic the movement of the liquid-vapor interface against surfaces.
In the first stage of simulation, pool boiling occurs under the normal earth gravity. After bubble generation and departure during certain time step, gravity is changed to the microgravity. In terms of energy balance, internal energy change is reflected during this step as a result of gravity change. For the comparison of interface movement, saturated liquid case where boiling phenomena occurs and subcooled liquid case in which bubble is not generated are simulated.
This study's findings offer critical insights into the behavior of cryogenic fluids in space, facilitating the design of more reliable and efficient spacecraft fuel systems.
Speaker: HangJin Jo -
133
Study of the thermo-mechanical properties of a lead-stainless-steel composite at 77 K
ALLEGRO is a proposed FCC-ee general-purpose detector concept with a noble-liquid electromagnetic calorimeter (ECAL) as one of its central detectors. Noble-liquid calorimetry is a strong option for future particle physics experiments – for both, hadron and lepton colliders. Such an ECAL is composed of a sandwich of 1536 multi-layer read-out electrodes realized as PCBs and the same number of absorbers immersed in a liquified noble gas at cryogenic temperatures. The absorbers are made of metallic composites using lead as core and stainless-steel as skin. The different thermal contraction coefficients of these materials as well as the resin used to glue them together, cause residual stresses in the layers. A careful study of this composite is needed to characterise its thermo-mechanical behaviour and to avoid high stresses at operating conditions. Theoretical and numerical studies have been carried out, as well as strength and contraction tests, with the aim to extract an equivalent Young’s Modulus and the thermal contraction between room temperature and 77 K.
Speaker: Fernando Aretio Zárate (CERN) -
134
A new 3-omega technique for the measurement of thermal conductivity and diffusivity of cryogenic helium and hydrogen and their mixtures
We present a new way to measure the thermal conductivity and diffusivity of cryogenic fluids using a modification of the 3-omega technique. These modifications include a wire-in-hole geometry that limits natural convection of the fluid around the measurement wire allowing for more accurate measurement. A complete theory of the thermal environment around the measurement wire is presented. This theory is validated by reference measurements on both hydrogen and helium, and to demonstrate the ability to perform diffusivity measurements in addition to conductivity measurements. Finally, completely new measurements on select hydrogen-helium mixtures are presented as well.
Speaker: Ben Hamilton -
135
Improved Heat Transfer Prediction Methods in Channels for Natural Gas Liquefaction
Liquefied natural gas (LNG), as a widely available and renewable fuel, can address the growing energy demand and significantly reduce greenhouse gas emissions. In the liquefaction of natural gas, pivotal components such as heat exchangers require reliable methods for predicting heat transfer coefficients. Existing prediction methods are mostly focused on conventional channels with hydraulic diameters larger than 3 mm. However, the condensation and flow pattern transition within the mini channels of compact heat exchangers remain obscure, attributable to the complexity of multi-component condensation in the natural gas liquefaction process. For example, the diffusion coefficient of methane-nitrogen at low temperatures is an order of magnitude lower than that of water-air. Hence it is necessary to further clarify the inhibitory effect of non-condensable gas on heat transfer of LNG. This research simulates the flow condensation of methane with and without nitrogen by adjusting the diffusion terms in the component transport model in horizontal mini channel with a hydraulic diameter of 1 mm. Comparative analyses are conducted with conventional channels with a hydraulic diameter of 3mm.Experimental data validate the proposed model, encompassing mass flow rates ranging from 200 to 600 kg/m2s, pressure conditions from 1 to 3 MPa, and non-condensable gas fractions from 0 to 20%. The findings reveal distinctive characteristics between flow condensation in conventional and mini channels. In annular flow, the distribution of the liquid film in the vertical direction of mini channels is more uniform, with the influence of gravity reduced and the influence of surface tension increased, preventing the condensate from accumulating towards the bottom. The thickness of the liquid film in the horizontal direction is reduced due to increased shear stress, leading to a decrease in thermal resistance. Furthermore, the criteria for transition from laminar to turbulent flow in conventional channels do not apply to mini channels. For flow condensation with non-condensable gas in mini channels, heat transfer coefficients decrease by over 20% at high vapor quality conditions (x > 0.8). A diffusion boundary layer exists at the gas-liquid interface, and the local concentration of nitrogen increases due to methane condensation, leading to increased vapor diffusion resistance and reduced mass transfer rate. Additionally, the decrease in methane partial pressure leads to a lower saturation temperature, resulting in a decrease in the driving force for condensation, further inhibiting methane condensation heat transfer. This comprehensive analysis holds significant value for designing compact heat exchangers in natural gas liquefaction processes.
Speaker: Jinglei Wang (Zhejiang University)
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129
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Tue-Or6: New Devices & Concepts Room B+C
Room B+C
Convener: Tripti Sekhar Datta (Indian Institute of Technology. Kharagpur. India)-
136
Heat transfer and thermodynamic stability study of a self-sustained vertical cooling loop in He I and He II
One of the cooling concepts of prototype cavity structures for the FCC is based on a self-sustained convection loop (open thermosyphon) with liquid Helium as a cooling fluid. A suggested novel cavity type is named Slotted Waveguide Elliptical Cavity (SWELL) with an estimated heat load for the 1.3 GHz prototype of 70 W. A vertically oriented 131 mm high cooling channel of 30 mm-diameter and needs to cool the main copper body of the niobium coated cavity quadrants. A stability effectiveness and thermal stability study will be presented for saturated liquid helium conditions at 4.2 K and 1.9 K He bath temperatures. The generated He flow in this cooling loop is generated in a self-sustained loop from a supply LHe bath. Tests of the heat transfer and flow stability have been conducted in a glass cryostat to compare recorded temperature data with the filmed flow behavior in the cooling channel. Short bursts of helium gas blowouts are recorded in the 30 mm tube cross section for a heat flux of 2.5 W/cm2 in He II conditions. The observed effects can be traced back to exceeding the critical heat flux in He II vertical cooling arrangement. The heat transfer data of nucleate boiling in He I and saturated conditions in He II are compared.
Speaker: Torsten Koettig (CERN) -
137
Experimental improvements to the acoustic expander with applications to cryogenic refrigeration
The acoustic expander is an innovative cryogenic component that uses gaseous pressure waves for work transfer as part of a continuous flow, recuperative cycle refrigerator. This expander uses passive reed-valves coupled to an acoustic resonator, much like a wind instrument, to produce refrigeration. The passive reed-valves are pressure-controlled by the imposed, static pressure difference across the expander and the natural oscillating pressure in the resonator. The resonator is a series of tubes and cones, the geometry of which has been optimized with numerical modeling. The practical implications of these simple components are that the acoustic expander does not require controlled valving or close-tolerance sliding seals at low-temperature, unlike existing piston- or turbo-expanders. This work presents new improvements to these first-of-a-kind acoustic expanders including the use of a single-frequency, numerically optimized resonator that allows for operation at an expansion pressure-ratio greater than 2 while maintaining competitive isentropic efficiencies above 50%. This prototype operates with compressed air working fluid and delivers cooling powers of around 100 Watts at room temperature. These expanders are expected to be useful in medium-scale refrigeration applications that are not well served by current small-scale Stirling cryocoolers or large-scale turbo-expander refrigerators.
DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited.
This material is based upon work supported by the Department of the Air Force under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of the Air Force.
Speaker: Jacob Adams -
138
Tracing characteristic evaluation of Spontaneously-Condensed Nitrogen Droplets in Cryogenic Wind Tunnels
Cryogenic wind tunnels (CWT) provide a means to perform high Reynolds number aerodynamic tests in a cryogenic environment and simulate hypersonic flights. Non-invasive measurement technology is an advanced measurement techniques applicable to CWT. However, the utilization of non-invasive measurement technology in CWT encounters significant challenges due to the absence of appropriate tracer particles. The present study evaluates the possibility of utilizing spontaneous condensing nitrogen droplets as tracer particles in CWT. Visualization experiments of non-equilibrium condensation was conducted to study the formation and distribution mechanism of liquid nitrogen droplets within high-speed airflow. The research revealed that the spontaneous condensing nitrogen droplets results in particle sizes at the micron and sub-micron levels, with a uniform distribution of droplets. Moreover, nitrogen droplets meet the essential criteria to serve as tracer particles of cryogenic flow with controllable condensation process. Accordingly, Euler-Lagrange model was built for the tracing evaluation of LN2 droplets in transonic flow around an airfoil. The results demonstrated that small-sized nitrogen droplets could satisfactorily follow the varying gas flow near the airfoil even with large angles of attack. However, nitrogen droplets experience increased dynamic pressure in high-speed flow fields, leading to greater trajectory deviation. Furthermore, evaluation metrics such as trajectory deviation, velocity matching, response time, and nitrogen droplet dispersion were identified. Subsequently, an evaluation model for the tracer capability of nitrogen droplets was proposed based on the multiple regression analysis for unveiling the interplay between the chosen metrics and the tracing efficiency. This research would provide theoretical support for advancing non-invasive measurement technologies used in CWT.
Speaker: Jiaxin Hou (Huazhong University of Science and Technology) -
139
World’s 1st Magnetic Density Separation NbTi magnet, conduction cooled magnet performance & separation results
The paper describes the commissioning of a conduction-cooled NbTi magnet system for Superconducting Magnetic Density Separation (SMDS), as well as its preliminary field tests on-location at the industrial end-user. MDS is a relatively new sorting technology that allows to sort multiple non-magnetic materials simultaneously, based on their mass density. A ferrofluid carries a mixed particle stream through the vertical magnetic field gradient of a flat-bed magnet, causing different materials to float at different heights. By using flat race-track type coils and minimizing their distance to the room-temperature ferrofluid, the magnetic field gradient can be maximized.
The magnet system with a flat-bed size 1.1 x 1.4 m$^2$; stored energy 0.74 MJ; operational current 300 A; and 5.2 T peak magnetic field in the windings was designed and constructed at the University of Twente. Key design choices were the use of a conduction-cooled dry magnet - allowing for a single-walled cryostat - and the use of stay rods that support the flat top plate of the D-shaped cryostat – allowing to minimize its thickness. The three 0.3 x 1.4 m$^2$ racetrack coils are shrink-fitted side-by-side in an aluminum alloy cassette that provides both thermal pre-stress and cooling. The coils are cooled to 4.5 K with a 1.5 W @4.2 K GM cryocooler and generate a maximum gradient of 20 T/m at the fluid bed.
We present the cryogenic performance, EM test results and quench protection of the magnet, that reaches nominal operation both with and without the ferro-fluid present. In addition, the first successful separation test with the system at the end-user’s premises are reported, including sorting campaigns with various waste materials.Speaker: Goncalo Tomas -
140
Demonstration of a novel electro-chemical hydrogen refrigerator
Eta Space and NASA are developing an Electro-Chemical Hydrogen Refrigerator (ECHR) demonstrator capable of reaching liquid hydrogen temperatures with no moving parts in support of Cryogenic Fluid Management (CFM) strategies for future space mission architectures. The demonstrator is powered by an electrochemical hydrogen compressor, custom-built by Skyre, Inc., with a supply pressure up to 207 barg and hydrogen flow rate of 0.6 kg/day. The Joule-Thompson (JT) cycle was chosen as the basis of the cold-box, which was engineered and assembled by the Cryogenics Test Laboratory at NASA Kennedy Space Center. The demonstrator is designed to provide 1 Watt of refrigeration at 23 K. Integration and testing was successfully conducted at the Eta Space facility in Rockledge, Florida, achieving a steady-state hydrogen saturation temperature of roughly 23 K. Subsequent testing is planned to quantify the isothermal refrigeration power of the system at 23 K, as well as the corresponding Carnot efficiency. A summary of the ECHR technology, including system benefits and potential applications will be discussed. Then, a detailed overview of the ECHR demonstrator, including cycle analysis, design and integration features, and test results will be presented.
Speaker: Daniel Hollibaugh (Eta Space LLC) -
141
Techno-economic analysis of low-cost air separation units with peak-shaving
Large-scale air separation units are pivotal in separating air into gases like nitrogen, oxygen, and argon, crucial for industries such as metallurgy, coal chemical, and petrochemical. However, the high energy consumption of these units keeps operational costs elevated. Moreover, the increasing peak-to-valley ratio in the power grid poses a threat to its stable operation. To address these challenges, this paper proposes a low-cost air separation unit with peak-shaving (LC-ASU). The LC-ASU compresses, liquefies, and stores ambient air in liquid air tank to provide liquid air for distillation columns during peak and off-peak time. It also stores the heat of compression. During peak periods, the unit utilizes the heat of compression to drive the Organic Rankine Cycle (ORC) for electricity generation. By increasing power consumption during off-peak time and reducing it during peak time, the LC-ASU significantly lowers electricity costs for the ASU while serving the role of peak-shaving for the power grid. In this paper, thermodynamic and economic models for LC-ASU are developed, and the influence of compression pressure and liquefaction temperature on system performance is analyzed. This study contributes to cost reduction in ASU and facilitates wider application adoption.
Speaker: Zhikang Wang (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China) -
142
Development of Glass Fiber Composite Axial Insulating Cryogenic Vacuum Barrier for Superconducting Feeders of SST-1 Tokamak
The cryo compatible and helium leak-tight vacuum barrier (VB) is necessary in the superconducting (SC) Tokamak, which is required to separate the vacuum between the machine cryostat and superconducting current feeder system. It is a dissimilar material joint that electrically isolates 2 kV DC voltage during the quenching of SC magnets. The current feeder system, which houses the 4.2 K vapor-cooled current lead and superconducting bus-bars for carrying electrical current up to 10 kA in a vacuum of less than 1x10-5 mbar. In the Stead State Superconducting Tokamak (SST-1) machine, the need for the replacement of failed alumina ceramic VB, the glass fiber composite VB was developed. It was a great challenge to design and fabricate a joint of metal and GFRP composite at cryogenic temperatures in contrast to the metal and ceramic joints, which insisted on the development of a high-toughness epoxy resin system for bonding. Considering the SC magnet application and stringent service needs of electrical isolation of 2 kV, helium leak tightness of 1.0x10-8 mbar-l/s at 300 K to 4.2 K temperatures and vacuum isolation, the most appropriate method selection is adhesive bonding. The epoxy resin-based dissimilar material joint in the form of a VB consists of boron-free S-glass fiber of G-10 grade, and stainless steel 316L joints were designed and fabricated using the wet filament winding process. The thermal contraction and distance between the conductors were optimized for the Paschen discharge event. The counter geometry and sharp edge surfaces have taken into account the electric field strength and dielectric breakdown phenomenon criteria. The real technical challenges were encountered, especially the differential thermal contraction variation of glass fiber, epoxy resin, and metal-induced high radial thermal residual stress in larger VB, like 5-inch-diameter joints, at low temperatures, which is prone to the development of cracks in the joints. To overcome the thermal stress and flexibility issues, cryogenic bellows were developed of 118 mm diameter and 0.25 mm thickness in three-ply construction and assembled with VB. The cryogenic bellows provide flexibility of axial 35 mm and lateral movement of 6 mm in SC hydraulic. The cryogenic VB underwent rigorous performance testing at 0–30 bar (g) pressure, a thermal cycle test at 77 K temperature and 10 kV electrical tests during each stage of development. The VB joints of different sizes were investigated for mechanical tensile breaking strength test in pull load condition. The fracture was found at the parent material location of the GFRP tube cross-section; no joints were found broken at the bonded epoxy resin section. The tensile strength test resulted 75 MPa in ½ inch metal to glass fiber VB, which is higher than the allowable bulk shear strength of GFRP (30 MPa) that is parallel to reinforced fiber and 20 MPa value of bonding shear strength of epoxy resin. The developed larger-size glass fiber epoxy-based VB overcomes the important issues of brittle failure and electrical breakdown occurrence due to the short gap between metal conductors and the short radial distance between the SC bus bar and ceramic VB. The VB were installed and validated in the SST-1 machine at operating conditions in the SC bus bar of the current feeder system. In-house-developed components save significantly high cost than imported available. It is not readily available item in the local or international market. The development has demonstrated the indigenous and ‘Make in India’ concept for a cost-effective and innovative solution which facilitated more availability as per requirement, elimination of dependency on foreign agencies and long delivery schedule of item. This component can be used for future indigenous fusion machine and electrical isolation application at low temperatures. For repeatability, acceptance and reliability, hundreds of dissimilar material joints of glass fiber and metal were fabricated; a failure rate of 5% was observed. In this work, the design, development, fabrication technique, mechanical, electrical and LN2 thermal shock performance tests and the results of cryogenic VB joints will be discussed.
Speaker: Rajiv Sharma (Institute for Plasma Research) -
143
Neutron imaging of an operational dilution refrigerator
The dilution refrigerator is a low temperature workhorse, used worldwide to provide temperatures in the millikelvin range for devices ranging from quantum computers through to dark matter detectors. Since its inception more than 50 years ago, the mechanism by which refrigeration occurs has been well understood. However, until this point, the only visual representations of this process were illustrations in reference textbooks.
Likewise, neutron radiography has been in existence since last century, and is widely used by both science and industry to investigate material properties at facilities such as the ISIS Neutron & Muon Source. The current state-of-the-art imaging instrument at our facility, IMAT, provides neutron radiography, neutron tomography and energy-resolved neutron imaging.
In this work we combine dilution refrigeration and neutron imaging to showcase a new capability for the field of low temperature physics. Previous work has proved the potential for discerning 3He from 4He using neutrons, here we take the next step by imaging an entire dilution refrigerator during operation.
Our setup allows the capture of high-quality images and videos showing condensation of fridge mixture, 3He/4He phase separation, and ‘single shot’ diagnostic procedures. In addition, it is possible to demonstrate the changing concentration of 3He in the mixing chamber. We expect this work to have a wide-ranging impact for educators, technicians, and dilution refrigerator engineers.Speaker: Christopher Lawson (ISIS Neutron and Muon Source)
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18:00
Exhibitors reception in Exhibition area Exhibition area
Exhibition area
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08:00
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Registration Desk and Publication OFfice open (08:30-18:00)
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08:20
Exhibition open (08:45-18:00) Exhibition Area (CICG)
Exhibition Area
CICG
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08:45
Opening statements Wednesday (8:45)
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Wed-Pl-3: Cryogenics for Hydrogen (plenary 3) Room D
Room D
Convener: Dimitri Delikaris (CERN)-
144
Cryogenics for Future Hydrogen Infrastructure
Liquid hydrogen is currently attracting a lot of attention for two applications: as a replacement for fossil fuels in heavy-duty trucks or planes and as a potential hydrogen carrier for energy transport over long distances. This is mainly due to the high energy density of LH2 in terms of mass. Other advantageous characteristics of LH2 are a) high purity, b) reduced risk potential due to low pressure, and c) extensive experience in handling LH2, as this fluid has been used commercially for decades for applications in space and electronics. Today, the relatively high specific cost is considered to be the main drawback of LH2. In the future, the cost of LH2 for mass production of LH2 can be significantly reduced through economies of scale, which in turn requires a concerted ramp-up of the supply chain from well to wheel. This presentation will discuss the LH2 supply chain mentioned above, including the interfaces to green/blue hydrogen production at the beginning of this chain and to LH2 applications at the end of this chain. An overview of available key hardware components and process plants will be given, and requirements for key hardware components for future large-scale infrastructure will be considered.
Speakers: Lutz Decker (Linde Kryotechnik AG), Alexander Alekseev (Linde GmbH, Clean Energy Technology R&D, Pullach/Germany; Technical University of Munich, TUM School of Engineering and Design, Department of Energy and Process Engineering, Institute of Plant and Process Technology)
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144
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09:35
Presentation Cryogenics Best Paper 2023 Award (Ho-Myong Chang) & ICEC Mendelsson Award (John Weisend)) Room D
Room D
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Wed-Pl-4 (Mendelsson Award winner): Cryocoolers for magnets (plenary 4) Room D
Room D
Convener: John WEISEND (ESS)-
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Development of 4K-GM cryocooler and its applications for superconducting magnets
In recent times, superconducting magnets cooled solely by cryocoolers, without the need for liquid helium, have widely adopted in both academic and industrial applications. The 4K GM cryocooler plays a crucial role in achieving cryocooler-cooled or conductively cooled superconducting magnets. In this presentation, the developments related to the 4K GM cryocooler and its application in superconducting magnet cooling will be shown. Before the 4K GM cryocooler was developed, conventional two-stage GM cryocoolers were employed to cool thermal shields of superconducting magnets which were cooled by liquid helium. These GM cryocoolers operating temperatures were limited around 10 K by their ineffectiveness of regenerators. To achieve lower temperatures of a GM cryocooler by enhancing regenerator efficiency, magnetic materials such as Er3Ni and HoCu2 were replaced the commonly used lead material. This breakthrough allowed for the first successful achievement of 4K cooling using a two-stage GM cryocooler in 1990.
Subsequently, the challenge started to cool superconducting coils with the 4K-GM cryocooler only. A NbTi coil was installed in a vacuum vessel and connected to the 4K cooling stage via a thermally conductive path. Another significant advancement was the high-Tc superconducting current leads, which dramatically reduced the thermal load at the 4K level. In 1993, the world’s first cryocooler-cooled superconducting magnet was successfully created. Over the past three decades, these magnets have become increasingly common and found applications in a wide range of research and industrial settings.Speaker: Toru Kuriyama (Toshiba)
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145
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10:30
Coffee & Tea break Exhibition & Posters area
Exhibition & Posters area
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Wed-Or7: Large Scale Cryogenic Systems 3 Room D
Room D
Convener: John Weisend (ESS)-
146
Cryogenic Developments for the Einstein Telescope (invited)
The Einstein Telescope (ET) is a third-generation gravitational wave detector planned in Europe, combining a low-frequency (LF) and a high-frequency (HF) laser interferometer. To exploit the full scientific potential of ET, cryogenic operation of the ET-LF core optics is crucial to suppress the fundamental suspension thermal noise, which dominates the detection sensitivity at low frequency, to the limits of Newtonian noise. This requires a new key technology development in ultra-low noise cryogenic cooling. Around the optics, the cryogenic design is driven by extreme-high vacuum requirements to limit particle adsorption. The presentation gives an overview on the development status of cryopumping, thermal shielding and detector cooling concepts, and the cryogenic infrastructure planning of this large-scale underground experiment.
Speaker: Steffen Grohmann -
147
First Cool Down and Heat Load Measurements in the DALS Cryomodule Test Bench
The Dalian Advanced Light Source (DALS), proposed by the Dalian Institute of Chemical Physics (DICP), Chinese Academy of Science, Dalian, China, is a new Free Electron Laser (FEL) project based on superconducting radio frequency (SRF) cavity technology. Testing the Q0 performance of the cavity and measuring the static and dynamic cryogenic heat loads of the cryomodule (CM) are an essential qualification work before the CMs are installed in the accelerator tunnel. To support the performance test, a dedicated cryomodule test bench (CMTB) is being constructed at DICP. In this paper, the conventional heat load measurement methods and instruments used in CMs test are summarized. To improve heat load test accuracy and eliminate errors introduced by the feed box, feedcaps and endcap in the CMTB, a specified test adapter vacuum box is designed and conducted to connect the feed cap and end cap directly without the CM in-between. The first cool down status of the test bench and preliminary test result using the test adapter vacuum box is reported in this paper.
Speaker: Xinbo Dong (Institute of Advanced Science Facilities, Shenzhen (IASF)) -
148
Design and progress of the helium refrigeration system for CRAFT superconducting magnet test facility
Comprehensive Research Facility for Fusion Technology (CRAFT) was one of the Chinese big science and technology facility. The objectives were to explore and master fusion DEMO level key technologies for next magnetic confinement fusion. In order to test the performance of superconducting magnet, a large-scale helium refrigeration system was proposed and under construction. In this paper, the specification of the helium refrigeration system has been analysed with the capacity of 6.0kW@4.5K +20g/s@50K +15kW@80K for a supercritical helium distribution system and a 250W@1.8K cooling loop with cold compressors. Process flow of the helium refrigeration system has been analysed concerning the different customers and various operation modes. The plant layout of the helium refrigeration system has been designed, including the compressor skid, oil removal skid and cold box. The process and present status of the helium refrigeration system would also be introduced.
Speaker: Xiao Fei Lu (Institute of Plasma Physics,Chinese Academy of Sciences) -
149
STEP Cryogenic Refrigeration – a Roadmap
Fusion is one of the most promising options for generating the cleaner energy the world badly needs. Recent milestones in fusion include the new JET3 world record of generating 69 megajoules of fusion energy for five seconds by feeding two milligrams of deuterium and tritium. This is enough to power 12,000 households for about the same period. Delivering fusion energy to the grid is a challenge of physics and engineering but to do so commercially will require industrial capability.
At the heart of the UK Government’s Fusion Strategy is STEP (Spherical Tokamak for Energy Production). The programme will build a prototype fusion energy plant at West Burton in Nottinghamshire, targeting operations in 2040. Demonstrating net energy from fusion will pave the way for the development of a fleet of future fusion powerplants around the world. The STEP Commercial Pathway is working with industrial partners to focus and develop the essential capability needed for commercial fusion power plants.
STEP and commercial fusion power plants will require large refrigeration loads at various cryogenic temperatures, probably 80K, 50K and 15K. The refrigeration load is likely to be equivalent to around 100kW at 4.5K. As net power production is the prime driver, the cryogenic plant will have to be as power efficient as possible. It also has to be reliable, to maximise production and minimise down time. This presents an opportunity for advances in the field of large-scale cryogenic refrigeration.
The challenges of deploying proven technologies in innovative ways, to drive up efficiency, will be discussed. Intelligent use of thermodynamic balances to optimise the refrigeration process will be explored. Experience of proven technologies in the areas of compression, heat exchangers and expanders will be shared. The roadmap through detailed design, manufacture, installation and operation will be presented, together with opportunities for the cryogenics community to get involved.Speaker: Paul Richardson (United Kingdom Atomic Energy Authority) -
150
Cryogenics for Quantum Computer : Upscale challenges
Quantum computing has recently gained interest from industry, opening new fields of applications. Air Liquide Advanced Technologies, thanks to its experiences on ultra-low temperature systems (CryoConcept, subsidiary has been commercializing Dilution Fridges for 20 years for scientific labs) and on Helium Refrigeration and Liquefaction systems for Physics and Industry, is actively developing solutions to address the many emerging challenges associated with Quantum Data Centers.
The prevailing technology and architecture for quantum computers currently rely on superconducting q-bit technology cooled below 20 millikelvins. The operation of these systems relies on more and more powerful dilution refrigerators, simultaneously thermalizing q-bits, communication cabling, and signal modulators. Over the last 40 years, the majority of dilution fridges have been "dry," meaning pre-cooling (50 K and 3-4 K) is performed using cryocoolers, particularly Pulsed-Tube Technologies. While these systems, used in numerous labs and R&D centers, offer many advantages, their scalability for larger quantum systems has raised several questions, notably concerning the increase in cold power capacity and overall energy efficiency.
This presentation will delve into the scalability of cryogenic systems dedicated to superconducting q-bit cooling in quantum data centers. After a description of capabilities and functionalities of present large “state of the art” dilution fridges, their first incremental challenges will be analyzed. Then, we will shed light on the critical importance of anticipating the impact of advancements in error correction, implementing multiplexing to minimize cable complexity, and enhancing q-bit coherence for remote system operation. The discussion will underscore the pivotal role of rethinking system architecture and refrigeration challenges in achieving these significant milestones for quantum computing infrastructure at scale. We will also present an energy benchmark for cryogenic solutions, or how a change in the thermodynamic cycle can pave the way to reduced operating costs of quantum data centers. By exploring these aspects, the presentation aims to contribute to the ongoing discourse surrounding the future of quantum computing and its integration into large-scale data centers, offering insights into the intricate challenges and innovative solutions within this burgeoning fieldSpeakers: Florian Martin (Air Liquide Advanced technologies), Jean-Marc BERNHARDT, Luc GAFFET, Mathieu Szmigiel (Air Liquide), Olivier GUIA -
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The CUORE cryostat, an infrastructure for rare-event searches at 10mK
CUORE is the world's largest bolometric experiment, featuring a detector comprised of 988 TeO2 crystals with a total mass exceeding 740 kg. Since 2017, CUORE has been collecting data at the Laboratori Nazionali del Gran Sasso in Italy, with the main goal of searching for the neutrinoless double-beta decay (0nbb) of 130Te. This process is of paramount importance in particle physics due to its implications in neutrino physics and on the conservation of the lepton number. A specially designed cryogen-free cryostat enables the achievement of a stable base temperature of about 10 mK, crucial for the optimal functioning of the detector. This apparatus has been meticulously designed to meet stringent experimental requirements, ensuring the detector's optimal functionality over a year-long period. The entire experimental volume, approximately a cubic meter in size, is maintained at a stable temperature with fluctuations smaller than 0.1 mK, minimizing detector noise. A strict selection of construction materials, predominantly high-purity copper, has been imposed to mitigate radioactive background, with approximately 7 tonnes of shielding lead integrated into the structure. At the end of the CUORE data-taking, the same cryogenic infrastructure will host the CUPID detector, an upgraded version of CUORE with enhanced sensitivity, aiming to search for the 0nbb of 100Mo with a half-life sensitivity beyond 1E27 yr. This presentation offers an overview of the CUORE cryostat, detailing its sub-systems and focusing on the solutions devised to meet all the requirements. We outline the various phases of cryostat commissioning until the cooldown of the CUORE detector, and describe its performance over the years-long data-taking period. Finally, we present the planned upgrades to the apparatus during the transition from CUORE to CUPID.
Speaker: Matteo Biassoni (INFN Milano-Bicocca (IT)) -
152
Heat load measurements of XFEL cryomodules using the helium evaporation method
The European XFEL Free Electron Laser (EuXFEL) at DESY is operated at 2K since January 2017. The first laser light was produced in May 2017 while the user operation began in September 2017. The electrons are accelerated in pulses with a repetition rate of 10 Hz. Each pulse is about 1.37 ms long; 650 μs are used for beam acceleration.
An R&D program is ongoing at EuXFEL and DESY to investigate a future upgrade of the EuXFEL linac to allow operation in the continuous wave and long pulse mode (High Duty Cycle - HDC operation), which will allow more flexibility in the electron and photon beam time structure.
The upgrade will increase the number of cryomodules from 96 to 112 by adding 16 new, HDC-designed cryomodules. The already existing cryomodules will not be modified.
In the HDC operation, the beam acceleration will take place at lower accelerating gradients but with longer accelerating pulses. The related increase of the heat loads will have to be taken over by an additional refrigerating plant to be built and installed at DESY. Precise knowledge of the future heat loads is therefore essential for the design of the cryogenic system of the HDC-upgrade.
This paper describes a heat load measurement method based on the amount of helium evaporated from the LHe II bath during a certain time period. A distinctive feature of the method is its insensitivity to eventual leaks across the seats of JT-valves. Furthermore, possible errors in the LHe II level readings can be avoided using this method.
This paper summarizes the experience gained so far with this method at the EuXFEL linac and at the CryoModule Test Bench (CMTB). Issues that have arisen during the measurements are discussed and conclusions are drawn. Results of the heat load measurements for different RF duty factors are presented for a single cryomodule at the CMTB.Speaker: Emna Abassi
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146
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Wed-Or8: Cryogenics for Aerospace Room A
Room A
Convener: Etienne Lallemand (Centre spatial de Liège, Université de Liège)-
153
Investigation on Efficient Cooling Methods for Cryogenic Fluid Pipelines
Cryogenic fluids, boasting diverse industrial applications, play a pivotal role in cutting-edge technologies. Notably, liquid helium (LHe) serves the purpose of cooling Earth-orbiting telescopes and satellites, while liquid hydrogen (LH2) plays a crucial role in the cooling of superconducting magnets and propelling space engines. Prior to achieving the efficient flow of cryogenic fluids, the necessary cooling of transfer lines and associated hardware to temperatures below the fluid's saturation point is imperative. The predominant method for heat dissipation involves employing the cryogenic fluid itself to quench the transfer system. However, the distinctive properties of cryogenic fluids, characterized by exceedingly low surface tension, standard boiling points, and kinematic viscosity, pose considerable challenges in maintaining effective cooling along transport lines, which traverse through diverse boiling regimes such as film, transition, and nuclear boiling. The selection of an appropriate cooling method for transportation lines demands meticulous consideration of trade-offs related to cooling efficiency, refrigerant consumption, and system complexity. This investigation introduces a robust three-dimensional model designed for simulating unsteady heat transfer and gas-liquid two-phase flow within LH2 pipelines. Rigorous validation against experimental data attests to the fidelity of the simulation results. Throughout the cooling cycle, the pipeline undergoes transitions in flow, including stratified smooth, wavy, and intermittent flows. Due to the extremely low liquid-to-gas density ratio and surface tension of hydrogen, the gas-liquid interface exhibits pronounced fluctuations, and the wavy flow dominates throughout the pipeline. A comprehensive comparative analysis of three cooling modes is conducted: constant flow, variable flow, and pulsating flow, focusing on key performance parameters such as flow rate, temperature, heat transfer coefficient, pressure drop, cooling time and hydrogen consumption. In conclusion, an evaluative framework for distinct pipeline cooling modes is proposed: a reasonable variable flow cooling mode exhibits certain advantages in both cooling time and liquid hydrogen consumption when compared with the constant flow cooling mode. A high flow rate in the initial stage facilitates rapid cooling, while the subsequent trickling flow in the middle stage proves conducive to conserving liquid hydrogen consumption. The pulse flow cooling method adeptly capitalizes on the performance benefits derived from intermittent flow. Specifically, within the cooling range of 40 K to 20 K, it substantially economizes liquid hydrogen consumption (15%-20%), albeit concomitant with an extended total cooling time (40%-60%). This study endeavors to conduct a thorough assessment of diverse cooling modes, offering theoretical insights to guide the high-efficiency cooling of cryogenic fluid pipelines.
Speaker: Shaolong Zhu (Zhejiang University) -
154
NASA's progress maturing zero boil-off technology to enable long-duration space missions with cryogenic propellants
Storing cryogenic propellants in space from months to multiple years duration and transfer of these propellants from one tank to another (refueling) are significant challenges on the critical path for returning humans to the moon, future Mars missions, and commercialization of cis-lunar space. State-of-the-art (SOA) storage duration for operational cryogenic stages is currently less than a day; cryogenic propellant transfer in space has never been demonstrated. NASA and its partners have studied solving the storage duration challenge through the integration of refrigeration technology with the propellant system, so-called Zero Boil-Off (ZBO) technologies, for several decades. Beginning in the late 1990s, NASA began to pursue focused technology development efforts to make ZBO feasible. The technology investments included advancements in passive thermal control technologies, insulation and components affecting conductive heat loads, development of high-efficiency high-capacity cryocoolers, assessing various methods to integrate cryogenic refrigeration with a spaceflight propellant tank, and physics-based and simplified modeling tools needed to design and optimize a ZBO system. This paper will summarize NASA’s past efforts that have contributed and provide an assessment of current maturity of both the key components and the integration of those components into a storage system capability. In addition, it will briefly present NASA’s planned remaining steps to complete ZBO technology maturation to the point that it can be infused and enable future long-duration missions with cryogenic propellants.
Speaker: Mike Meyer -
155
Cryogenic Tests of an Airborne Liquid Hydrogen Tank for a Manned Aircraft In the HEAVEN Project
With the growing public awareness on the consequences of global warming, and increasingly facing competition from other modes of land transportation, aviation has no more choice but to rapidly achieve radical technological breakthroughs in the field of low carbon propulsion.
Several studies show that the largest share of aviation emissions is caused by short- and medium-range aircraft, serving rather short routes (1000-3000 km with a mean at 1500 km and 100-150 passengers). Regional airplanes (20-80 passengers), used for even shorter routes, are mostly equipped with internal combustion powertrains that operate in the range of 1-2 mega-Watts. Alternatives can now be seriously considered for them, based on the technologies of electric motors and hydrogen fuel cells, with extended flight autonomies, thanks to the use of liquid Hydrogen.
As an ardent promoter of Hydrogen Energy, Air Liquide joined in 2018 the HEAVEN European consortium, co-funded by the FCH-JU of the European Community. The aim of this trailblazer project is to demonstrate that an existing 4-seater aircraft (the HY4 from H2FLY), can be safely and efficiently operated with liquid Hydrogen and fuel cells by 2023, that will pave the way to future large aircraft.
After many flights successfully performed since 2016 by using high pressure, gaseous Hydrogen to feed a fuel cell, this aircraft was upgraded by adding a liquid H2 tank in order to increase its autonomy.
Air Liquide advanced Technology (France) has designed, manufactured and qualified the tank, which successfully flew 6 hours in Slovenia in September 2023.
Firstly, this paper presents the design of the tank, which is based on our several decade-long experience in realizing and operating liquid Hydrogen systems, for both ground and space applications. The tank was manufactured in the first half of 2022 and underwent an extensive ground test campaign in liquid Hydrogen, aiming at getting a safe-for-flight clearance in order to fly in 2023. The paper presents the test rig and the cryogenic test results, which encompasses all functions from cool down, filling and flight usage. Then, we discuss the operations we did at Maribor airport (Slovenia) during the flight test campaign. A broader outlook is then discussed about what a Hydrogen-based aviation could look like in the future, with a focus about the necessary Hydrogen infrastructures in airports.
Speaker: Loic JEUNESSE -
156
Feasibility study on isothermal storage of two cryogens in a single tank with a metal common bulkhead
Abstract: Liquid-oxygen-liquid-methane reusable rocket technology is currently a hot topic in the field of spaceflight. Storage of liquid methane and liquid oxygen in a single tank but with a common bulkhead partition is the most compact and favorable scheme. Reduced or even zero boil-off loss of the cryogenic bipropellants is one of the key endeavors for prolonging the storage duration and extending the transport capability. Usually, two cryogens with different saturation temperatures are separated by a partition made of some low-conductivity materials or insulation structures, which creates difficulties in the processing and manufacturing of the tank. Instead of keeping the pressure on bilateral chambers close to each other, an idea is proposed to have the partition made of the same metal as the main body of the tank, which turns out a temperature equilibrium result on both sides. To explore the feasibility of the new scheme, a small-scale storage system with a stainless-steel common bulkhead tank is designed and established, and is tested by measuring the transient thermodynamic behavior of the liquid oxygen and liquid methane on both sides during the self-pressurization and venting processes. In addition, the testing rig allows supplying cooling power to a shield surrounding the tank, which enables zero boil-off of the liquid oxygen and liquid methane. Experiments show that zero boil-off storage of both liquid oxygen and liquid methane can be easily realized at a common temperature of 105.8 K, with a 3.17 W cooling power provided. However, the pressures in the liquid oxygen and liquid methane chambers are 399.36 kPa and 67.86 kPa respectively (Scheme 1), which means a large pressure difference between the two sides, and even worse a vacuum state in the methane chamber. Consequently, helium is charged into the liquid methane chamber as a non-condensable gas to increase its pressure (Scheme 2). The thermodynamic behavior of the fluids during the self-pressurization and venting process are recorded again and compared with that in Scheme 1. The results indicate that Scheme 2 significantly prolongs the storage duration, with a 64.91% increase in self-pressurization and venting time on the liquid oxygen side, and a 20.26% increase on the liquid methane side, compared with Scheme 1 with the same filling ratio and boundary conditions.
Keywords: common bulkhead storage, zero boil-off, self-pressurization and venting, helium gas
Speaker: Wujie Zhang (Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240, China) -
157
Modelling LH2 tank operations for hydrogen-powered aircraft using generalised thermal models
For the next-generation of aircraft, cryogenic liquid hydrogen (LH2) is a front-running option for serving as propulsion fuel due to its high gravimetric energy density. However, significant advances in terms of LH2 storage and distribution need to be established to have LH2 as a viable option of aircraft propulsion fuel. Advanced thermal management of an LH2 tank is crucial, since boil-off can result in significant loss of aircraft flight range. To reveal the thermal behaviour of the LH2 tank during operation, in this paper, we present the thermal modelling performed in the COCOLIH2T-project. A generalised thermal model has been set up, usable for any LH2 tank size. With this model, tank operation modes like cold refuelling, warm refuelling, defuelling, and dormancy are simulated. The core of the simulation model is based on the pressure-enthalpy characteristics of parahydrogen, simulating the LH2 stored in the inner tank as a single node. The main thermal insulation of the LH2 tank architecture considered is a vacuum insulation with MLI used as radiation barrier between outer and inner tank. Furthermore, the thermal connections between outer tank and inner tank have been characterized thermally.
For the refuelling model, the thermal masses of the composite structure, MLI, and inner-to-outer-tank spacers were accounted for. A boiling characteristic was determined to simulate the interaction between the liquid/vapour-mixture of H2 with the composite inner tank. The Leidenfrost effect significantly affects this boiling behaviour at the wall, and therefore has a strong effect on the thermal cooldown time of the inner tank during the warm refuelling process.
The tank internal pressure was analysed, such that during defuelling operation, the pressure inside the tank remains within practical bounds, i.e. not too high due to structural integrity, and not too low to sustain outflow of LH2 towards a low-pressure sink. The pressure can be elevated by supplying ambient temperature, high pressure GH2 to the inner tank.
Additional simulations on the behaviour of LH2 have been carried out, revealing the effects of boil-off and sloshing on the transient thermal management of the tank.
The models presented in this paper serve as general models for the purpose of revealing the thermal behaviour of a vacuum- and MLI-insulated LH2 tank. For the COCOLIH2T project specifically, the design considered has an inner tank volume of 1100 L, with a heat leak budget of 40 W. The simulation models enable this tank design to progress towards a TRL4 demonstration of the LH2 tank in a ground-based test rig. The TRL4 demonstration will eventually serve as the final milestone of the project.
Speaker: Arne K. te Nijenhuis (NLR - Royal Netherlands Aerospace Centre) -
158
Developments in liquid hydrogen on-board systems and ground-based infrastructures for sustainable aviation
To reduce the environmental impact of aviation, liquid hydrogen has been identified as promising future aircraft fuel. The liquid hydrogen can be used directly in the combustion turbine engine or in a fuel cell in combination with an electric motor. While the first option still produces nitrogen oxides, the second option has the potential of zero-emission.
Many initiatives are ongoing to investigate the use of hydrogen as energy source for aviation. In the Netherlands, Cryoworld plays a significant role in these LH2-aviation projects as liquid hydrogen knowledge partner. Cryoworld is involved in developing and manufacturing the on-board liquid hydrogen storage tanks and distribution systems required, as well as the ground-based cryogenic infrastructure.
This paper introduces the general requirements for on-board storage and distribution of LH2. It discusses and compares in more detail the principle cryogenic system designs, the mechanical design of the storage tank and relevant safety aspects. Furthermore, the design of the ground-based infrastructure will be described. The paper ends with a summary of design considerations for liquid hydrogen aircraft tanks and components, and the challenges in general for on-board cryogenic systems.
Speaker: Hendrie Derking (Cryoworld BV) -
159
Cooling system for the MEESST MHD heat flux and radio blackout mitigation HTS Magnet probe
Radio Blackout and extreme heat fluxes are critical problems occurring during spacecraft (re-)entry into planetary atmospheres. Both occur at the front surface of the spacecraft due to the compressed and partially ionized plasma. Both can be catastrophic for the mission with damages to the protection material due to heat or the complete loss of GPS data telemetry or communication with ground stations for extended periods of time. The MEESST (Magneto-Hydro-Dynamic Enhanced Entry System for Space Transportation) European project investigates a mitigation solution for both effects by developing simulation tools and ground-based plasma experiments based on the use of magneto-hydro-dynamic (MHD) principles. An experimental probe was designed and manufactured to study radio blackout and heat flux mitigation in plasma wind tunnels at the Von Karman Institute for Fluid Dynamics (VKI, Belgium) and at the Institute of Space Systems (IRS, Germany), respectively. The probe encompasses a non-insulated and conduction-cooled HTS magnet, operating near 20 K and producing the magnetic field required for the MHD plasma experiments. The magnet is housed in a cryostat surrounded by a water-cooled shell, designed to protect the probe from the plasma jet heat. While the operation of the probe in the plasma environment was rather challenging, the magnet and the cooling system behaviors were quite stable during the first campaign of experiment at VKI.
We report, here, on the design of the probe, detailing the main design points with regards to the cooling system, including the cryogenic loop required to maintain the 5-pancakes REBCO (Rare Earth-Barium-Copper-Oxide) magnet near 20K, and the external water-cooled shell designed to sustain the extreme heat fluxes imposed by the plasma. We will finish with a brief overview of the tests performed to demonstrate the expected operation of the system in its test environment.Speaker: Matthieu Dalban-Canassy (Absolut System)
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153
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Wed-Or9: Stress & Strain Effects Room B+C
Room B+C
Convener: Jun Lu-
160
Can Stainless Steel Meet the Challenges of Future Cryogenic Engineering Systems?
As the demands on cryogenic engineering systems continue to evolve with advancements in high-energy physics, novel fusion devices, and the expanding hydrogen economy, the question arises: can stainless steel rise to the challenge? Relying in superconducting magnet technology, the magnetic fields required for a variety of very ambitious engineering projects are increasingly high: 16 T for FCC – hh (the hadronic version of the Future Circular Collider), 12 T for EU DEMO (the European fusion device that will succeed ITER) and 23 T for ARC (the Affordable, Robust and Compact fusion device of the Massachusetts Institute of Technology). However, this increase in magnetic field is not accompanied by an increase in the size of the cryogenic engineering systems, thus the need for high-strength structural materials becomes increasingly apparent.
The physical and mechanical properties of high-strength austenitic stainless steels and their importance for the structural integrity of cryogenic engineering systems are discussed. A state – of – the art 316LN will be compared with a very high strength grade: FXM-19. Challenges faced in the processing of the material and how they are translated to the cryogenic mechanical properties are also discussed.
Additionally, results issued from cryogenic tests on an unconventional high - manganese high - nitrogen grade (P506) are presented, showing how promising the properties of this grade at cryogenic temperature are.
This work highlights the crucial role of high-strength austenitic stainless steels in ensuring the safe and reliable operation of cryogenic engineering systems. Furthermore, it emphasizes the critical need for the development of these materials to advance fusion energy technology, high-energy physics, and high-temperature superconductors.Speaker: Ignacio Aviles Santillana (CERN) -
161
Transverse stress limits of Bi-2212 Rutherford cables at 11 T, 4.2 K
For high-field accelerator magnets of the future, Bi-2212 round wires are an interesting option thanks to superior Jc compared to Nb3Sn for magnetic fields above 13 T. The round shape of the wires makes it possible to use established Rutherford cabling technology. The large thermal margin results in training-free coil demonstrators. In accelerator magnets, however, Bi-2212 Rutherford cables can be subjected to transverse stresses exceeding 100 MPa due to Lorentz forces. The effect of transverse stress on recent Bi-2212 cables has not been investigated thoroughly yet. In a collaboration between LBNL, NHMFL and the University of Twente, we test the transverse stress tolerance of four Bi-2212 Rutherford cables. The cables are made with 17 strands (Ø0.8 mm) containing 55x18 filaments with precursor powder made by Engimat. The cables undergo overpressure heat-treatment (OPHT) at 50 bar at the ASC-NHMFL on a reaction holder designed to match the transverse stress measurement rig at UTwente. After heat treatment, the cables are transferred to the measurement holder and vacuum impregnated with CTD-101k epoxy resin. The samples are then tested in the transverse stress rig up to 200 MPa at 4.2 K in a background magnetic field of 11 T. Two samples have been already measured. A 5% critical current reduction was observed at 170-200 MPa for one sample and 120-150 MPa for the second sample. A slight progressive critical current reduction was observed in both samples when cycling between 10 and 200 MPa. The filaments were examined using a SEM after etching the silver matrix. However, no large-scale filament cracking was observed.
Speaker: Simon Otten (UTwente SuperACT) -
162
Onset of mechanical degradation due to transverse compressive stress in Nb3Sn Rutherford cables as a function of heat treatment and impregnation.
This work presents observations on crack formation in Nb3Sn Rutherford cables that underwent a variation in the heat treatment cycle and the
resin used for impregnation. The main purpose of the study is to compare
the crack initiation limits and propose a combination of parameters to improve the mechanical strength of the cables. While lowering the final dwell
time of the heat treatment cycle has shown to improve the damage onset
limit, there is a trade-off in the electrical performance. In this context,
impact on critical current, residual resistivity ratio of the strands are also
presented. Results from microstructure analysis performed on cable samples subject to the transverse compression, with a variation in the heat
treatment cycle and impregnation resin, are compared. Following this,
differences in the damage onset and evolution are also explored.Speaker: Kirtana Puthran (CERN, KIT) -
163
Design and application of HTS magnet for magneto-hydro-dynamic plasma shielding in radio blackout and heat flux mitigation experiments
Since the early days of space flight, the so-called radio-blackout phenomenon occurring during hypersonic flight or during atmospheric entry into a celestial bodies’ atmosphere is well known. The compressed and partially ionized species in the hot plasma in front of the spacecraft can block radio waves leading to a complete loss of communication with ground stations, data telemetry, and GPS for a significant period of time. For the Gemini and Apollo missions radio-blackout phases lasted around 3-4 minutes while the early space shuttle missions experienced up to 30 minutes long radio-blackout phases. In addition to the radio blackout, the hot plasma causes high heat flux on the spacecraft structure. In 2003 a launch damage of the thermal protection systems (TPS) of the space shuttle Columbia led to the destruction of the spacecraft during reentry. Different types of TPS, e.g. ablative TPS, refractory insulation, radiatively or actively cooled TPS, have been developed and used on different missions.
In the framework of the European project MEESST (Magneto-Hydro-Dynamic Enhanced Entry System for Space Transportation) magneto-hydro-dynamic (MHD) based mitigation of both effects has been investigated by developing suitable simulation tools and ground-based plasma experiments. A high-temperature superconducting (HTS) magnet has been developed, commissioned and set in operation for radio-blackout and heat-flux-mitigation experiments in plasma wind tunnels at the Von Karman Institute for Fluid Dynamics (VKI, Belgium) and at the Institute of Space Systems (IRS, Germany), respectively. The non-insulated, conduction-cooled HTS magnet was designed to fit in a warm-bore cryostat (bore diameter 30 mm, space for enthalpy probe) with a water-cooled shell. It consists of 5 pancake coils wound with 4 mm wide REBCO (Rare-Earth Barium Copper Oxide) tapes with inner and outer winding radii of 33 and 71.5 mm, respectively. Four of the pancake coils contain soldered splices due to the short length of available tapes. Six soldered joints were necessary for the series connection of current leads and pancakes.
We present design, construction and test results of the MEESST magnet. The main focus of the presentation will be on the performance of the magnet and cryogenic system during the plasma experiments at VKI and IRS. Operation of the magnet in the plasma environment turned out to be challenging due to the harsh environment accompanied e.g. by the high heat flux and due to the ionized particles causing electronic noise in temperature and voltage signals. Melting of a water-cooled heat shield protecting cables, vacuum and cryogenic transfer lines, as well as shorts in the current circuit due to melted cable insulation were issues that had to be solved during the experimental campaigns. Despite the underestimated issues, it was possible to operate the non-insulated magnet stably in the experimental campaigns.Acknowledgement:
The MEESST project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 899298.Speaker: Sonja Schlachter (Karlsruhe Institute of Technology) -
164
The mechanical research on high strength CICC jacket with YS>1500MPa@4.2K used for future fusion magnets
Increasing magnetic field intensity in limited space is an important strategy to obtain high parameter plasma and improve the fusion power. The next generation of fusion magnets will have a peak magnetic field greater than 17T, such as China Fusion Engineering Test Reactor (CFETR) central solenoid magnet. The development of high strength and high toughness jacket has become one of the challenges in the application of high-field cable-in-conduit conductors (CICC) for CFETR. 0.2% proof stress of jacket should be over 1500 MPa at 4.2 K for CICC, thus 316LN and JK2LB jackets developed by ITER do not meet the requirements. Nitronic 50 (N50) super-austenitic stainless steel material has great optimization potential for the development of jacket. ASIPP has developed the the modified N50 material together with China Iron and Steel Research Institute, Metal Research Institute, etc, and the CICC jacket was made some R&D work. The entire process of CICC preparation, including extrusion, bending, straightening and aging, was simulated using the modified N50 stainless steel jacket. The circle-in-square jackets prepared showed a yield strength higher than 1550 MPa, fracture elongation is higher than 30% and a fracture toughness KIC better than 260 MPa·m1/2 after cold work and aging at 4.2 K. This paper will focus on the preparation, cold work processing and performance test of the modified N50 jacket. This study will present experimental data and discuss the feasibility of modified N50 as a high-magnetic field jacket material for next-generation fusion reactors.
Speaker: Weijun Wang -
165
Impact of hydrogen embrittlement on cryogenic mechanical properties of 304 steel
Within the framework of the “AppLHy!” pilot project, the Karlsruhe Institute of Technology (KIT) is investigating the transport and application of liquid hydrogen (LH2). Due to the advantages of LH2, such as high energy density, high purity, storage at low pressure and the possible facilitation of the available cryogenic temperature level, various application scenarios are being investigated.
In this work, the influence of the hydrogen embrittlement on mechanical properties of the austenitic steel 304 from room temperature down to 20 K is investigated. The hydrogen content of the material is varied using a high pressure (max. 200 bar), high temperature (max. 300°C) hydrogen charging chamber. Tensile and fracture measurements are performed at different temperatures to evaluate the influence of the hydrogen content on the mechanical behavior. The results are reflected with regard to the microstructure and possible deformation mechanisms.Speaker: Klaus-Peter Weiss (KIT, Institute for Technical Physics)
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160
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Lunch Restaurant
Restaurant
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Wed-Po-2.1: H2 & LNG 2 Poster area
Poster area
Convener: Francois Millet (CEA)-
166
A study of an LNG cold energy cascade utilization system coupled with liquid air energy storage
Liquefied natural gas (LNG) is considered an advantageous energy source in the current transition stage of energy structure reform due to its cleanliness and high quality. A large amount of high-grade cold energy is released in the process of LNG regasification. However, most of the LNG receiving stations in China fail to utilize LNG cold energy effectively in the actual operation process, and there is a large waste of cold energy. Liquid air energy storage (LAES) is a large-scale energy storage technology that is easy to realize multi-energy coupling. An LNG cold energy cascade utilization system incorporating LAES technology was proposed in this paper. Facing the demand of LNG cold energy utilization in Tangshan City, China, the high-grade cold energy is first used to achieve cryogenic compression of air, the medium-grade cold energy is applied to refrigerated warehouses with different temperature zones in a temperature-controlled sequence, and the remaining cold energy is used to achieve cooling of data centers. Thermodynamic sensitivity analysis and economic analysis of integrated system parameters were performed. The performance of an optimized LNG cold energy cascade utilization system was obtained.
Speaker: Zhaozhao Gao (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
167
A study on hydrogen liquefaction coupled with liquid air energy storage
Liquid air energy storage (LAES) is one of lager scale energy storage method which may be widely used in a society with large percentage of photovoltaic (PV) and wind power. However, photovoltaic (PV) and wind power often located in remote areas in which the energy need is week, which lead to energy transportation is very important. Liquid hydrogen is a very efficient carrier to transport energy but which pocess's energy consumption is very high. Thus, a system LAES coupled with hydrogen liquefaction which use the advantage of LAES and liquid hydrogen is proposed and studied in this paper.
Speaker: Wang Zhiping -
168
Analysis on sealing performance of piston rings used in the liquid hydrogen pump
The sealing structure has a significant impact on the performance of high-pressure liquid hydrogen reciprocating pumps. Piston ring sealing is one of the significant sealing methods employed in such pumps. This paper establishes a leakage calculation model for the piston ring sealing structure in high-pressure liquid hydrogen reciprocating pumps. And the impact of different dimensions on the leakage rate is analyzed and discussed. This work provides a theoretical foundation for the design of liquid hydrogen pumps.
Speaker: Shaoqi Yang (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
169
CFD modelling of the non-isobaric evaporation of cryogenic liquids in storage tanks
Cryogens, such as liquefied natural gas or liquid hydrogen, are conventionally stored in highly insulated tanks. These tanks are susceptible to heat transfer from the surrounding environment. The temperature difference between the ambient air and the cryogen inside the tank drives this heat transfer, leading to cryogen heating and evaporation. As the cryogen continuously evaporates, the pressure inside the tank gradually rises—a phenomenon known as self-pressurization. When the tank reaches its maximum allowable working pressure (MAWP), excess evaporated cryogen is released as a boil-off gas (BOG). Proper management of BOG is essential to mitigate safety and environmental risks and minimize economic losses due to the gradual loss of stored cryogen over time. Despite the development of several models for non-isobaric cryogen evaporation, none of them consistently achieve accurate predictions for pressure, liquid, and vapor temperature profiles across a practical range of applications.
This research presents a new CFD model relevant to non-isobaric cryogen evaporation. The model considers the heat influx from the surroundings to the liquid and vapour phases, and the heat transfer between the phases. The phase change sub-model considers two contributions: an interfacial energy balance far from the tank wall and direct wall-to-liquid conduction near the wall. The model comprises a new single-phase CFD model for the liquid phase and a 1-D model for the vapour phase. The CFD model has been implemented in the open-source computational fluid dynamics toolbox OpenFOAM to facilitate its reproducibility.
The model provides detailed information on liquid and vapour temperature profiles, liquid velocity profiles, pressure build-up, and evaporation rates. Below the vapor-liquid interface, liquid natural convection is dampened by thermal stratification. This stratification occurs due to an increase in the interfacial temperature caused by rising pressure. As pressure increases, the temperature gradient below the interface dampens liquid phase natural convection in this region. Above the tank bottom, vortical currents emerge as a result of natural convection driven by bottom heating. These currents play a crucial role in mixing the liquid phase, which explains the reduced levels of liquid thermal stratification in scenarios with low liquid filling. Additionally, the model highlights that the pressure build-up is primarily governed by vapour heating, particularly during the initial stages of evaporation.
The model was used to analyse liquid velocity profiles for two sets of experimental data for the evaporation of liquid nitrogen. Two empirical parameters, namely the wall heat partitioning fraction and the overall heat transfer coefficients, were fitted to represent experimental uncertainty on wall heat ingress. The results show that most external vapour heat ingress does not reach the vapour phase bulk. Instead, it is transported downwards through the walls and transferred to the liquid at the liquid-vapour-wall contact point, driving phase change. Heat conduction from the walls to the interface has a significant effect, even for low heat fluxes, and cannot be neglected.
The developed model requires simulation times three orders of magnitude lower than a full multiphase CFD model. It is thus seen as an efficient tool that can aid the optimisation of the design and operation of cryogenic storage tanks. The model can simulate cryogen evaporation in large-scale storage tanks using parallel processing by changing only the input dictionaries. Similarly, it is directly applicable to any tank that presents axial symmetry and is easily extended to arbitrary geometries. For long-term cryogen storage involving pressurisation and boil-off gas removal cycles, the model can be fitted to a single pressurisation cycle and used to predict future cycles.
Speaker: Felipe Huerta (Department of Chemical and Bioprocess Engineering, Pontificia Universidad Católica de Chile) -
170
Design and Commissioning of a Medium-Scale Hydrogen Liquefaction Plant
This study presents the design and commissioning process of a medium-scale hydrogen liquefaction plant of 1.5 tons of liquid hydrogen per day (TPD), utilizing a Helium Brayton refrigeration cycle augmented with Liquefied nitrogen pre-cooling.
The design involved comprehensive simulation and analysis to optimize the plant's performance. The specific energy consumption (SEC) of the plant was calculated to be 18.2 kWh/kg LH2, with an exergy efficiency of 21.5%. An exergy analysis was performed to identify the processes within the plant that contribute most to exergy destruction. The analysis revealed that the compression process, expansion process, and heat transfer in the LN2 pre-cooling heat exchanger are the primary sources of exergy destruction sorted by the severity of the losses. These findings are crucial for understanding where improvements can be made to increase the overall efficiency of the plant.
The commissioning of the plant began with the conditioning of the system, which included purging, leak testing, and ensuring all components were properly aligned and functioning. Next, the control system was debugged to ensure that all automated processes and controls were functioning correctly. Then the plant was cooled down to lower than 20K for hydrogen liquefaction. Finally, performance tests were conducted, the measured hydrogen liquefaction rate is 1.59 tons per day, the specific energy consumption is 15.1 kWh/kg LH2, and the Para-hydrogen content in the liquid hydrogen output is 98%. The test results indicated that the plant's operational performance met the design specifications, suggesting that the design and commissioning processes were successful.
Speaker: lianyou Xiong (Technical Institute of Physics and Chemistry, CAS) -
171
Experimental and theoretical investigation on avoiding freezing phenomena of Printed Circuit Heat Exchanger for cryogenic liquid hydrogen vaporizer
This study is performed to investigate the effect of the freezing phenomena in cryogenic liquid hydrogen vaporizer experimentally and theoretically. Whenever cryogenic fluid is used as the working fluid for heat exchanger, heat exchanger is exposed to the risk of freezing due to low temperature profile inside heat exchanger. To avoid the freezing phenomena inside heat exchanger, the flow and thermal characteristics of heat exchanger should be figured out. Generally it is well known that a printed heat exchanger (PCHE) is one of the most popular solution for cryogenic liquid hydrogen vaporizer. Hence, the purpose of this study is to experimentally investigate the flow and thermal characteristics of a printed circuit heat exchanger (PCHE) for cryogenic liquid hydrogen vaporizers. Also, this study is conducted to identify the conditions under when freezing occurs and to present guidelines to avoid freezing when using PCHE. To conduct laboratory-scale PCHE experiments prior to using liquid hydrogen, liquid nitrogen is used as the working fluid in cold channel. Laboratory-scale PCHES are designed and fabricated using diffusion bonding. Glycol water is used as the working fluid in hot channels for exchanging heat between the cold and hot channels. To determine the freezing conditions in PCHE, the heat transfer performance of laboratory-scale PCHE and the pressure drop in the hot channel is investigated. Furthermore, relatively large deviations in thermo-physical properties are taken into account to evaluate heat transfer coefficient and freezing conditions inside PCHEs. The results of this study may shine light to suggest a guideline about avoiding freezing problems in PCHE.
Speaker: Wookyoung Kim (Korea Institute of Machinery and Materials (KIMM)) -
172
Experimental investigation of 1,300 L zero-boil-off (ZBO) liquid hydrogen storage tank
A 1,300-liter-capacity liquid hydrogen (LH2) storage tank has been constructed and tested. The thermal insulation system of the LH2 storage tank is designed to have a boil-off rate (BOR) of 1.5 vol.%/day and a refrigeration system is introduced to achieve zero-boil-off (ZBO) of LH2. A two-stage GM-type pulse tube refrigerator (PT815, Cryomech) is utilized for the refrigeration system. The LH2 storage tank mainly comprises a vacuum chamber, radiation shield, and internal reservoir. The aluminum shield is conductively cooled by the first stage of the cryocooler and it also has a vapor-cooled loop for rapid initial cooling. The stainless-steel reservoir has a fin-array heat exchanger to suppress pressure elevation due to the vaporized hydrogen at its top side. The fin-array is cooled by the second stage of the cryocooler. The annular space between the outer shell and the internal reservoir is evacuated to 10-5 mbar. Although it was originally intended for storing LH2, due to safety regulations, liquid nitrogen (LN2) is utilized to figure out the thermal characteristics of the tank. At the initial process of cooling, LN2 was supplied to the vapor-cooled loop and the internal reservoir, simultaneously. When the internal reservoir was filled approximately 40% with LN2, all the valves were closed with the cryocooler on. The refrigeration system was controlled to maintain an internal pressure of 102 kPa. The experimental results were compared to the simulated results using modified temperature conditions of LN2.
Speaker: Jiho Park -
173
Heat transfer study on cryogen evaporation in stationary and moving tank
The cryogen evaporation rate is of prime concern in various industrial as well as research settings. Even with high insulation of cryogenic tanks, heat in-leak from ambient is unavoidable. The thermal characterisation of cryogenic fluids is quite important during their storage due to external heat inleaks. Due to their low viscosity, cryogens are prone to large liquid motions (sloshing) during their transportation. This phenomenon causes a higher rate of internal heat generation due to viscous dissipation. In addition to this, the thermal stratification in the cryogenic storage container is disturbed. These have an impact on the pressure and temperature of the tank, depending on the intensity of sloshing. In the case of an isobaric tank (open vent), loss of boil-off gases happens, while for a close vent condition, self-pressurization of the tank takes place. The availability of experimental data with regards to, both isobaric and non-isobaric evaporation of cryogenic liquids, is very limited. Due to this, validation of various thermodynamic and CFD models is still a challenging task.
In the present work, as a first step, a transient two-phase thermodynamic model, for a stationary liquid nitrogen cylindrical tank, is developed for two cases, first to understand the boil-off rate (isobaric condition /vent open) and second to measure transient pressure evolution (closed condition /vent close) due to external heat in-leak. Experiments are performed for the validation of the model with a 25-liter cryogenic tank of cylindrical geometry, considering liquid nitrogen as the working fluid. Experiments are carried out in both stationary and moving (slosh) conditions of the cryogenic tanks. Sloshing exhibits a higher boil-off rate than a stationary tank as demonstrated by experimental results due to interface fluctuations and forced convection.
Due to the insulation of cryogenic vessels, the boiling mechanism is governed by interfacial surface evaporation. In isobaric conditions, keeping constant ullage pressure, thermal stratification in both liquid and vapour phases is studied for the stationary condition of the cryogenic tank. To understand the temperature stratification, thermocouples are placed vertically along the axis of the tank at different heights. The liquid phase is thermally homogeneous during isobaric evaporation, except for the boundary layer caused by natural convection. Temperature stratification in the vapour domain tends to exhibit a pseudo-steady state except in the zone near to the interface.
When the vent is closed, self-pressurization leads to an increase in ullage pressure inside the tank due to the continuous evaporation process. A theoretical equilibrium model is developed in the present work so as to generate an expression for the rise in pressure and drop in liquid level based on time. It integrates the Clausius-Clapeyron equation to relate the saturation temperature with the saturation pressure. Experiments are performed to measure the pressure evolution inside a 110-liter cryogenic tank in stationary conditions. The effect of transient pressure build-up on interface temperature and liquid thermal stratification is discussed in this paper.Speaker: Saurabh Kumar Singh (IIT Bombay) -
174
Investigate the effects of hydrogen-rich environment on the tensile properties of thermoplastic polymers for liquid hydrogen service
Adopting hydrogen fuel has been recognised as a promising route to realise net-zero emission by academia, industry and government. It is challenging to most materials for storing and distributing liquid hydrogen at 20 Kelvin (K). While metallic materials have traditionally been considered for liquid hydrogen storage and distribution, recent discourse in both academia and industry, particularly within the aviation sector, has increasingly explored the use of light-weight materials for constructing liquid hydrogen tank structures, such as fibre-reinforced composite materials. However, the substantial weight of metallic materials and the occurrence of microcracks due to mismatches in coefficients of thermal expansion between fibres and resin have constrained their utility for liquid hydrogen storage and distribution. Thermoplastic polymers have emerged with potential solution for liquid hydrogen storage and distribution components. High density thermoplastic polymers have already been explored when acting as the liner material on Type IV tanks holding compressed hydrogen gas at room temperature and 350 bar pressure [1]. Thermoplastic polymers might provide solutions for seals in components like pipeline joints, valves, pumps and flexible hoses [2,3] for transferring cryogenic hydrogen. However, there is limited study about the behaviours of these polymers at 20 K. The authors have conducted the first study of the strain rate effects on the mechanical behaviours and failure mechanisms of three candidate thermoplastics with promising performance at 20 K. The coefficients of thermal expansion between 300 - 4 K were also measured to guide the design of potential sealing configurations for hydrogen service down to 20 K. More fundamental is the current knowledge gap surrounding the performance of thermoplastics operating consistently at cryogenic temperatures and possible deterioration in mechanical properties after exposing to hydrogen-rich environment for long-periods. This new study will aim to characterise the long-term effects of hydrogen aggression on the tensile properties of thermoplastic polymers at 20 K. Three types of thermoplastic polymers Polypropylene (low molecular weight), FEP (medium molecular weight) and PEEK (high molecular weight) are deliberately selected to inspect possible variations with molecular weight. All materials will be tested as thin films to encourage more rapid hydrogen diffusion and absorption into the material, with the aim to amplify any effects. The hydrogen gas charging technique will be deployed to soak samples inside a pressure vessel rated for 200 bar and up to 373 K. The achievement of hydrogen saturation is traced using a Hy-Energy gas absorption analysis system. Finally, the hydrogen absorption rate of the three polymers, the duration required to obtain “full charged/saturated” samples given the current state-of-art, and the effects of hydrogen-enrichment upon the tensile properties of thermoplastic films at 20 K will be summarised and discussed.
Acknowledgements
This project was supported by the UKRI STFC Grant (Grant No. ST/T001844/1). In addition, facilities from the Institute of Cryogenics and the Chemistry department of University of Southampton are gratefully acknowledged.
References
[1] Wang Z, Wang Y, Afshan S, Hjalmarsson J. A review of metallic tanks for H2 storage with a view to application in future green shipping. International Journal of Hydrogen Energy. 2021 Feb 3;46(9):6151-79.
[2] Bo K, Feng H, Jiang Y, Deng G, Wang D, Zhang Y. Study of blister phenomena on polymer liner of type IV hydrogen storage cylinders. International Journal of Hydrogen Energy. 2024 Feb 7;54:922-36.
[3] Cui Y, Yan J, Li J, Chen D, Wang Z, Yin W, Wu Z. Cryogenic Mechanical Properties and Stability of Polymer Films for Liquid Oxygen Hoses. Polymers. 2023 Aug 16;15(16):3423.Speaker: Zhenzhou Wang (Institute of Cryogenics, University of Southampton) -
175
Performance of an advanced liquid air energy storage system based on cold energy utilization at LNG receiving station
Liquefied natural gas (LNG), recognized as one of the cleanest fossil fuels, is currently the most rapidly expanding primary energy source, offering abundant cold energy during the gasification process. The integration of liquid air energy storage (LAES) with LNG cold energy utilization not only facilitates the efficient utilization of LNG cold energy but also enhances the energy efficiency of the LAES system. However, the desynchronization of the regasification process at the LNG receiving station and the cold energy utilization process results in an imbalance between the supply and demand of LNG cold energy, thereby limiting the scale and efficiency of cold energy utilization. In this study, we propose a system to stabilize the utilization of LNG cold energy. The system employs the intermediate storage unit to preserve the cold energy from the LNG, which is subsequently channeled to the LAES. The process is designed to integrate cold energy from LNG receiving stations and enhance the efficiency of LAES. In this study, we conduct detailed calculations and discussions on the system using a developed composite thermodynamic model. The effect of different parameters such as the compressor inlet temperature, liquefaction rate, and expansion pressure were analyzed and compared. This research offers a practical example of LNG cold energy utilization, contributing to the advancement of industrial applications.
Speaker: Junxian Li (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
176
Thermal analysis of repurposing liquified natural gas tanks for liquid hydrogen storage
Liquid Hydrogen (LH2) is emerging as a high potential energy storage medium in the accelerating Hydrogen economy to achieve net zero targets by 2050. LH2 possesses the advantage of high volumetric energy density compared to compressed gaseous Hydrogen. However, currently LH2 usage is restricted by both production and storage issues. Scalability and constructability limitations, capital cost for build new infrastructure, compatibility of materials for cryogenic temperatures, and cryogenic boil-off losses due to the low boiling point of LH2 limit the large-scale LH2 storage tank development. Pre-stressed concrete composite storage containers are frequently used to construct large-scale Liquified Natural Gas (LNG) storage facilities operating at cryogenic temperatures where structural rigidity is provided by the concrete. However, there is still a concern that, despite the relatively environmental stewardship of LNG, its long-term viability as a primary fuel tends to decline due to CO2 emissions. These infrastructures situated in energy export terminals with port infrastructures, and they’ll be obsolete in the future with the elimination of hydrocarbons. If these hundreds of millions worth infrastructure can be repurposed to LH2 storage or any other purposes need for LH2 supply chain, it can drastically reduce the capital cost of new energy infrastructure required for commercial LH2 export and import. Therefore, this study examines the potential, challenges and required modifications to repurpose existing above-ground LNG storage tanks to store LH2, considering the thermal analysis.
In the current context, above-ground storage predominates among LNG storages due to their increased capacity, generally topping around 200,000 m3 ranging from 50,000 m3, in addition to less complicated maintenance and ease of installation. These tanks generally tend to be cylindrical, where the capacity differentiates on large scales based on demand. These tanks are developed over the years in 3 generations, increasing their safety, reliability, and capacity, known as single containment tanks, double containment tanks, and full containment tanks. In this study. a tank of size 200,000 m3 was modelled with a three-layer insulation system which falls under full containment configuration. Nickel steel and prestressed concrete were used as the materials of the inner and outer tank, respectively. The prestressed concrete tank section was simulated by incorporating reinforcements into concrete to model realistic scenarios of prestressed concrete.
The thermal analysis of this study consists of three different simulations to evaluate the 1. Temperature distribution across the tank shell with the existing insulation materials, 2. Applicability of vacuum insulation to minimize boil-off of LH2 with existing insulation materials, 3. Applicability of alternative insulation materials to minimize LH2 boil-off. As insulation materials, 1. multi-layer insulation, 2. fiberglass, 3. glass bubbles, 4. aerogel blanket, 5. perlite, and 6. aerogel powder were considered. LH2 boil-off quantity was calculated using both static and dynamic boiloff modelling techniques. The dynamic boil-off model utilizes the concept of the superheated vapour model which is based on the fact that liquid and vapour temperatures exist with a temperature gap in cryogenic storage tanks rather than at saturated equilibrium. This comprehensive analysis paves the way to identify technically and economically feasible solutions that can be incorporated into mega-scale LNG tanks during the conversion to LH2 tanks. Also, the results of this study can be utilized when developing new LNG tanks, so that the features required for LH2 storage can be incorporated in the designing process.Speaker: Susiri Costa (The University of Melbourne) -
177
Topology optimization of cryogenic heat transfer in stressed rods for large liquid hydrogen tanks
The heat leakage of cryogenic equipment is primarily attributed to multilayer insulation and solid heat conduction at a macroscopic level. However, there has been limited research on optimizing solid heat transfer. Traditionally, the design criterion for materials subjected to cryogenic temperatures has been based on their yield strength or ultimate tensile strength at room temperature due to considerations for room temperature loading. In reality, the strength of materials generally increases at cryogenic temperatures. Additionally, thermal conductivity at cryogenic temperatures can be several times or even orders of magnitude smaller than that at room temperatures. This provides ample opportunities for optimizing heat transfer in applications with cryogenic temperature loading, such as large-scale liquid hydrogen storage tanks. Based on the topology optimization algorithm, this paper optimizes rods with different temperatures, forces and materials and obtains the minimum heat transfer profile while meeting strength requirements. The applicable scope of topological optimization in stressed rods at cryogenic temperature is also analyzed. This research is of great significance for optimizing heavy-duty structural components at cryogenic temperatures.
Speaker: Shixian Wu (Zhongshan Institute of Advanced Cryogenic Technology)
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166
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Wed-Po-2.2: Materials, Testing & Electronic Devices Poster area
Poster area
Convener: Simon Otten-
178
A Boiloff Calorimetry Test Configuration for the Characterization of Thermal Insulation Systems in Flammable Background Gasses
In support of efforts related to the design of future industrial liquid hydrogen storage tanks, the Cryogenics Test Laboratory at NASA Kennedy Space Center has recently begun thermal performance characterization of various insulation systems in different gas background environments, including nitrogen, helium and hydrogen, using the Cryostat-100 (CS100) liquid nitrogen boiloff calorimeter. The CS100 is a vertical-cylindrical geometry, capable of measuring heat load and vacuum pressure ranges from 100 mW to 100 W, and 1e-8 torr to ambient pressure respectively, via the ASTM C1774, Annex A1 standard methodology. Flammable gas testing required numerous augmentations to the standard CS100 hardware configuration and controls software, and modifications to the Lab facility to ensure a safe test campaign. These included double-containment of the CS100 vacuum chamber and most supporting hardware, with continuous inert gas purging using nitrogen; remote control of valves and vacuum pumps; and hydrogen and oxygen detection systems. The design and implementation of these unique modifications led to safe and successful CS100 hydrogen testing, and is presented and discussed in-detail.
Speaker: Adam Swanger (NASA Kennedy Space Center) -
179
Acoustic Emission Analysis of Tensile Damage in Porous Carbon Fiber Composite Laminates from 20 K to 300 K
Carbon fiber reinforced resin matrix composites (CFRP) are widely used in cryogenic engineering due to their light weight, high strength and corrosion resistance. Practical applications often involve processing CFRP structural components with holes. However, the presence of these holes have an important effect on the overall mechanical properties of the material. In this study, we introduce the acoustic emission (AE) technique to characterize the mechanical properties of materials within the temperature range of 20K to 300K. Through the application of acoustic emission (AE) technology, the static load axial tensile damage process of carbon fiber composite laminates containing holes in cryogenic environments was monitored in real time. The effects of opening shape and size on mechanical behavior and failure mechanism of carbon fiber composite laminates were studied. Based on the analysis of experimental data, the range of peak frequency (PF) in different damage stages was determined, and the tensile failure mechanism of porous carbon fiber composite laminates was analyzed with AE characteristic parameters.
Speaker: Rong Bao (Technical Institute of Physics and Chemistry, CAS) -
180
Comparative Analysis of Reed Switches and Hall Sensors at Cryogenic Temperatures: An Argument for a Cost-Effective Alternative for Cryogenic Applications
Hall sensors are commonly used as a non-contact way to relay positional data inside a cryostat to an external motion controller. However, cryogenic Hall sensors can be cost prohibitive and require peripheral electronics to interface with the motion controller. Here we contrast the accuracy and reliability of non-contact reed switches in cryogenic environments against the commercially available cryogenic Hall effect sensors. Accuracy for both units was optically measured using a filter wheel cooled down to 77K, while reliability and yield was determined by thermal-cycling multiple units down to liquid nitrogen (77K) and liquid helium (4.2K) temperatures. Lastly, we also argue that the lower cost and ease-of-implementation of reed switches make them better suited for many cryogenic motion control applications.
Speaker: Charles Jones (Infrared Laboratories) -
181
Development and experimental validation of a versatile test bench for thermal contraction measurements down to 1.8 K
The use of cryogenics plays a major role in the operation of modern high-energy accelerators and ensures the superconducting state of beam-guiding and focusing magnets. A profound understanding of the thermo-mechanical behavior of the structures and components is therefore crucial, particularly for the strain-sensitive Nb$_3$Sn-based superconducting coils. Inaccuracies in considering processes like thermal contraction can substantially impact the performance of the magnets. Despite its considerable contribution to the strain-state, the scarcity of commercial thermal contraction measurement devices capable of examining these materials to temperatures as low as 2 K has limited the available information on the thermal contraction within these complex systems. The Mechanical Measurement Laboratory at CERN initiated thus the development of a customized dilatometric test bench in collaboration with the external company attoCUBE. The resulting setup features an optical displacement sensor based on Fiber-Optic Fabry-Pérot interferometry and with its integration into a closed-cycle-cryostat, this test bench enables temperatures from room temperature down to a minimum of 1.8 K.
The initial setup underwent an extensive testing campaign with several optimization iterations to achieve accurate measurements. Simultaneously, we elaborated an appropriate sample preparation that addresses the limitations in the examinable materials caused by the optical requirements of the interferometric method. It followed an experimental validation using single-crystal silicon as a certified reference material from the National Metrology Institute of Japan (NMIJ), yielding an error of less than 0.03∙10$^{-3}$ in the relative change of length ΔL/L$_0$. However, the system’s significant repeatability demonstrated in these initial validation tests permits a correction of the dominant systematic errors, resulting ultimately in an uncertainty better than 0.01∙10$^{-3}$ in ΔL/L$_0$ over the entire temperature range. Given this level of uncertainty, this setup is well-balanced between accuracy, simplicity, and time-efficiency, facilitating dynamic thermal contraction measurements across the entire low temperature range within a 10-hour timeframe for a full measurement cycle.Speaker: Stefan Hoell (CERN) -
182
Experimental study of a novel coaxial annular tube convective heat switch
Thermal switches are used in cryogenic systems to manage temperature, which helps in speeding up the cooling process. The convective heat switch is a thermal switch that controls the heat transfer between different components. Previously, we investigated a thermal switch of a novel structure using CFD methods and gained some helpful information for processing. In this research paper, we determined the structural dimensions of this thermal switch based on simulation results. This thermal switch can be easily machined depending on its design, which holds true during actual processing. We conducted cooling experiments and thermal conductance tests and subsequently compared the results with those obtained from simulations. Furthermore, we have discussed the characteristics of the three phases of the convective thermal switch: initiation, acceleration, and disconnection. This study can help us better understand natural convection at low temperatures.
Speaker: Yu Zhang (Southern University of Science and Technology) -
183
Feasibility Study of Rayleigh Backscattering Optical Fibre Strain Measurement Technique for Determining the Thermal Expansion of Lightweight Composite Structures
The determination of the thermal expansion of lightweight composite structures, such as honeycomb panels is of great interest for various high added value industries. However, those measurements are challenging, as they are typically not possible with with well-established methods due to their complex geometries. In this study, we investigate the feasibility of using the Rayleigh backscattering optical fibre strain measurement technique to determine the thermal expansion of composite structures.
To determine strain using Rayleigh backscattering technique, an optical fibre is attached to a surface. When the surface experiences deformation, the deformation causes strain in the fibre, which leads to changes in the backscattered light intensity. However, in this study, we propose a novel approach where the fibre is only bonded in two points, allowing to decouple thermal effects over the fibre by comparison with an unstrained fibre. To validate the feasibility of this technique, CTE measurements obtained with Rayleigh backscattering technique over well-known materials, as invar, were compared with measurements over the same materials performed with a horizontal push-rod dilatometer. Our results show that this novel approach is a practical method for determining the thermal expansion of assembled composite structures. The technique is non-destructive, requires minimal sample preparation, and can provide high-accuracy measurements. These findings have significant implications for the design and optimization of composite structures in various applications, such as particle detectors, aerospace, and automotive industries.Speaker: Oscar Sacristan De Frutos (CERN) -
184
In situ Mechanical Characterization of Hollow Specimens with Hydrogen and Helium Environments at Ambient and Cryogenic Temperatures
The Application of Liquid Hydrogen project (AppLHy) aims to investigate the combined transportation of liquid hydrogen as chemical energy carrier and the use of superconductors for efficient electrical energy transport in a hybride pipeline. It is crucial to evaluate material properties for the development of such a hybrid pipeline operating under cryogenic temperatures and exposure to liquid hydrogen. Therefore is is necessary to develop test methods to obtain mechanical material properties in relevant gas atmospheres, at various temperatures and pressures. Related testing setups are often large and complex, requiring careful monitoring to avoid dangerous leaks of hydrogen. This study presents an in situ mechanical tensile testing method using hollow specimens filled with gas, which increases safety and reduces complexity during experiments. Hollow cylindrical specimens made from three different materials were used for testing: austenitic steel as a high-strength material, copper as a lower-strength material, and ferritic steel API 5l X60 as an example of pipeline steel. Inside the hollow specimens, an environment of hydrogen or helium was created at pressures up to 200 bars. Tensile tests were conducted at temperatures ranging from room temperature to the cryogenic temperature of 20 K.
Results showed that the strength and ductility of the materials varied based on the internal gas pressure, temperature, and the type of gas used. After testing, fractographic analysis revealed some extent of material embrittlement due to internal hydrogen exposure during the tests. These findings highlight the significant impact of hydrogen on changing material properties both at ambient and cryogenic temperatures. Benefits and future potential of using the in-situ method for better understanding how materials behave under different temperatures, pressures, and environmental conditions are discussed.Speaker: Elvina Gaisina -
185
Influence of room temperature pre-strain on cryogenic tensile properties of modified N50 austenitic stainless steel
Chinese Fusion Engineering Test Reactor (CFETR) is considered to be one of the most ambitious fusion energy projects capable of producing large-scale nuclear fusion reactions, whose superconducting magnet system consists of the toroidal field (TF) coils, central solenoid (CS) coils and poloidal field (PF) coils. The modified N50 austenitic stainless steel has been determined to be applied as the jacket material of the CICCs (Cable-In-Conduit Conductors) of both the TF coils and the CS coils and the case material of the TF coils in the CFETR, which would undergo a series of pre-deformation during the manufacture process at room temperature. It is proved that mechanical properties of the modified N50 could meet the service requirements of future conductors of the CFETR, however, the knowledge of effect of pre-strain on cryogenic mechanical properties of the modified N50 is limited. In order to investigate the influence of tensile pre-strain at room temperature on cryogenic tensile properties, especially the yield strength (Rp0.2), ultimate tensile strength (Rm), elongation at fracture (A), and the microhardness (HV0.3) of the modified N50 with different tensile pre-straining amounts of 0%, 15%, 25%, and 35% were measured at room temperature (300K), liquid nitrogen temperature (77 K), and liquid helium temperature (4.2 K), respectively. Moreover, the microstructure evolution of the modified N50 was investigated through the scanning electronic microscopy (SEM) and the transmission electronic microscopy (TEM), which would indicate fractured morphologies and also dislocation accumulations of the pre-strained modified N50. In addition, the strain hardening behavior of the modified N50 was compared with that of the ITER-grade 316LN. This work would provide more reliable mechanical data of the modified N50 in cryogenics applications.
Speaker: jingjing dai (Technical Institute of Physics and Chemistry) -
186
Instrumentation selection for cryogenic HTS coil gamma irradiation at doses up to 10MGy
Tokamak Energy has completed a project to build our understanding of the performance of HTS coils under gamma radiation up to doses of 10MGy. A cryogenic HTS test rig was built to enable this, and testing was carried out at the Gamma Irradiation Facility at Sandia National Laboratories.
One of the key challenges of this unique experiment is instrumentation selection. Instrumentation on the HTS coils under test are exposed to gamma radiation up to doses of 10MGy while at cryogenic temperatures. The selection of sensors and design of instrumentation hardware in the cryostat was critical to deliver accurate and reliable experimental results.
This poster will focus on the selection and performance of key components, including temperature and magnetic field sensors, for operation in a cryogenic and gamma radiation environment.
Speaker: Vicky Bayliss (Tokamak Energy) -
187
Low Temperature Hybrid Graphene-Silicon Charge Amplifier
This study presents a novel charge amplifier design top operate cold (77K), tailored for amplifying signals originating from devices such as Silicon Photomultipliers (SiPMs) and High Purity Germanium Detectors (HPGe), commonly employed in fundamental physics experiments. The distinctive feature of the proposed charge amplifier lies in its utilization of a front-end transistor fabricated from graphene, integrated with a silicon-based differential amplifier. The graphene device employed is a Graphene Field-Effect Transistor (GFET), functioning analogously to a conventional Field-Effect Transistor (FET) but with the unique capabilities provided by graphene.
This device harnesses the inherent advantages of an FET, including high input impedance, while capitalizing on graphene-specific benefits such as low noise and high conductivity. These attributes make it particularly well-suited for the targeted application, enhancing overall performance and meeting the stringent requirements of experiments in fundamental physics.Speaker: Marcos Turqueti -
188
Mismatch and retention time analysis of cryo-DRAMs down to 4 K
Static random-access memories (SRAMs) are commonly used in high access-rate applications due to their fast operation and compatibility with CMOS logic. Nevertheless, their significant power consumption and limited storage density render them impractical, particularly for cryogenic applications where power constraints hinder scalability. In contrast, dynamic random-access memories (DRAMs) can address the issue of density by storing data as a charge on a capacitor (or parasitic capacitor), requiring fewer transistors per memory cell. However, the need for frequent refreshing to overcome leakages on the charge-storing node leads to a significant power consumption. It is widely recognized that at cryogenic temperatures (CT), the subthreshold slope (SS) decreases, while the threshold voltage of CMOS increases, aiding in reducing subthreshold leakage. Additionally, the mismatch in different transistor parameters also increases. Recently, there has been a growing interest in determining whether DRAMs can outperform SRAMs at CTs based on criteria such as power consumption, retention time, and latency or access time. Known for their density benefits, DRAMs have been observed to surpass SRAMs at 4 K due to the significant decrease in leakage current. This improvement is attributed to the inherent nature of DRAM cells, which rely on charge storage mechanisms rather than continuously powered latches like SRAMs. At lower temperatures, the reduction in thermal energy suppresses carrier generation, resulting in decreased leakage currents in DRAM cells. Consequently, DRAMs exhibit better energy efficiency and greater reliability compared to SRAMs in cryogenic settings. However, one notable limitation is the mismatch in retention time among DRAM cells operating at CTs. To date, there have been no studies reporting on the impact of mismatch on DRAM performance as it is cooled down to 4 K. This study delves into this effect by examining the mismatch through an array of 9x10 DRAM cells. The FPGA generates the read/write/refresh sequence for the DRAMs die mounted in a Lake shore probe station. When the read signal is activated, it triggers an internal counter that stops once the DRAM output falls below a set threshold (600 mV in this particular study). The supplied digital voltage ranges from 1 V to 1.4 V to examine how it affects the retention time of the cells and the mismatch across the entire array. Due to the anticipated rise in the threshold voltage at 4 K, the operational cells start functioning at an elevated supply voltage of 1.2 V compared to room temperature (RT) operation. The decrease in subthreshold leakages at 4 K and the increase in the threshold voltage of the transistors are two conflicting mechanisms that can influence whether the retention times will increase as the temperature drops or not. This effect becomes noticeable when examining the data collected for three different VDD values: 1.2 V, 1.3 V, and 1.4 V at two temperatures, 293 K and 4 K. At 4 K, the retention times decreased by half when supplied at 1.2 V, while at 1.3 V, there was a 200 % increase in retention times, and at 1.4 V, the retention times increased by approximately 225 %. Another parameter examined in this research is the mismatch not only at the pixel level but also among the various cells of the 90 pixel array. The former is assessed by conducting numerous acquisitions and deriving the standard deviation () of the normal distribution of retention times for the same cell. The results show that at RT the deviation is 0.28 ms independently of the supply voltage value. After the cooling process, there is an increase in mismatch among different pixels by 100 %, 25 %, and 100 % at 1.2 V, 1.3 V, and 1.4 V, respectively. This data offers valuable insights into the retention time characteristics of DRAMs and the impact of cooling on mismatch, which is essential for designers, particularly those considering the use of memory cells in cryogenic applications like quantum computing or SNSPD arrays that require operation around 4 K.
Speaker: Jad Benserhir -
189
Non-Destructive Measurement of Electrical Conductivity in Thin-Film Nb coated Cu for SRF Cavities using Planar Eddy Current Sensors
Superconducting Radio Frequency (SRF) cavities are critical components in particle accelerators, responsible for accelerating charged particles to high energies. Traditionally, these cavities use bulk niobium (Nb) due to its exceptional superconducting properties at cryogenic temperatures. However, limitations like localized defects can hinder performance by causing power absorption and abrupt transitions (quenching) from the superconducting state. To address these limitations, thin-film Nb superconductors deposited on copper (Cu) substrates are emerging as promising alternatives. These thin films offer several advantages, including high thermal conductivity, high critical fields, and reduced Nb usage. Assessing the purity of Nb in SRF cavities is crucial for optimal performance. A key parameter used for this purpose is the Residual Resistance Ratio (RRR). This ratio compares the material’s resistance at cryogenic temperatures to its room-temperature resistance. Higher RRR values generally indicate higher purity and, consequently, better superconducting properties. While established methods like 4-probe DC and
AC measurements effectively measure RRR in bulk Nb, they are not suitable for thin films. This lack of a suitable, non-destructive technique poses a significant challenge in characterizing thin-film Nb superconductors for SRF applications. This study presents a non-destructive approach for measuring the electrical conductivity (and hence RRR) of thin-film Nb superconductors. The method utilizes planar eddy current sensors, which interact with the sample without any physical contact, making them ideal for delicate thin films. The study investigates the change in the impedance of the sensor coil when placed near a thin-film Nb-coated Cu sample. As the sample is brought closer to the coil, eddy currents are generated within the Nb film due to the interaction with the sensor’s electromagnetic field. These eddy currents, in turn, affect the impedance of the sensor coil. The focus of the study lies on the frequency dependence of the resistive component of the impedance. This component directly relates to the sample’s conductivity and offers valuable information for characterizing the Nb film. The reactive component, on the other hand, provides less information. Experiments show a distinct minimum in the difference between the resistances measured with the Nb-coated Cu target and the Cu substrate only called ∆R. This minimum is observed consistently across various Nb film thicknesses (ranging from 0.3 to 3 micrometers) and temperatures (both room temperature and cryogenic temperatures). This unique signature allows for the extraction of conductivity data using a well-established theoretical model. This work presents experimental data on the difference in resistance ∆R measured at various frequencies for thin-film Nb coatings of different thicknesses on Cu substrates. The measurements were conducted at both room temperature and cryogenic temperature. The electrical conductivity of the Nb films was then determined by analyzing the minimum point observed in the ∆R data using the theoretical model.Acknowledgments
The Science and Engineering Research Board, Government of India funded this work (Reference Grant No. CRG/2021/000398).Speakers: Namitha Venugopal (Cochin University of Science and Technology), Pankaj Sagar (Cochin University of Science and Technology) -
190
Optimising grip designs for the tensile testing of advanced engineering materials at cryogenic temperatures
The aviation industry’s transition to using hydrogen as a sustainable fuel is undoubtedly pushing the boundaries when it comes to materials that can withstand the cryogenic temperatures that liquid hydrogen (LH2) must be sustained at. To develop such materials, it is imperative that testing and characterisation methods are fit-for-purpose and accurately measure the required properties at the associated environmental conditions. For decades, there has been a lot of research generated around the nuances of cryogenic mechanical testing of materials, mainly for the space/aerospace industries, as well as for characterising superconductive materials for particle physics. The typical test setups mainly consist of a load frame (commonly a universal test machine) and the device that is responsible for cooling the test space down to the desired cryogenic temperature. Regarding the latter, a standard environmental test chamber can be used in conjunction with liquid nitrogen evaporative cooling to achieve temperatures as low as ~100K. For reaching lower temperatures, a cryostat operating with liquid nitrogen or helium is typically required. When it comes to mechanical testing however, the method of the load introduction to the specimen is also critical. Ensuring that the specimen is well aligned with regards to the load direction and that the load is exerted fully on the specimen without any relative motion or compliance throughout the fixture is of outmost importance. Gripping the specimen is especially challenging at cryogenic temperatures, as the fixtures and jigs typically used for room temperature testing, are not suitable for low temperature use. Therefore, there are numerous issues that can be observed when testing with non-cryogenic rated equipment at cryogenic temperatures. The most common, would be the slipping of specimens in the grips because of trapped moisture that has iced, as well as loosening of any threaded and load bearing connections because of thermal contraction of the different components that are commonly made from different materials. In this work, a novel gripping system has been developed, allowing for tensile testing of advanced engineering materials at cryogenic temperatures. Two different design approaches have been proposed for optimising the test procedures and are hereby presented. The performance validation is done in two tests setups. The first consists of an environmental chamber where gaseous nitrogen is used to achieve a target temperature of 110K, while the second one is in a liquid flow cryostat where the test space is submerged in liquid nitrogen at 77K. The requirements, and modifications necessary for reaching 20K are being investigated, with heater elements being introduced to bring liquid helium to a gaseous state and achieve the temperature of liquid hydrogen (~20K).
Speaker: Nassos Spetsieris (National Physical Laboratory) -
191
PLASTIC FLOW INSTABILITY IN AUSTENITIC STAINLESS STEELS AT A WIDE RANGE OF TEMPERATURES: FROM MACROSCOPIC TESTS TO MICROSTRUCTURAL ANALYSIS
Austenitic stainless steels (ASS) of AISI 304 (EN X5CrNi18-10), AISI 316L (EN X2CrNiMo17-12-2), AISI 316LN (EN X2CrNiMoN17-11-2) grades characterized by excellent mechanical properties and corrosion resistance in a wide temperature range (4 K - 900 K). Thus, they find numerous applications in the automotive, aviation, nuclear and chemical industries as well as in space and superconducting technology where temperature changes from room temperature, even to absolute zero. The collars of dipole magnets in LHC, the steel expansion joints or the jacket of the Cable-In-Conduit Conductors (CICC) in ITER are good examples of austenitic stainless steel applications. The correct design of structural elements and instrumentation that operate without breakdown throughout the service time requires an understanding of the deformation and fracture mechanisms inherent in a wide range of temperatures, from near 0 K to room temperature. The lack of in-depth recognition of these processes has become a critical problem for large research infrastructures such as LHC or ITER. The plastic behaviour of metastable austenitic stainless steels is controlled by temperature. It is seen when comparing the stress-strain curves of ASS for a tensile test at 4 K, 77 K and at room temperatures. During tensile tests of austenitic stainless steels at cryogenic temperatures (4 K), unusual behaviour is observed – plastic flow instability. This effect also called a discontinuous plastic flow, is reflected by stress oscillations on the stress-strain curve. Moreover, the Lüders-type effect is observed. At room temperature, in turn, for a 304 specimen with a long enough gauge length and below critical strain rate, the plastic front propagation occurs. Therefore, the different modes of plastic flow instability in austenitic stainless steels are observed depending on the temperature. When temperature approaches absolute zero the tendency of metastable ASS to diffusion-free phase transformation during plastic deformation increases. It is experimentally proven that in ASS at cryogenic temperatures, the deformation-induced phase transformation is coupled with discontinuous plastic flow. The work aims to investigate the plastic flow and hardening processes of metastable 304 and 316L steels in the context of 316LN, stable due to diffusion-free martensitic transformation. The basis is in-situ tensile tests at room temperature, registered using the DIC and EBSD methods. In this way, the development of deformation fields and the accompanying evolution of the microstructure are identified. The coupling of the observations carried out on two levels allows us to explain the differences in the mechanical and microstructural response of the considered steel grades.
DIC-enhanced experimental platform with a multi-detector array for materials testing at cryogenic temperatures
The first time the 3d full-field strain evolution was captured during a tensile test at liquid nitrogen (77K). The DIC-enhanced experimental platform with a multi-detector array is used during tensile tests of advanced materials at temperature near to 0K. The unique research tool is equipped with: (i) thermistors system to measure temperature distribution, (ii) a force link to measure applied force, and (iii) the acoustic emission system. The tested specimen will be immersed in a glass cryostat with an active and passive insulation system to maintain thermal stability during tests at 4K. The signals from multi-detector system will be simultaneously recorded together with strain field evolution background. Based on the experimental results the deformation behaviour of austenitic stainless at cryogenic temperatures can be identified. Moreover, the constitutive models of advanced materials near to 0K will be validated.Speaker: Jakub Tabin (Institute of Fundamental Technological Research, Polish Academy of Sciences, 02-106 Warsaw, Poland) -
192
Status of cryostat design for cryogenic payload suspension studies for the Einstein Telescope
The Einstein Telescope (ET) is a third generation gravitational wave detector planned in Europe, combining a low-frequency (LF) and a high-frequency (HF) laser interferometer. Cryogenic operation of ET-LF in the temperature range of 10 K to 20 K is essential to suppress the suspension thermal noise, which dominates the detection sensitivity at
frequencies below 10 Hz. This requires suspension materials with high thermal conductivity and low mechanical dissipation at cryogenic temperatures. The baseline design currently considers two suspension concepts, using monocrystalline suspension fibers made of silicon or sapphire, and/or a thin-wall titanium suspension tube filled with static He-II. The mechanical Q-factor provides physical insight into dissipative mechanisms of material samples and their applicability as cryogenic suspensions in gravitational wave detectors. It is measured by the ring-down method, exciting the suspensions to resonant vibrations and analyzing the decay time. For this purpose, a test facility is being designed that enables full-size studies with various suspension materials and geometries. This includes also the integration of a noise-free He-II supply for investigating dissipation mechanisms in the static He-II column inside suspension tubes, which is a new field of research. We present the design progress,including specific design conditions imposed by the experimental campaigns.Speaker: Xhesika Koroveshi (Karlsruhe Institute of Technology (KIT)) -
193
The design and experimental research of a simple multiaxial test apparatus at cryogenic temperature
Structural materials are often in a complex stress environment during cryogenic service. For example, superconductors and structures will be subject to support load, thermal residual stress, and electromagnetic force. Composites used for storing cryogenic liquids also bear with the joint action of the axial and radial load produced by internal high pressure. The complex stress state has a significant role in the failures of materials, and thus it is important to investigate the deformation and fracture behaviors of materials under complex loads at cryogenic temperatures before the practical applications. However, independently applying multi-axial loads to specimens at cryogenic temperatures is challenging and costly. In this paper, a three-axis loading device based on the uniaxial tensile machine was designed. The three-axis loading device converts the uniaxial motion into the triaxial motion with displacement ratio control, capable of applying orthogonal compression, tensile compression, and tensile bending loads to the specimen at cryogenic temperatures. The shape of the specimen is designed based on orthogonal patterns. The device can be adjusted to realize the application of loads with different displacement ratios such as 1:1:1, 1:2:2, 1:0.5:0.5, and so on. Finally, the feasibility of the device was verified by simulation and cryogenic temperature experiments, especially at 77 K and 4.2 K.
Speaker: Yining Huang (Technical Institute of Physics and Chemistry, CAS) -
194
Two-dimensional discrete dislocation dynamics simulation of 316LN discontinuous plastic flow under cryogenic tensile behavior
Abstract: The serrated yielding (discontinuous plastic flow, DPF) of metallic materials at cryogenic temperatures has always been a research hotspot in the field of plastic deformation of cryogenic-temperature materials, with this topic typically confined to phenomenological theory. This study simulated the cryogenic-temperature dislocation glide and vacancy diffusion by establishing a two-dimensional polycrystalline structure of 316LN within the physical framework of discrete dislocation dynamics (DDD). The dependency relationship between dislocation glide velocity and temperature has been established. The model indicates that the accumulation of dislocations at static obstacles continues to increase below 35K with the decrease of stacking fault energy, which causes the continuous increase in local creep stress until the failure limit is reached. It contributes to the macroscopic stress-strain curve to exhibit discontinuous plastic flow, i.e., serrated yielding.
Speaker: Liancheng Xie
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178
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Wed-Po-2.3: Cryogenic Applications & Cryocoolers 1 Poster area
Poster area
Convener: Torsten Koettig (CERN)-
195
A 15 W@76.8 K lightweight Pulse Tube Cryocooler operating at 100 Hz
Abstract. In previous research, we have developed a high frequency lightweight pulse tube cryocooler, which can obtain a cooling capacity of 10 W at 80 K at the operating frequency of 126 Hz and input power of 250 W. Recently, we further improved the performance of this pulse tube cryocooler by optimizing the phase shifters and changing the cold finger structure. In this paper, the parameters of the optimized pulse tube cryocooler are introduced and tested. This pulse tube cryocooler has a total weight of 4 kg, a cold finger diameter of 22 mm and a length of 48 mm. The regenerator is filled with #635 stainless steel screens. At an operating frequency of 100 Hz, an input power of 250 W, a hot end temperature of 300 K and the charge pressure of 6 MPa, a minimum temperature of 35.2 K and a cooling capacity of 15 W at 76.8 K can be achieved. The relative Carnot efficiency is 17.4%.
Keywords: pulse tube cryocooler · phase shifters · 6 MPa · 100 Hz · 15 W@76.8 KSpeaker: Min Gao (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China) -
196
A 150 K High Frequency Micro Pulse Tube Cryocooler
A micro coaxial pulse tube cryocooler has been developed to meet the space application requirements of high operating temperature infrared detection. To optimize the cooling performance of the cryocooler, the experiments were designed to study the coupling between the compressor and the cold fingers. Driven by a double-piston opposed linear compressor with the mass less than 200 g, this cryocooler uses the inertance tubes and buffer as phase shifter and has the regenerator with a diameter of 10 mm. The effect of the length of regenerator and inertance tube on cooling performance at different frequencies were investigated through a series of experiments. This cryocooler can provide more than 0.5 W at 150 K with a 10 W input electric power. This paper describes the coupling characteristics and presents test data of performance in detail.
Speaker: Ziyao Liu (Technical Institute of Physics and Chemistry, CAS) -
197
A high efficiency single-stage 30 K pulse tube cryocooler
The 40 K low-temperature environment is crucial for the operation of long-wave infrared detectors. To explore higher efficiency in 40 K cryocoolers, this paper designed and manufactured a single-stage 40 K pulse tube cryocooler. Through rigorous experimentation, we determined the optimal inertance tube and charging pressure for the cryocooler, subsequently subjecting it to performance testing. Additionally, to assess its adaptability to diverse environmental conditions, we conducted thorough evaluations of the cryocooler's cooling performance across a range of hot-end temperatures. Notably, when heat was rejected into ambient temperature environment, with an input electrical power of 200 W, the cryocooler obtained a cooling capacity of 3.2 W/40 K, reaching a relative Carnot efficiency of 10.3%.
Speaker: Yanen Li (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
198
A single-stage high frequency 40K pulse tube cryocooler
To develop a long-wavelength infrared detector, a 40K pulse tube cryocooler is needed to provide reliable and low-noise cooling power. Traditionally, it is generally believed that to improve efficiency, a 40K pulse tube cryocooler needs to operate at around 40Hz. However, low frequency cryocoolers are heavier and are not preferred for use on satellites. In this paper, a lightweight pulse tube cryocooler working at 88Hz is designed. The inertance tubes, along with the reservoir, serve as the only phase-shifter to guarantee the stability. Currently, the cryocooler has achieved a no-load lowest temperature of 26 K. It has a cooling capacity of 7W at 40K while operating at 500W of electrical power, and it weighs only 8kg. The efficiency relative to the Carnot efficiency was approximately 8.8%. The performance characteristics of the designed cryocooler are presented in detail.
Speaker: Lingjiao Wei (Technical Institute of Physics and Chemistry, CAS) -
199
Design of a moving magnet type free piston Stirling cryocooler for futuristic space application
The usage of free-piston Stirling cryocoolers is increasingly prevalent in space technology, particularly to cool infrared sensors on satellites and space related devices. The distinctive characteristics of free-piston Stirling cryocoolers render them highly suitable for cooling these infrared sensors, primarily due to their effective and dependable cooling capabilities, which are crucial for ensuring optimal sensor performance. Free piston Stirling cryocoolers are capable of producing the cooling effect that ranges from milli watts to few watts according to the cooling process. The weight constraint of the cryocoolers is very important for space applications. Therefore, miniature type Stirling cryocoolers are suitable for space applications. In this study, an integral type free piston Stirling cryocooler was designed and optimized by using SAGE software. The design features an electromagnetically driven, resonating mechanism with a clearance seal setup to ensure optimal efficiency, COP, and minimal system vibration. The engineered integral type free piston Stirling cryocooler can achieve a no-load temperature of 50 K, with a corresponding refrigeration capacity of 1000 mW and upratable to 1500 mW at 80 K. Initially, a parametric evaluation of the cryocooler was carried out to assess the impact of various design features and operational parameters. The parametric analysis was done and focused primarily on factors such as regenerator wire mesh geometry, phase angle, and displacer clearance, with regard to their influence on the cooling performance of the cryocooler. For the compressor part of the integral type free piston cryocooler, the liner motor required was designed using Ansys Maxwell software. In this context, a linear motor of the moving magnet type was chosen. The moving magnet-type linear motor generates axial forces by means of Lorentz force, propelling the piston to compress the working fluid. An advantageous aspect of employing linear motors in cryocoolers is the pure rectilinear motion generated by them which further mitigates wear and tear, ultimately leading to an extended operational lifespan. The study was also conducted by replacing the single mesh regenerator with a multi-mesh regenerator. Parametric analysis of the modified integral type cryocooler with a multi-mesh regenerator was also conducted to find out the optimum combination of the multi-mesh regenerator to improve the performance of the system. From the analysis, it was evident that in an integral type cryocooler with a multi-mesh regenerator, the performance of the system increases when the coarser mesh is arranged at the hot side and the finer mesh is arranged at the cold side of the regenerator tube.
Speaker: Biju T Kuzhiveli (National Institute of Technology Calicut) -
200
Evaluating Fluid-Induced Vibrations in Sorption-Based JT Coolers
The ETpathfinder (ETPF) is a scaled prototype of the Einstein Telescope Gravitational Wave Observatory (ET), aimed at testing and refining the necessary technologies for gravitational wave detection. The ETPF utilizes two Fabry-Perot Michelson Interferometer arms with mirrors that are cryogenically cooled using liquid nitrogen (LN2). One of these arms requires additional cooling of its mirrors to about 10 K, essential for achieving the desired sensitivity levels in the detectors. This extra cooling is crucial for the accurate measurements demanded by third-generation laser-interferometry detectors in the ETPF and later in the ET, necessitating a cooling system that emits minimal vibrations. To address this requirement, the University of Twente has already proposed a modular cryochain design, employing a combination of sorption-based compressors and Joule-Thomson (JT) cold stages. This design features a parallel cascade configuration with stages at 40 K (neon), 15 K (hydrogen), and 8 K (helium), providing cooling powers of 2.5 W, 0.5 W, and 0.05 W, respectively. The cooler chain is advantageous due to its minimal vibration levels, achieved by having no mechanical moving parts. This characteristic is critical to ensure that the vibration levels at the 8 K cold-tip do not exceed the seismic background vibrations at the ETPF site. Specifically, these vibrations must stay below the environmental vibration threshold of 30 nm peak-to-peak, with an amplitude spectral density of 4 nm/Hz within the vital 2 - 20 Hz bandwidth. Therefore, evaluating the low but present vibrations emitted by the sorption JT cooler is essential. The predominant vibrations arise from fluid flow in the various JT cold stage components, such as tubing, bends, JT restriction devices, and evaporators. Our initial approach involved evaluating these fluid-induced vibrations and forces through fluid-structure interaction (FSI) simulations and preliminary room temperature measurements. This foundational research lays the groundwork for more detailed future characterizations of relevant fluid-induced vibrations in sorption-based JT coolers.
Speaker: Arvi Xhahi -
201
Evaluation of vibration characteristics of a 1.5W 4K pulse tube cryocooler with improved first stage cooling capacity
Pulse tube (PT) cryocoolers are a type of cryogenic refrigerator used to achieve ultra-low temperatures of approximately 4.2K. They are renowned for their low vibration characteristics during operation, as they lack an internal displacer, which is present in GM cryocoolers. As a result, PT cryocoolers are extensively utilized in various applications, including dilution refrigerators for quantum computers and physical property measurement systems that require minimal mechanical vibration-induced noise. In the field of physical and chemical applications, there is a growing need for enhanced first stage cooling capacity. To address this demand, Sumitomo Heavy Industries has developed the RP-182C2S as an upgrade to our existing 1.5W 4K PT cryocooler, the RP-182B2S. This upgrade offers a substantial improvement in first stage cooling capacity, increasing it from 36 W at 48K to 42W at 45K, while maintaining the second cooling capacity and interface on the cylinder side. From a vibration standpoint, increasing the cooling capacity can potentially have negative effects on vibration characteristics. This is primarily due to factors such as the larger cylinder size and changes in operating pressure conditions. Another factor to consider is the alteration in the gas intake and exhaust direction of the cold head piping, transitioning from a horizontal design (used in 1.0W 4K PT cryocoolers) to a vertical design (implemented in 1.5W 4K PT cryocoolers). These modifications may also impact the vibration characteristics. Moreover, while vibration measurements of cryocoolers are typically conducted in room temperature environments, it is essential to perform such measurements in cryogenic environments to achieve more accurate and realistic results. In this study, we developed a test bench enables vibration measurements in a second stage condition at 4.2 K. We used this setup to conduct vibration measurement on the RP-182C2S, the upgraded version of the current 1.5W 4K PT cryocooler (RP-182B2S) , as well as the RP-082B2S, a smaller 1.0W 4K PT cryocooler, which served as the comparative cryocoolers. Our aim was to evaluate the impact of the upgrade and changes in piping direction on the vibration characteristics of PT cryocoolers.
Speaker: Ryoya Sato (Sumitomo Heavy Industries, Ltd.) -
202
Experimental optimization of phase for a 20K thermal-coupled two-stage high-frequency pulse tube cryocooler
Abstract: With the rapid advancement of space technology, there is a continuous increase in demand for long-wave infrared detection devices, leading to higher requirements for two-stage pulse tube cryocoolers operating at liquid hydrogen temperatures. The performance of the cryocoolers is closely related to the inertance tube size. In order to improve a two-stage thermal-coupled pulse tube cryocooler’s performance in the liquid hydrogen temperature range, this study conducted phase optimization experiments, analyzed the effects of different inertance tube combinations on the cryocooler’s performance. The optimal operation frequency, power factor, no-load cooling temperature, cooling capacity and rCOP were compared for cryocoolers with different inertance tube combinations. After preliminary optimization, the cryocooler achieved 586mW/20K cooling power with a total electric power consumption of 185W, resulting in a rCOP of 4.43%.
Speaker: Yanjie Liu (Technical Institute of Physics and Chemistry, Chinese Academy of Science) -
203
Performance improvement of low pressure interance pulse tube cryocooler
Abstract: Pulse tube (PT) cryocoolers are versatile systems which can be used, among other applications, for cooling sensors down to very low temperatures in order to increase their sensitivity through the strong reduction of the thermal background noise of measurements. Therefore, PT cryocoolers must be miniaturized and operate without bringing vibrations into the total system. Thus, the mechanical pump usually used in these systems as the compressor stage, could be replaced by a Knudsen pump whose principle is based on the thermal transpiration obtained by applying exclusively a tangential temperature gradient along a surface, without the action of any moving part or external pressure gradient. However, as rarefaction conditions are needed in the gas flow for the thermal transpiration effect to be efficient, limited pressure levels can be obtained at the pump outlet.
To develop such a PT cryocooler, numerical studies have shown their importance in predicting the influential parameters on flow inside the pulse tube. The main objective of this work is thus to use CFD methods to examine the cooling performance at low charging pressure and optimize the design parameters of miniaturized PT cryocoolers. The operating pressure has been set to 2 bar with a pressure amplitude ranging between 1 and 2 bar. The numerical studies were performed using two-dimensional axisymmetric analysis of an inertance pulse tube cryocooler (IPTCC) with the help of the commercial CFD tool ANSYS FLUENT. As a fundamental case, the geometrical set-up investigated by [1] is considered. After achieving periodic steady state, numerical results have been compared. The numerical studies at low pressure have shown that cooling performance can be improved by increasing the pressure ratio. In addition, it was demonstrated that the recirculation flow pattern observed near the cold end of the pulse tube was due to the scaling down of individual part components of the IPTCC, their aspect ratio (length to diameter ratio) being kept similar. This recirculation zone increases the flow velocity near the cold end and reduces the cooling performance. In this study, the design parameters (such as inner diameter, length) of part components have been carefully modified to develop uniform flow with the aim to improve the cooling efficiency of the device.References:
[1] T.R. Ashwin, G.S.V.L. Narasimham, and Subhash Jacob. CFD analysis of high frequency miniature pulse tube refrigerators for space applications with thermal non-equilibrium model. Applied Thermal Engineering, 30(2):152–166, 2010Speaker: Maimuna Torsa Rafique (Karlsruhe Institute of Technology) -
204
Post-assembly adjustable gas-gap heat switch
A gas-gap heat switch is a device of which the thermal conductance is controlled by regulating the pressure of a working gas in a gap between warm and cold surfaces. The on-state conductance is largely determined by the gap distance, and as such minimization of the gap is often a design objective. By pumping out the gas or adsorbing it onto a getter, there is virtually no conductivity through the gas and, therefore, the off-state conductance is determined by the enclosing structure. This enclosing structure has to hermetically seal the gas space, and to mechanically support and separate the warm and cold sides of the switch.
In the process of assembly of the heat switch, twisting and tilting of the planes or the hermetic seal could bring the opposite surfaces in thermal contact, resulting in failure of the switch. This may be prevented by taking less risk in the design by increasing the gap, in turn reducing the on-state conductance and thus degrading the performance. We present a gas-gap heat switch design using bellows as the hermetic seal. The position of the planes can be adjusted using spacer rods after welding the switch shut. This avoids having to derisk in the design process, allowing for narrower gaps and a very high on-state performance.Speaker: Koen Lotze (University of Twente) -
205
The experiments of a two-stage pulse tube cryocooler with pressed Er-plated screen as regenerator material
Regenerator is an important part in regenerative cryocoolers, which is the main part to provide cooling power through the heat exchange of the helium and the matrix inside that. When the temperature is below 20 K, the specific heat capacity of the helium increases and exceeds that of the stainless steel, which limits the process of heat transfer in the regenerator and limit the increase of the cooling power of cryocoolers at 20 K. In order to increase the cooling power of the two-stage thermal-coupled pulse tube cryocooler working in the 20K temperature zone, the regenerative material was optimized in this paper. Stainless-steel screen, Er-plated stainless-steel screen and pressed Er-plated stainless-steel screen were used as the regenerative material. The porous parameters and the experimental results of these kinds of materials were compared.
Speaker: Yanjie Liu (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
206
Theoretical and experimental study of a two-stage coaxial type Stirling pulse tube refrigerator
The Stirling pulse tube refrigerator is regarded as one of the development directions of space refrigerators due to its advantages of no moving parts at the cold end, low vibration, light mass and long life. The Stirling pulse tube refrigerator in the liquid hydrogen temperature region, as the front refrigerator of the pulse tube refrigerator in the liquid helium temperature region, will have a direct impact on the cooling capacity and efficiency of the third-stage pulse tube refrigerator in the liquid hydrogen temperature region. In this context, this paper carries out theoretical and experimental research for the two-stage coaxial stirling pulse tube cooler in liquid hydrogen temperature region, and realizes the cooling capacity of 0.5W@30K with the input electric power of 400W, which lays the foundation for the next step of adding the third-stage pulse tube refrigerator to realize the temperature of liquid helium temperature region.
Speaker: Chushu Fang
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195
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Wed-Po-2.4: Instrumentation & Process Control Poster area
Poster area
Convener: Takanobu Kiss-
207
Analysis of combined air-breathing and rocket engine for single stage to orbit vehicle
Numerous studies are currently being carried out on a global scale to develop advanced technological solutions for Single Stage To Orbit (SSTO) and hypersonic flights. These technologies are highly demanding and challenging due to the technical requirements involved especially the design of the propulsion system for the spacecraft and aircraft. Synergetic engine, which uses Rocket Based Combined Cycle (RBCC) technology with air-breathing propulsion in combination with rocket propulsion is proposed to have the potential for SSTO and hypersonic travel. This engine works in two different modes - Air-breathing mode and Rocket mode. In the air-breathing mode, the engine makes use of the oxygen present in the atmosphere rather than using a separate oxidizer tank starting from the takeoff itself. Despite efforts to minimize its usage, a certain quantity of onboard oxygen is required to sustain the necessary thrust. Once it gains sufficient velocity and altitude, the engine switches from the air-breathing mode to the rocket mode where the onboard oxygen supply is utilised at higher rates. In the air-breathing mode, the air taken in through the intake section of the engine is utilised as the oxidiser in the combustion chamber of the rocket and gaseous hydrogen is used as the fuel. The combustion products are then expanded through the rocket nozzle to generate thrust. Once a predetermined velocity as well as altitude is reached, the intake starts to close. As the intake is closing, the demand for the separate oxygen supply gradually increases to maintain the thrust. Eventually, the engine will be purely switched into the rocket mode. The air intake is eventually shut down and only the onboard oxygen will be used for the combustion process.
This engine technology under development, makes use of cryogenic propellants hydrogen and oxygen along with an intelligent, calibrated and timely supply of the intake air to propel. The basic thermodynamic cycle of this multifluid system is available in the open literature, but the detailed analysis of this engine technology is limited. The present study is devoted to investigating the multifluid thermodynamic lines of the synergetic engine in its air-breathing configuration by incorporating the possibility of regenerative cooling of the nozzle. A flight condition with an altitude of 25 km and Mach number 4 is being considered for the analysis. The existing thermodynamic circuit is modified and redesigned to incorporate the changes. The different fluid lines involving air, helium, hydrogen, oxygen and pre-burned exhaust gas are being analysed. For each of these lines, the temperature, pressure, specific heat at constant pressure, specific enthalpy, mass flow rate, heat transfer rate, and work transfer rate are calculated at different stations. The stations of the loop are analysed based on the physics and reference literature, with suitable assumptions to reduce the complexity. Governing equations of flow - conservation of energy and isentropic relations have been used across the steady flow devices for calculations. Darcy-Weisbach equation with the Swamee-Jain equation for the friction factor is being considered for calculating the pressure drop in the regenerator coil. The combustion chambers of the system are analysed using NASA CEARUN rev4. Finally, the rocket nozzle thrust is determined, and a simplified computer model of the system is created. This work proposes an interlinked thermodynamic loop towards the development of a synergetic engine with cryogenic propellants that can find mutual property variations at each location corresponding to different inlet conditions and component specifications.Keywords: Rocket Based Combined Cycle (RBCC), Synergetic Air-Breathing Rocket Engine (SABRE), Single Stage To Orbit (SSTO), Air-breathing rocket engine
Speaker: Biju T. Kuzhiveli (National Institute of Technology Calicut, India) -
208
Automation of Superconducting Cavity Cooldown Process Using Two-Layer Surrogate Model and Model Predictive Control Method
Superconducting cavity is the key equipment of the superconducting accelerator, which provides higher acceleration voltage and higher frequency power per unit length, and saves equipment space. Superconducting cavities need to be gradually cooled from ambient temperature (300K) to the superconducting temperature (4.2K or below) during the test and operation. The temperature difference on the cavity must be strictly limited during the cooldown process to prevent excessive thermal stress on the surface of the superconducting cavity. Since this cooldown process for the superconducting cavity is a typical large hysteresis, non-linear process that is difficult to control automatically using decoupled proportion integral derivative (PID) methods directly, a less efficient manual control scheme is normally adopted. In this paper, 3D numerical simulation, 1D pipe and 0D tank model with artificial neural network (ANN) were combined to generate a two-layer surrogate model that can balance computational accuracy and speed, to improve the automation and cooling efficiency of the superconducting cavity cooldown process. In order to achieve automatic control of the cooling procedure for the superconducting cavity, a model predictive control (MPC) approach was also built on the basis of this two-layer surrogate model. According to the results of the experiment test, the improved method could realize a quick and smooth cooldown process of the superconducting cavity, during which the temperature difference on the cavity could satisfy the requirements. Additionally, the improved automatic cooldown method was more adaptable and saved 40% more time than the original manual control method. The foundation for a more intelligent automated control of future large cryogenic systems or other system with the large hysteresis, non-linear properties, was laid.
Speaker: Keyu Zhu (中国科学院高能物理研究所) -
209
Capacitance-based mass flow rate measurement of 2-phase hydrogen in a ½ inch tube.
Mass flow rate is a critical measurement parameter when designing cryogenic hydrogen fluid systems. It is vitally important not only in custody transfer applications for calculating financial obligations but also in fundamental heat transfer research and fluid system design applications to optimize chill down performance, maintain thermal equilibriums, and provide feedback control for pumps and valves. However, due to the large temperature differential between cryogenic fluids and the environment, there is often unavoidable multiphase flow during system chilldown or even in steady state operation. Current available measurement techniques are not equipped to deal with the complex multiphase flow inherent in cryogenic fluid systems. Mass flow measurement inaccuracy due to multiphase flow can cause financial loss, system instability, and even component failure, resulting in a strong market demand for a multiphase cryogenic mass flow meter to optimize and control sophisticated and costly cryogenic systems. This paper presents a solution in the form of a novel capacitance-based technique for measuring the multiphase mass flow rate of cryogenic hydrogen in a terrestrial environment. The device was calibrated and tested on a ½” tube multiphase hydrogen flow loop at a cryogenic hydrogen test facility. An error of ±2% full scale was achieved across a range of flow conditions, including transient and steady states.
Speaker: Benjamin Straiton (Tech4Imaging) -
210
Commissioning of the Cryogenic control system for Cryomodules at ESS SRF Linac
The Cryomodules are critical components in the European Spallation Source (ESS) accelerator, playing a crucial role in connecting spoke cavities to high-beta elliptical cavities in the SRF Linac. These Cryomodules provide the necessary environment for operating, Spoke (Spk) cavities, Medium-Beta (MBL) and High-Beta (HBL) elliptical cavities, which are responsible for accelerating protons from 90 MeV to 2.0 GeV. The Cryomodule houses two double-spoke cavities per Spoke cryomodule and four elliptical cavity packages for MBL and HBL cryomodule, which need to be cooled to 2K to become superconductive and accelerate the beam. There are 13 SPK, 9 MBL and 21 HBL cryomodules to be installed and commissioned on the ESS accelerator.
An automation control system was developed to control and operate the cryogenic circuits, consisting of temperature, pressure, level, and flow sensors, heaters, and automatic valves connected to a control system based on a Programmable Logic Controller (PLC) integrated into EPICS through the Controls Network.
The commissioning of the cryogenic control system involves checking all sensors, actuators, and closed-looping based logic, including temperature curve validation, pressure sensor calibration, and valve initialization, to certify the proper functioning of all components and all special automatic functions including Operator Panel Interface (OPI) connection and deployment. The operationalization started in spring of 2023 with SPK-110 and MBL-020. Subsequently, cryomodules will be installed and commissioned every month, leading up to a total of 25 units, in preparation for the first beam operations scheduled for December 2024.
This paper describes the development and commissioning activities involving the control system deployment for starting operations. Future activities will encompass the discussion of integrating this control system with the CMDS master control system, overseeing the simultaneous operation of all cryomodules and the distribution system. Additionally, plans for integrated testing with various other SRF Linac components will be addressed.
Keywords: Cryogenic Valves, Cryogenic Sensors, Heating elements, Controls, Programmable Logic Controller, EPICS, Cryomodule.Speaker: Adalberto Ferreira Melo Fonotura (ESS ERIC) -
211
Design, Fabrication, and Characterization of an Interdigitated Micro-Capacitive Level Sensor Coupled with Signal Conditioning Circuit
Cryogenic liquid level sensors play a vital role in industries handling ultra-low temperature cryogens, including medical, aerospace, and energy sectors. Monitoring levels within cryogenic storage tanks is critical to prevent issues such as pressure buildup from overfilling, insufficient supply from underfilling, and temperature fluctuations. Depending on the precision required, level measurement in cryogenic storage tanks can be either continuous or discrete, tailored to the specific demands of the application. In the case of large cryogenic storage tanks, discrete-level measurement methods such as optical fiber point-level sensors, optical frequency-based point-level sensors, and hydrogen depletion-type capacitive sensors are commonly utilized due to their practicality. For specific applications such as level monitoring of liquid propellants(LH2) in launch vehicle storage tanks, hydrogen depletion capacitive-type level sensors are often preferred. These sensors operate on the principle that the capacitance between two plates changes with the variation in its permittivity as the level of hydrogen increases or decreases. However, these sensors tend to be quite heavy, constituting a significant portion of the overall weight of the sensor module.
In this paper, we report the design, development, and characterization of an Interdigitated micro-capacitive (IDC) level detection sensor coupled with its signal conditioning unit, which can be the best alternative for the above application. The developed sensor is very compact, and lightweight (128 mg), has low power consumption, and high sensitivity. They were also compatible with cryogenic settings, where precise and reliable sensing is essential. Functioning on the principle of capacitance modulation caused by alterations in the dielectric medium, IDC sensors are capable of exhibiting capacitance variations typically ranging from 20 to 100 femtofarads, enabling the detection of even subtle dielectric changes. The sensor has an overall size of 7mm diameter, and features six interdigitated fingers per electrode, each having a width and pitch of 250μm. The IDC sensor was designed and modeled using COMSOL Multiphysics FEM software. A customized signal conditioning circuit was also developed to enhance the precision sensing capabilities of the developed IDC sensor. The circuit includes a matched set of monostable multi-vibrators along with a set of digital components that provide the difference in the timing pulses. The generated timing pulse is fed to an averaging circuit to produce voltage corresponding to capacitance variations. The response time of the sensor along with the
parameters will be discussed in the paper.Acknowledgment
The authors gratefully acknowledge Suracsh Filters Pvt Ltd for funding this work.Speakers: Hrithik Krishna Raj, Pankaj Sagar (Cochin University of Science and Technology) -
212
Design, measurements and calculation model validation of the orifice-type flowmeter for FAIR SIS100 Local Cryogenic System
One of the major components parts of the Facility for Antiproton and Ion Research (FAIR) international accelerator facility currently being built at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany, will be the Heavy-Ion-Synchrotron SIS100. This machine will consist of 6 sectors housing few hundreds of superconducting magnets made of Nuclotron type cable, which is cooled by two-phase helium at a temperature of 4.5K. Each two sectors will be supplied with cooling and electrical current from a Feed Box via By-Pass Lines, which connect to the magnets.
More than 30 precise and reliable mass flow measurement devices are required for the SIS100 Local Cryogenic to function properly throughout the system. Flowmeters with such properties available on the market are based on the Coriolis principle, that apart from their high cost. They are characterized by, among others: high flow pressure drop, large geometry or large measurement range, what limits their use in some locations of the system. Therefore, to meet the SIS100 Local Cryogenic System design requirements, based on the design guidelines and calculation models included in the ASME MFC-14M-2003 standard, Wroclaw University of Science and Technology (WUST) in Poland has developed 3 orifice-type flowmeters. Their design is adapted to the expected ranges of helium mass flows as well as to the measurement ranges of differential pressure transmitters, which will be used to determine the flow rates. One of the of the flowmeter design types has been produced by Kriosystem Ltd, Poland. In order to confirm the correctness of both, the design and computational models for the developed flowmeters in pressurized, cold pressurized and subcooled liquid helium conditions, GSI conducted tests of the flowmeter on a dedicated test stand. The paper presents details of the design of the developed and tested orifice-type flowmeter, describes the test stand and the measurement procedure, as well as presents and discusses the measurement results and their comparison with the computational model.Speaker: Jaroslaw Polinski -
213
Development of an adsorption dehumidification system to supply dry air for the cryogenic refrigerator
When a cryogenic cooling system is implemented, humidity control of the facility space is very important, and the input of latent heat energy due to condensation sometimes adversely affects the performance of the cryogenic freezer. The adsorbent-based dehumidification system to be developed in this study has the advantage of improving the cooling efficiency of the cryogenic freezer by controlling the moisture in the equipped space and reducing the overall process energy consumption. In the case of adsorption-type dehumidification, since dehumidification is performed using the adsorption and desorption phenomenon of an adsorbent, it does not require a temperature below the dew point temperature like a dehumidification system using an existing vapor compression system, so energy consumption is low, but a heat source above room temperature for desorption may be required. Since a relatively large amount of energy can be consumed to produce hot air for desorption, research on the development of adsorbents with a relatively low desorption temperature is being conducted. The adsorption-based dehumidification system to be developed in this study is a system capable of continuous adsorption and desorption processes at 30 ℃ and 45 ℃ , and in the case of desorption temperature, it is expected that heat from waste heat or cryogenic cooling processes can be recovered and used.
Speaker: Jung-Gil Lee (KITECH) -
214
Development of EPICS-based control system for RAON SCL2 cryogenic system
The RAON heavy ion accelerator is a facility for finding rare isotopes through IF and ISOL and consists of a superconducting accelerator (SCL) and an experiment facility using accelerated beams. For the integration of various devices comprised of large scientific facilities, the RAON control system integrates distributed control systems using EPICS. A cryogenic system has been built for the low-energy section (SCL3), and the VB (Valve-Box), which consists of various valves of the cryogenic system, is controlled through the RAON control system. This paper explains how to build a RAON control system for a cryogenic system for the high energy section (SCL2). In the cryogenic control system of the SCL2 section, the EPICS IOC and control server were configured using an improved standardization method than SCL3, and this explains how flexibility was provided for adding devices and changing details for multiple valve boxes. .
Speaker: Sang-Gil Lee (IBS/RISP) -
215
Development of the Control System for the ESS Cryogenic Moderator System
The European Spallation Source (ESS) is one of the largest science and technology infrastructure project being built in Sweden. Protons at 2 GeV (with a normal current of 62.5 mA) are delivered by a superconducting linear proton accelerator and are injected onto a rotating tungsten target at a pulsed repetition rate of 14 Hz. Neutrons via spallation reaction are moderated to cold and thermal energies by dedicated moderators. Initially, the ESS installed two hydrogen moderators above the target wheel. The cryogenic moderator system (CMS) was designed to circulate subcooled liquid hydrogen at a temperature of 17 K and a pressure of 1.0 MPa to remove the nuclear heating at the moderators, which is estimated to be 6.7 kW for a 5-MW proton beam power. The liquid hydrogen is transferred from the CMS cold box (CBX) to a distribution box (DB) via a main transfer line (HTL) and is split into each moderator transfer line. The CMS is cooled via a plate-fin type heat exchanger by a large-scale 20 K helium refrigeration system, referred to as the Target Moderator Cryoplant (TMCP) with a cooling capacity of 30.3 kW at 15 K. The valve box functions to mitigate transient thermal disturbances caused by the proton beam injections by rapidly adjusting the feed helium flow rate to the CMS within a few seconds. During the CMS cooldown operation, hydrogen gas at 1.9 MPa to the CMS CBX from the hydrogen filling station (FS) located outside the Target building.
The Control Systems implemented at ESS play a pivotal role in synchronizing and ensuring the continuous operation of the various equipment responsible for neutron production for the experimental programs. ESS standardizes on a small set of hardware technologies, or hardware families, for control and monitoring tasks. For control systems operating at low frequencies (<10Hz), industrial automation Programmable Logic Controllers (PLC) by Siemens are utilized. To ensure seamless integration across all control systems, ESS employs the Experimental Physics and Industrial Control System (EPICS) framework. Integration with EPICS is achieved through a custom python-based software tool developed in-house by ESS. This tool generates the necessary code sets to enable integration between a PLC and EPICS Input Output Controller (IOC).
The CMS Basic Process Control System (BPCS) is responsible of controlling a wide array of equipment, consequently the system logic was designed with modularity, ease of expansion, and maintainability in mind. As the first step for the different device types, generic software control blocks with a wide range of features and Operator Interface (OPI) block icons and faceplates were developed. The functionality of these blocks and OPIs developed for the CMS BPCS were also implemented in other BPCSs at ESS.
The process logic is distributed across three distinct PLC CPUs for the CMS CBX, DB and FS, interconnected via an isolated Local Area Network (LAN). Communication between the CMS PLC CPUs is facilitated through open user communication for data exchange over the integrated PROFINET interface of the CPU.
On the other hand, the TMCP control system comprises multiple PLC Central Processing Units (CPU) and Remote Input Output (RIO) modules, and is delivered by Linde Kryotechnik AG, and integrated into EPICS To seamlessly integrate the TMCP and CMS into a unified system, a PROFINET (PN) communication was established utilizing a PN-PN bus coupler. A dedicated control block and Operator Interface (OPI) implemented within the CMS BPCS allow for (enable to) starting and stopping of compressors and turbines, regulation of feed and return temperatures of the TMCP, control the system discharge (high pressure – HP) and suction (low pressure – LP) pressures.
Additionally, utilizing the functions listed above, various Local Protection Functions (Monitoring Function and Failure Actions) were implemented to systematically shut down the CMS for any aberrant occurrences, following a predefined sequence. These functions were verified during the CMS commissioning activities to ensure that they meet the requirements.Speaker: Attila Zsigmond Horváth (European Spallation Source) -
216
EU-DEMO TFC WP4 current discharge thermohydraulical analyses and models: impacts of radial plates on operation domain with safety consideration.
Previous studies performed for the JT-60SA TF Coils, have shown an important influence of the AC losses energy deposition, heat transfer from case to Winding Pack and cooling capacities, on the general current discharge behavior, in particular the helium pressure and temperature increase in the cooling loop.
Some parametric studies have been performed with the Fast Assessment of Operating Window (FAOW)- Superconductors Thermohydraulical and Resistive Electrical Analytical Model (STREAM), developed and used at CEA-IRFM. The results confirm, as a function of the different initial current values, the safe operation of TFC (within particular no opening of relief valves connected to cryodistribution loop).
Similar current discharge studies and analyses are presented on the EU-DEMO TFC WP4 (Winding Pack 4) design, quite similar to ITER TFC design, with radial plates. DEMO TFC WP4 comprised Nb3Sn Cable-In-Conduit Conductor (CICC) inserted into stainless steel plates, forming with pancakes and ground insulation the Winding Pack inserted into a thick stainless steel case. These FAOW-STREAM calculations and analyses show the importance of heat transfer from case to WP, as well as the convective heat exchange power (and coefficient) in case cooling channel and CICC. Also the relevance of the characteristics of cryodistribution loop and heat removal capacities in heat exchanger has been emphasized. The helium temperature and pressure increases are evaluated as well as the temperature margin, and the analyses of a potential induced quench during the current discharge (severe quench at high current, or smoothed quench at low current). Nevertheless, the calculated results show that a quench is induced, nearly 7 s after beginning of each nominal value current discharge as the helium and conductor temperature reach the current sharing temperature. These analyses demonstrate the impacts of the radial plates in the operation domain, with safety considerations.
Preliminary results and qualitative analyses are extrapolated to ITER-TF Coil current discharge with FAOW-STREAM model. Due to this model rapid execution time duration (only few minutes), compared to other numerical codes (few hours, or few tens of hours), these kind of studies can be also useful for further detailed performances analyses with possibility of real-time feed-forward calculations/controlSpeaker: Sylvie Nicollet -
217
Experimental investigation of a dual flow transfer system for liquid helium
In transfer stations for liquid helium, single-flow transfer lines are often used to transfer the liquid into a smaller mobile dewar. During this process, a considerable amount of the liquid evaporates due to heat leak and especially pressure losses in the transfer line. Regardless of the liquefier’s efficiency, this evaporation loss contributes to a significantly higher running time of the condenser and a higher primary energy input to generate the net liquid volume. To overcome this, a laboratory setup was realized as a combination of a flexible double-flow transfer line and a cold liquid pump, which can reduce these losses drastically. In this article, the authors report on their current test results on filling performance, operating losses and practicability.
Speaker: Johannes Doll (TU Dresden) -
218
Incorporating new subsystem into an existing cryogenic controls system
Brookhaven National Laboratory (BNL) has been operating the Relativistic Heavy Ion Collider (RHIC) for over 20 years. Superconducting magnet operations on RHIC rely on the stable operations of the Cryogenic Control System (CCS) to process and circulate 48,000 gallons of 4K helium supporting RHIC’s superconducting magnets. Over the years of RHIC operations, several subsystems requiring cryogenic cooling have been added to RHIC’s CCS. The latest addition is the sPHENIX detector that has a 1.5T superconducting solenoid at its core. A new cryo-distribution and cryo-controls system was developed and deployed to operate the sPHENIX magnet in 2022 and 2023. The new CCS architecture and infrastructure installed for sPHENIX is based on the future EIC CCS design. This was an opportunity to modernize the CCS for the local sector of RHIC around sPHENIX, as well as a demonstration of the complete future EIC CCS. This paper will review the hardware and software architecture implemented for the sPHENIX CCS, lessons learned from initial operations, and how to extend and improve this design for EIC.
Speaker: Brian van Kuik (Brookhaven National Laboratory) -
219
Insertion thermometry experience at CERN
CERN cryogenic facilities have an extremely large quantity of temperature measurement points, most of them are performed by using non-removable sensors installed either in the fluid or in the insulation vacuum side of reservoirs or pipes; the mounting of these sensors, is standardized in most of CERN equipment and provide very reliable results.
On the other hand, insertion thermometry is present in industrial supplier’s equipment, desirable for low pressure gaseous cold helium environment due to the poor heat transfer coefficient between the fluid and the pipe wall complicating the measurement on the insulation vacuum side. Insertion thermometry requires a capillary that, in the case of CERN equipment, has a wide variation of both inner diameter and overall length. Furthermore, the capillary is prone to inner pipe restrictions due to inappropriate bending or solder joints. The main advantage of insertion instrumentation is the exchangeability of damaged sensors; however, installation can be extremely difficult in presence of restrictions and it is not trivial to ensure that the temperature sensor end-location reached the end of the capillary inside the cold fluid’s vessel.
The wide variation of the insertion capillary parameters is due to the fact that CERN’s equipment is specified for turn-key operation, and it is provided by a variety of manufacturers. An effort was therefore made to analyse and document all variations for the insertion capillaries existing in the 8 LHC (Large Hadron Collider) cryogenic plants to design a new type of insertion thermometer. It is based in a sufficiently rigid wire with centring beads that permit pushing, along the capillary, the temperature sensor corresponding to the standard types used in the LHC. All poorly working insertion thermometers were replaced during the long shutdown maintenance on the LHC cryogenic plants, as well as on the CMS detector associated cold-box during nominal operation.
In addition, a new insertion thermometer has been developed with the insertion wire replaced by a PCB (Prototype Circuit Board) of which various widths have been manufactured. At the end of the PCB, a spring probe acting as an electrical contact is attached to ascertain that the capillary is fully inserted, assuming that the capillary as well as the cryogenic equipment are made of electrically conducting material. The thermometer and spring contact signals are routed with copper tracks on the PCB. The insertion PCB length can be reduced in 25 mm increments by cutting the excess length.
The paper presents the design of both wire and PCB based insertion thermometers, application examples and the field operational feedback.Speaker: Nicolas Vauthier (CERN) -
220
Instrument Design for the Accelerator Cryogenic System
In the accelerator cryogenic system, various sensors and instruments are used to measure important parameters such as temperature, pressure, flow rate, liquid level, and heating power. These sensors and instruments are installed in valve boxes, pipelines, gas storage tanks, and accelerator modules. The data measured by these sensors and instruments is collected through PLC (Programmable Logic Controller) and stored in the database. These data can be used to debug the operation of the cryogenic system and provide important support for the safe, reliable and stable operation of the accelerator. This paper describes the selection and working principle of the temperature sensor, Coriolis flowmeter, superconducting level meter, pipe heater and other instruments used in the accelerator Cryogenic system. This paper focuses on the installation process and calibration methods of these sensors. The engineering experience for the use of instruments will contribute to similar accelerator cryogenic systems in the future.
Speaker: Dong Jichao (Institute of Advanced Science Facilities, Shenzhen) -
221
Liquid helium level sensors on a PCB carrier with integrated temperature reading
A flexible liquid helium level gauge has been developed to compensate lack of commercial availability to procure replacement level gauges for the LHC 1.8 K refrigeration unit cold box requiring an active measurement length of about 1 m. The main difficulty for manufacturing the level gauges is related to the insertion capillary requiring an overall length ranging from 1.75 m to 4.30 m. The liquid helium level gauge is based on a NbTi superconducting wire attached to a PCB (Prototype Circuit Board) carrier including two surface mounted heating resistors and a Cernox© temperature sensor at the bottom tip of the gauge.
The superconducting wire selected is made of a single 0.049 mm NbTi filament with a copper cladding resulting in a wire overall diameter of 0.079 mm. The copper cladding is removed by using standard PCB manufacturing chemicals instead of nitric acid, that is extremely hazardous to handle.
The temperature sensor at the tip complements the measurement of absolute pressure of the saturated liquid helium bath (1.8 K cold box phase separator) and provides useful information to assess whether liquid helium is present.
A first batch of 26 liquid helium level gauges with various active measurement lengths has been manufactured and tested. The collected data permitted to optimize the complete etching of the copper cladding and to provide revisions to the PCB layout thus improving the measurement accuracy and addressing minor issues concerning the manufacturing yield.
The liquid helium levels gauges are validated in both normal and superfluid helium bath, the experimental data permits to select a single operating condition that permit a smooth measurement across the liquid helium lambda transition.
The level gauges are characterized by applying a slow electrical current sweep permitting to assess the loss of the superconducting state along the wire. In superfluid helium the penetration of the normal state is qualitatively well correlated with data reported in the literature for the peak flux in horizontal wires.
The paper presents the design requirements, the main basic components, and the manufacturing steps of the superconducting liquid helium level gauge. Experimental data are also presented demonstrating the correct operation of the proposed novel gauges.Speaker: Juan Casas-Cubillos (CERN) -
222
MODERN VALVES FOR CRYOGENICS- DESIGN CONSIDERATIONS with FOCUS ON LIQUIFIED HYDROGEN and HELIUM
ABSTRACT- Oral Presentation
Modern Cryogenic Valves – design Considerations with focus on liquified Hydrogen and HeliumLeire Colomo, Ander Gabirondo 1)
1) AMPO Poyam Valves, ES- 20213 Idiazabal, Gipuzkoa, SpainCryogenics with the gases like helium, hydrogen and sometimes also with neon, nitrogen, or air gain today more attraction as enablers for new green technologies in the energy sector as well as further industrial areas as in chemistry, semiconductor, steel and glass production etc.
Cryogenic helium in all stages is used to cool superconducting devices allows efficient high energy research and fusion research. Liquefied hydrogen is a high dense energy vector and could be at the same cooling superconducting cables and power devices. Neon seems a potential candidate to enable highly efficient cryogenic processes. Subcooled liquefied nitrogen is used to cooling high temperature superconductor cables and devices in the power system. The cryogenic process of liquefying and warming up air is used to store fluctuating production renewable power.
Consequently, valve industry face techno-economic complex challenges to answer the demands of this expanding sectors that will play an essential role the upcoming decades.This paper describes identified techno and economic challenges for a modern cryogenic valve. Focus is on applications in liquified hydrogen but also considerations regarding the special requests for helium are highlighted. Some key design topics are
Thermal efficiency.
Flexibility to absorb thermal contractions in the connection piping.
Interior and exterior tightness
Valve flow capacity.
Precise flow control
Flexible actuating system with low energy consumption
Suitable for industrial serial manufacturing processes
In this paper, AMPO POYAM VALVES will present an innovative solution concept that meets the challenges of the cryogenic service condition over the entire temperature and pressure range and brings a modern valve concept to the market considering up to date manufacturing technologies and thus offers added value to the efficiency of the high-tech cryogenic processes.Speaker: LEIRE COLOMO ZULAIKA (AMPO POYAM VALVES) -
223
Qualification of 0-60 mbar pressure transducers for the LHC HL-LHC environment at CERN
The LHC (Large Hadron Collider) upgrade (HL-LHC) at CERN, requires the procurement of 0-60 mbar absolute pressure sensors with an absolute accuracy of +/- 0.3 mbar and a radiation Total Integrated Dose (TID) that may reach 100 kGy. Unfortunately, commercial sensors with embedded electronics cannot be used due to the effort required for qualifying electronics for radiation environments. Such a low-pressure range is usually measured through the deformation of a relatively large diaphragm and the sole passive sensors available commercially use magnetic coupling for the measurement of the deformation. An industrial partner, ABB© provided CERN with their low-pressure measuring cell that is based on a piezo resistive bridge measuring the diaphragm deformation. This cell is used in their commercial device that, apart from the radiation requirements, is compatible with the accuracy requirements. In radiation environments, 0-100 mbar pressure sensors have been installed and operated successfully in CERN’s accelerators complex (LHC and SPS), the sensors being manufactured respectively by NICHE© (not anymore available) and the ABB© passive cell.
A radiation qualification test was performed with a gamma source targeting a 100 kGy TID. The sensors under test were a Valydine© DP10 and an ABB© passive pressure cell. The pressure sensors were attached to a leak-tight sealed cell, the cell temperature can be adjusted and therefore the pressure followed the perfect law of gases.
The paper presents the radiation measurement set-up, the readout electronics located in a radiation-free location and the results of the irradiation. The sole sensor capable of withstanding the HL-LHC upgrade TID requirements is the Validyne© sensor that is not sensitive to ambient temperature variations but for which the cable is part of the sensor impedance.Speaker: Juan Casas-Cubillos (CERN) -
224
Qualification of standard pressure sensors for applications in superfluid helium at CERN
The paper focuses on the qualification process employed to ensure the precision and reliability of radiation tolerant pressure sensors, originally developed to operate within the temperature range of -40°C to +125°C, in superfluid Helium for CERN cryogenic installations.
The initial stage of the qualification protocols took place at the CERN CryoLab facility. The qualification methodology involves a systematic evaluation of sensor impedance, leak testing, and the characterization of the output signal drift correlated with temperature variations, with a focus on addressing potential vulnerabilities associated with cryogenic temperatures down to 4.5 K. All the steps, including thermal cycling, cryogenic exposure, and pressure fluctuations, were implemented to assess key performance parameters such as sensitivity, response time, and accuracy across a wide temperature spectrum.
The second phase consisted in the installation of pressure sensors in the CERN SM18 magnet cryogenic test facility on upgraded benches for testing the HL-LHC magnets and validate their use in several cryogenic operation conditions down to 1.9 K. Although the sensor's original specification and design did not include operation in immersed liquid helium, the measurement results indicate satisfactory performance. A comparison was made between these results and measurements obtained from sensors at room temperature equipped with capillaries.
The paper will outline the qualification processes and present the measurement outcome of cryogenic pressure sensors in low-temperature environment.
Speaker: Douglas Valencon (CERN) -
225
Simulation Analysis and Optimization on Steady-state Characteristics of Cryogenic Distillation for Helium Isotope Separation
The helium isotope separation system based on cryogenic distillation represents a pivotal part in the purification of helium-3 (3He). In this study, we designed and simulated a cryogenic distillation column using the tridiagonal matrix algorithm. The liquid holdup and pressure drop for each theoretical stage were modeled using a general packed column model, with predictions based on known packing and fluid properties. We also predicted the steady-state separation characteristics of the column under various conditions. Our investigation focused on the impact of parameters such as the number of theoretical stages, feed location, flow rates, and feed composition on product quality, condenser duty, and liquid holdup. The optimal operating conditions were identified with a 4% mixture of 3He/(3He+4He) in saturated liquid condition, resulting in 99.9% yield of 3He at the top of the column. The current research significantly contributes to the guidance of complicated experiments involving cryogenic distillation of helium isotope.
Speaker: Huan Chen (Technical Institute of Physics and Chemistry CAS) -
226
Strategies against thermo-acoustic oscillations in cryogenic valves and plants
Thermo-acoustic oscillations (Taconis oscillations) are the characteristic phenomenon for the cryogenic systems, where one end of the pipe is in continuous contact with the extremely cold process fluid and the second end of the pipe is directly exposed to the warm ambient temperature. As warmer fluid has the smaller density and therefore arises, the warm end is normally placed at the top and the cold end at the bottom. The reason behind is that in that way the fluid mixing is limited, and convection heat is reduced. However, under several specific conditions the layers of fluid can start to oscillate between warm and cold end, bringing an enormous heat load to the cold system (up to 1000 times larger than without oscillations). This phenomenon is very undesirable as it not only affects the cryogenic process due to heat input, but also causes the freezing of the external surfaces of the installation.
Systems operating with supercritical liquid or superfluid helium are the most vulnerable to the occurrence of thermo-acoustic oscillations, as the driving force for the phenomenon is the warm-cold end temperature ratio. Other factors that have a decisive role if oscillations appear or not, are: the ratio of warm-to-cold space of the pipeline, the volume occupied by the fluid inside (in particular the diameter-length combination), the length of the pipeline itself, the operating parameters of the fluid and its properties. It should be emphasized, that the mentioned factors favor the occurrence of thermo-acoustic oscillations but do not indicate conclusively whether it will in fact occur or not; from this reason the designer of the cryogenic installation should assess the risk of the oscillations on a case-by-case basis.
Cryogenic valves in combination with unfavorable operating conditions are vulnerable to the occurrence of thermo-acoustic oscillations. However, undertaking the appropriate precautions can reduce or completely abolish the probability of their appearance. This publication illustrates different possibilities to avoid or reduce the risk of thermo-acoustic oscillations in the plant.
Speaker: Nicola Magginetti -
227
The adsorption characteristics of helium on different activated carbons at 4.5-77K
The adsorption isotherms of helium on two kinds of activated carbon in the temperature-pressure range (4.5-77 K, 0.1 -1.0 MPa) have been measured with a cryogenic adsorption device. Most of the existing studies primarily focused on cryopumping or law pressure gas removal processes with very limited research specifically targeting helium isotope separation. Furthermore, all have used liquid helium immersion refrigeration. In this study a cryogenic adsorption device has been established and consisted of a 4 K cryostat (Gifford McMahon (GM) Cryocooler), Setaram gas sorption measurement and a temperature controller. The experimental techniques for obtaining adsorption isotherms have been described in detail in this paper. By analyzing the adsorption curve, the optimal temperature and pressure conditions for helium adsorption can be obtained, better activated carbon adsorbents can be selected, and the isosteric heats of adsorption can be derived from these isotherms. These findings could potentially facilitate the development of helium isotope adsorption separation units.
Speaker: nn Dai (中国科学院理化技术研究所) -
228
Thermal contact resistance using time-resolved EUV diffraction -- a novel technique to study conduction-cooled superconducting RF cavity
Cryocooler-based conduction cooling has gained traction in replacing liquid He baths for cooling in applications such as superconducting radiofrequency cavities owing to their compact design and simplified construction. Conduction cooling near room temperature is also being explored for dissipating heat from electronic chips. One of the primary governing factors in conduction cooling is thermal contact resistance between two different metals, which, for example, varies from 0.1 to 0.35 K/W between 3.5 and 6 K for a bolting force of 3 to 7 kN between high-purity aluminum and niobium. However, the contact resistance is generally far from the intrinsic thermal contact resistance expected of metal contact, thus leading to losses at the contact.
With the present study, we aim to measure the intrinsic thermal contact resistance between two distinct materials using time-resolved EUV diffraction measurements. The intrinsic value will serve as a benchmark for evaluating the thermal contact's effectiveness, which is currently lacking.
EUV diffraction measurements rely on depositing periodic arrangement of the top layer on another material and instantaneous laser heating the top layer using a pulsed laser source. The resulting heating profile is measured via diffraction from another pulsed source in the extreme ultraviolet (EUV) range synchronized with the pulse used for laser heating. To demonstrate the efficacy of the proposed approach, we deposit 10 nm of Nickel (Material 1) in a periodic arrangement on top of Silicon (Material 2) with a width of 250 nm and a period of 1000 nm using electron beam lithography and electron beam evaporator. The deposition provides a near-ideal contact between the two materials for characterization. We heat the periodic Nickel grating using a pulse of 50 femtosecond duration centered at 800 nm. The subsequent heat transfer from Nickel to silicon is measured using a high-harmonic EUV pulse of 30 to 40 nm wavelength. The EUV pulse diffracts from a periodic Nickel grating and is detected using a multi-channel plate coupled with EMCCD. The resulting measured change in diffraction profile with time is fitted to an effective Fourier model to extract the thermal contact resistance, which is found to be the order of 10^(-9) m^2K/W at room temperature for the studied thermal contact. The proposed approach offers an extremely high sensitivity in measuring thermal contact resistance. For comparison, if we assume the contact area is 1 cm^2 between aluminum and nickel, the thermal contact resistance will be 10^(-5) m^2K/W, which is nearly four orders of magnitude higher than the sensitivity of the present setup. The above-demonstrated experimental setup for nickel/silicon at room temperature is a proof of concept. However, it could be extended to evaluate thermal contact effectiveness for superconducting RF cavities or thermomechanical heat switches used in dilution refrigerators. The precise measurements will also allow us to assess various surface treatment techniques further to improve thermal conduction.
D.B. acknowledges the financial support from the Science & Engineering Research Board (SERB) under project no. CRG/2022/001317.
Speaker: Dipanshu Bansal (Indian Institute of Technology Bombay) -
229
Upgrade of Vertical Test Stand for 650 MHz Superconducting RF Cavities for CEPC
Hundreds of 650 MHz superconducting radio-frequency (SRF) cavities with ultrahigh intrinsic quality factor (Q0) and accelerating gradient (Eacc) will be adopted for CEPC, which are obtained during vertical test at 2.0 K. In order to meet the demand for low-temperature testing of materials and bulk testing of SRF cavities, the vertical test stand of Platform of Advanced Photon Source ( PAPS) was upgraded accordingly with cryogenic refrigeration and microwave RF systems.The upgraded system provides three vertical test dewars, each providing 100W thermal load at 2K for superconducting cavity testing and operation. It supports five 650MHz superconducting cavities to be tested at one time by cooling down, and is equipped with microwave test system, T-mapping test system, temperature, flux probe and radiation detector and other related test equipment. In addition, the digital self-excitation scheme is upgraded and used in the microwave test, and the vertical test accuracy is considered to realize real-time error analysis and display.
Speaker: Lingxi Ye (IHEP)
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207
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Wed-Po-2.5: Large Scale Cryogenic Systems 4 Poster area
Poster area
Convener: Eric Fauve (STANFORD)-
230
2 K system exergetic optimisation and helium recovery system for FCC-ee
At its ttbar stage, FCC-ee is expected to require over 200 cryomodules housing 800 MHz bulk niobium superconducting radio frequency cavities operated at 2 K, and more than 60 cryomodules housing 400 MHz niobium-sputtered copper cavities operated at 4.5 K. The complexity, energy intensity, and scale of the associated cryogenic system requires a holistic design approach. Topics such as sustainability or resilience against prolonged electrical grid perturbations become integral to this process. Thus, helium preservation, energy efficiency, and integration constraints are considered in the current conceptual design phase.
This paper details the design of the very low-pressure system used to maintain the cavities at 2 K. The operational variables of its distribution line have been addressed in a parametric manner using a combination of numerical simulations and exergetic analyses. The results enable the comparison of various implementation options, directly linking them to the energy consumption of the refrigerator. Subsequent sensitivity analyses reveal that while a central heat exchanger architecture is preferred for integration aspects, it is overall less energy-efficient than a distributed one at lower heat exchanger effectiveness values. Finally, we propose a helium recovery system based on diesel-powered compressors of up to 1 MW to preserve the cryogen inventory during incidents. Initial sizing allowed to extract the additional space, cooling water and electricity requirements needed for its implementation.
Speaker: Boyan-Kaloyanov Naydenov Popov (CERN) -
231
Conceptual design of the Divertor Tokamak Test (DTT) Cryogenic System
The Divertor Tokamak Test (DTT) facility (https://www.dtt-project.it/), currently in initial phase of construction at the ENEA Frascati Research Center, is designed to explore critical components of tokamak, such as the divertor, in plasma regimes that are relevant for ITER and DEMO (as far as power loads are concerned), and where plasma core and edge properties are fully integrated. To achieve this goal, considerable amounts of additional power will be injected in DTT, whose ambitious program is spread over several years with different operational phases. During the initial plasma operations (phase 1) 3 MW of ICRH, 14.5 MW of ECRH, and 7.5 MW of NNBI will be available. Additional power, up to a total of 45 MW, will be afterwards installed, on the basis of the results of Phase 1 and of technologies that will be available at that time. Moreover, in order to be relevant for DEMO, the DTT facility is designed to produce sufficiently long plasma pulses, thus requiring the adoption of a superconducting magnet system.
DTT magnet system includes 18 Toroidal Field (TF) coils, 6 Central Solenoid (CS) modules and 6 poloidal Field (PF) coils. All superconducting coils are supported by a cold structure with thermalized gravity supports and thermally protected in a cryostat with actively cooled thermal shields. The coils and their structures need to be cooled by supercritical helium supplied at about 4.3 K. The thermal shields have to be cooled with a circulation of pressurised helium between 80 K and 100 K. The superconducting coils are connected to the power supply by means of superconducting feeders which need to be maintained at 4.3K. High Temperature Superconducting (HTS) current leads, which operate between ambient and cryogenic temperatures, require cold helium gas flow at 50 K. To allow helium and hydrogen adsorption, cryopumps behind the divertor targets require 2 cryogenic helium streams, one at 4.3K for the cryopump panels and one at 80K for cryopump baffles.
The Cryogenic System has to cool-down the cryogenic users and keep them at their design temperatures during different operation modes and plasma scenarios. The overall cryogenic capacity is estimated around 11 kW equivalent power at 4.5K.
This paper gives a general overview of the cryogenic system requirements, the conceptual design, the layout and a description of the main components such as: the Helium Compression Station (HCS), the Warm Gas Storage (WGS), a Refrigerator Cold Box (RCB), an Auxiliary Cold Box (ACB), the Main CryoLine (MCL), the Cryogenic Valve Boxes (CVB) and the cryodistribution to the final users.Speaker: Morena Angelucci (ENEA) -
232
CRYOGENIC SYSTEM FOR THE HIGH ENERGY PHOTON SOURCE AT IHEP
High Energy Photon Source (HEPS) is a high-performance and high-energy synchrotron radiation light source with a beam energy of 6GeV and an ultra-low emittance of better than 0.06nm×rad. The HEPS is mainly composed of accelerator, beamlines and end-stations. The HEPS would provide the synchrotron beam with will brilliance higher than 1×1022 phs/s/mm2/mrad2/0.1%BW. And the hard X-ray with photo energy up to 300 keV would be provide in order to satisfy the requirement of in operando experiments. No less than 90 high performance beamlines and end-stations are capable to be built around the storage ring. To support a cryogenic environment temperature demand of the HEPS, a large cryogenic system must be built. And to meet HEPS’s extremely high requirements for ant-micro-vibration, compressors units of the cryogenic system are placed in the cryogenic hall, and other cryogenic equipment such as cold box, Dewar and cryogenic distribution valve box just as close as possible to cryogenic devices. As a result, the distance of the transmission pipes are elongated. So an appropriate cryogenic cooling scheme, transmission line diameter, low cooling loss and long-distance cryogenic fluid transfer and distribution are key technologies.
The cryogenic system includes a helium refrigerator system and a nitrogen cryogenic plant. The helium refrigerator system has been consisted of a helium refrigerator on a capacity at 2000W@4.5K, a cryogenic distribution transfer system and helium recovery and purification system for 10 superconducting radio frequency cavity cryomodules. The pressure stability at ±1.50mbara of the low pressure in helium compressors has achieved, which is a great significance to these superconducting radio frequency cavities. The nitrogen cryogenic plant is crucial for creating and maintaining operational conditions of the thermal shield of superconducting radio frequency cavity cryomodules, precooling the helium refrigerator coldbox, cooling photon beamline cryostats and cryogenic inserts in the HEPS. The nitrogen cryogenic plant has an average capacity about 50kW at 80K in the HEPS phase I. The nitrogen cryogenic plant is mainly included of nitrogen cycle refrigerator system at 7000W@90K and 100Nm3/h, two liquid nitrogen tanks and cryogenic fluid distribution tube network. The HEPS project engineering implementation has started at June 2019 and will be finished in the end of 2025. The Schematic diagram, status and recent machines commissioning of the cryogenic system are described in this paper.Speaker: Rui Ge -
233
Design, installation and commissioning of the cryogenic system for NNBI test facility
Cryopumps are used as the main pumps of cryo-vacuum systems in the Negative Neutral Beam Injectors (NNBI) test facility to pump gas to generate and maintain the vacuum gradient environment. To cool the cryopumps, a 1000 W@4.5K cryogenic system was built, which provides 4.5 K supercritical helium for cryopanels and 77 K liquid nitrogen for radiation baffles. The major cryogenic system components include helium recycle compressor, oil removal system (ORS), cold box, LHe Dewar, cryogenic distribution box, recovery compressor, helium purifier, gas bag, helium tanks, and LN2 tanks. Design, fabrication, and installation of most of the 1000W@4.5K helium refrigerator was carried out at ASIPP. This paper presents an overview of the design, installation and commissioning of the cryogenic system for NNBI test facility.
Speaker: Zhigang Zhu (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) -
234
Development and Commissioning of 1KW @ 4.5K Cryogenic System for Superconducting Test Facility of CRAFT
As national major science and technology infrastructure, Comprehensive Research Facility for Fusion Technology（CRAFT) is being built by ASIPP. Cryogenic system is an important part of the research for superconducting magnets. ASIPP designed and developed a 1KW@4.5K helium cryogenic system to meet some cryogenic testing, such as a conductor performance research platform and a central solenoid model coil test facility. The helium system can provide a cooling capacity more than 1KW, and reserve 3.8K cooling mode. In 2023, the system has been tested successfully, and the performance index of the refrigerator reached the expected requirements. This paper describes the design of CRAFT 1KW @ 4.5K cryogenic system and the results of cooling testing.
Speaker: Qiyong Zhang (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) -
235
Development and performance test of a cryogenic environment simulation facility for building elements
The cryogenic mechanical property tests of building elements are significant to ensure the safety of cryogenic-related buildings, such as LNG facilities, air separation plants, polar research station, etc. A cryogenic environment simulation chamber with large inside space, low temperature refrigeration and temperature control module is a key basic test facility for the construction of these buildings. A -120℃ cryogenic environmental test facility is developed and tested by the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (TIPC, CAS). The facility consists of a cryogenic chamber, a mixed-refrigerant Joule-Thompson (MRJT) refrigerator and electric control units.
The cryogenic chamber is cooled by the MRJT refrigerator with inside dimension of 3m(L)×3m(W)×1.5m(H) and inner volume of 13.5 cubic meters. Building elements of concrete, steel or other materials could be tested in it. In order to handle the test elements conveniently, stainless steel slide rails with small rollers are installed on the floor of chamber, which are free of bears and oil lubrication. A full-width pneumatic chamber gate is designed for the access of large-scale testing elements. An optimized forced air circulation finned-tube evaporator is employed to cool down the air and testing elements in the chamber, driven by four motor split type centrifugal fans. 200 mm thick polyurethane foam board is used for insulation. Several temperature sensers are set at the center and corners of the chamber to test its cooling performance. A PID controlled electric heater is integrated in the evaporator for control temperature.
The refrigerator is based on a single-stage separation type MRJT cycle, driven by a 28 kW oil-lubricated semi-hermetic reciprocating compressor. The mixture of nitrogen, methane, ethylene, ethane, propane, isobutane and isopentane is used as refrigerant. High-pressure warm refrigerant is cooled through a recuperation process by low-pressure cold refrigerant in three stages of aluminum plate-fin heat exchangers. A dephlegmator is employed to separate the oil and high-boiling components in refrigerant before entering heat exchangers to avoid the clogging at the cold end. Cold mixed-refrigerant is sent to the evaporator of cryogenic chamber to supply cooling power. The refrigerator is cooled by a finned-tube after-cooler, free of cooling water supply. All the components of the cryogenic chamber and refrigerator are integrated on a skid, which is easy to transport.
In the performance test, chamber temperature of -80℃ is reached in 3.5 hours without load. The lowest temperature of -123.8℃ is reached in the cryogenic chamber after a 24 hour no-load cooling period. Concrete columns with total weight of 1.2 ton are used as the load, which are cooled to -80℃ in 11 hours, -100℃ in 15 hours and -111℃ in 21 hours (column center temperature). For normal utilization, it takes 2.5 hours to reach -60℃ and 4 hours to reach -80℃. The temperature fluctuation of cryogenic chamber is within 1.5℃. The temperature heterogeneity is within 2℃ (the temperature difference of the chamber center and corners). This cryogenic environment simulation test facility is successfully utilized in the research on cryogenic mechanical properties of a building technology laboratory, which is more economical than the former liquid nitrogen cooled test facility.
Acknowledgement
This work is supported by the National Natural Science Foundation of China under the contract number of 51625603 and 52006230, Autonomous project of the Key Laboratory of Cryogenic Science and Technology (No. CRYO20230303), QingDao CASFuture Research Institute CO., LTD. (21–8–1–1-qy), and the China Postdoctoral Science Foundation (2023M733584).Speaker: Haocheng Wang (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
236
First operation of the cryo supply for Wendelstein 7-X cryo vacuum pumps
The stellarator fusion device Wendelstein 7-X (W7-X) consists of a vacuum vessel and 70 superconducting coils located within a vacuum-isolated cryostat. The coils generate the magnetic field that confined the high-temperature plasma and keeps it away from the first wall of the vacuum vessel. A thermal shield inside the cryostat protects the cold components from thermal radiation. A helium refrigerator with an equivalent cooling power of 7 kW at 4.5 K produces cold helium for the cooling of the superconducting coils and the cold structures to 3.9 K. The refrigerator also supplies helium at 60 K for the current leads of the coil feeders and supplies helium in a range of 50-80 K for the cryostat thermal shields.
Between 2018 and 2021, W7-X was upgraded with 10 Cryo Vacuum Pumps (CVP) in order to enhance the neutral gas exhaust during plasma operation in the sub-divertor region of the vacuum vessel. The supply of the CVP requires a cryo supply system that consists of a four-channel transfer line with a length of 55 m running from the refrigerator to a distribution valve box below the W7-X cryostat. From there 10 transfer lines run to the 10 supply ports at the W7-X cryostat. The process pipes of the transfer lines are connected to each CVP.
The four-channel transfer lines contain two helium process lines (feed and return) and two nitrogen process lines (feed and return). The helium flow cools the cryo panels of the CVP at a feed temperature of 3.9 K in a parallel cooling schema. A two-phase nitrogen flow cools the thermal radiation screen to 80 K. First operation of the cryo distribution with connected CVP was conducted in 2022 and 2023.
The paper presents the design parameters of the cryo supply system with respect to heat loads, allowed pressure drop and required mass flow rates, and compares the values with measurements. The helium cooling of the cryo panels was done with a total mass flow rate of 250 g/s and a cooling temperature of 3.9 K. The achieved liquid nitrogen supply ensured an outlet temperature of the flow in saturation condition. A controlled cool down of the CVP from 300 K to 4 K could be achieved for the helium cooling circuit. Cool down of the thermal shield with liquid nitrogen was done with a small liquid nitrogen flow.
In addition, the paper discusses the impact of the cryo pump operation on the operation of the helium refrigerator. The helium cooling of the magnet system and the cooling of the cryogenic pumps are closely coupled in the design of the helium refrigerator. It turned out that the transient operation modes of the CVP had significant impact on the other cooling circuits. While the superconducting coils operate stationary at 4 K over a week, the cryo pumps are cooled down from 60 K to 4 K for CVP operation and heated up to 60 K for regeneration of adsorbed hydrogen. Warm up to 300 K over the weekend and cool down back from 300 K to 60 K for a full regeneration cycle was also required in addition. Heat load changes in sub cooler baths and heat exchangers, changes in mass flow rates or redirection of flow paths produced complex operation scenarios that required manual operations. The detailed planning of CVP operation in support of the experimental program needed to take into account the time consuming mode changes in the cryogenic system.Speaker: Michael Nagel -
237
HIE ISOLDE CRYOGENIC OPERATION RESULTS AND RECENT UPGRADES
The High Intensity and Energy ISOLDE (HIE-ISOLDE) enables the acceleration of medium to heavy radioactive isotopes at energies reaching 10 MeV per nucleon, a significant increase from the previous configuration limited to 2.8 MeV per nucleon. The journey towards this achievement involved a progressive deployment of radiofrequency cryo-modules starting in 2015. In 2018, the final configuration was reached with successful operation of four high-beta radiofrequency cryo-modules in series. This paper presents an overview of the operational results over the last 8 years, but especially focuses on the recent enhancements made in 2023 to the cryogenics system and tested during the last physics run. A comprehensive overhaul of the cryo-module operation process was implemented to minimize restart times following unexpected interruptions, to facilitate operator handling and to harden the process control structure. Hardware modifications have also been implemented to improve equipment availability and were successfully commissioned. The paper also introduces future upgrades studies towards improving the availability of the cryogenics system, based on tests performed in 2022 and 2023 out of the physics run, assessing the cavities warming time and temperature stabilization in degraded mode when only the shields were cooled with gaseous helium circulation between 80 and 90K.
Speaker: Nicolas Guillotin (CERN) -
238
Preliminary research of the fast cooldown (FCD) problem of SRF cavities using CFD method
With the development of superconducting accelerator devices, higher requirements have been proposed for the quality factor Q0 of superconducting cavities to reduce the operational costs of cryogenic systems. Numerous studies have indicated that fast cooldown (FCD) of the cavity can generate significant temperature gradients on the surface, contributing to the expulsion of magnetic flux and reducing the residual resistance. However, there remains a lack of research on how to optimize the FCD parameters for cryogenic system, as well as the thermodynamic processes involved in the cooling of the superconducting cavity. This paper firstly reviews the current research progress on the impact of FCD on superconducting cavity flux expulsion. Furthermore, the CFD method is utilized to study the heat transfer of cavity during fast cooldown, providing reference and guidance for optimization of fast cooldown parameters.
Speaker: ZHENG SUN (Dalian Institute of Chemical Physics) -
239
Process design and calculation of DALS test facility cryogenic system using Ecosimpro
The Dalian advanced light source (DALS) is a new FEL project based on SRF technology. The DALS test facility is used to test the key components of DALS, which requires a 370 W @ 2 K cryogenic system and is expected to be completed by end of this year. Dynamic simulation is often used in the cryogenic system process design and control logic optimization, it also plays a very important role in the process calculations during design phase. This paper introduces the method of process calculation using software Ecosimpro. Key components such as thermal shield, SRF cavity and cryomodule are modeled based on Ecosimpro platform. Main operation modes including steady state operating mode, cooldown mode and safety relief mode are simulated, the simulation results were compared with those calculated using Excel and HEPAK software, the dynamic simulation software can be used to obtain more accurate process parameters in dynamic processes such as cooldown, safety relief, which is favorable for the design of cryogenic system and selection of components.
Speaker: ZHENG SUN (Dalian Institute of Chemical Physics) -
240
Seat leak tests and commissioning of control valves in the cryogenic distribution system of the ESS superconducting linac
The European Spallation Source (ESS) is a neutron-scattering facility which will use a pulsed 2.0 GeV proton beam generated in the linear accelerator (LINAC) for releasing high-energy neutrons in the ESS target station. The 2K superconducting linac comprises 13 spoke and 30 elliptical cryomodules. The cryogenic distribution system (CDS) connects the cryogenic plant with the 43 cryomodules through a 400 meters long cryogenic multi-transfer, 43 valve boxes and an endbox.
The CDS consists of 373 control valves in total. There are 8 and 10 control valves in each elliptical and spoke valve boxes, respectively, and 3 valves in the end box. The control valves are used for regulating or blocking the process helium flows. The seat tightness of the CDS valves is crucial especially for warming up individual cryomodules, which is required for potential short-term maintenance or repair activities in the cryomodule while keeping the others in cryogenic conditions. What is more, leaks over valve seats might cause moisture or ice formation on room temperature uninsulated pipes for warmup and cooldown valves or add heat load to the cryogenic system. Valve initialization and leak tightness tests were firstly performed with warm helium in the second half of 2022 before the first CDS cooldown. The tests revealed many leaks above the specified acceptable leak rate of 10E-4 mbar.l/s with several of them reaching even 10E2 mbarl/s. The major bulk of those leaks were fixed before and after the 2nd CDS cooldown that followed in 2023. This paper describes the seat leak test method and results, as well as the possible causes of the observed leaks and the taken solutions for repairing the insufficiently tight valves.
Speaker: Jianqin Zhang (European Spallation Source ERIC) -
241
Second cool down of the superconducting cavities of RAON Accelerator with the cryogenic helium distribution system
RAON (Rare isotope Accelerator complex for ON-line experiments) heavy ion accelerator can accelerate heavy ions with the superconducting cavities. Since superconducting cavities require superconductivity to accelerate ions, the cryogenic system has been developed and tested for cryogenic cooling and stable cryogenic environment (4 K, 2 K) of the cavities. Second full cool down of SCL3, one of the superconducting linear accelerator of RAON, has been successfully carried out in 2024. The cryogenic helium distribution system of SCL3 consists of the main distribution box, 44 valve boxes, 55 cryomodules and the end box. It provides helium from cryogenic plant to cavities for stable cryogenic operation. This paper focuses on the results of second cool down of the cryogenic helium distribution system and cryomodules. Furthermore, several issues and improvements for stable cryogenic operation are introduced.
Speaker: Inmyung Park -
242
Second cool-down result of SCL3 cryogenic plant for Korean heavy ion accelerator, RAON
Korean heavy ion accelerator (RAON) consists of two superconducting linear accelerators of which names are SCL3 and SCL2, respectively. We finished the first cool-down and the first beam commissioning of whole SCL3 section in 2023. In 2024, we conducted second cool-down of the SCL3. We successfully finished the second cool-down from ambient temperature to 4.5 K and 2.05 K for whole SCL3 section. At this time, we was able to reduce total cooling time based on our experience during the first cool-down. In this paper, our cool-down result and cool-down strategy to reduce the cooling time would be introduced in terms of cryogenic plant’s view. Also, several lesson learns and occurred issues on the cryogenic plant during preparation of the second cool-down and in the middle of the second cool-down would be discussed.
Speaker: Junghyun YOO (Institute for Basic Science) -
243
SLAC Cryoplant Comparison: Evaluating Performance of Identical Systems
SLAC commissioned a continuous-wave superconducting linear accelerator (CW SCRF Linac) in 2023 to support its new Linac Coherent Light Source (LCLS-II). To refrigerate the Linac, SLAC has installed two helium cryoplants, each boasting a cooling capacity of 4 kW at 2.0 K. By 2023, SLAC completed the commissioning of both cryoplants. One cryoplant is currently supporting LCLS-II, while the other is set to be connected to the future upgrade, LCLS-II HE. In this paper, we present a detailed performance comparison of the two identical cryoplants, focusing on the warm compressor and 4.5 K cold box systems.
Speaker: Akanksha Apte (SLAC) -
244
The FCCee collider and booster: study of the SRF cryogenic systems and machine architectures
The first step of the Future Circular Collider (FCC), under study in the framework of an international collaboration led by CERN, features a highest-luminosity high-energy lepton collider (FCC-ee), optimised to study with high precision the Z, W, Higgs and top particles over a period of about 15 years starting from 2047.
Beams of electrons and positrons will have to be accelerated over increasing levels of energies (from 45.6 GeV to 182.5 GeV) while reducing current intensities (from 1.28 A to 5 mA) to keep the level of synchrotron radiation (SR) losses at 100 MW (50 MW per beam). The superconducting radiofrequency (SRF) system of the collider will have to cope with this wide range of operating parameters. The SRF system combines elliptical cavities at 400 MHz, niobium-sputtered on copper, operated at 4.5 K, and cavities at 800 MHz, bulk niobium, operated at 2 K. The increase in particle energy needs is met by increasing the number of cavities installed, housed in cryomodules, during scheduled machine upgrades. A second accelerator, the booster, in the same tunnel and requiring an SRF system of its own, will also be needed for continuous injection of new particles into the collider to compensate the beam current as it loses particles colliding in the detectors.
The collider and booster SRF are separate systems, installed in two different machine points and operated independently. At its highest energy, the FCCee collider and booster will count 66 cryomodules at 400 MHz, and 272 cryomodules at 800 MHz, each housing four cavities, and covering a total SRF length of about 3.3 km, for a total RF electrical power consumption of almost 150 MW and requiring an unprecedented cryogenic cooling capacity in particle accelerators.
This paper describes the SRF system integration, illustrating the machine architecture and the choice made on the vacuum and cryogenic schemes, including considerations to cope with a staged installation. Concepts of the cryomodules, their interfaces to the cryogenic distribution system and to the RF power distribution will also be covered, including preliminary operational aspects and cryogenic safety considerations.Speaker: Vittorio Parma (CERN)
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230
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Wed-Po-2.6: Large Magnet Systems Poster area
Poster area
Convener: Amalia Ballarino (CERN)-
245
A new cryogenic test facility for superconducting magnets at IMP
To test the superconducting magnets for HIAF, CiADS and other scientific research projects, a new cryogenic test facility is under construction at IMP in Huizhou City. The cooling power of the refrigerator in this test facility is 500 W @ 4.5 K, the liquefaction capacity is 150 L/h. Three vertical test cryostats and three horizontal test benches are planned. The inner spaces of the three vertical test cryostats are Φ700mmL5000mm,Φ850mmL8000mm and Φ1000mmL8000mm correspondingly. The horizontal test benches are designed to both working in 4.5 K bath cooling and forced-flow cooling. A standalone precooling and warming up unit which can supply 30 g/s helium gas at 80K is designed to cool down and warm up the magnets. The cryogenic plant is now under debugging, and the six test terminals are under construction. The design and the status of the cryogenic test facility is shown in this paper.
Speaker: Dongsheng Ni (Institute of Modern Physics Chinese Academy of Sciences) -
246
Assembly process and quality control of the magnet cryostats for the HL-LHC project at CERN
As part of the High Luminosity Large Hadron Collider Upgrade (HL-LHC) at CERN, new focusing quadrupoles, separation and recombination dipoles, and corrector magnets will be installed on either side of the ATLAS and CMS experiments. Specific cryostat designs were developed to allow for the operation of these magnets at 1.9K. A base design concept is progressed into 19 cryostat types to comply with requirements that depend on tunnel integration, cryogenics, instrumentation, and cold mass dimensions. The assembly process for the cryostats is split into two main phases: Phase 1 involves inserting the cold mass and thermal shield assembly into the vacuum vessel, while in Phase 2 a so-called service module is added to provide specific features and interfaces for installation in the LHC tunnel. In 2022, the production of the first cryostat began following the completion of the design, the procurement of components, the definition of the assembly process and the availability of a magnet cold mass. Six cryostat assemblies have been completed at the level of Phase 1, and one cryostat is well advanced towards completion of Phase 2 by mid-2024. This paper presents an overview of the assembly process and the quality controls utilised to ensure consistent high-quality execution during the assembly of each cryostat. It examines several aspects, such as the specialised tooling utilised during the assembly, how strict leak testing requirements are met, as well as detailing some of the issues encountered and lessons learned.
Speaker: Alisdair Douglas Seller (CERN) -
247
Cryostats for the HL-LHC magnets: Pre-series production, assembly infrastructure and project plans
The superconducting system of the High Luminosity LHC project (HL-LHC) at CERN comprises a total of 38 new cold masses, prototypes and spares included, all requiring cryostats for magnet operation at 1.9 K. These cryostats shall ensure optimal thermal performance, as well as magnet alignment stability over the machine lifetime. Specific cold mass dimensions and a multitude of interfaces related to cryogenics, power supply and instrumentation resulted in 19 cryostat assembly types. Having so many design variants relative to the number of units to be built is a challenge in terms of cost, resources, and schedule management. Our answer was the development of a modular concept maximising component sharing between cryostat types, which also allows for a common assembly infrastructure. To date, manufacturing of cryostat components is nearly finished, and a pre-series comprising the first cryostat assemblies for each cold mass type has been built up to the stage of readiness for cold testing. This paper presents our experience and lessons learnt from component manufacturing and first assemblies, how we setup an assembly hall with purpose-built tooling, and insights on logistics and resources. We also explain our plans to ensure timely delivery of the cryostat assemblies, without compromises to the high reliability level expected for equipment that will become part of the 27 km long particle collider. Installation in the LHC machine is planned for the next LHC long shutdown, starting in 2026.
Speaker: Delio Ramos (CERN) -
248
Design of a cryogenic test platform for CICC cooled by superfluid helium forced flow
A cryogenic test platform has been designed and conceived for the research of forced cooling of Cable in Conduit Conductor (CICC) by superfluid helium. Main research object of this platform is to obtain the hydrothermal properties of the Cable in Conduit Conductor (CICC) when it is cooled by superfluid helium forced flow. The superfluid helium flow loop and the superfluid helium acquisition system comprise the entire cryogenic test platform. Driving force of the superfluid helium flow loop comes from a Fountain Effect Pump (FEP). By decompressing and throttling 4.2K liquid helium, superfluid helium at 1.8K is obtained. Detailed parameters and mechanical structure designs of the entire platform will be presented in this paper.
Speaker: Ziwu Li -
249
Design of the cryogenic system of the CYCIAE-2000 MeV superconducting magnet
GeV-class proton beam with an average power of several megawatts have many important applications in particle physics towards the intensity frontier, as well as in the accelerator driven subcritical system, and material science. In 2019, China Institute of Atomic Energy (CIAE) proposed an isochronous FFAG conceptual design with capability of producing 2GeV/6MW CW proton beam. The main magnet of this isochronous FFAG adopts a 10 fold symmetric FDF structure design. And each single focusing magnet or defocusing magnet uses high-temperature superconducting magnet design with varing gradient in a large radial range, operating in the temperature range of 20 K to 30 K to provide both sufficient focusing force and high energy efficiency. In order to ensure the superconducting coils have a uniform temperature distribution as well as to ensure the cryogenic system has a low energy consumption, the helium gas recycling cooling of high temperature superconducting coils is used in superconducting magnet systems. This paper introduces the schematic design of the cryogenic structure for the CIAE-2000 MeV superconducting magnet.
Speakers: Suping Zhang (China Institute of Atomic Energy), hongji zhou -
250
Design study of a superconducting dipole magnet with active shielding for a heavy-ion rotating gantry
A superconducting magnet for a rotating gantry has recently been developed to reduce the size and weight of the gantry which is the core equipment of the heavy ion radiotherapy system. The superconducting magnet consists of a saddle-shaped superconducting coil surrounded by an iron yoke. The weight of one superconducting magnet can reach several tons, with the iron yoke accounting for most of the magnet's weight. The rotating gantry must have precise rotation control under the condition that several superconducting magnets are mounted on its frame. In this study, we propose a superconducting gantry magnet with active shielding to reduce the magnet weight, thereby simplifying the control system and the frame structure of the rotating gantry. An active shielding coil is used instead of an iron yoke to shield the stray magnetic field, which leads to a reduction in the magnet weight. The previous study indicated that the use of an active shielding coil in a superconducting magnet realizes a significant reduction in magnet weight compared with the use of an iron yoke. In addition, the study demonstrated the electromagnetic (EM) and structural feasibility of the magnet with active shielding. In the previous study, however, the three-dimensional configuration of superconducting coils was not taken into account. In this study, we conducted a design study of the three-dimensional coil configuration for a superconducting magnet, based on the coil cross-section designed in the previous study. This presentation reports the details of the designed coil configuration and the magnetic field distribution generated by it. Additionally, the influence of coil alignment errors on EM forces and the influence of cooling-down on coil deformation are discussed.
Speaker: Tetsuhiro Obana (NIFS) -
251
Detailed study of the cryogenic jumper connections between the cryogenic distribution line and the superconducting magnets of the High Luminosity LHC upgrade at CERN
The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) project will require a new cryogenic system to cooldown the new superconducting components in the final focusing regions for the ATLAS and the CMS experiments. The existing magnets will be replaced with newly developed superconducting magnets that will operate in pressurized HeII at 1.9 K with a generated heat load of several hundred Watts per magnet. The liquid and gaseous helium needed to cool the magnets will be supplied by means of a new cryogenic distribution line (QXL). The connection to the QXL is performed at specific service modules through cryogenic jumpers that must provide all the required cryogenic and mechanical functions while considering the very limited space available in the LHC tunnel. The jumpers must provide the flexibility required for installation and allow, while in cryogenic conditions, the displacements due to thermal contraction and to the remote alignment system of the magnets.
This article presents the functional requirements and the design constraints of the connections. It describes the development of the QXL cryogenic jumpers from the conceptual stage to the design after a combination of preliminary design studies and tests. This includes the definition and validation of the mechanical compensation scheme adopted for the vacuum vessel and the cryogenic lines, the thermal shield, and the vacuum barrier between the QXL and the magnet insulation vacuum. Finally, the article reports on the testing campaign carried out to provide an improved characterization of the flexural and axial stiffness of metallic flexible hoses used in the design of the cryogenic lines.Speaker: Fabio Merli (CERN) -
252
Development and testing of the internal sliding support for the Cryogenic Distribution Line for the HL-LHC
HL-LHC (High Luminosity LHC) is an upgrade of the LHC accelerator that will achieve a significantly higher level of integrated luminosity than the original LHC assumptions. As a result of the HL-LHC project, about 150 meters of the accelerator will be completely replaced on both sides of the P1 and P5 collision points. This will require a new cryogenic distribution system, consisting of a multi-channel cryogenic transfer line, service modules, return modules, and junction modules to the existing cryogenic system. During the design of the multi-channel cryogenic line, one of the biggest challenges was the design and verification of the internal sliding support. It required both thermal analysis and mechanical calculations taking into account the forces acting on the support during the operation of the equipment, failure, pressure testing, and transportation. During the development of the sliding support, several tests were carried out to verify the mechanical properties of the components made of G10 composite. The paper summarizes the design, development, and experimental verification of the sliding support.
Speaker: Bartosz Łoziński (KrioSystem Sp. z o.o.) -
253
Development status of a NbTi conduction-cooled superconducting quadrupole magnet combined with dipole correctors for the ILC main linac
In the International Linear Collider (ILC) main linac, superconducting quadrupole (SCQ) magnets combined with dipole correctors, together with superconducting radio frequency (SRF) cavities, will be used to transport and accelerate electron and positron beams to the collision point. The SRF cavity accelerates the beam up to 125 GeV per side, the SCQ focuses the beam, and the dipole collectors steer the beam and transport it along with the geoid.
SRF cavities need to be assembled in a clean room in order to minimize dust intrusion for keeping the best performance. On the other hand, SCQs are not recommended to be brought into the clean room because it is difficult to produce SCQs clean compared to SRF cavities. Therefore, the ILC-SCQ was designed to be split into two parts to allow assembly outside the clean room. In addition, it is cooled by thermal conduction from a liquid helium supply pipe not by liquid helium immersion, contributing to cryomodule simplification.
A 5-year plan to manufacture one ILC-type cryomodule began at KEK in 2023 with international collaboration. A prototype SCQ is being manufactured in JFY2024, and a stand-alone performance evaluation test in a cryostat is scheduled to be conducted in JFY2025. For this purpose, a cryocooler-cooled cryostat has been designed and the fabrication is in progress. In the ILC, because of the high accelerating gradient of the SRF cavities and the high magnetic field gradient of the SCQs, it has been pointed out that field-emitted electrons, so called “dark current”, from the cavity inner surface may cause SCQ’s quench by absorbing their energy at superconducting coils. In this presentation, the status of SCQ fabrication, cryostat for stand-alone testing, and dark current countermeasures will be reported.Speaker: Tomohiro Yamada (High Energy Accelerator Research Organization) -
254
Effect of thermal contact between gas-cooled REBCO conductors on hot-spot temperature in fusion magnets
A thermal and hydraulic analysis is presented to highlight the importance of thermal contact between gas-cooled REBCO conductors in cryogenic stability. For compact and efficient HTS fusion magnets, a variety of conductors are under development to stack REBCO tapes in a rigid jacket. In accordance with the leading group, the conductors are cooled by forced-flow of gaseous helium around at 20-30 K. One-dimensional distribution of gas temperature and pressure is rigorous calculated along an entire cooling loop of double-pancake winding in toroidal-field magnet, by taking into account the thermal interaction between adjacent conductors. The key parameters in this analysis are taken from the preliminary model of a KSTAR winding pack. It is clearly verified that the thermal contact plays a crucial role in the location and temperature level of internal hot spot. Thermal insulation by minimizing the axial contact between double-pancake windings is proposed as an effective method to protect the REBCO conductors from an excessively high temperature at inner layers. Details of gas-cooling schemes are discussed for the application to the winding pack design of high-field HTS magnets.
Speaker: Ho-Myung Chang -
255
High-gradient magnetic separation for wastewater treatment based on direct-conduction cooling superconducting magnets with large diameter, room temperature aperture
The development of cryogenic technology has greatly reduced the cost of large-diameter superconducting magnets and the difficulty of operation, making it possible for industrial fields. Our team has developed a large-diameter (room temperature aperture of more than 400 mm) superconducting magnet with direct-conduction cooling by a single GM refrigerator, which has improved the cooling efficiency, thermal stability and safety of the superconducting magnet, and it has been adapted in wastewater treatment. Based on the strong magnetic field generated by the superconducting magnet as well as carefully designed magnetic gradient, a series of devices have been developed and applied in several projects in China. In addition, an automated, continuous high-gradient magnetic separation system, as well as a cleaning system and a magnetic species recovery system have been developed to achieve efficient, continuous and stable operation of device. Furthermore, an integrated superconducting magnetic separation wastewater treatment device has been formed through integrated design, which has demonstrated significant performance on chemical oxygen demand (COD), total phosphorus and suspended solids.
Speaker: Chuanjun Huang -
256
Investigation of the influence of residual strain of epoxy resin on critical current of HTS tape by using fiber Bragg grating sensors
Epoxy resin is used to improve the mechanical properties, insulation properties and thermal conductivity of superconducting magnets. The second-generation high temperature superconducting (HTS) tapes have significant mechanical strength anisotropy due to their multi-layer structure. In the cooling process, stress concentration occurs between the layers due to the different cooling shrinkage rate of each layer of materials, and the cooling shrinkage of epoxy resin is much larger than that of the HTS tape, making this situation more serious, resulting in strong stress on the conductor. It may cause the crack, spalling, or even fracture of the superconducting layer, and then result in the decline of the critical current. Therefore, it is necessary to study the influence of the curing residual strain of the epoxy resin and of the cooling shrinkage on the attenuation of the electrical properties of the HTS tape, so as to avoid the performance degradation of superconducting magnets to a certain extent. In the present work, the fiber Bragg grating (FBG) sensors were used to monitor the strain of the YBCO tape during curing and cooling process, and the critical current before and after the epoxy resin curing was measured. It was found that brought about 12,000 µε strain to the tape upon the pure epoxy resin cured and cooled to 77 K, whereas the critical current was reduced by about 5 A. In addition, we studied the impregnation of epoxy resin with glass fiber cloth on the tape, and found that the residual strain was greatly reduced to less than 3000 µε, and the critical current did not degrade at all. In this way, by embedding the FBG sensors, the degradation of the critical current can be corresponded to the curing and cooling process, which further guides the performance improvement of the epoxy resin and curing process.
Speaker: Wanyin Zhao (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
257
LHC cryogenics and helium management in case of a major power outage
The Large Hadron Collider (LHC) houses a very large inventory of helium (totalizing 150 tons, including the strategic operational reserve) which must be properly managed and secured in the event of a major power outage. This paper presents dynamic simulations of the LHC cryogenic system following such an event and analyzes the different possible scenarios with their consequences. The simulations are first compared with experimental data obtained during relatively short power outages to validate the model. Then, the simulations are used to predict the behavior of the LHC cryogenic system and the evolution of helium inventory in the event of a longer power outage for different applied strategies.
Speaker: Benjamin Bradu (CERN) -
258
Mechanical design of the multi-channel liquid helium cryogenic transfer lines
The cryogenic distribution system for the High Intensity Heavy-ion Accelerator Facility (HIAF) under construction at IMP has about 146 m cryogenic transfer lines. These transfer lines will be installed between a distribution box on the surface and the connection valve boxes located 12.3 m underground in the tunnel. The transfer line consists of 28 sections. Due to space limitations the lines may have complex routings and require several angular sections. The lines consist of a vacuum jacket, a thermal screen and five internal helium headers. Specific fixed and sliding supports and compensation systems were devised for each line to allow for thermal contraction of the cryogenic pipes. This paper presents the mechanical design of the multi-channel liquid helium cryogenic transfer lines along with fabrication details.
Speaker: Li Zhu (Institute of Modern Physics, Chinese Academy of Sciences) -
259
Operational experience and maintenance strategies developed over nearly three decades of continuous operation of the AGOR superconducting cyclotron cryogenics system
The AGOR superconducting cyclotron at the Particle Therapy Research Center (PARTREC) in The Netherlands has been operational with its main coils kept continually at cryogenic temperatures since the mid-1990s. A Sulzer TCF50 Liquefier is used to supply liquid helium (LHe) to operate the cyclotron’s two superconducting main coils and two superconducting extraction channels. The extraction channels are routinely warmed to room temperature. When not operating the cyclotron no LHe is required in the cryostat housing the coils. However, in order to keep the cyclotron’s main coils adequately cooled to avoid damage or warping of the accelerator from thermal stresses, the liquefier supplies cooled helium gas (GHe) across the coils during non-operational periods. Since AGOR’s commissioning, it has been a policy to forego much of the regular, preventative maintenance to the cryogenics system that is common in other facilities to avoid shutting down the liquefier for more than two or three consecutive days. A longer shutdown of the liquefier could lead to long downtimes and could potentially cause catastrophic damage if the coils of the superconducting magnet warm up in an uncontrolled way. For this reason, we can offer the cryogenics community a unique insight into a cryogenics system that has been run almost continuously since the mid-1990s. We will report on many years of experience with our system and on findings that come from recent maintenance activities that became necessary following a persistent unstable behavior of the system that arose in 2018.
Speaker: Brian Jones (UMC-Groningen PARTREC) -
260
Optimization of 1 T HTS main magnet for Extremity MRI using Real-Coded Genetic Algorithm
The present study focuses on the optimal design of a 1 T main magnet operated at 65 K consisting of second-generation (2G) high-temperature superconductor (HTS) tape wound in the shape of double pancake (DP) coils for Extremity Magnetic Resonance Imaging (E-MRI) scanners by using the population-based real-coded genetic algorithm (RGA). In the RGA, the minimum length of HTS tape consumption is used as a fitness function for a given central field of 1T with a field homogeneity of less than 20 ppm inside a diameter of spherical volume (DSV) of 80 mm. The simulated binary crossover (SBX) and polynomial mutation functions are considered for creating the modified solutions in each iteration, and elitism is used for faster convergence to the optimal solution. The above algorithm is implemented by using a finite element method (FEM) package (i.e., COMSOL Multiphysics) along with MATLAB Live-Link. The FEM package is used to calculate all the parameters related to the HTS magnet, i.e., maximum perpendicular field (B_⊥), central magnetic field, field homogeneity, stresses, and 5 gauss-stray field, while the selection, crossover, and mutation operations are evaluated in MATLAB. The minimum length of HTS tape consumption for two cases: non-insulated (NI) and Kapton-insulated DP coil-based magnets, is compared.
Speaker: SUMIT KUMAR CHAND (Research Scholar) -
261
Recent developments of dark matter research magnet systems at Oxford Instruments
Superconducting magnets play a key role in the search for dark matter particles such as axions. This application benefits from a large B2V factor within the magnet bore. A low B field region in close vicinity of the main magnet and a low temperature environment are also required for the detection. Oxford Instruments has developed a range of large bore superconducting magnet systems for dark matter research. We are presenting the design and performance of recent systems.
The 12 T, 320 mm bore, liquid helium bath cooled magnet system, built for the Center for Axion and Precision Physics Research (CAPP) in South Korea, achieves high magnetic energy stored in the microwave cavity within the magnet bore to maximise signal output power. A cancellation coil located above the main magnet enables field-sensitive measurements close to the magnet. The challenges of making such a system are described.
The Proteox™ MX system designed for the Quantum Sensors for the Hidden Sector (QSHS) collaboration in the UK, features a smaller, actively shielded, Cryofree® magnet. This design not only provides a low field region for the readout electronics but also reduces the radial stray field significantly. The integrated dilution refrigerator, which delivers a base temperature below 10 mK, cools down both the electromagnetic resonator and the quantum electronics, greatly improving the signal-to-noise ratio. The advances already made to further developments in dark matter research are described.
Speaker: Yuwei Ge (Oxford Instruments NanoScience) -
262
SMES HTS tape length optimization using ANN based digital twin
Artificial Neural Network (ANN)-based digital twins are increasingly utilized in scientific research applications, replacing Finite Element Method (FEM) models to save time and resources. These ANN models deliver rapid and accurate results comparable to the FEM models on which they are trained. Optimization, employing metaheuristic methods like the Genetic Algorithm and Particle Swarm Optimization, for High-Temperature Superconducting Magnetic Energy Storage (HTS SMES) solenoid-type coils tends to be time-consuming due to the increased variables from multiple FEM simulations.
An ANN-based model focusing on a single Double Pancake (DP) with varying inner diameter, number of turns, and supporting layer thickness was trained to calculate magnetic flux density distribution using a solved FEM model. Subsequently, SMES optimization was conducted to minimize length while maintaining a fixed stored energy of 1 MJ and hoop stress within 250 MPa. The axial placement of these coils at varying distances was considered in the optimization process. The magnetic field was determined by the vector sum of the magnetic fields from each coil. Real coded genetic algorithms were employed for optimization. The speed and results of the optimization were compared with magnetic field calculations based on the interpolation function available in MATLAB. Parallel processing was utilized within MATLAB for faster calculationSpeaker: Sumit Kumar Chand (Indian Institute of Technology, Kharagpur, India) -
263
Study on Extreme Condition Stability of Miniaturized High-Temperature Superconducting Magnets Based on Sterling Conduction Cooling System
In order to meet the demand for high-performance magnetic fields in extreme environments such as magnetic levitation trains, compared with traditional copper or permanent magnets, superconducting magnets with high current density can achieve light weighting of the overall system, which is of great significance for the safe operation and cost saving of high-speed magnetic levitation. In this paper, a miniaturized high-temperature superconducting magnet structure is designed, which provides cooling for the magnet through Sterling conduction cooling instead of traditional liquid helium or GM refrigerators with large compressors, reducing the weight of the superconducting magnet from over 200 kg to below 50 kg. In addition, aiming at the operating conditions of high-temperature superconducting magnets under 10-g acceleration and during operation, stability analysis calculations of Sterling conduction cooling high-temperature superconducting magnets under background magnetic fields of 0.5 T, 1 T, and 2 T are carried out based on the T-A numerical analysis method. The results show that under a maximum operating current of 60 A, the stability margin of the superconducting magnet still exceeds 1000 mJ/cc. Furthermore, through analysis of AC losses, the superconducting magnet will only experience quenching when the current frequency exceeds 250 Hz, meeting the high-frequency excitation operation requirements of superconducting magnets. Finally, the low-temperature characteristics of the Sterling conduction cooling high-temperature superconducting magnet are verified through cooling and energization tests, and the magnet maintains stable operation for over 10 hours under conduction cooling with a temperature difference not exceeding 1 K, confirming the feasibility of the miniaturized conduction cooling superconducting magnet proposed in this paper, laying the technical foundation for the safe service of high-speed magnetic levitation extreme condition superconducting magnets in the future.
Speaker: Haiyang Liu (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) -
264
The Design of a Curved Cryostat for the 90° Superconducting Magnet
Abstract—In order to enable the 90° curved Discrete Canted-Cosine-Theta (DCT) superconducting magnet for heavy ion Gantry to operate at low temperature normally, a 90° curved cryostat that can rotate on a rotating frame is developed. 18 voltage leads for quench detection and 7 temperature sensors for detecting temperature changes during cooling and excitation are arranged into the superconducting magnet. For the convenience of processing and welding, the outer Dewar and thermal shield of the cryostat are both welded from three cylinder bodies. The cryostat beam center tube passes through the center of the superconducting magnet, and the beam center tube is formed by bending a seamless stainless steel tube. There is a thermal shield center tube between the beam center tube and the inner wall of the superconducting magnet. To prevent contact between the inner wall of the magnet, the center tube of the beam, and the center tube of the thermal shield due to cold shrinkage deformation, a circular ring of material G10 is arranged in the gap between the tubes. The cryostat uses four high-temperature superconducting current leads, two of which are connected to the superconducting cables for power supply to the magnet, and the other two are connected to the copper wires for quench protection of the magnet. To ensure the stability of the superconducting magnet during rotation and the concentricity between the beam center tube and the beam axis, the superconducting magnet is fixed on the Dewar surface of the cryostat with 12 carbon fiber straps. A heat leakage calculation is conducted on the cryostat. The results show that the first stage heat leakage is 57W@50K, and the second stage heat leakage is 1.5W@4.5K. Therefore, two GM refrigerators are used for the superconducting magnet for the normal operation of superconducting magnet. Strength verification is conducted on the static, transportation, and rotation conditions of the cryostat (mainly at 0°, 60°, 90°, and 180°). According to the analysis results, 12 carbon fiber straps can ensure the stability of the superconducting magnet and ensure the concentricity of the beam center tube and the beam axis of the superconducting magnet during is within ±0.3mm during the rotation process. The 90° curved cryostat is being processed and assembled, and the relevant design parameters will be further verified by experiments.
Index Terms—90° curved cryostat, heat leakage, strength verification, curved superconducting magnetSpeaker: Yang Yao -
265
The Design of a Horizontal Testing Cryostat for the Superconducting curved magnets of Compact Synchrotron
A superconducting heavy ion therapy device is developing in Lanzhou, and its gantry and synchrotron require curved superconducting magnets to reduce size. To cool and test the performance of superconducting magnets by horizontal placement, a horizontal testing cryostat was designed for the curved superconducting magnet of the heavy ion therapy device. A superconducting magnet is a Discrete Canted-Cosine-Theta (DCT) superconducting magnet consisting of a set of two-pole coils and two sets of quadrupole coils. The deflection radius of the superconducting magnet is 2000 mm, the theoretical deflection angle is 45-degree, the aperture of the good field area is 60mm, and the maximum central magnetic field is 3.2 Tesla. With the maximum operating current reaches nearly 400 A, 6 pairs of 500 A High-temperature superconductivity (HTS) current leads are required to be powered. For the testing needs of 45-degree superconducting magnets and other curved superconducting magnets in the future, the horizontal testing cryostat is designed with eccentric flanges and different bases to accommodate superconducting magnets with a deflection angle of 30-60 degrees and a deflection radius of 1000-2500 mm. In addition, the design of the eccentric flange can be adapted to different diameters of warm bore tubes by replacing the flange with different inner diameters. To facilitate superconducting magnet installation, the horizontal testing cryostat is designed with slide rails for superconducting magnet support and installation, supported by three POSTs. The static heat load of the horizontal testing cryostat is about 2.0134 W@4.2 K, 141.256 W@50 K. In the process of rapid excitation, there is AC loss in the superconducting coils and the metal parts such as radiation screen, and the dynamic heat load is about 6.958 W@4.2 K, 132.8 W@50 K. In order to conduct cooling and maintain the low temperature of 4.2K for superconducting magnets and 50K for radiation screen, six two-stage GM cryocoolers with 1.8 W@4.2 K and 35 W@50 K cooling capacity are required. For the 45-degree curved superconducting magnet with a cold mass of about 800 kg, it takes 6 days to theoretically cool down to 4.2 K, and the rewarming time after quench is about 5.5 hours. The horizontal testing cryostat is being processed and assembled, and the relevant design parameters will be further verified by experiments.
Speaker: Weiyu Qiao
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245
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15:30
Coffee & Tea break
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Wed-Or10: Cryocoolers Applications Room D
Room D
Convener: Holger Neumann (Karlsruhe Insitute of Technology - Insitute for Technical Physics - Cryogenics)-
266
Vibration-free Mirror Coating Test Facility for the Einstein Telescope
The Einstein Telescope is a proposed ground-based third-generation gravitational wave observatory. The extreme sensitivity with which current second-generation gravitational observatories have measured gravitational waves is to be improved even further. One of the ways in which this is achieved is by cooling down the mirrors of the interferometers. Brownian noise, mainly originating from the coating of the mirrors, scales with temperature and as such can be suppressed by operating at cryogenic temperatures. Development of the mirror coatings is an ongoing process and the performance of these coatings (in terms of noise) will need to be tested.
Characterisation of mirror coating noise requires a cryogenic setup of which the background noise contribution is limited to an absolute minimum. We achieve this by using an off-the-shelf cryocooler combined with a thermal storage unit (TSU). The cryocooler is switched off during mirror coating characterisation and the low operating temperature (typically 10 K) is maintained by the TSU, thus allowing for vibration-free experiments. The mirror is then stabilised at its operating temperature using a controllable heat switch to tune the heat flow from the mirror test platform to the TSU.
We will present the design of this system and simulations demonstrating the intended operation. Furthermore, the next steps in towards the realization of the system will be discussed.Speaker: Koen Lotze (University of Twente) -
267
Release of 4K GM-JT cryocooler system RJT-100ST
GM-JT (Gifford-McMahon-Joule-Thomson) cryocooler systems consist of GM cryocooler for pre-cooling and JT cryocooler system. GM-JT cryocooler systems have the cooling capacity of several GM or PT cryocooler systems by combination of GM and JT cryocoolers. This leads to better power consumption (efficiency), footprint, and maintenance costs for the customer's system.
Last November, SHI released RJT-100ST, stage type of GM-JT cryocooler systems coupled with E-77A and J117V compressors. It has a cooling capacity of 9W at 4.2K and a very high COP of 6.4E-4.
In this session, we present the overview of RJT-100ST.Speaker: Toshiya Nagai (SHI) -
268
Investigation of a Helium cooling circulation loop on a 1.3 GHz cavity structure
This paper presents a novel cryogenic cooling method for Superconducting Radio Frequency (SRF) cavities, utilizing a cold helium flow passed through a brazed capillary for their cooling. Such novel and drastically reduced helium content cooling scheme can be applied to a wide variety of superconducting cavities, and it has many advantages compared to the traditional cooling method of SRF cavities in a liquid helium bath. The paper describes cooling options and configurations concerning helium forced flow heat transfer at the capillary surface plus the conduction pathway and the resulting temperature distribution in the cavity itself. A detailed description is provided for the proof-of-concept cryogenic performance test stand, which studies the relevant parameters for a 1.3 GHz prototype cavity.
The results of the numerical evaluation of heat transfer and pressure drop relations for two-phase and single-phase supercritical flow, as well as the results of the mechanical vibration measurements, are cited. Moreover, the results from the cold commissioning of the experimental system are outlined, demonstrating that the cavity could reach a minimum temperature of 6.5 K with an applied heat load of 1 W, with a He circulation loop based on a 1.8 W @ 4.2 K cryocooler. A LHe booster heat exchanger has been introduced to achieve even lower temperatures and ensure consistent inlet conditions for further evaluation of cavity cooling efficiency. These data form the basis for future experimental validation campaigns in the temperature range of 4.2 K to 10 K and helium pressures of up to 2.2 MPa. Special attention is paid to possible new introduced effects of mechanical vibrations or temperature gradients along the cooling capillary when compared to a stagnant He bath cooling.Keywords — Dry cavity cooling, superconducting radiofrequency (SRF) cavities, low temperature, helium capillary cooling
Speaker: Maria Chioteli (CERN) -
269
Mechanical design of a superconducting magnet for gravity compensation
Magnetic compensation of gravity allows for ground-based experiments to be carried out under weightless conditions at reasonable cost and without the time limitation of systems such as zero-g airplanes or drop towers. In this paper a superconducting magnet for gravity compensation is described. The magnet warm bore diameter is 380mm and the center field is 2T. The magnet is comprised by nine solenoid coils wound on two separated mandrels. The magnet is conduction cooled by two GM cryocoolers. Mechanical design and analysis of the cold mass are presented in this paper, especially the effect of different structure material selection, pre-tension force on the wire during winding, and big holes on the mandrel. Cryostat design and analysis are present in this paper, including the heat load analysis, cold mass support design and thermal shield design. Cooling down and charging results show that the magnet can run at its design current very well.
Speaker: Xinglong Guo (Suzhou Bama Superconductive Technology Co., Ltd) -
270
Investigation of Structure Effects on Jet Impingement and Energy Recovery in Miniature Open-cycle Joule-Thomson Cryocoolers
Abstract: Joule-Thomson (J-T) effect is pivotal in refrigeration applications spanning a broad spectrum of temperature ranges. Miniature open-cycle J-T cryocoolers stand out for their remarkable cooling speed, capable of fast cooling from room temperature to 100 K within mere seconds. This rapid cooling capability renders them ideal for addressing immediate and transient cooling requirements, such as the cooling of infrared chips. In the cooling process of such a cryocooler, the high-pressure refrigerant undergoes pre-cooling in a heat exchanger and throttling to two-phase state before impinging on the cold plate. Subsequently, the backflow discharged into the atmosphere after passing through a cold energy recovery process in the heat exchanger. Crucially, this pre-cooling and energy recovery process depend on the performance of the heat exchanger, which serves as a critical factor governing the cooling temperature and cool-down time of the cryocooler. While previous research has extensively examined the structures, efficiency, and numerical models of heat exchangers, the equally vital jet impingement aspect affecting the cryocooler's cool-down time, has not received enough attention. It is necessary to study the energy recovery and jet impingement separately, as the heat exchanger solely influences the temperature and liquefaction rate of the jet, whereas the cryocooler's cooling efficiency is directly dictated by jet impingement. In order to study the impacts of structure and operational conditions on energy recovery and jet impingement of cryocoolers, three conical Hampson-type J-T cryocoolers were designed and tested under various working conditions. Several key factors were considered, including orifice diameter, jet height, cold plate heat transfer enhancement, backflow gap, half-cone angle, and the height of heat exchanger. Simultaneously, three crucial parameters, cold plate temperature, jet temperature, and cylinder pressure, were meticulously measured throughout the cooling process. To facilitate a comprehensive analysis, richer insights were derived by making reasonable assumptions grounded in the measured data. The experimental results demonstrated that the mass flow rate within the J-T cryocooler undergoes two distinct phases, that is, pipeline-dominant stage and the orifice-dominant stage. The temperature difference in two-phase impinging jet heat transfer is crucial for rapid cooling because it can alter the boiling mode and heat flux. Regarding the impact of structure on performance, it was found that higher jet height is beneficial for single-phase jet cooling during the pipeline-dominant stage of mass flow rate, and larger orifice diameters and backflow gap are preferable when pressure drop and heat transfer efficiency are satisfied. Moreover, larger cone angles lead to better energy recovery capacity for Hampson-type heat exchangers, and the length of the heat exchanger needs to be determined by the heat exchange efficiency of the refrigerant. The most significant improvement in cryocooler’s performance is the enhanced heat transfer treatment of cold plate.
Keywords: Miniature J-T cryocooler, Jet impingement, Energy recovery, Structural analysisSpeaker: Xing Xiao (Huazhong University of Science and Technology) -
271
Commissioning and first results of an experimental setup for the characterization of cryogenic pulsating heat pipes
For the cooling of new superconducting components, cryocoolers are increasingly favored over traditional immersion bath cooling. The efficient thermal connection between superconducting elements, like coils, and cryocoolers is vital for the system performance. Pulsating Heat Pipes (PHPs) utilize two-phase flow to transfer heat from a warmer evaporator section to a colder condenser part using both latent (phase change) and sensible (circulation and oscillation) heat transfer mechanisms. Their main advantage compared to conventional links made of solid material such as copper are their high thermal performance and low weight. While water-based PHPs are well-established, the potential of cryogenic PHPs, particularly for cooling superconducting components, remains underexplored. Addressing this, the Paul Scherrer Institute (PSI), in collaboration with VDL Enabling Technologies Group (VDL ETG), has initiated a project to develop and assess cryogenic PHPs tailored for superconducting applications.
This paper introduces a new experimental setup for cryogenic PHP characterization. It outlines the design, instrumentation, and operational procedures of a vertically oriented 20-tube neon PHP. The PHP design features an adiabatic section measuring 19.5 cm, with 316 L steel tubes of 1 mm inner and 3 mm outer diameters. The results and benchmarking of the experiments conducted with this PHP are shown. Experimental conditions varied across condenser temperatures (27 and 30 K) and filling ratios (15 to 90%), with evaporator heat loads incrementally increased between 0 and 20 W. The low thermal resistance observed offers encouraging evidence for the potential of this system in cooling high-temperature superconducting coils.
Speaker: Carolin Zoller (Paul Scherrer Institut (PSI)) -
272
PT410 Cold Head dynamic characterization
In the design of a cryostat, the characterization of their cryocoolers is critical for vibration-sensitive applications. These components are used for achieving and maintaining low temperatures. In this work, the characterization of the PT410 pulse tube cryoocoler through modal and microvibration testing has been conducted.
Modal testing was conducted to examine the natural frequencies and vibration modes of the cold head. Additionally, microvibration testing was performed to determine the interface forces caused by the operation of the cryocooler on the mechanical mounting interface and the accelerations induced on the thermal interface of their cold stages.
The first bending modes of the cryocooler have been determined by the modal test. The forces are measured directly by triaxial load cells and the accelerations of the different stages of the cryocooler are obtained using accelerometers.
The characterization has been performed in a test bench, mechanically designed for accurate measurements. Taking into account that the cryocooler cold head is supplied by a helium flow pulse, this gives one source of vibration that must be controlled, an additional support was implemented for the supply line elements.
In short, this study provides a precise measurement of the dynamic characteristics and mechanical stability of the PT410 cold head. The findings are relevant for the design and development of cryogenic systems where vibrations are critical.This work was supported by the grants PID2020-115325GB-C31**
Keywords: cryogenics, cold head, pulse tube, microvibrations, testing, modal**
Speaker: Sandra Pérez Barrio (Instituto Nacional de Técnica Aeroespacial, Departamento de Cargas Útiles Espaciales, Área de Ingeniería Termo Mecánica) -
273
C400 – 10 K remote helium cooling loop for ions carbon cyclotron application
To improve the precision and the efficiency of cancer treatment, a new kind of radiotherapy using ions carbon is under development in France. This project called C400, involved a 400 Mev/u cyclotron composed of a 15 tons supraconducting magnet cooling by a 470 L liquid helium bath.
In order to cool down of the magnet from 300 K, Absolut System designed, manufactured and tested a high capacity 10 K Remote Helium Cooling Loop. This system is a forced Helium 4 cooling loop cryostat which is providing a progressive and controlled cooling for the application from 300 K to 10 K. The cryostat is equipped with two Gifford-MacMahon AL630 cold heads, two double stage Pulse Tube PT420 cold heads and a LN2 tank corresponding to seven cooling stages. Helium flow controlled by two cryogenic circulators has a range of 0.1 to 5 g/s. Pressure range from 1 to 4 bars, can be adjusted to optimize the efficiency depending on the Helium temperature. In C400 Project, our cryostat also provides LN2 to other equipment such as cryogenic transfer lines, magnet and quench tank thermal shields.
It will guarantee the best cooling for the supraconducting magnet before the liquefaction phase takes place under 10 K. Moreover, when quench will occur, all the Helium gas will be recovered in tanks. Our 10 K Remote Helium Cooling Loop will cool once again Helium gas from the tanks permitting to recycle all Helium gas and restart quickly the cyclotron. Thus, the 10 K Remote Helium Cooling Loop is an innovative solution permitting to cool down the C400 cyclotron as many times as it will need, from a 300 K Helium gas storage in complete autonomy even if quench occurred.
Speaker: Paul HILLIERE (Absolut System)
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266
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Wed-Or11: Application H2 and LNG 1 Room A
Room A
Convener: Yonghua Huang-
274
Development of a lab-scale hydrogen liquefaction system
The demand for small quantities of liquid hydrogen available at any time for testing of equipment and technologies for liquid hydrogen applications is growing. Therefore, several initiatives have started to develop a small-scale hydrogen liquefier with a liquefaction capacity in the range of 1 to 10 kg/day. The EHLAS (Economic Hydrogen Liquefaction And Storage) project is one of them and aims to develop an efficient and affordable lab-scale hydrogen liquefier.
Within the EHLAS project, two liquefier concepts are investigated. The first concept is based on using two single cryocoolers to achieve hydrogen liquefaction at a rate up to 10 kg/day. The main drawback of this concept is the low overall efficiency and high costs of the liquefaction process due to the COP and costs of the cryocoolers, respectively. Therefore, a second concept is developed that is based on a single-stage cryocooler, Joule-Thomson expansion and a recirculation loop of hydrogen gas with heat exchanger and a compressor to improve the efficiency and reduce the costs of the liquefaction system. With the current design, a liquefaction capacity of 5 to 6 kg/day can be reached.
This paper summarizes the status of the EHLAS project. It discusses the hydrogen liquefier concepts, the principle designs and performances. Further, the design of the compressor and heat exchangers will be described and the results of the validation experiments will be presented. The paper ends with giving an overview of the manufacturing status of the system.
Speaker: Hendrie Derking (Cryoworld BV) -
275
Customized hydrogen liquefier system for applications up to 50 kg per day
Based on its expertise in cryogenics and on its experience with more than 50 cryostats in operation, ABSOLUT SYSTEM has developed an industrial liquefier system of hydrogen, for applications up to 50kg of liquid hydrogen per day. The liquefier uses Cryomech cold heads, a well-known technology at Absolut System, which is a distributor of this hardware and which ensures its maintenance.
The configuration of the liquefier can be adapted to fit the customers requirements and to optimize its costs: it can be delivered with a capacity from 10 of LH2 per day and up to 50 kg of LH2 per day, with the possibility to upgrade the system later by adding cold heads, in the limit of 50 kg of LH2 per day.
The liquefier can also be delivered together with a full liquefying system:
-Liquefier inside a container, to ease its storage and its transport
-With a LH2 storage, optimized to fit with the liquefier capacity and operation
-With LH2 transfer lines
-With instrumentation as LH2 massflow measurements and online ortho / para analyser
This system brings flexibility and robustness to the customer.Speaker: Younesse Maaizi (Absolut System) -
276
Experimental study on the thermal performance of printed circuit heat exchangers used for liquid hydrogen fueling stations
As the hydrogen mobility market has grown in recent years, liquid hydrogen fueling stations, which are capable of delivering higher amounts of hydrogen than gaseous hydrogen fueling stations, have attracted increasing attention. Liquid hydrogen fueling stations include evaporation systems that convert liquid hydrogen into gas and heat it up to the right temperature. For normal operation, the evaporation systems must be able to convert liquid hydrogen into gas at a rate of at least 100kg/hr. Whether they can meet these requirements or not depends on the performance of the heat exchanger, which is a core equipment of the evaporation systems. The problem is that heat exchangers used in hydrogen fueling stations are very large compared to ordinary heat exchangers due to the high pressure and cryogenic environment in which they operate. As the increase of the heat exchanger size leads to the increase of the system size and reduces the economic feasibility, a key issue in the development of liquid hydrogen fueling stations is to minimize the size of the heat exchangers by maximizing their effectiveness. In this study, it is investigated whether Printed Circuit Heat Exchangers (PCHEs), which are known to have high effectiveness, can be applied to liquid hydrogen fueling stations. To this end, lab-scale PCHEs are designed and fabricated, and their performance is evaluated by using an experimental facility capable of creating a cryogenic environment. Due to regulatory restrictions, liquid nitrogen is used to conduct the experiment instead of liquid hydrogen, and 50% ethylene glycol water mixture is used as a working fluid for the hot side. The PCHE material is SUS 316L, and the number of plates is two each for the cold and hot sides. For the parametric study, four PCHEs are fabricated using a combination of cold side plates with channel diameters of 1mm and 2mm, and hot side plates with channel diameters of 2mm and 3mm. Their performance is evaluated by measuring the flow rate, temperature and pressure at the inlet and outlet sides of the PCHEs. It is found that the effectiveness of the PCHEs is ranged from 0.75 to 0.99 depending on the flow rate and the channel diameter. The effectiveness increases as the flow rate increases and the cold side channel diameter decreases. The hot side channel diameter does not have a significant effect on the effectiveness of the PCHEs. The results of the experiments confirm that the effectiveness of PCHEs can be close to 1 in cryogenic environments if the flow rate and channel diameter are properly designed.
Speaker: Minchang Kim (Korea Institute of Machinery and Materials) -
277
A preliminary experimental study on thermal stratification in horizontal cylindrical cryogenic liquid storage vessels
Thermal stratification is of major concern in the design of cryogenic liquid storage vessels. In closed (isochoric) storage systems, a developing thermal stratification leads to higher pressure increase rates compared with isothermal conditions and therefore to premature boil-off losses. The development of a thermal stratification is a consequence of non-uniform distribution of the heat inleak into and subsequent heat transfer processes inside the storage system. For conventional storage geometries, i.e. vertical cylindrical dewar vessels, the processes and relations inside the fluid are well understood. However, the application of cryogenic liquid hydrogen as an alternative fuel for future sustainable mobility mostly implies the usage of horizontal cylindrical vessels with fixed-floating bearing arrangements. This setup changes the distribution of the entering heat flow and causes a substantially different temperature profile inside the storage vessel. Experimental data on thermal stratification in horizontal cryogenic liquid tanks are not found in literature; data generated by means of simulation are scarce. As a first step for better understanding the thermal stratification in horizontal cylindrical cryogenic storage units, a standard laboratory liquid helium dewar vessel was investigated. For this, the vessel was put in a horizontal position while the temperature distribution at different cross sections of the tank was measured. This paper reports on those preliminary experimental results.
Speaker: Thomas Just (Technische Universität Dresden) -
278
Design optimization and heat transfer characteristics of multilayer insulation structures for liquid hydrogen tanks
An excellent insulation performance can promote the development of liquid hydrogen (LH2) due to its characteristics of easy evaporation. To improve the storage efficiency of LH2 and further enhance the performance of multilayer insulation structure (MLI), an experimental setup has been designed and fabricated based on the evaporation calorimetry to test the performance of MLIs. Thermodynamic parameters such as the apparent thermal conductivity and the influence of each factor on the insulation performance are obtained. The correlations for MLI heat leakage calculation are also fitted based on the experimental results. Based on the heat leakage correlations, the MLI layer density and the vapor-cooled shield locations are optimized to achieve the optimal insulation performance of LH2 tanks. This study is of great significance for developing low heat leakage insulation structures and improving the efficiency of LH2 storage and transportation.
This work was supported by the National Key Research and Development Program of China (No. 2022YFB4002900) and the Youth Innovation Team of Shaanxi Universities.
Speaker: Hongyu Lv (Xi’an Jiaotong University) -
279
Permeability testing of fibre reinforced thermoplastic pipes – validation and results
A key challenge of designing cryogenic hydrogen fuel systems for future zero emission mobility is the reduction of the overall system weight by using lightweight engineering. Especially in the context of aviation, fibre reinforced thermoplastic composite materials (FRT) are considered as alternative construction materials for fuel line systems. However, permeation of hydrogen through FRT is not negligible, in contrast to conventional stainless steel. Further, their permeability is heavily dependent on the composite’s structure as well as the specific geometric shape in which the material is used, in this case as hollow profile structures. Thus, permeability qualification of newly developed FRT must be conducted with specimens that represent the FRT structures in question as well as the influence of the corresponding manufacturing process for tubular structures. Two previous papers already describe the concept and first validation measurements of such a permeability test rig for FRT pipe specimens. This paper completes the validation of this test rig. First results of helium permeation through FRT tube structures at both room temperature and cryogenic conditions are reported. A comparison of room temperature permeation through cryogenically cycled and uncycled samples is also presented as well as the fabrication approach for the tubular FRT samples.
Speaker: Thomas Just (Technische Universität Dresden) -
280
Using Waste Cold from LNG Conversion to Enhance Cold Food Supply Chains in India
Abstract
The post-harvest losses of agricultural produce in India are as high as 40% compared to about 2 % in the UK. Fresh perishable crops contain 65 to 95 % water when harvested and are at risk of spoilage due to microbial activity, water loss, and higher respiration and sprouting under ambient conditions for a long time. Hence there is a need to preserve agricultural produce by maintaining it below ambient temperatures. Presently, huge amounts of agricultural produce are being wasted due to a lack of proper storage techniques and an integrated cold supply chain in India. The cold chain denotes the series of actions and equipment required to maintain a product within a specified low-temperature range from harvest to retail and consumption. A temperature-controlled supply chain network with storage and distribution involves the transportation of temperature-sensitive perishable products through thermal and refrigerated packaging methods
Natural gas is liquefied by cooling it (at 112K) to reduce its volume for shipping. LNG receiving terminals, also called regasification facilities, receive LNG ships, store the LNG until required, and send out gaseous methane into the local pipeline grid. At the receiving terminal, the Liquefied Natural Gas (LNG) undergoes a regasification (reheating) process before being supplied to customers, and in the process, vast amounts of cold are lost to the environment. There is a great opportunity to harness the wasted/ stranded cold at the LNG terminals to produce liquid air and provide zero-emission cooling and power in a wide range of applications, static as well as mobile. This energy recycling at LNG terminals can develop dedicated gateways for perishable foods in the region and could be a potential and viable alternative source of refrigeration for cold storage /cold chain with zero CO2 emissionPresently 90% of India’s cooling capacity and annual refrigeration and air-conditioning is based on hydrofluorocarbons whilst about 10% is based on ammonia. India’s cold chain investment is rapidly increasing which will dominate other refrigeration units and it is expected to be based on conventional refrigeration systems. There is a pressing need to develop sustainable and low carbon dioxide emission cold chains. Part of the solution may be to use the huge untapped resource of cold associated with LNG production.
Currently, India has four regasification plants in Petronet’s Dahej, Kochi LNG terminals, Shell’s Hazira plant, and the Dabhol terminal, with a total capacity of 25 million tonnes per annum (MMTPA) where approximately 500-640 Megawatts of waste cold energy can be recovered. India is in the process of enhancing its LNG import many fold in the next few years
In this context, the paper explains the concept of the cold chain and the importance of temperature control for increasing the shelf life of produce. It summarizes the current status of cold storage in India and highlights, in an Indian context, the prospect of an agri-food cold supply chain using LNG
Key Words-Cold Chain, Liquefied Natural Gas, Refrigeration, Perishable cropsAcknowledgements present work is under the TRANSSITioN project funded by the Science and Technology Facilities Council (STFC) Global Challenges Research Fund (GCRF) (grants ST/S002871/1 and ST/T001313/1). It combines broad and diverse experience from India and the UK to investigate sustainable improvements to the vegetable supply chain in India. Dr Swapan C Sarkar is also thankful to Dr D.Roychowdhury and Suvrajyoti Sarkar two associates of CRCT at Jadavpur University, India for their help and co-operation in preparing the present manuscript.
Speaker: Swapan Chandra Sarkar (CENTRE FOR RURAL & CRYOGENIC TECHNOLOGIES, JADAVPUR UNIVERSITIES, KOLKATA-700032,INDIA) -
281
Experimental study of cryogenic fluid flow in porous thermal insulation materials
Porous thermal insulation materials, such as polyurethane foam, glass wool or glass fiber, have been widely used in the field of cryogenic storage and transportation systems. In situations where cracks or holes occur in the package wall layer, the stored cryogenic liquid will leak and penetrate into the porous media. The liquid evaporates and diffuses in the porous media and absorbs a large amount of latent heat of vaporization from the surroundings, which may even cause system damage. Therefore, in order to predict the influence caused by the leakage process on the cryogenic storage and transportation system, it is very important to investigate the fluid dynamics and diffusion characteristics of cryogenic fluid in porous media. In this study, an experimental se-up was built based on a typical kind of LNG cargo containment system to explore the cryogenic leakage behavior inside the porous thermal-insulation materials. The transient temperature and pressure fields were studied under different inlet conditions. The experimental results indicated that the transient temperature is greatly influenced by the inlet conditions and the properties of the fluids. As the liquid content at the inlet increases, the minimum temperature inside the porous media decreases. The lowest temperature of the hull plate reaches 78K in 30 minutes when liquid nitrogen is injected through a 4mm diameter hole at an inlet pressure of 0.04MPa. The pressure field is nonlinear in the glass wool, and the pressure drop is the largest in the entrance region.The results of this study are helpful in predicting the leakage problem and determining the leakage level that will occur during the operation of the containment system. .
Speaker: Peng Xu (Shanghai Jiao Tong University)
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274
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Wed-Or12: Superconductors & Applicatons Room B+C
Room B+C
Convener: Hans Van Oort (University of Twente)-
282
Production of 2G HTS tape at Faraday Factory Japan
Faraday Factory Japan (FFJ) has established the world’s largest facility for manufacturing of 2G HTS tape and is ready to further expand production capacity with anticipated demand growth. At present, the factory capacity exceeds 1,000 km of 12 mm wide tape per year (or 3,000 km of 4 mm wide tape).
Over more than a decade on the 2G HTS tape market, the selling price of FFJ HTS tape halved with each ten-fold increase of production and sales. This has been possible thanks to the approach we take to scale-up. When increasing the production volume, we improve all three elements that determine the capacity of a manufacturing line: (1) throughput (tape line speed), (2) process up-time, and (3) manufacturing yield. This has been an ongoing effort at FFJ that secures the continuous reduction of production cost with scale-up, as opposed to the alternative approach of merely multiplying identical production units that has a limited potential to cost reduction.
Today, the vast part of demand on HTS tape comes from high-field compact fusion. We strive to satisfy the needs of other HTS applications, maximising the use of synergies in requirements to tape among different applications. At present, all tape at FFJ is produced to fusion specifications, and for other applications we post-process the already made “fusion-specs” tape, to the extent technically possible and economically reasonable, in order to keep the low price.
The mass-produced FFJ tape contains YBCO superconductor, is based on Hastelloy substrate with the nominal thickness of 40 microns and the width of 4 and 12 mm, and is electrically stabilised with 5 microns of copper per side. Offered post-processing includes thicker copper layer, solder plating, soldered stacks of two tapes, and insulation.
With demand from fusion dominating the market, it is not economically reasonable to make tape with significantly different parameters, for instance, on substrates with a thickness other than 40 microns, or in widths other than 4 or 12 mm, or with different REBCO composition. With future appearance of large-volume demand on tape with different specifications, however, FFJ is ready to diversify the product offer accordingly, up to building factories dedicated to making tape for specific HTS applications.
Speaker: Alexander Molodyk (Faraday Factory Japan) -
283
A REBCO coating process for high-field applications
In the initial design phase of the Future Circular Collider (FCC), concerns arose regarding high beam impedance coupling of the inner walls, posing a risk of destabilizing the particle beam due to high image current. To address this challenge, a collaborative effort with CERN led to the development of a REBCO coating process that preserves their low surface impedance [1].
This endeavor extends beyond the FCC, offering significant benefits to various high-field applications. Notably, it has been demonstrated to enhance the quality factor of RADES's axion dark-matter haloscopes [2]. Moreover, our coatings hold potential for enabling RF-cavities to operate at higher acceleration voltages by substantially reducing ohmic power loss in cavity walls, an aspect currently under investigation in partnership with SLAC.
Here we focus on the optimization of coating quality for non-flat geometries, achieved through a novel approach of delaminating coated conductors before soldering. We will examine this methodology across multiple contexts, including RADES's axion haloscopes, a prototype of the FCC's beam screen, and a decagonal cavity constructed for investigating the photodesorption of REBCO in collaboration with KEK.Speaker: Neil Lamas -
284
A Data-Driven Approach for Modelling the Relationship between Fabrication Parameters and Critical Currents of REBCO Coated Conductors in a Real-Scale Pulsed Laser Deposition System
With the progress of applications such as compact nuclear fusion reactors and power devices using high temperature superconducting wires, the need for REBCO coated conductors (CCs) is increasing, and manufacturing of the REBCO CCs is shifting to mass production stage. On the other hand, the combination of process parameters in the REBCO CC manufacturing is diversified, and it is still insufficient for full-scale mass-production and commercialization which guarantee wire performance, yield, reliability, and cost reduction, therefore the innovation of CC manufacturing technology becomes an urgent issue. In this study, a data-driven approach, which fuses our reel-type high throughput critical current (Ic) measurements and machine learning, is applied to a real-scale REBCO CC Pulsed Laser Deposition system, and the behavior of a complicated process dependence of Ic has been successfully modeled. Using the combinatorial sample in which the manufacturing condition was systematically changed, we have collected over 20,000 data points on the relationship between the manufacturing conditions and Ic. A deep neural network (DNN) model was trained based on these data in order to describe the relationship between fabrication parameters and Ic. We have demonstrated that the Ic of the CC can be predicted from the process parameters by using this trained DNN model. Behavior in the multilayer deposition of the REBCO layer, which is inevitable in the practical CC production, is also studied. This technique allows us to break away from the conventional trial-and-error approach, and to quickly find the optimum manufacturing condition of the REBCO CCs in silico.
Acknowledgements: This work was supported by JSPS KAKENHI Grant Number JP19H05617.
Speaker: Takanobu Kiss (Kyushu University) -
285
Fabrications and superconducting properties of Ba1-xKxFe2As2 composite round wires
Iron-based superconductors (IBS) are promising candidates for high-field applications not only because of their advanced superconducting properties but also due to the cost-effective powder-in-tube method. While IBS tapes have achieved high critical current density (J$_c$) above J$_c$(4.2 K, 10 T)=2×10$^5$ A/cm$^2$, improving the J$_c$ of round wires has been challenging. Here, we fabricated the Ba$_{1-x}$K$_x$Fe$_2$As$_2$ single- and multi-filamentary composite round wires by the hot-isostatic-pressing (HIP) method and the high-strength sheath aided deformation method. The high pressure (~200 MPa) at high temperatures (~750 $^o$C) induced isotropic contraction of the wires and achieved a nearly 100 % dense superconducting core in the HIP Cu/Ag wires. Comparatively, the Vickers hardness of the stainless steel (SS) sheath strengthened round wires proved competitive even without high-pressure sintering. Finite element simulation indicated that groove rolling applied a large deformation stress, overcoming the high yield strength of SS, and densified the grains in the filaments. Electron backscatter diffraction (EBSD) and microstructure analysis revealed that drawing and groove rolling induced fiber texture and concentric texture, respectively. Finally, material cost and thermal stability are discussed based on the new conductor architecture. These findings underscore the importance of conductor design and deformation processes for achieving low-cost, high-performance iron-based superconducting wires and tapes.
Speaker: Chiheng Dong (Institute of Electrical Engineering, Chinese Academy of Sciences) -
286
Effects of the adhesions between impregnation system and coil components on the training of Nb3Sn Rutherford cables
Within the framework of the study of future high-energy particle colliders, high-field (15-16 T) Nb3Sn magnets are being developed. These magnets are usually impregnated using epoxy resin with glass fiber to provide electrical insulation and mechanical support to the conductor.
However, several phenomena are often observed: first, the high-stress conditions applied during pre-load, cool-down, and powering of magnets lead to cracks in the resin. Then, during powering, high Lorentz forces may break the epoxy bond at the interface between cables and components, and provoke a detachment of the coils and conductor motions. Later, friction phenomena may appear. This irreversible behaviors are likely to release enough energy to trigger quenches of the conductor. Understanding and reducing the causes of these phenomena can help to significantly reduce the number of quenches and increase the maximum quench current during the training phase of magnets and therefore improve the performances of future high field magnets.
First, a new experiment has been designed and carried out at CEA Paris-Saclay to reproduce and characterize the mechanical behavior of the interfaces between the impregnation system and the coil components. Various adhesion interface configurations were compared, varying the material of the component (titanium and stainless steel), and the roughness of their surface.
A second campaign has been carried out at the University of Twente. The goal is to characterize the training behavior of Nb3Sn Rutherford cables in representative conditions, and to reproduce the detachment phenomena under low contact pressures. To do so, an existing experimental setup has been redesigned to allow an accurate measurement of the compressive stress below 10 MPa. Then, Nb3Sn Rutherford cables has been subjected to a gradual release of the transverse compressive force under a background field of 11 T. The corresponding training has been studied and compared to the measurement of the critical current of the cable under stable conditions.Speaker: Guillaume Campagna (CEA Paris Saclay) -
287
Modeling of Electro-Thermal Quench of a REBCO Superconducting Coil for Aircraft Propulsion Motors
REBCO superconducting coils for aircraft propulsion motors boost magnetic flux density and output power which in turn improves the power-over-weight ratio. However, self-heating which can be due to either an AC current or a short-circuited DC voltage could cause thermal quench in HTS stator coils. Therefore, it is needed to analyze the complex interactions between electromagnetic phenomena and electrothermal reactions within this configuration. Electro-thermal modelling can provide valuable insights into this aspect. Indeed, this kind of modelling is required for motor design in order to ensure the safe operation of HTS motors. In this contribution, we study by computer modelling the electro-thermal quench behavior in a racetrack coil by assuming either adiabatic conditions or heat exchange with the coolant. For the latter, we assume either liquid nitrogen immersion or a given temperature at one of the edges of the coil, ranging from 20 to 77 K. We perform coupled electro-magnetic and electro-thermal analysis using a novel and robust software that we developed, which is based on the Minimum Electro-Magnetic Entropy Production (MEMEP) and the Finite Difference Method (FDM) for the electromagnetic and thermal models, respectively. We have found that screening currents caused by AC high frequency voltages under regular motor operation could cause electro-thermal quench. In addition, relatively low DC voltages due to accidental faults are sufficient to cause electro-thermal quench. Curiously, this quench starts at one of the turns at the coil center, even for uniform properties of the superconductor and other materials in thermal contact with it. This causes the current to roughly drop to 90% of the original. In conclusion, the computer modelling method that we developed can realistically predict the electro-thermal quench behavior in coils for superconducting motors, providing useful insights for their design.
Speaker: Arif Hussain -
288
Correlating growth rate with vortex pinning and defect microstructure in Transient Liquid Assisted Growth (TLAG) of superconducting REBCO film
High costs have hindered the practical use of REBCO coated conductors, despite their promising properties for a wide range of applications. A potential way for lowering the costs is by increasing the growth rate of the superconducting material while keeping high critical current density values [1]. The novel high throughput growing method Transient Liquid Assisted Growth (TLAG) [2,3] is promising in this aspect, since it can achieve ultrahigh growth rates of up to 1000nm/s. In the TLAG process, a Ba-Cu-O transient liquid is formed where the rare earth (RE) is dissolved and fast diffused to the growth interface, enabling ultrahigh REBCO growth from the liquid phase. The use of different RE modify their solubility in the liquid and therefore their effect on the nucleation and growth rates. In this work, we aim to understand the effect of growth rate on the microstructural defects generation and superconducting properties of REBCO films (RE = Y, Gd) grown by the TLAG method. For that purpose, simultaneous in-situ resistivity and in -situ x-ray diffraction (XRD) at synchrotron facilities are being used during TLAG growth to provide insights into the nucleation and growth mechanisms and enable the determination of the growth rate dependence with the process parameters. In this respect, the oxygen pressure where the films are grown is seen as a very relevant parameter. Post-growth non-destructive analysis, such as magnetic granularity studies [4] are providing information on the percolative grain size, grain boundary and grain critical current densities. In particular, a clear dependence of the critical currents with the grain size is observed. Additionally, Transmission Electron Microscopy (TEM) is used to examine the defect microstructure at different growth rates, and angular dependent transport measurements has enabled to study the vortex pinning behaviour under different magnetic fields, temperatures and angles [5]. Preliminary results reveal a clear dependence of process parameters with microstructure and properties, expanding from a very defect to a very clean defect microstructure landscape. Overall, this presentation will summarise the understanding of the different observations to identify the key parameters that determine the growth rate and the corresponding vortex pinning landscape.
[1] T. Puig et al, Nat. Rev. Phys. (2023)
[2] L. Soler et al, Nat. Commun. (2020)
[3] S. Rasi et al, J. Phys. Chem. C (2020)
[4] A. Palau et al, Phys. Rev. B (2007)
[5] F. Vallès et al, Commun. Mater. (2022)
Speaker: Ona Mola Bertran (ICMAB - CSIC) -
289
Qualification of the round REBCO cables of the SC-Links of HL-LHC
CERN is developing high-current superconducting links (SC-Links) to power the superconducting magnets of the High Luminosity upgrade of the Large Hadron Collider (HL-LHC). These SC-Links consist of up to 120 m long magnesium-diboride (MgB2) cables containing multiple insulated circuits and feature a total DC capability of up to 120 kA at a temperature of 20 K. The MgB2 cables are spliced on one side to multiple, round NbTi cables that are operated in LHe and on the other side to about 3 m long, round high-temperature superconducting (HTS) rare-earth-barium-copper-oxide (REBCO) cables that bridge the 20 K to 55 K temperature gap and connect to the current leads.
As the round REBCO cables will be part of the LHC powering circuits rigorous quality control measures have been implemented to ensure the optimal performance. In addition, as multiple REBCO cables connected in parallel are used for high current rating circuits, a homogeneous internal resistance of all constituent tapes is essential in assuring balanced current distribution among the parallel cables and their tapes. Quality control measurements are therefore performed in three stages: Firstly, after tape reception to validate the transport properties and to determine the internal resistance. Secondly after cabling to exclude with extracted tape measurements any cabling related degradation and lastly after splicing of the cable extremities to validate the transport properties of each cable.
These measures are essential for assuring the integrity and performance of the superconducting material, for the homogenization and for the validation of the produced REBCO cables. Only fully qualified RBECO cables without any cabling related degradation are used for the SC-Links of the HL-LHC.
In this work, we present the quality control procedures and measurements as well as the statistical distributions of the results.Speaker: Aisha Saba (CERN)
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282
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Registration Desk and Publication Office open (08:30-17:00)
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Exhibition open (9:00-16:00) Exhibition area
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Thu-Or13: Cryogenics Instrumentation & Devices Room D
Room D
Convener: Johan Bremer (CERN)-
290
Numerical modeling and design of the acoustic expander for cryogenic refrigeration
Cryogenic refrigerators can be broadly classified as either continuous flow machines or oscillating flow machines. The acoustic expander is a new hybrid approach that combines the best aspects of these two machines. Globally, the working fluid moves continuously through the recuperative heat exchanger of the cycle while locally the working fluid oscillates in the acoustic expander. This promising concept has been demonstrated experimentally through the use of reed-valves coupled to an acoustic resonator. This work develops a high-fidelity numerical model that captures non-linear acoustic effects for the future design and optimization of these acoustic expanders. The numerical model solves the fully compressible Navier-stokes equations for various 2D and 3D resonator geometries including both harmonic quarter wave resonators and non-harmonic Helmholtz resonators. The reed valve behavior is simplified using pressure-dependent boundary conditions that can be tuned to represent a variety of reed characteristics. The coupled reed-resonator system spontaneously oscillates at its natural resonance frequency and the numerical model predicts the resonator quality factor and isentropic expansion efficiency. We compare the results of the 2D/3D numerical model to a 1D model implemented in DeltaEC. Finally, the numerical model predictions are validated by experimental data. The acoustic expander unlocks new cryogenic cooling paradigms with applications to superconducting magnets and electronics, infrared imaging, quantum sensing, and cryogenic propellant management.
DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited.
This material is based upon work supported by the Department of the Air Force under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of the Air Force.Speaker: Nathaniel O'Connor (MIT Lincoln Laboratory) -
291
Transient numerical investigation on sealing performance of square labyrinth seal in the liquid hydrogen piston pump
Liquid hydrogen piston pumps are widely used for transferring liquid hydrogen due to their low investment, low power consumption and high flow rate. To maintain high efficiency in working condition, it is essential to prevent internal leakage. Labyrinth seals, which are a form of non-contact sealing, have a simple structure, low wear and allow for thermal deformation. They are not limited by fluid temperature and generate less friction heat. In recent years, research on labyrinth seals has primarily focused on their structural parameters, with more emphasis on testing their static sealing performance and less on the leakage of the dynamic system. This paper establishes a two-dimensional transient model of a labyrinth seal which takes into account the reciprocating motion of the piston to predict transient leakage in a liquid hydrogen piston pump. The article analyses the sealing performance of a labyrinth seal with square cavity using overlapping mesh and dynamic mesh techniques to simulate its reciprocating motion. The differences between the static and dynamic models, as well as between the labyrinth and clearance seals are compared through the simulated results. The influence of key parameters on the sealing performance is also examined. As the pressure inside the cylinder increases, the leakage rate increases. To reduce the leakage rate, it is recommended to increase the number of the square cavity and use square cavities with an appropriate length-to-height ratio.
Speaker: Xiujuan XIE (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
292
Experimental investigation of a cryogenic printed circuit heat exchanger
With the growing demand for compact and large-capacity cryogenic refrigerators nowadays, large-temperature-span cryogenic heat exchangers (HX), as the key and bulky components, are studied to achieve performance and volume advantage. The printed circuit heat exchangers (PCHE) are supposed to a promising candidates for compact HX for their lower resistance, and flexible design, which have been widely applied in normal and high-temperature fields such as fuel cells and supercritical carbon dioxide Brayton cycles.
However, relatively little research has been developed on PCHE application in cryogenic zones, especially in situations with large-temperature-span. This research deficiency of the large-temperature-span cryogenic HX seriously drags the compactness of cryogenic refrigerators. Thus, a cryogenic PCHE for reverse Brayton refrigerators, working between 80 K - 300 K, is proposed and tested in this article, whose heat transfer efficiency is designed to 97.5%. Arranging the proposed micro-fins channel, the cryogenic PCHE achieved a high heat transfer area density (≈2200 m2/m3), demonstrating a good thermal-hydraulic performance and high compactness. Then, a cryogenic test is designed and set up to investigate the thermal-hydraulic performance of the proposed PCHE. The experimental platform in the designed vacuum chamber can achieve the calculated relative uncertainties of the key heat transfer coefficient and pressure drop at 6.3% and 0.25%, respectively. Nitrogen as the experimental working fluid flows through the hot side and cold side. For the hot side, inlet temperature and mass flow vary from 290 K to 300 K and 1.2 g/s to 1.9 g/s, respectively. For the cold side, inlet temperature and mass flow vary from 290 K to 300 K and 1.2 g/s to 1.9 g/s, respectively. The effect of the key operation parameters on the thermal-hydraulic performance of the proposed PCHE is revealed, while the compactness and effectiveness of the proposed PCHE structure are validated.
Considering the high difficulty of compact HX fabrication and cryogenic experimental conduction, the experimental investigation proposed in this paper is useful for further theoretical design and optimization.This work was supported by a grant from the Joint Fund of National Natural Science Foundation of China(NSFC) and Enterprise Innovation and Development(U21B200139).
Speaker: Zixin Zhang -
293
Flow characteristics of cryogenic perforated plate balanced flowmeter
Compared with the traditional standard orifice flowmeter, the perforated plate balanced flowmeter has a more stable flow field and a lower pressure loss, making it more suitable for measuring low-temperature fluids, such as liquid methane, liquid oxygen, liquid hydrogen and so on. In this study, a calculation model of the perforated plate balanced flowmeter is established. The simulation analyzed the effects of structural parameters such as equivalent diameter ratio, orifice thickness, and operating conditions such as liquid subcooling, inner wall roughness, on the discharge coefficient, pressure loss coefficient, and cavitation characteristics of the perforated plate balanced flowmeter. The results show that the equivalent diameter ratio and subcooling have almost no effect on the discharge coefficient, the pressure loss coefficient is affected by the equivalent diameter ratio but not by the subcooling, and a smaller equivalent diameter ratio and subcooling make liquid hydrogen more susceptible to cavitation. The increase of orifice thickness or the decrease of inner wall roughness will increase the discharge coefficient and decrease the pressure loss coefficient.
Speaker: Yihan Tian (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
294
Cryogenic helium valves deflection and relaxation in ESS linac cryogenic distribution system
Large scientific facilities make extensive use of cold helium in different thermodynamic states for cryostating of superconducting cavities or magnets. The helium is supplied to cryomodules by cryogenic distribution system which may contain tens of valve boxes and hundreds of cryogenic valves. Cryogenic control valves are considered as a critical part of every cryogenic distribution system not only due to their importance for realization of different operation modes of the system, but also due to low mechanical stability of the valves resulting from their specific design. As the valves actuators and positioners are located in room temperature, the valves create thermal bridges between room and low temperature elements. To protect these components from freezing and reduce undesirable but unavoidable heat inputs into the cryogenic temperature environment, the heat conduction through the body and stem of the valves need to be strongly reduced. It can be achieved by using low thermal conductivity materials as stainless steel or G-10 (epoxy resin-glass fibers composite), reducing the cross sectional area of the conduction path and increasing its length. These requirements are contradictory from mechanical point of view as imply a thin and elongated, thus, susceptible to lateral deformations valve stems and bodies construction. The valve deformations may result from stresses produced during their manufacturing, improper transport, welding of the valve with valve box vessel and process pipes or cyclic thermal and pressure loads during the cool-down and warm up of cryogenic system. The commissioning of European Spallation Source linear accelerator cryogenic distribution system revealed valve deflections, partly combined with lack of the valve tightness. An optical method of noninvasive measurement of long-stem cryogenic valve straightness has been elaborated and compared with direct deflection measurements. The allowable value of the valve deflection has been estimated on the basis of mechanical analysis and the procedure of the deformed valve relaxation has been proposed and successfully implemented. The deflected valve correction does not require a full cut of the valve box and is limited to a minimal intervention at the upper part of the valve. The paper presents the method, its validation by the opening of one of the valve boxes and provides the limits of the method applicability.
Speaker: Jaroslaw Polinski (Wroclaw University of Science and Technology)
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290
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Thu-Or14: Instrumentation & Process Control Room A
Room A
Convener: Velisa Vesovic (Imperial College London)-
295
LCLS-II LINAC 2K Pump-down and Controls Automation
The SLAC National Accelerator Laboratory's upgrade to the LCLS-II, featuring a 4 GeV superconducting linear accelerator with 37 cryomodules and two extensive helium refrigeration systems supporting 4 kW at 2.0 K, represents a significant advancement in accelerator technology. Central to this upgrade is a sophisticated 2K system with five stages of centrifugal cold compressors, operating across a pressure range from 0.026 mbar suction to 1.2 bara discharge. This paper presents a streamlined approach to automate the intricate processes of pumping down the LINAC from 1.2 bara to 31 mbar with transition to RF operations in 90 minutes, LINAC re-pressurization to 1.2 bara after a trip, alongside an RF compensation technique for uninterrupted RF operations. It provides a comprehensive overview of the automated functions, sequences, control logic, and machine protections integrated into the system, shedding light on the design decisions and experiences gained during its integration and commissioning.
Speaker: Swapnil Shrishrimal (SLAC National Accelerator Laboratory) -
296
Advancements in cryogenic cable harness technology: Enabling connectivity for extreme-temperature environments in space and earthbound missions
Cryogenic space missions with extremely low temperature experiments such as Herschel, Ariel and Athena present unique challenges on cable assemblies in order to connect electrical devices in a temperature range down to a few millikelvin with those at room temperature. Similar demands are encountered in earthbound telescopes such as ALMA, ELT, and VLT, where large temperature variations challenge harness development.
The critical challenge with low-temperature cable assemblies is to reconcile physically contradictory requirements for the conductor material. While low thermal conductivity minimizes heat flux, sufficient electrical conductivity is essential for power and signal transmission between hot and cold electronics. Achieving optimal thermal and electrical properties for each system involves using selected conductor materials with low thermal conductivity and sufficient electrical conductivity, along with minimizing wire diameter and maximizing transmission paths. Heat sinks strategically placed in the system to facilitate optimal heat flow, conducting heat out of the wiring harness at designated positions.
Extremely thin wire diameters, even as small as 0.1 mm, necessitate advanced production technologies, including soldering, crimping and high-precision work under microscopic conditions. The physical properties, combined with vibrations, temperature cycles, and vacuum conditions, demand the highest quality standards in production and testing for both space missions and earthbound cryogenic systems.
Our study analyzes material properties to select suitable conductor materials, including Brass, phosphor bronze, manganin, niobium-titanium, and steel. Steel wire offers the lowest thermal conductivity with acceptable electrical conductivity suitable for signal transmission. We have developed processes to reliably solder and crimp very thin wire diameters of steel, building upon Herschel's technology.
PTFE and polyimides serve as insulation materials for cryogenic cables, providing high electrical insulation strength and low thermal conductivity. Both loomed and classic cryogenic harnesses with EMI shielding have been developed for various applications.
The production of cryogenic cable assemblies with these wire and insulation materials involves the development of new manufacturing processes for reliable connector termination using new soldering and crimping techniques, capable of withstanding cryogenic and vacuum conditions.
Consideration is also given to the termination of the stainless-steel shield connection, along with the development and optimization of heat dissipation elements for cryogenic harnesses.The validation of developed manufacturing methods and processes occurs during the qualification phase. Non-destructive electrical verification is conducted by measuring cable resistance, while destructive testing methods, including pull-out tests and micrograph analysis, ensure mechanical resilience.
Thermal cycle simulation during qualification ensures that the connections and materials withstand a sufficient number of cold/hot cycles throughout the entire service life of the cable assembly. Comprehensive qualification, including electrical tests, micrograph, and pull-off tests, confirms the absence of degradation.
This conference presentation will showcase sample harnesses featuring solder and crimp connections and heat sinks, accompanied by corresponding mechanical and electrical tests with and without completed temperature cycles.The completion of cryogenic technology development related to cryogenic cable assemblies paves the way for the success of future scientific missions, pushing the boundaries of what is technically feasible in extreme-temperature environments.
Speaker: Michael Berens (Glenair GmbH) -
297
Measurement and control architecture of research cryostats
At ZEA-1 we develop, build and operate, among other things, cryostats for scientific applications to liquefy gases such as hydrogen, e.g. with variable ortho para content for the moderation of neutrons. Further areas of application include Raman spectroscopy and particle image velocimetry (PIV) with cryogenic liquids, testing and calibration of sensors and actuators at cryogenic temperatures and freezing of fluids to grow crystals at cryogenic temperatures.
Following the guiding principle of reliability, modularity and open source, the sensor and actuator networking as well as the measurement and control architecture of our research cryostats have been fundamentally rethought. The control logic of the cryostat, the measurement analysis, the calculation and storage of the data, the human-machine interface as well as the visualization of the measurement and machine data were largely virtualized using containers. The required hardware has been reduced to a minimum and connected to the virtual environment via an encrypted data line, regardless of whether the connection uses the 5G standard, WLAN or LAN. The safety of the cryostat is guaranteed in two stages. In case of a power outage or major incident, mechanically closing valves and buffer volumes ensure that the cryostat can return to a safe warm state without external intervention. Generally, the expanded process fluid remains enclosed in the cryostat, so that pressure relief valves and a ventilation system are only redundantly implemented for additional safety. To prevent hacker attacks and/or conscious or unconscious operating errors, there is an isolated small dual-core Cortex®-M7 + M4 microcontroller unit directly at the cryostat, which shares the sensors and actuators with the virtual system. The commands and data sent by the microcontroller to the cryostat actuators take precedence over those of the virtual controller, so that in case of an error, the microcontroller system takes over control and brings the cryostat back to a safe state. A special IO-Link master handles separating the bus systems of the virtual and microcontroller systems as well as prioritizing access to the sensors and actuators connected via IO-Link. Thanks to the high degree of virtualization, the control, sensor and measurement system of the research cryostats can be designed modularly, and individual components can be added dynamically - even during ongoing operation. The same applies to software applications, as the entire data stream, consisting of measurement, system and control data is standardized and stored in a database optimized for time series. Standardized interfaces enable the integration of long-term data analyzes and, in the future, the real-time integration of AI applications. The three main components of the virtual environment are the data flow programming application NodeRed, the InfluxDB time series database and Grafana for data visualization. All three software applications have an open-source license, which eases their use by different groups of people and collaboration between scientists from different affiliations. Thanks to the modular design, virtualization and the associated reduction in necessary hardware, our research cryostats can be built very compactly. This enables us to transport the cryostats and integrate them into existing experiments across Europe. For example, in August and November 2023, one of our research cryostats was integrated into an experiment at the Budapest research reactor to provide liquid parahydrogen to moderate neutrons, while in June, July and December 2023 it was in use at the prototype of the high-brilliance neutron source in Jülich.Keywords: research cryostat, measurement system, control architecture, IO-Link, interface to AI applications, container virtualization, database, data visualization
Speaker: Eberhard Rosenthal (Forschungszentrum Juelich GmbH, Central Institute of Engineering, Electronics and Analytics – Engineering and Technology (ZEA-1)) -
298
Visualization of second sound waves based on laser interferometry
Superfluid helium (He II) serves as a crucial refrigerant for cooling superconducting resonators, enabling the attainment of remarkably high acceleration gradients in particle accelerators. The presence of quantum vortices in He II attenuates second sound waves and influences heat transfer. Consequently, a comprehensive understanding of the attenuation of second sound waves by quantum vortices is pivotal for comprehending heat transfer in He II and can also aid in identifying surface defects in superconducting resonators. To address this, we devised and constructed an interferometry-based test bed for visualizing second sound waves. He II is procured by depressurizing liquid helium in a tank, which is connected at its base to a square stainless steel channel. Two viewports are positioned in the middle of the channel, while corresponding viewports are provided in the outer cavity, allowing the passage of a laser through the He II. At the channel’s base, a heater induces the production of second sound waves and quantum vortices in He II through thermal drive. Utilizing the M-Z interference method, object light traverses He II via the viewports and interferes with reference light, producing interference fringes that are captured by a high-speed camera. A heating pulse from the heater generates second sound waves in the He II, transmitting temperature fluctuations to the viewports and causing distortion of the interference fringes. Through this process, we have successfully obtained clear interferometric images of second sound waves, represented by deformed interferometric fringes. By comparing these with the undeformed fringes, we have inverted the information regarding the temperature field in the imaged region. We also conducted a one-dimensional simulation of the channel and compared it with the experimental results, showing a good consistency between the two.
Speaker: Guoliang Li (Zhejiang University) -
299
Electrical capacitance volume sensor for microgravity mass gauging: advancements in sensor calibration for microgravity fluid configurations and propellant management devices
Microgravity mass gauging has gained increasing importance in recent years due to the acceleration in planning for long term space missions as well as in-space refueling & transfer operations. It is of particular importance with cryogenic propellants where periodic tank venting maneuvers and leak detection place a special emphasis on accurate mass gauging. Several competing technologies have arisen, but capacitance mass gauging has several distinct advantages due to its low mass, non-intrusiveness, and whole volume interrogation technique. Capacitance based measurement has also seen recent success in measuring cryogenic liquid nitrogen and hydrogen volume fraction and flow rate. However, the effects of gravity on fluid behavior make the calibration and testing of these sensors difficult on the ground. In this paper a prototype sensor is constructed that can emulate fluid positions in microgravity and gravity configurations. Experimental propellant fills and drains are conducted using a simulant fluid with similar electrical properties to cryogenic propellants. This expanded dataset is compared with previous simulation results and used to construct a machine learning model capable of calculating the fluid mass in tanks both with and without propellant management devices.
Speaker: Matt Charleston (Tech4Imaging, LLC)
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295
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Thu-Or15: Materials & Testing Room B+C
Room B+C
Convener: Klaus-Peter Weiss (KIT, Institute for Technical Physics)-
300
Review on progresses of the homemade 15T LTS solenoidal background magnets using for material testing facility and ultra-high magnet fabrication：Magnet Design, Manufacture and Testing
High-field magnets play a crucial role in various research fields, contributing to the exploration of material properties under extreme conditions and advancing knowledge in biology, chemistry, geology, and more. The Comprehensive Research Facility for Fusion Technology (CRAFT) project aims to establish a comprehensive laboratory with functionalities related to superconducting materials, AC loss, structural materials, thermal hydraulic, non-destructive detection, and high voltage research. Within the CRAFT project, a key focus is the development of a background field superconducting magnet for the critical current test system of superconducting materials. The specifications include a central field strength not less than 19 T, a cold hole diameter larger than 70 mm, a test sample temperature range of 4.2-80 K, and an operational temperature control accuracy of up to 30 mK@10 K. The 19 T/70 mm magnet comprises two main parts: a 15 T/150 mm Nb3Sn+NbTi all-superconducting background field magnet and a 5 T/70 mm REBCO high-temperature superconducting insert magnet. Since 2019, the project has implemented a step-by-step plan to overcome challenges in low-temperature superconducting magnet technology for various apertures. The goal is to achieve key technology research for the 19 T/70 mm high and low temperature hybrid superconducting magnet by 2024.
The group involved in the project has successfully designed and prepared the 15 T/70 mm aperture low-temperature superconducting hybrid magnet in the initial stages. Significant experimental experience and key technologies have been accumulated. Currently, the focus is on the design and preparation of the 15 T/150 mm aperture low-temperature superconducting magnet.
This report primarily addresses scientific challenges and experimental verification methods encountered during the design and preparation of the 15 T low-temperature all-superconducting magnets. It also outlines the upcoming research plan of the ultra-high field magnets in our group.
Speaker: Peng Gao (Institute of Plasma Physics Chinese Academy of Sciences) -
301
Structural and thermal design of cryogen-free mechanical property testing cryostat
In-situ mechanical property testing of materials at cryogenic temperatures is critical for the advancement of cryogenic engineering. Liquid hydrogen is emerging as a promising hydrogen storage and transportation medium to ensure the global decarbonization process. The development of liquid hydrogen infrastructure to meet the anticipated surge in demand necessitates a thorough exploration of novel materials and material properties, in both existing and novel materials such as composites, at cryogenic temperatures. Mechanical properties of materials that are pivotal in the designing process of infrastructure systems, therefore, need to be accurately quantified within the in-situ cryogenic environment to ensure the reliability and validity of the properties.
Historically, in-situ cryogenic mechanical property testing cryostats have primarily relied on the use of liquid cryogens such as liquid nitrogen (77K) or liquid helium (4K) to establish cryogenic conditions. Up to now, most of the testings were conducted using liquid nitrogen, a low-cost cryogen compared to liquid helium, and that limits the availability of the material property dataset at 77K, in which properties up to 20K are required for liquid hydrogen system designs. Considering the limitations of available material property datasets and the difficulty and cost of handling cryogens, this study introduces a novel approach by presenting the structural and thermal design of a cutting-edge cryogen-free cryostat tailored for conducting tensile and compression testing of materials at cryogenic temperatures. This cryostat has been carefully engineered in compliance with industry standards such as ASTM D638, ASTM E8/E8M, and ASTM D3039/D3039M, catering to the specific requirements of tensile testing for plastics, metals, and polymer composites. Notably, the system possesses a tensile loading capacity of 50 kN. The cryostat consists of a two-stage Gifford-McMahon (GM) cryocooler integrated into a customized self-reaction tensile testing jig system. The heating system incorporated at the second stage of the cryocooler provides the capability to control the temperatures of the system and to establish the system temperature at 20 K, ensuring material testing at the liquid hydrogen storage temperature range.
Structural integrity and performance of the testing jig system were rigorously assessed using Finite Element Analysis (FEA) to ascertain proper load-transferring mechanisms during mechanical testing. Components of the jig system were comprehensively evaluated for yield and buckling failure considerations, accounting for variations in room and cryogenic temperatures. Furthermore, the thermal design of the cryostat was carefully conducted, taking into account various heat transfer mechanisms such as heat conduction, convection, radiation, and free molecular heat transfer inherent during equipment operation. Both numerical analysis and FEA were utilized for thermal design to calculate the heat losses. Notably, heat conduction emerged as the primary source of heat loss, predominantly due to the loading rod that gets exposed to both room and cryogenic temperatures. This comprehensive approach of structural and thermal analysis ensures the efficacy and reliability of the cryostat in facilitating accurate mechanical property testing at cryogenic temperatures. Also, it lays a foundation to design and develop other mechanical property testing cryostats with minimal error. The cryogenic mechanical testing set up capable of carrying out stress and thermal fatigue testing. Furthermore, the testing set-up is equipped with two observation windows, enabling monitoring of specimen deformation using Digital Image Correlation (DIC) techniques. It will allow capturing of stress versus strain behaviour, which is vital to characterise the materials' fracture toughness, plasticity, ductility, and fracture behaviour. Also, composite fracture can be monitored using microscopic cameras so that micro-crack generation and propagation can be monitored for composites, which is vital to evaluate the leak and permeation of LH2 composite storage tanks.Speaker: Shanaka Baduge (The University of Melbourne) -
302
Analytical investigation and experimental validation of thermal & AC characterization of HTS Tape for modular superconducting fault current limiter
Abstract. A short circuit test set up is used to generate a fault with a specific number of cycles at input AC voltage of 20, 40 & 60 on a specific length of HTS tape immersed in liquid nitrogen. The fault current characteristics at 78 K by using copper and SS laminated HTS tape were measured at different operating voltage and with variable no of cycles. The voltage, current and temperature profile during the fault and the recovery is monitored with time and same has been analyzed. The resistance of wire with temperature along with corresponding nucleate boiling heat transfer coefficient was evaluated and validated with theoretical value. The experimental details along with the result will be discussed in detail in this presentation.
Speaker: Tripti Sekhar Datta (Indian Institute of Technology. Kharagpur. India) -
303
Sensing of cryogenic temperatures by superconducting NbTi(N) thin-film S-shaped Split Ring Resonators
Abstract
In the last decades, the precise control of ultra-low temperature environments has turned out to be of primary importance for the development of novel cryogenic applications. As a matter of fact, the accurate monitoring of temperatures well below 10 K is crucial for preserving the quantum properties of superconducting and spin qubits [1-2]; moreover, recent superconducting high-energy particles detectors strongly rely on radiation-induced or thermally-assisted breaking of Cooper pairs [3-4], for which sensing temperatures with a sub-millikelvin resolution is necessary.
Nowadays, the state-of-the-art for cryogenic thermometry mainly consists of thermistors in 4-wires configuration, for instance based on Pt capsules [5] or CERNOX® thin-films [6]. Such devices, showing wide temperature ranges, more than 103 Ω/K sensitivity for T < 10 K, mechanical robustness and compact dimensions, are currently widely exploited in standard multiple-stages cryostats. Nevertheless, one of the main drawbacks of this technology is the need for at least 4 DC wires for each sensor in the cryostat, which potentially increases the amount of heat conduction paths and the complexity of cables assembling. Alternative solutions to this market-leading technology include the recent development of thermometric systems exploiting different physical principles, such as kinetic inductance variations of transmission line superconducting resonators [7] and two-levels systems inside superconducting circuits and resonators [8-9].
In this work, we present a superconducting thermometer consisting of a S-shaped Split Ring Resonator (S-SRR), for which T-induced variations of its kinetic inductance result in resonance frequency shifts. The choice of such a scheme is motivated by the possibility to ideally excite multiple sensors, situated in different locations of a cryogenic environment, with only one single RF transmission line. Moreover, S-SRRs have also proved to optimally couple to standard CPWs [10], whose technology is nowadays massively exploited in the design of quantum electrodynamics (QED) circuits. Therefore, such a thermometer could be also non-invasively integrated to directly monitor the cryogenic temperature of operative DUTs.
Such devices consist of 100 nm thick films of both NbTi and NbTiN patterned on sapphire substrates, respectively showing 1.46 ± 0.04 pH/□ and 1.62 ± 0.06 pH/□ sheet kinetic inductances. Basing on preliminary studies [11], a microfabrication process flow, relying on a combination of standard direct laser writing and SF6-based reactive ion etching (RIE), has been optimized to accurately microstructure the superconducting thin-films, with a limiting lateral resolution of 700 nm and a line-width transfer accuracy better than 100 nm. Several NbTi(N) S-SRRs, with resonance frequencies around 1 GHz, have been fabricated and tested in the variable temperature insert (VTI) of a superconducting cryo-magnet. Resonance frequency shifts of 4.5% for NbTi and 7.5% for NbTiN, in the range from 3 K to their critical temperature (8.3 K and 11.8 K, respectively), have been recorded, together with maximum Q-factors up to 40’000. Such results validate the implementation of these resonators as cryogenic thermometers over all their superconducting range, showing performances comparable with the devices previously reported in literature [7-9].References
[1] M. Göppl et al., AIP J. Appl. Phys., 104 (2008) 113904.
[2] P. Scarlino et al., Nat. Commun., 10 (2019) 3011.
[3] P. Day et al., Nature, 425 (2003) 817–821.
[4] M. Naruse et al., J. Low Temp. Phys., 199 (2020) 614-621.
[5] R. Rusby et al., Rev. Gen. Therm., 35 (1996) 338–343.
[6] S. S. Courts et al., AIP Conf. Proc., 684 (2003) 393–398.
[7] H. Yu et al., SN Applied Sciences 4 (2022) 67.
[8] M. Scigliuzzo, et al., Phys. Rev. X 10 (2020) 041-054.
[9] J. Wheeler et al., Appl. Phys. Lett. 117, (2020) 192601.
[10] A. K. Horestani et al., ICEAA (2019) 0485-0488.
[11] R. Russo et al., MNE 19 (2023) 100203.Fundings and Acknowledgments
This work received fundings from the Swiss National Science Foundation, (SNSF Ambizione Grant PZ00P2_193361). The authors would like to thank the Center of Micro/Nanotechnology (CMi) of EPFL for the microfabrication facilities, support from the staff and the allocation of student subsidies.
Speaker: André Chatel (EPFL - STI IEM - LMIS1)
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300
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10:30
Coffee & Tea break
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Thu-Or16: Large Scale Cryogenic Systems 5 Room D
Room D
Convener: Sangkwon Jeong (KAIST(Korea Advanced Institute of Science and Technology))-
304
Overview and status of the cryogenic system for SHINE accelerators
The Shanghai high repetition rate x-ray free electron laser (XFEL) and extreme light facility (SHINE), a quasi-continuous wave hard XFEL facility, is currently under construction. The superconducting accelerators of SHINE require cryogenic cooling at 2 K for cavities, 5 K for cold interception, and 40 K for thermal shields, respectively. In this paper we present the overview and recent progress of the SHINE cryogenics system that mainly consists of the cryoplant generating the cooling power, the cryogenic distribution system that delivers the cryogen to the accelerators, and the utility system to serve liquid nitrogen together with the helium management. With considerable safety margins, three sets of large helium cryoplants are being built in two cryo-stations at the front and end of the SHINE accelerators, respectively. Each cryoplant could provide a cooling power of 4 kW at 2 K. Up to now, all the equipment belonging to the three cryoplants has been installed. The warm compressor station, 4.5 K cold box, 2 K cold box, and the interconnecting cryogenic transfer line in between for the first set of cryoplant are being commissioned and are likely to reach the nominal performance in the coming months. This progress improves the cryogenic capability of the SHINE facility and will enable the joint commissioning and operation of the SHINE accelerators in the future.
Speaker: Jiuce Sun (ShanghaiTech University) -
305
Thermal performance test of the cryogenic transfer line for SHINE cryogenic system
Thermal performance of the cryogenic transfer line with long distance and multi-channels is crucial to the efficiency of large helium cryogenic systems built for Shanghai high repetition rate x-ray free electron laser and extreme light facility (SHINE). We have performed several tests to measure the thermal performance of the cryogenic transfer lines developed and optimized for SHINE. The method of liquid helium evaporation rate was chosen to calculate the heat load. In order to fill liquid helium into different channels of the cryogenic lines ready for the test and also measures the corresponding mass flow rate of evaporating helium gas from each channel, respectively, an experiment test setup has been designed and built utilizing the cryogenic system for the SHINE test facility. In total, we have measured three types of cryogenic transfer lines, and the heat load of 0.2 W/m was achieved for the 2 K circle. These results verifies the modified design and are anticipated to improve the cooling power transfer efficiency of the SHINE cryogenic system.understand the mechanism of heat in-leak and verify the modified design.
Speaker: Jiuce Sun (ShanghaiTech University) -
306
Commissioning progress of the first cryoplant for SHINE accelerator
This paper presents the commissioning progress of the first accelerator cryoplant for Shanghai high repetition rate x-ray free electron laser and extreme light facility (SHINE). To fulfill the cooling needs for the superconducting cavities in the SHINE accelerator, three cryogenic plants were contracted to Air Liquide Advanced Technologies (ALAT) in 2020. Each cryoplant could provide 4 kW cooling power at 2 K and mainly consists of a warm compressor station (WCS), a 4.5 K cold box, and a 2 K cold box. Following the success delivery and installation, the WCS had been commissioned and the final 100 hours test were achieved at the middle of 2023. Afterwards, the commissioning of the 4.5 K cold box progressed as expected and the first drop of liquid helium was obtained at the end of 2023. The 2 K cold box commissioning were enabled when the installation of the cryogenic transfer line in between had been finished. At the beginning of 2024, the cold compressor had been successfully tested to achieve the 2 K super-fluid inside the 2 K cold box. The promising commissioning progress of the first cryoplant demonstrates the capability to deliver cryogenic cooling to the SHINE accelerator that are being constructed.
Speaker: Shuai Zhang (Shanghai Advanced Research Institute, Chinese Academy of Sciences) -
307
Overview and Status of the Long-Baseline Neutrino Facility Far Detectors Cryogenics System
The Sanford Underground Research Facility (SURF) will host the Far Detectors of the Deep Underground Neutrino Experiment (DUNE), an international multi-kiloton Long-Baseline neutrino experiment that will be installed about a mile underground in Lead, SD. Detectors will be located inside four cryostats filled with almost 70,000 metric tons of ultrapure liquid argon, with a level of impurities lower than 100 parts per trillion of oxygen equivalent. The cryogenics infrastructure supporting this experiment is provided by the Long-Baseline Neutrino Facility (LBNF). This contribution presents modes of operation, layout and main features of the LBNF Far Detectors cryogenics system, which is composed of the following subsystems: argon receiving facilities, nitrogen system, argon distribution system, argon purification and regeneration systems, argon circulation system, argon condensers system, internal cryogenics, miscellaneous items, and process controls.
An international engineering team is designing these systems and will manufacture, install, test, commission, and qualify them. This contribution describes the main features, performance, functional requirements, and modes of operation of the LBNF Far Detectors cryogenics system. It also presents the status of the design, along with present and future needs to support the DUNE experiment.
Speaker: David Montanari (Fermi National Accelerator Lab. (US)) -
308
CERN NEUTRINO PLATFORM CRYOGENICS, THE DARKSIDE-20K EXPERIMENT
The CERN Neutrino Platform contributes to a globally coordinated programme of neutrino research. This international effort entails the development of state-of-the-art cryogenic systems in support of large-scale, liquid argon Time Projection Chamber detectors (TPC).
The DarkSide-20k experiment represents the first significant step for the development of the future generation of larger liquid argon, direct Dark Matter detectors. This experimental apparatus, which will be installed in the Laboratori Nazionali del Gran Sasso (LNGS) in L’Aquila, Italy, features a dual-phase TPC filled with radio-pure underground liquid argon (UAr), surrounded by a 600 t bath of liquefied atmospheric argon (AAr). The design of the associated cryogenic system is based on the commissioning and operational experience acquired by the development of the ProtoDUNE cryogenic systems, which have been successfully operated for 2 years in a charged particle beam at CERN.
In synergy with the CERN Neutrino Platform, the DarkSide-20k AAr cryogenic system has been developed to tackle the stringent fluid process and argon purity requirements. A set of activated charcoal-based Radon filters has been integrated in the AAr system to address the additional requirement of a radon-free environment, in addition to the copper-based and metal aluminosilicates-based filters already implemented in the ProtoDUNE apparatuses. Furthermore, the DarkSide-20k system features a dedicated valve box equipped with cold gas filters to purify both the cryostat boil-off and the warm gas return from the cryostat ports before recondensation.
This paper outlines the development of the cryogenic system for the DarkSide-20k experiment and discusses its potential applications for future research endeavours.Keywords: Liquid Argon, Purity, Cryogenic Systems.
Speaker: Tiziano Baroncelli (CERN)
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304
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Thu-Or17: Hydrogen Liquefaction, Storage and Use 2 Room A
Room A
Convener: Fridolin Holdener (shirokuma GmbH)-
309
Cryogenic H2 for heavy-duty trucks: applying fundamental thermodynamics to solve clean transportation challenges
Over the last few years, a number of projects dedicated to the full scale demonstration of cryogenic H2 systems for clean mobility have been successfully carried out at Air Liquide’s Campus Technologies Grenoble (ex-ALaT), in Sassenage (France). Those pioneering prototypes have been designed and operated together with world class industry leaders, and pave the way towards a realistic, cost effective, rapidly refueling and safe clean transportation future. In this paper, we present the challenges associated with heavy duty truck transportation, the unique cryogenic designs that were developed to address that market, and the major results obtained thus far.
LH2 has many merits when considering volume and mass limited, and also refueling time sensitive, near zero emission large transportation applications ranging from aircrafts, boats, rails to trucks. Indeed, its high (volumetric) energy density enables to drastically reduce the gravimetric and volumetric footprint of benchmark 350 to 700 bar gaseous H2 storage, while also providing much more easily scalable transfer solutions. The sensitivity of LH2 to heat ingress remains its main challenges, and transitioning the use of the molecule from industrial applications (mostly, distribution) to a near zero emission transportation fuel commodity necessitates to develop new cryogenic system and process architectures capable of optimizing performances (cost, safety, footprint) along the entire supply chain, up to onboard the vehicle.
Thanks to detailed functional and engineering analyses, engineers at Campus Technologies Grenoble (ex-ALaT) have been developing a complete mobile solution, comprising the bulk supply of LH2, the refueling system and the storage onboard the vehicle for the heavy-duty applications and relying on the so-called “sLH2” (for “sub-cooled LH2”) approach.
The sLH2 standard represents a great compromise between low pressure LH2 and high-pressure CcH2 (for “cryo-compressed H2”) standards: it offers single flow refueling (no need for communication), reasonable cost (no expensive materials for the storage, low CAPEX and OPEX at refueling station), holding times of a few days (compatible with the application), and high technological maturity (well known components and processes).
This presentation will cover key features of sLH2 refueling and storage, from fundamental thermodynamics understanding of critical performance indicators such as dormancy, state of charge, pressure boundaries, 2 phase to supercritical transitions; to full scale implementations into systems developed together with global industry leaders.
Speaker: Loic Jeunesse (Campus Technologies Grenoble) -
310
Measurements on the catalytic ortho-parahydrogen conversion using hydrous ferric oxide
The increased demand for hydrogen as an energy vector and storage medium results in a constantly growing need for higher liquefaction capacity. However, the design of the required ortho-parahydrogen converters is currently subject to major uncertainty. The data on the activity of the current standard catalyst hydrous ferric oxide, commercially available as “Ionex-Type O-P Catalyst” (Ionex) by Molecular Products, are outdated and partially contradictive. The HyCat project, currently conducted at Dresden University of Technology, aims to create a new set of highly accurate design data for ortho-para converters. For this reason, a sophisticated measurement apparatus has been set up in the past years, allowing the testing of ortho-para catalysts in the entire operational of range modern large-scale hydrogen liquefaction plants. This work presents first activity measurements for Ionex at several conversion conditions.
Speaker: Sebastian Eisenhut -
311
Experimental Investigation of Continuous Ortho-Para Hydrogen Conversion for Hydrogen Liquefaction within the Range of 40-80 K
Ortho-para hydrogen catalytic conversion stands as a pivotal process in hydrogen liquefaction. Continuous conversion, the most energy-efficient, is realized by placing catalysts inside channels of heat exchangers. Experimental data is significant to reveal the underlying mechanism of thermal-flow-conversion process and optimize the conversion process, which is still lacking in the accessible literatures. In this investigation, a cryogenic experimental platform for heat exchangers with ortho-para hydrogen conversion is constructed where ortho-para hydrogen conversion coupled with heat transfer and flow is measured. The GM-cryocoolers are utilized as the cold source and helium acts as the refrigerant in heat exchangers tested. The hydrogen can be cooled to an impressive 36 K at an operating pressure of 2 MPa, sustained by a mass flow rate of 1 g/s (equivalent to 3.6 kg/h). A set of crossover tests are carried out regarding the heat exchanger parameters, the catalyst parameters, and the operating state of the fluids, and experimental correlations the catalyst-filled heat exchanger are proposed by measuring parameters such as temperature, pressure, flow rate, and para-hydrogen concentration. Furthermore, the mechanisms of flow and heat transfer coupled with catalytic conversion are elucidated. This study provides technical support for the design of continuous conversion heat exchangers.
Speaker: Junjie Teng (Zhejiang University) -
312
Trial measurement for para-to-orthohydrogen back conversion under the Fe(OH)3 catalyst condition at J-PARC cryogenic moderator system
In the neutron scattering experiments using MW-class pulsed neutron sources, specific pulse shape characteristics, such as high intensity, narrow pulse width and short tail etc., are required. Such pulsed neutrons are typically generated by moderating spallation neutrons using liquid hydrogen. Liquid hydrogen is known as a unique moderator material for the neutrons. However, there are two distinct states with different nuclear spins of hydrogen molecules: ‘orthohydrogen’ and ‘parahydrogen’. It is essential to maintain the appropriate state of liquid hydrogen molecules for effective neutron moderation.
In low temperature condition, liquid hydrogen molecules undergo a transition from the orthohydrogen to the parahydrogen, achieving a more stable state. The neutron scattering cross section of the parahydrogen drastically decreases significantly to about a hundred times smaller values than those of the orthohydrogen, at neutron energies below 14.5 meV. Therefore, this unique characteristic of parahydrogen neutron scattering cross section is utilized to decelerate neutron effectively. It is important to maintain a significantly high parahydrogen concentration, to obtain good moderator performance.
However, parahydrogen changes into the orthohydrogen due to collisions with the neutrons during the neutron moderating process, which is called as ‘para-to-orthohydrogen back conversion’. Previous studies theoretically have predicted that an increase in orthohydrogen concentration caused by the back conversion can strongly impact the pulse shape of the neutrons. Experimental investigation has been recently conducted to measure the increase in orthohydrogen concentration.
In this study, we propose a new experimental method which easily simulates the condition of the pseudo para-to-orthohydrogen back conversion in the J-PARC cryogenic hydrogen moderator system (CMS). Normal hydrogen gas was temporarily introduced to the CMS at a temperature of 20 K and a pressure of 1.5 MPa to attain a desired parahydrogen concentration, exceeding equilibrium concentration by 1%. We evaluated the deterioration of the Fe(OH)3 catalyst performance using a Raman spectroscopy. Details of the proposed experimental method and the obtained results will be explained.Speaker: Gen Ariyoshi (Japan Atomic Energy Agency) -
313
Prediction of pressure evolution with artificial neural network using extended datasets for non-venting liquid hydrogen tanks
Nowadays, storage of liquid hydrogen (LH2) has become a promising solution to many energy applications compared to conventional fuels. However, self-pressurization phenomenon due to heat leakage into LH2 tanks still represents a bottleneck for its development. Accordingly, accurate prediction of the pressure evolution of LH2 is of great importance and urgent requirement for safe storage, transportation and utilization. As known, storage of LH2 in a tank is a complex multi-physics problem with accompanied thermodynamic phenomena and complicated fluid-fluid and solid-fluid interactions resulting from heat and mass transfer processes. Due to such complications, thermodynamic homogeneous model (THM) cannot alone capture the complex hidden features and characteristics of LH2 self-pressurization phenomenon. Consequently, THM cannot provide accurate predictions of the pressure evolution in non-venting LH2 tanks. In the present work, artificial neural network (ANN) as an intelligent approach will be integrated with THM to give a whole picture about LH2 self-pressurization phenomenon based on the combined experimental and theoretical basis. More clearly, based on extended datasets from THM as well as the experimental data, one accuracy-improved ANN model is developed using MATLAB software to improve the prediction ability of both the thermodynamic homogeneous model solely as well as the normal ANN model established alone based on the experimental data. Compared to the normal ANN model, the improved ANN model based on the thermodynamics theory from THM has achieved a maximum improvement of over 20 % in the average prediction error, when applied to one established LH2 tank from literature work. This research provides an effective approach based on the ANN methodology combined with one theoretical model to improve the prediction of pressure evolution in LH2 tanks. The integration of artificial intelligence techniques based on experimentations into the theoretical basis from thermodynamic models holds great potential as a promising avenue for future research.
Speaker: Anas A. Rahman (Assistant Professor of Mechanical Engineering) -
314
First commissioning of the ESS cryogenic moderator system using nitrogen and helium
At the European Spallation Source (ESS), a 5 MW beam of 2.0 GeV proton with a nominal current of 62.5 mA driven by an accelerator will impact a tungsten wheel target at a repetition rate of 14 Hz and a pulse length of 2.86 ms. The fast neutrons produced via spallation process are reduced to cold and thermal neutrons of lower energy levels by passing through a thermal water pre-moderator and, subsequently, up to two liquid hydrogen moderators. Initially, the ESS is to install two hydrogen moderators above the target wheel and plans to replace them by four moderators positioned above and below the target in the future. The calculated nuclear heating is 6.7 kW for the proton beam power of 5 MW, whereas that for the four moderators is 17.2 kW. A cryogenic moderator system (CMS) has been designed to continually supply subcooled liquid hydrogen with a temperature of 17 K and a parahydrogen fraction of more than 99.5% to each moderator placed in parallel at the flow rate of more than 240 g/s to maintain an average temperature rise at the moderator within 3 K. The heat load is effectively removed by a large-scale 20 K helium refrigeration plant, which is called the Target Moderator Cryoplant (TMCP), with a maximum cooling capacity of 30.3 kW at 15 K. The TMCP commissioning was carried out independently without connecting the CMS until December 2022. Operational procedures, including a cooldown, warm-up and beam injection modes, were thoroughly studied to establish an automatic TMCP-CMS control system. The installation of the CMS was completed in January, 2024. Initially, CMS-TMCP commissioning took place without connecting the moderators, utilizing nitrogen and helium before hydrogen operation. The CMS cooldown and warm-up processes were studied based on prior simulation results conducted by the authors and operational parameters were optimized. Additionally, performance tests, such as hydrogen pumps, a He-H2 heat exchanger, pressure drop and heat load have been conducted.
Speaker: Hideki Tatsumoto (European Spallation Source ERIC (ESS)) -
315
Structure Design of a Novel Corrugated Membrane for Large-scale Liquid Hydrogen Storage
The large-scale storage of liquid hydrogen allows efficient and inexpensive hydrogen energy utilization. Conventional liquid hydrogen storage tanks commonly adopt a high vacuum double-shell spherical configuration, as observed in the tanks used by the National Aeronautics and Space Administration (NASA) and the Port of Kobe. However, this kind of tank faces load distribution challenges, affecting the strength and stiffness of the support system, especially as tank volumes increase. This study proposes a novel corrugated membrane structure for large-scale liquid hydrogen storage. The corrugated membrane, featuring orthogonal symmetry with corrugations that merge at intersections to form a natural cruciform curvature, can reduce the thermal stress induced by extremely low-temperature environments. Finite element analysis reveals that the structure with specific configurations effectively maintains a relatively low-stress level under harsh conditions, fulfilling material strength criteria. This innovative approach promises improved low-temperature performance and simplifies manufacturing, potentially reducing construction costs and time frames for large-capacity liquid hydrogen storage solutions.
Speaker: Xinyuan Liu (Zhongshan Institute of Advanced Cryogenic Technology)
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309
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Thu-Or18: Cooling strategies, LN2, Links, Health & Safety Room B+C
Room B+C
Convener: Hirotaka Nakai (KEK)-
316
FCC-ee cavities RF power coupler: study on the optimal cooling strategy to boost the cryomodule energy efficiency.
The RF fundamental power coupler (FPC) in SRF accelerating systems can have a major contribution to the cryogenic power consumption. In the framework of the FCC feasibility study, the focus on the energy saving is of primary importance given the size of the machine, with 264 cavities at 400MHz and 488 cavities at 800MHz for the collider, and 600 cavities at 800MHz for the booster, at the ttbar working point. Additionally, this early stage of the design leaves freedom in exploring and comparing alternatives within a limited number of constraints. In this paper we present the comparison between active vapor cooling and fixed temperature heat interception for the FPC, with the aim of minimizing the heat loads to the helium bath - at 4.5K and 2K for the 400MHz and 800 MHz cavities respectively – along with the overall cryogenic cost of the design solution. The choice for the FPC cooling method impacts the energy consumption, given the low efficiency of low-temperatures heat extraction, but it also affects the integration design of the coupler in the cryomodule, the cryogenic lines layout, and eventually the overall size of the cryomodule, with consequences on the tunnel space needs.
In this paper, the results - concerning the temperature field on the FPC outer conductor, and the cryogenic cooling needs - are presented for the two cooling strategies and different coupler geometries. The data are derived with a semi-analytical model, describing the different heat transfer phenomena and the selected cooling strategy. The model is parametric with respect to the geometry and the RF inputs (RF power per cavity and electro-magnetic field across the outer conductor). In this way, it is possible to maintain flexibility towards the variations, in shape and heat loads, generated by integration choices, RF design constraints, and RF operating conditions across the four FCC working points. Additionally, the model serves as a tool to guide the design of the FPC, evaluating the direct impact of a choice on the final performances of the coupler in operation.Speaker: Karin Canderan (CERN) -
317
Optimization of cryogenic mixed-refrigerant cascades for intermediate cooling stations of the long-distance superconducting power cable SuperLink
In Munich, Germany, a 15 km long superconducting power cable is planned to provide a high-power connection within the 110 kV network. To ensure safe and economic operation, efficient liquid nitrogen re-cooling stations are needed at several points along the cable. Within the SuperLink research project, next generation cooling systems for such operations are being developed.
As an alternative to Brayton coolers operated with helium or neon, cryogenic mixed-refrigerant cycles (CMRC) are being investigated as a compact and economic cooling option for this application. The wide-boiling refrigerant mixture can be tuned to efficiently match the cooling needs of the superconducting power cable. Since the use of high-boilers increases performance, but also poses the risk of freeze-out at the very low temperatures needed, a cascade process is proposed. While the precooling stage is using a mixture of nitrogen and flammable refrigerants, the main cooling stage is running on a mixture of nitrogen, oxygen and neon. In this contribution, a Differential Evolution algorithm is used to optimize the operating conditions of such a cascade, i.e. mixture compositions, pressures and precooling temperature, within the large parameter space.Speaker: Friederike Boehm -
318
Pressure Relieving Approach for the S3FEL Cryogenic Distribution System
Shenzhen Superconducting Soft-X-ray Free Electron Laser (S3FEL), located at Shenzhen, China, aims to construct a new light source that can generate high brightness X-Ray pulses between 40 eV and 1 keV at repetition rate up to 1 MHz. The S3FEL is based on superconducting accelerator technology comprised of 25 cryomodules (CMs) operating at 2 K temperature with 5 K thermal intercept circuit and 40 K thermal shield. The cryogenic distribution system (CDS) supplies and returns cryogens to 2 K, 5 K and 40 K flow circuits of the CMs strings, via vacuum insulated cryogenic pipes, valve boxes, and feed and end caps. To prevent overpressure of the process circuits of CDS and CMs, pressure relief devices shall be sized for all circuits to meet capacity requirements. In this paper, all credible failure scenarios and the determination of heat flux will be presented. The preliminary design results of the relief system will be discussed. Also, the relieving approach of sub-atmospheric 2 K circuit which has dual pressure ratings in the CM will be discussed.
Speaker: Xinbo Dong (Institute of Advanced Science Facilities, Shenzhen (IASF)) -
319
An experimental analysis of flow and mass transfer characteristics of cryogenic liquid nitrogen and oxygen countercurrent on the structured packing
The structured packing is one of the core internals in the cryogenic distillation column. In the past, testing and development of packings were mostly based on ambient hydraulics and fluids, which may deviate considerably from actual cryogenic testing. Therefore, it is necessary to reveal the falling film flow characteristics of cryogenic fluid on the surface of structured packing and study the influence of microstructure of structured packing.
In this study, a cryogenic falling film visualization experimental system was designed and built. The visual images and flow parameters of liquid nitrogen（LN2） on the surface of corrugated packing were obtained. The actual cross-corrugation and inlet wetting coverage data were extracted, and compared with the results of hydraulic experiments at room temperature. At the same time, the influence of the micro-texture structure on the surface of the structured packing on the wave enhancement mechanism and mass transfer performance of the cryogenic fluid was studied, and the influence of mass transfer mode and pore size on the falling film flow characteristics of cryogenic working fluid in the hole was revealed.
The results show that within the same range of ReL numbers, the wetting rate of LN2 is approximately 2.68 times higher than that of water. Only when the ReL of water reaches a certain value(denoted as 2162.71) and develops into a fully wetted film flow on the packing surface, its wetting rate can achieve the same level as LN2. The liquid flow angle and inlet wetting coverage of LN2 are also higher than that of water. LN2 exhibits different interface fluctuations on the microtexture and flat surface, which can strengthen the interphase mass transfer. Based on a reference plate with a wavelength of 2.8 mm and an amplitude of 0.3 mm, the gas-phase mass transfer coefficient (GPTC) can be improved by 47.4% when the amplitude is increased to 0.4 mm, and the GPTC can be improved by 11.5% when the wavelength is decreased to 2.2 mm.The experimental results clarify the optimization direction of the micro-texture on the surface of the cryogenic distillation packing. Under cryogenic conditions, the existence of small holes can promote the passage of rising gas, so perforation may be a breakthrough to reduce the pressure drop of cryogenic distillation column, but the choice of pore size is also worth considering. Cryogenic distillation structured packing perforations should be less than 6mm in diameter. It can be concluded that the cryogenic liquid has good wettability. By adjusting the structured packing used in cryogenic distillation, such as using different micro-textured surfaces or changing the perforation diameter, the distillation performance of the packing can be further improved.Speaker: Yixuan Teng (Zhejiang University) -
320
Heat transfer and vapor behavior on microstructure surface in liquid nitrogen for application to cryopreservation of living cells
Cryopreservation technique of living tissue and cells is used in long term storage and transportation. Human ES / iPS cells could be useful in regenerative medicine. During cryopreservation of human ES cells, there is a problem that the survival rate after freezing and thawing process is low compared with mouse ES cells. The survival rate of these cells after cryopreservation process (cooling and thawing) depends on the cooling rate and the type and concentration of cryoprotectant. There are two options to improve the cell survival rate by the control of the cooling rate. One is in the slow cooling rate under conditions where the rate of occurrence of the intracellular and the extracellular freezing is optimal. Another is in the high cooling rate that causes the vitrification freezing. When the cooling rate is very high, such as the direct immersion in liquid nitrogen, the cells freeze in the vitrification state and the ice crystals don't form. However, in the case of the cooling by the direct immersion in liquid nitrogen, film boiling occurs and the vapor layer covers the surface of cooling object. As the result, the heat transfer characteristics from the cooling object to liquid nitrogen deteriorate.
From this background, the heat transfer characteristics during cooling in the cryopreservation have been clarified in order to further improve the cooling rate in the case of the direct immersion in liquid nitrogen. It has been reported in our previous studies that the cooling rate can be improved with the microstructure in cooling surface and it is confirmed by the temperature measurement at 1 mm from the inner surface of the cooling object that the changes in surface condition can effect on the temperature variation near the inner surface. On the other hand, the mechanism of the heat transfer promotion by the surface microstructure is not clarified though it is considered that the heat transfer promoted by the increase in surface area and the change in the behavior of the vapor layer and bubbles due to the hydrodynamic instability during boiling in the liquid nitrogen.
In the present study, the effect of the surface microstructure on the heat transfer characteristics in the cooling object using cryopreservation is investigated and the variation of the cooling rate with the surface condition is examined. A microstructure imitating the shape of stainless steel mesh (60 mesh/inch) is manufactured on the surface of the cooling object (polypropylene cryo-vial) using a computer numerical control lathe (CNC lathe). Agar is used as a simulated living tissue and is filled inside the cooling object. The temperature sensor is installed near the inner wall in the agar. For the variation of the vapor behavior with the surface condition, the visual observation of the vapor bubbles is conducted by use of the high-speed video camera. It is confirmed that in the case of the cooling object with the surface microstructure, the cooling rate is improved by about 75 % compared with the no-machining condition. The mechanism of the heat transfer promotion through the surface microstructure is examined.Speaker: Masakazu Nozawa -
321
Development of a cryogenic detection chain for low field MRI
Low-field (<10mT) Magnetic Resonance Imaging (MRI) opens the possibility to perform medical imaging at a fraction of the cost of conventional MRI. As signal vanishes with lower applied magnetic field, it becomes necessary to use an ultra-sensitive and ultra-low noise detector to acquire medically relevant images in a reasonable time. Thanks to their exceptional noise performances, Superconducting Quantum Interference Device (SQUID) detectors are particularly well-suited for this application. To preserve signal integrity it is however necessary to reduce noise, which is dominated by the Johnson noise generated in the MRI detection coil. It is therefore primordial to cool down the whole detection chain. Previous designs [1] made use of a SQUID detector connected to a low-temperature superconducting coil hosted in a non-metallic liquid helium cryostat. Such a design however has high running costs and lacks geometric flexibility to perform imaging of body parts, mainly due to the technical choice of using a Nb detection coil placed on the 4K stage of the cryostat.
At Chipiron, we are making a 1mT MRI machine built around SQUID detectors. We report on the realization of a dry 4K cryostat by a collaboration between Chipiron and MyCryoFirm, a division of Pasqal. This cryostat is compatible with the stringent requirements of SQUID-MRI that is capable of hosting SQUID sensors at 4K and a deported cryogenic detection setup predicted to work at 45K. By reducing both the temperature and the resistance of the detection chain, this cryostat will significantly improve the signal-to-noise ratio of SQUID-MRI experiments. In addition, superconducting materials with transition temperatures in the few tens of Kelvin such as MgB2 wires are under investigations to realize a fully superconducting detection chain thus achieving ultimate imaging performances.
[1] Seton et al., Cryogenics 45 (2005)
Speaker: Bastien Dassonneville -
322
Operation and control of superfluid helium in a Healthcare device
While the search for novel superconductors toward higher current carrying capacities and lower transport losses in different types of superconducting wires continues, so far, there is no record of any “liquid superconductor”.
Superfluid helium, however, “conducts” heat without thermal resistance due to its very high thermal conductivity below its Lambda transition point.
For superconducting magnets, different cooling schemes are employed using superfluid helium. These systems usually relate to internal or forced convection modes capable of transferring high heat loads. The inherent hydraulic quantum properties of He-II, like viscosity and density e.g., are therefore used in pumps (so-called fountain effect pumps (FEPs)), as described by the London equation, and enable the generation of a self-sustaining forced flow when using filters, optimized to work as “Superleaks”. Those pumps have successfully been integrated in large superconducting applications e.g., like fusion magnets, accelerators, or dedicated gyroscopes. All these applications primarily depend on the peculiar flow characteristics of the superfluid helium component.
As of today, there is no technical application that solely relies on the high thermal conductivity of the superfluid helium film as a heat transfer medium through copper/steel interfaces at temperatures below 1 K.
To fully utilize that specific physical quantum property however, the interposing superconducting film needs to be well controlled in static, as well as transient cryogenic operating conditions.
In this paper we present cryogenic engineering insights of trials and tribulations faced, when implementing, containing, and operating those thin superfluid helium films in a clinical environment for a medical Healthcare platform, that takes full advantage of this unique thermal conductivity and sound properties, that superfluid helium provides.Speaker: Ernst Wolfgang Stautner (GE HealthCare – Technology & Innovation Center, Niskayuna, USA) -
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Implementation and Enhancement of Safety Measures in SST-1 Cryogenic System at 77 K and 4.2 K
At IPR, in Steady State Superconducting Tokamak (SST-1), cryogenic division have two sections, one is 4.2 K and other 77 K temperature that is used for cooling of superconducting magnet material coils and for reduction of heat loads etc. The working at cryogenic temperature and high pressure environment is drastically different than working at room temperature, the material behaviour, its strength, unexpected results. There are various sub-systems of cryogenic helium plant which needs attention and regular inspection with respect to safety concern for working personnel and prevention to the damage of the systems. The cryogenic systems are namely, high pressure at 150 bar (g) in helium gas pressure vessels, safety mountings as safety valve, rupture disc and Non-Return Valve (NRV), LHe and LN2 fluid cryogenic transfer lines, Thermal and vacuum insulation in the system, 80 K vent line, high pressure helium gas cylinders for filling and testing, various low temperature lab experiments as materials testing at 4.2 K and 77 K and high pressure. The kind of problems occurred in systems during operation has been solved efficiently by conducting the performance and validation tests at operating conditions to prevent the repetition of that problem. The average helium leak orders of 10-2 to 10-4 mbar-l/s of identified helium leaks were improved to ≤ 1x10-6 mbar-l/s. In this paper, the hands on experience will be shared of repairing LN2 cryogenic transfer line, replacement of old insulation and vacuum of 80 K cryogenic transfer lines, identification, rectification and mitigation of helium leaks in cryogenic systems, in-house repairing, development of seals, installation and performance tests on safety valves with NRV in the recovery line of high pressure helium gas vessel etc. are the major tasks carried out with safety aspects. This talk also covers the mandatory aspects of cryogen safety, its handling, hazards & its cusses, protection and preventive measures, cryogenic and high pressure safety guidelines and actions at an emergency conditions and lesson learnt in the different sub-systems of cryogenic plant. The implementation of safety measures enhanced the performance of cryo systems without encountered any accident and un-acceptable events.
Keywords: Cryogenics systems, 4.2 K and 77 K temperature, Helium leak tightness, Safety implementation
Speaker: Rajiv Sharma (Institute for Plasma Research)
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Inspiring Women in Science & Cryogenics Room B+C
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Convener: Marta Bajko (CERN) -
Thu-Po-3.1: Cryo-aerospace, Quantum Systems & Materials Poster area
Poster area
Convener: Alisdair Douglas Seller (CERN)-
324
A comparative study of rapid chill-down technologies in cryogenic applications
Transporting cryogens, particularly for cryogenic propellant fueling, through pipelines from a storage tank is an indispensable process for undertaking a stable cryogenic mission. When cryogenic liquids are introduced into flow components at ambient temperature, they are bound to encounter vigorous two-phase instabilities including boiling and evaporation. The preliminary step of lowering the temperature of hardware to the cryogenic fluid's saturation level, a process referred to as "chill-down" or "quenching," is fundamental for ensuring the delivery of a cryogenic liquid devoid of vapor. Achieving temperature reduction via phase change in heat transfer comes at the cost of using up irreplaceable propellant. Consequently, it is of paramount importance to shorten the chill-down period and lessen the mass load of the cryogenic fluids being employed. To reach this purpose, the present study is aimed to evaluate the effectiveness of rapid chill-down strategies by examining an insert of passive device against a surface treatment approach in the flow passage. Through analysis across various Reynolds numbers, it becomes clear that each method offers unique benefits regarding liquid mass consumption and the time required for chill-down process. An in-depth examination of the experimental data sheds light on how these approaches affect the thermal and hydraulic dynamics throughout the cooling phase.
Speaker: Minsub Jeong -
325
A Comprehensive Overview of Gravity Measurement Utilizing a SQUID
In this study, we present a comprehensive overview of gravity measurement method utilizing SQUID (Superconducting QUantum Interference Device) at cryogenic temperatures, along with the associated equipment. The measurement of gravity is an exceptionally delicate process, susceptible to real-time changes influenced by environmental factors. Therefore, a highly stable and high-resolution measurement system is crucial. To dachieve stable measurements at cryogenic temperatures, we engineered a magnetically shielded liquid helium cryostat. Meticulously designed to ensure optimal magnetic shielding through a superconducting magnetic shield, this cryostat exhibits remarkably high efficiency in maintaining a cryogenic liquid reservoir. Due to the low value of the first critical field (Hc1) of niobium, the cryostat is enveloped by traditional high-permeability materials, μ-metal, serving as the primary shielding within the external housing. A superconducting gravimeter is a device designed to detect minute displacements of a proof mass levitated in a superconducting environment, responding to changes in gravity. The proof mass in the superconducting gravimeter module, uniquely developed by KRISS, is levitated through electromagnetic force, with the current in the levitation coil set to persistent mode. We demonstrate the equilibrium position of the levitated proof mass by evaluating the change in the coil inductance. Additionally, we discuss the gravimeter and its superconducting circuits, presenting preliminary results from Earth Tides measurements.
Speaker: Gracia Kim (Quantum Mass Metrology Group, Korea Research Institute of Standard and Science (KRISS)) -
326
A hybrid 3He Joule-Thomson cryocooler using a spiral flow channel evaporator for space applications
The 3He Joule-Thomson (JT) cryocooler utilizes the JT effect of 3He to typically achieve the temperature of below 2 K. When the 3He JT cryocooler obtains the temperature of below 2 K, the working fluid at the JT impedance must be in a choked state, which means the Mach number of working fluid at the JT impedance is 1. The working fluid behind the JT impedance at this situation is two-phase fluids. In addition, the pressure of the working fluid behind the JT impedance is usually below 20 kPa. Thus, it is crucial for the hybrid 3He JT cryocooler to efficiently extract the cooling capacity from the low-pressure high-speed two-phase flow. Considering that there is no gravity at space, a new evaporator using the centrifugal force with spiral flow channels is designed, manufactured, and applied in the hybrid 3He JT cryocooler.
Speaker: Ziyao Liu (Technical Institute of Physics and Chemistry, CAS) -
327
A user-tuneable heat link for use at temperatures below 4K
Experiments to characterise the physical, chemical and electrical properties of superconducting materials and electronics often require measurements to be made at a number of fixed temperature values within a desired cryogenic temperature range. Temperature-controlled cold tables working in the range 4 to 300K are widely available, however the technology used in these systems is not directly transferrable to the sub-4K temperature
In this paper we describe the design and experimental demonstration of a tuneable heat link that is specifically designed for use at temperatures below 4K. Our tuneable heat link operates by active control of a convective flow of Helium 3 gas within a closed loop. The gas flow is initiated and controlled by electrically heating a small gas pod containing 3He adsorbed onto activated charcoal. The tuneable link is a compact, fully sealed unit (i.e. it requires no external gas connections) with no moving parts. It is designed to have an off-state conductance of approximately 35 microwatts with the ends tethered at 4K and 1K respectively. This means that it can be used with the 'cold end' thermally tethered to a sub-kelvin sorption module without unduly loading the module.
We will present data from experimental tests of the tuneable heat link to establish its off-state and on-state thermal conductance under a range of operating conditions. We will compare these data with the design models for the heat link and discuss practical use scenarios.
Speaker: Benjamin Steele (Chase Research Cryogenics Ltd) -
328
Analytical model for the calculation and optimisation of cryogenically cooled current leads and wire interconnects
The study of heat transfer in conduction cooled current leads and digital electronic interconnects is of vital importance during the design of cryogenic electronic systems where the cost of cooling increases exponentially as temperature decreases. It is a thermally complex problem that combines heat transfer due to conduction between the hot and cold ends of the leads, as well as the Joule heating effect generated by the current flow within. This is especially important when high power delivery is required (1W per wire, for example) to a cryogenically cooled system. The problem is often simplified by the application of the Wiedemann-Franz law, which states that the ratio of the electronic contribution of the thermal conductivity (κ) to the electrical conductivity (σ) of a metal is proportional to the temperature (T)[1], κ/σ=LT. Where L is a proportionality constant known as the Lorenz number. This is an empirical law that holds relatively well for most metals and has been shown to work well at high or very low temperatures (a few Kelvin), but not necessary in between [2]. The law has been used to derive the thermal analytical model that describes the minimum heat flux to be dissipated at the cold end of the current leads Q_min|(L/A=opt)=I√(L_0 (T_h^2-T_l^2 ) ) [3], where L is the length of the lead and A is its cross-sectional area. However, at cryogenic temperatures (4.2K to 300K) the Wiedemann-Franz law loses precision, and a more general approach must be taken. By taking into account the individual temperature dependance of the thermal conductivity and electrical resistivity of the metal, one can calculate the minimum heat flux for all metals at all temperatures, Q_min|(L/A=opt)=I√(2∫_(T_c)^(T_h)κρdT). This model, though more generally applicable, still has certain limitations to its usefulness. Firstly, it is only valid for an optimal L/A, which though preferable as it minimizes the heat flux that must be extracted, is not always possible due to other constraints during the design process. It also does not provide information regarding the temperature distribution along the length of the leads. Thus, in this paper a general case, 1D analytical model is proposed that describes the temperature distribution along metal wire interconnects between digital electronics at different temperature levels. This model can be applied to the design of cryogenic electronics systems where the accurate measurement of heat flux is crucial, such as cryo-CMOS, superconducting electronics, and quantum computers. As it is a general case model, it can be used to optimise the geometry of the leads, but it can also determine the feasibility of non-optimal systems by calculating the temperature distribution along the lead length. This will provide critical information regarding the increase in heat flux at the cold end above the minimum, as well as the value of T_max and its position between T_h and T_c. The new model can also handle non-uniform Joule heating along the length of the lead, as is quite common in microwave power distribution systems with some amount of impedance mismatch. The model has initially been validated by comparisons with the direct solution of the second order differential equations and will later be validated through experimentation.
- Jones, William; March, Norman H. (1985). Theoretical Solid-State Physics. Courier Dover Publications. ISBN 978-0-486-65016-6.
- Rosenberg, H. 2004. The Solid State. Oxford University Press.
- McFee, R. Review of Scientific Instruments 30(2), pp. 98-102 (1959).
Speaker: Suzanne Dang (Absolut System) -
329
Cryogenic liquid propellant densification system using multiple ejectors
Normally cryogenic liquids such as oxygen or hydrogen are used as propellants of the launch vehicle. Densification of propellants means the density of propellants are increased by decreasing the cryogenic fluid temperature. Compared to common incompressible liquids, the density of cryogenic fluids changes more sensitively according to the temperature. Therefore, this densification technology is actually used in current launch vehicle, and it increases the fuel efficiency of launch vehicle since the more propellant could be stored in the same propellant tank volume. There are several kinds of method to densify the propellants by cooling down the temperature of liquid propellants. One of the densification methods is decreasing the pressure of propellant tank under the atmospheric pressure by using a vacuum pump. In fact, ejector could be used instead of the vacuum pump. Ejector is a simple device and has no moving parts, so it is clean and highly reliable which is more appropriate to use in launch vehicle. In this study, an ejector is designed and its performance is tested to cool down the liquid nitrogen temperature below 77 K. The ejector is installed at the top of the liquid nitrogen tank, and high-pressure nitrogen gas is used as the primary fluid of ejector. Then saturated vapor of nitrogen in the tank is suctioned to the secondary fluid of the ejector. The test result showed that the entrainment ratio decreased over time. The reason is that both the secondary flow rate and the tank pressure decrease during the subcooling process. The optimum ejector geometry such as the nozzle diameter and the mixing throat is determined from the operating condition of the ejector like the primary and secondary flow inlet pressures, temperature, and mass flow rate. Therefore, the optimum size of each ejector component should be different at different subcooling pressure. This means multiple ejectors rather than a single ejector would be a more effective way for a subcooling system with ejector. Optimum ejector geometries at different secondary flow inlet pressures were calculated by 1-dimensional ejector model, and the performance of subcooling system with multiple ejectors is investigated.
Speaker: Jisung Lee (Korea Aerospace Research Institute) -
330
Design and Performances of a Table-Top 500 mK Cryostat for a 100 Spin-Qubits Quantum Computing Application
A powerful table-top cryogenic plateform has been developed for Quantum computing applications. The system offers a cold plate optimized for the CMOS qubits technology developed by CEA/LETI for the QuCUBE ERC synergy project. The goal is to demonstrated a 100 CMOS-Qubits system, scalable to more than 1000 Qubits. The cryogenic system is designed for 100 mW cooling power at 500 mK, compatible with the present demonstrator.
The solution chosen is a high-flow helium-3 Joule-Thomson cycle pre-cooled by a 4 Kelvin Pulse-Tube. The table-top architecture is preferred in order to keep an easy access to the quantum components and to the control electronics installed. The pulse pulse-tube and the high flow Joule-Thomson heat exchangers cycle are mounted in a separate ‘coldbox’.
The application cryostat offers three temperature levels: a 50 K stage coupled to the pulse-tube first stage by a pressurized helium circulation loop, a 5 K stage coupled to the second pulse-tube stage by a conductive copper link, and a 500 mK stage coupled to the Joule-Thomson cycle evaporator.
The pumping speed required (~1000 L/s) is achieved by four turbopumps in order to reach 4 mmol/s helium-3 at 10 Pa on the evaporator. The cooldown time of the system is less than 12 hours, achieved by a cooling loop before starting the Joule-Thomson system.
We report the performances achieved both with helium-3 and helium-4 use and the flexibility to adapt the temperature requirement to the cooling power needed in a more demanding case to reach 1000 –CMOS Qubits.Speaker: victor doebele (CNRS) -
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Design and Performances of an Optical Cryostat at 2 K
We have developed a versatile cryogenic platform for research in optics. The optical cryostat offers an experimental volume of 100 x 100 x 100 mm with up to five 2-inches optical accesses. The cold plate is cooled to a temperature below 2K with 50 mW power available. The cryogenic system is based on a two-stages 4 Kelvin Pulse Tube and a 2 K helium Joule-Thomson cooler. The Pulse-Tube cold head is separated in a ‘coldbox’ in order to minimize the occupation on the optical table. The thermal coupling is realized by an active pressurized helium circulation loop between the Pulse-Tube first stage and the optical experiment cold chamber. The circulating helium line additionally reduces the vibrations induced by the cryoocoler in the experimental chamber, which are generally very detrimental in optics.
We describe the design and the performances of the system in operation. The integration of the Joule-Thomson cooler minimizes the cooldown time of the optical cold chamber with the addition of a pre-cooling circulation loop.
To vary the temperature according to the user's needs, we control a flow restriction that changes the evaporator pressure and, in turn, the temperature of the cold plate between 2 - 4 K. To achieve higher temperatures (4 K – 300 K), we propose to control the flow in the pre-cooling loop.
We evaluate the vibrations transmitted to the optical chamber by using a laser velocimeter with a sensitivity of 20 nm/s/Hz ½ in the frequency range 0.5 Hz – 22 kHz. In terms of displacements, this method is able to measure a few nm at 1 Hz. Because the mechanical links between the cryocooler and the optical platform is made by a fluid circulation, the vibration transmission is expected to be reduced. We describe the method used to minimize that transmission by a very soft suspension of the cold box. The results are discussed and the compatibility with Raman measurements at temperatures below 2 K discussed.
As a first application, we study the thermal coupling of an Erbium-doped crystal by optical spectroscopy. To do so, we have developed an original method for in-situ optical sensing of the sample temperature, based on the particular electronic structure of erbium under magnetic field.Acknowledgments
This work has been financed by Absolut System, CNRS-G2ELAB-Absolut System (research con-tract#116420) and the ANRT/CIFRE grant contract N°2021/0803 to support Marek Zeman’s PhD the-sisSpeaker: Marek Zeman (CNRS, Absolut System) -
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Development of cryogenic cooling system for low emission future aircrafts
In order to reach the goal of 50% reduction of emissions by 2050 set by civil aviation industry bodies, the exploration of new and potentially disruptive technologies has become more and more crucial for Airbus in the last few years.
Aircraft electrification, identified as a major pillar of the de-carbonization strategy, while presenting major technological challenges, will also open new and interesting opportunities for optimized architectures in terms of simplification and efficiency.
As explored during the ASCEND project [1], liquid hydrogen stored on board to be converted into electricity in the fuel cells of future low emission aircrafts, enables the possibility to design and operate the powertrain components at cryogenic temperature and possibly to replace conventional conductor materials with superconductors. This would lead to substantial improvements in terms of global aircraft efficiency and weight, but also open new design space thanks to the high current density typical of the superconducting technology.
Each component of a future Megawatt scale powertrain will have different cryogenic cooling requirements, in terms of operating temperature, heat losses and temperature uniformity. For example, the superconducting electrical motor would typically have heat losses of few thousands of Watts in the temperature range of 40/50K and the Motor Control Unit would typically feature some tens of kiloWatt of dissipation in the temperature range of 100/150 K with temperature uniformity between different components to be kept within few degrees. The superconducting DC distribution would be operated below 77 K and the heat losses would be on the order of hundreds of Watt at the interface of the current leads.
In order to allow the operation of such a future MW scale powertrain, one of the major challenges is the development of an efficient cryogenic cooling system able to maintain the components at their working temperature by optimizing the requirement in terms of liquid hydrogen, possibly not exceeding the amount needed by the fuel cells in each phase of the flight mission, including the transients[2].
Additionally, the cryogenic cooling system shall also meet the needs typical of the aircraft industry in terms of weight, space, installation and maintainability constraints, but also to take into account safety and reliability standards. In this work we present the progress in the design of the cryogenic cooling system for a future aircraft Megawatt scale powertrain.[1] L. Ybanez et al., "ASCEND: The first step towards cryogenic electric propulsion", Proc. IOP Conf. Ser.: Materials Sci. Eng., vol. 1241, 2022.
[2] L. Ybanez et al., “Cryogenic electric propulsion system: ASCEND main results and perspectives”, Conference: MEA2024Speaker: Swapnil Kharche (Airbus UpNext) -
333
Experimental investigation and performance prediction of cryogenic temperature sensor for cryogenic rocket engine using artificial intelligence techniques
Cryogenic sensors are widely adopted in cryogenic and semi-cryogenic rocket engines to measure the temperature values. These sensors are in-house developed resistance sensors and are calibrated in between 4.2 K to 300 K to ensure the desired redundancy, accuracy, and repeatability before their authentic use in space missions. With our in-house wet cryogenic calibration facility, these sensors are calibrated and post-processed for plotting graphs of resistance versus temperature in appropriate ranges and developing fitting equations. In this paper, an attempt has been made to use artificial intelligence techniques to predict the resistances as a function of temperatures for the first time. The raw data of a typical cryogenic sensor has been collected from the experimental investigation and categorized into three categories: about 70% of data is used for training, 15% data is used for testing, and the remaining 15% is used for validation purposes. Various types of membership functions and training algorithms have been selected during training the neural network and the effect of each of them on the predicted value has been compared. It is noticed that the accuracy of the prediction of resistance as a function of temperature is better than that of the polynomial equation.
Speaker: D.S. Nadig -
334
Heat Dissipation induced by Microvibrations in Low Temperature Systems
Low temperature detectors operating at sub-Kelvin temperatures and in the FIR or X-ray wavelengths, are a key feature of space missions addressing the science of the universe. The thermal stability of the coldest cooling stage to which they are thermally coupled is crucial to their performance. This performance could significantly be compromised however, by the fluctuations of the thermal dissipation due to microvibrations. These low-level mechanical vibrations may originate from the cryocoolers of the cryogenic chain that generates said needed sub-Kelvin temperatures, but also from spacecraft-level systems such as reaction wheels (RW) and solar array drive mechanisms (SADM) to name a few. The coldest cooling stage of said instruments, typically an adiabatic demagnetization refrigerator (ADR), is often only able to provide a few microwatts of cooling power. It is therefore crucial to minimize the heat load (and its variations) to the coldest stage well below the microwatt level.
The study discussed in this article explores dissipation induced by microvibrations in a gas-gap heat switch, a common elementary device in space cryogenics and ubiquitous in sub-Kelvin applications, with a special focus given to the low-level measurement methodology. The heat switch is studied in a 1.2 K to 4.2 K helium-bath environment and excited by means of an external mechanical shaker. Findings show that heat dissipation is induced by microvibrations in the heat switch, as well as in its associated instrumentation and wiring, of the order of several microwatts for several millig of mechanical excitation.
Speaker: Thomas Adam (Univ. Grenoble Alpes, CEA, IRIG-DSBT) -
335
Impact of cold finger geometry on low temperature pule tube cooler performances
Pulse tube developments at CEA/SBT are focused on low-temperature Pulse tube cryocoolers, and more specifically on a basis of the cold tip architecture of the PT15K cooler previously developed by ALAT/TCBV/CEA. This pulse tube cooler was made to work at 15K, here, the objectives are to decrease its working temperature in order to produce a significant cooling power around 8K or lower.
A “last” stage of a low temperature PT cooler has been developed at CEA few years ago and reached a temperature of 4K while precooled at 20 K, nevertheless, it was too demanding in term of heat flux at pre-cooling interface to be compatible with our current space like PT pre-coolers.
Here we adopt a step-by-step approach to decrease the working temperature while keeping reasonable level of heat flux at interfaces, leading to a better overall thermodynamic efficiency. The first step was to modify slightly the architecture of the pulse tube cold finger in order to add a second interface for pre-cooling. The second step involves dimension reductions of the PT 15K cold finger to reduce the heat flux at pre-cooling interfaces.
Several pulse tube geometries have been designed, built and tested in order to evaluate the heat flux required at precooling interfaces, as well as the evolution of the pulse tube performances. The influence of the pre-cooling temperature, and the heat flux associated have been studied for different interface temperatures to create a large database. Coupling this data base with the performance database of an existing two-stage PT cooler can be used to optimize a future three-stage cooler.
All these preliminary results were obtained using a standard stainless steel mesh regenerator. In the future, tests will be carried out with a regenerator featuring a specific heat anomaly to improve performance at low temperatures.Speaker: Lucas Methivier (Univ. Grenoble Alpes, CEA, IRIG-DSBT) -
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The Mode Selector Mechanism (MSM): a bi-stable cryo-actuator operated at 4.2K
A cryogenic environment implies a lot of constraints and uncertainties when it comes to the use of mechanical parts since the material properties are thermally dependent. This is even more true when the mechanical part ensures the motion of a mechanism. In that context, the Centre Spatial de Liège (CSL) has developed a specific mechanism with 3D printed parts. The Mode Selector Mechanism (MSM) is a bi-stable cryo-actuator operated at 4.2 K developed by Centre Spatial de Liège. The MSM development started as part of the far-infrared spectrometer SAFARI on the ESA/JAXA SPICA space telescope. It is taking place now in the preparation and anticipation of next generation cryogenic missions.
The MSM is characterized by its ability to switch between two stable positions an optical part, such as a mirror, at ambient as well as at cryogenic temperature (4.2 K). The particularity of this bi-stable actuator is a passive locking at both positions, to prevent electromagnetic interference sources. The actuator is also optimized regarding the energy dissipated during actuation. For that reason, specific elements such as magnets, copper coils, and flexible pivots, designed and 3D printed by CSEM, are included in the actuator.
In this talk, we present first the setup and results for the characterization of the main components at cryogenic temperature. We highlight the challenges and solutions implemented during the development of dedicated test benches for magnetic field, electrical resistance, and mechanical torque measurements adapted to cryogenic temperature. For instance, conduction was minimized between ambient and cold areas, and molecular conduction from Helium at low pressure was added during transients to improve test dynamics. We conclude with the characterization of the MSM mechanism at 4.2 K, including the time of commutation between both positions and the power consumption.Speakers: Etienne Lallemand (Centre spatial de Liège (CSL), Université de Liège (ULg)), Tanguy Thibert (Centre spatial de Liège (CSL), Université de Liège (ULg))
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Convener: Caroline Fabre (CERN)-
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Analysis of fault current limiting performance of resistive-type hybrid SFCL for parallel operation of distribution transformers
Recently, the increasing domestic power demand has led to an expansion of power facilities, resulting in a decrease in system impedance and subsequently causing an increase in fault currents. These fault currents surpass the interrupting capacity of conventional circuit breakers, leading to significant economic losses due to equipment malfunctions and damages. Although solutions like circuit breakers and power fuses exist, circuit breakers take 0.1 seconds to interrupt fault currents, while power fuses, though faster, have significantly lower fault current interrupting capacities. To address this issue, research and development efforts are underway for superconducting fault current limiters (SFCLs), capable of swiftly reducing large fault currents.
This paper analyzes the quench characteristics and operational principles of a hybrid superconducting fault current limiter developed by LS ELECTRIC. The SFCL in this study operates at a rated voltage of 22.9[kV] and a rated breaking current of 2000[A], featuring a configuration with a Fast-Switch(FS) connected in series with the High-Temperature Superconductor(HTS), complemented by a parallel Current-Limiting Resistor(CLR). Using Power System CAD (PSCAD), the SFCL and the power system are simulated to confirm the effectiveness of SFCL application in power systems.
Under normal current conditions, the SFCL maintains a superconducting state until a fault occurs, at which point the fault current exceeds a threshold, leading to the appearance of a superconductor quench resistance before half a cycle. This paper mathematically models and simulates these characteristics using PSCAD. Furthermore, the resistive hybrid SFCL initially relies on the superconductor to handle most faults until the Fast-switch operates at the current zero-crossing point. Subsequently, the current-limiting resistor intervenes to restrict fault currents, a principle modeled and applied to a case study of parallel operation of distribution transformers in PSCAD.
The parallel operation of distribution transformers, aimed at equitably distributing load to reduce underutilization and enhancing reliability by supplying power from parallel circuits during distribution line faults, is considered by power companies to improve energy supply efficiency. However, parallel operation of transformers decreases system impedance, accompanying a critical drawback of increased fault currents. SFCLs offer significant advantages in transformer parallel operation due to their minimal impedance under normal conditions and rapid fault current reduction capabilities during faults.
Through simulation, this paper verifies the operational effectiveness of SFCLs by connecting them to the secondary side of distribution transformers and assessing fault current magnitudes during both isolated and interconnected transformer operations. It examines various fault scenarios, including voltage phase angle differences and fault locations, to ascertain the applicability of SFCLs in power systems.
Speaker: Dong Eun Kim (LS ELECTRIC Co., Ltd.) -
338
Cold mass suspension system of a rotating gantry for medical applications.
In particle therapy of cancer, the radiation dose to tissues around the tumour can be reduced by employing a rotating gantry—a mechanical structure allowing the delivery of the beam to the patient from various angles. Gantries for ion therapy can benefit from the integration of superconducting magnets to minimize the size and weight of the machine. One significant challenge associated with the suspension system of superconducting elements is related to the management of their accuracy during both the alignment phase and operational stages. Concurrently, heat flow from room temperature to cryogenic levels through the suspension system must be restricted. The design of the supports must consider the variability of the load during operation, i.e. guarantee accuracy of the cold mass pose (position and rotation) under its own weight during a 360° gantry rotation. A literature review on existing suspension architectures has been conducted, leading to the proposal of an over constrained 8-support architecture as one possible solution. A lumped parameter model is presented to derive the pose of the suspended object as a function of the stiffness of the supports and the vacuum vessel.
The geometric architecture of the suspension system has been optimized minimizing the effect of the elasticity of the supports. A comparison of possible materials for the suspension elements has been done, among these, carbon fibre supports allowed to achieve a good compromise between stiffness and thermal insulation performances.Speaker: Luca Piacentini (Riga Technical University (LV)) -
339
Comparative study on the effects of isochoric cryopreservation and liquid nitrogen flash freezing on the quality of fish
Freezing and cryopreservation are critical for maintaining the quality of organism, which has been widely used in food and medical industries. However, the generation of ice crystal during cryopreservation process can inevitably induce tissue injures and consequently damages the organism quality. Lowering the freezing point and accelerating the freezing rate are helpful to suppression the ice crystal damage. Therefore, isochoric cryopreservation and liquid nitrogen flash freezing are conducted to investigate the different effects of these two freezing methods on fish body in this work. The influence of different packaging methods, freezing pressures/temperatures, freezing rates and cryopreservation time on the quality of the quality of fish body including volume, water holding capacity, color, and taste are systematically tested and analyzed in this work. Furthermore, an in-situ investigation is also conducted to reveal the evolution mechanism of cellular activity of fish body under different freezing methods by optical microscopy and scanning electron microscopy. In addition, the heat transfer processes under different freezing system are also calculated and analyzed to evaluate the energy consumption. Finally, an optimized freezing and cryopreservation process is proposed to keep the quality of fish products with lower storage-transportation costs and carbon emission.
Speaker: Zeju Weng (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
340
Cryogenic facility set up for superconducting accelerator magnets and power transmission lines at INFN
The Italian National Institute for Nuclear Physics (INFN) is currently involved in technological activities based on superconductivity. Two projects are running into the Test Facility for Large Superconducting Magnets and Superconducting Line at the Physics Department of the University of Salerno (Italy): both are devoted to the test and commissioning of superconducting devices, such as superconducting magnets for synchrotrons, and power transmission line. Presently, the THOR (Test in HORizontal) program is dedicated to the Site Acceptance Tests (SAT) of quadrupole doublets modules (QDM) for the SIS100 accelerator, part of the FAIR facility under construction at the GSI in Darmstadt. The IRIS project (Innovative Research Infrastructure on applied Superconductivity) funded under PNRR/NGE targets the application of superconductivity to the Green Transition: it aims to set a test facility for superconducting power transmission line based on MgB2 cables long up to 120 m, operating a 25 kV and 40 kA and at a temperature of about 20 K. Both programs rely on cryogenic plants, one fully operating for the THOR project and one under procurement for IRIS, aiming also at strengthen the already existing one. The former is made of a cold box able to supply supercritical He at 4.5 K up to 15 g/s for a total cold power of 200 W at 4.5 K + 500 W at 77 K when in refrigeration mode, the latter will be able to supply up to 22 g/s of pressurized He gas at 20 K , for a total power up to 500 W. The plants have a 190 kW and 135 kW SFC screw compressors for pure He. Both cryogenic systems have the possibility to produce liquid He, having a Joule-Thomson stage and an internal purifier.
The facility will be described in this work, with a focus on the cryogenic operational aspects. We will present the THOR cryogenic plant and discuss on issues and solutions for the optimization of the cryogenic test program of the SIS100 QDM. On the other hand, the design and development advances for the IRIS project will be presented.Speaker: Domenico D'Agostino (INFN-Napoli, Gruppo Collegato di Salerno, 80084 Fisciano, Italy) -
341
Design and optimization of the cryogenic structure of the concentric high temperature superconducting cable joint
Due to merits of low loss, large capacity and compactness, concentric high temperature superconducting (HTS) cable has become an ideal solution to the of large-capacity power transmission in a narrow path. As the three phases in the concentric HTS cable are wounded one-by-one in the same former, the non-superconducting joints are concentrated in a short range. The same cooling method as the normal section will cause local temperature rise and subject to hot spots risks. This paper conducts a systematic study on the cryogenic cooling structure design of the joint of the concentric HTS cable. The heat generation mechanism is analyzed and a heat-flow-electricity coupling model is established. Based on heat transfer enhancement method and computational fluid dynamic (CFD) simulation, the effects of different structure parameters on the temperature rise, flow resistance, and pressure drop of the joint are studied and the optimal cryogenic structure is proposed. The results are of great significance to the safe and stable operation of the joint in engineering application of the concentric HTS power transmission.
Speaker: BANGZHU WANG -
342
Design, implementation, and preliminary testing of the interlocks and safety functions for the CMDS (cryomodule and cryogenic distribution system) master system at the European Spallation Source ERIC
The current paper introduces the design and implementation of the Interlocks and Safety Functions implemented for operating the cryogenic system of the European Spallation Source (ESS) superconducting Linear Accelerator (LINAC), emphasizing the integration of individual cryomodules and valve boxes within a unified system controlled by a master CMDS (Cryomodules and Cryogenic distribution System) PLC.
The study focuses on the practical implementation of these Interlocks and Safety Functions for the entire cryogenic systems in the superconducting LINAC, validating the design with some preliminary tests before cooling down the Accelerator. The paper evaluates the primary goals which include protecting the machine from overpressure or overfilling; electricity, network, or compressed air shortages; control system or instrumentation failure; loss of cryogenics or vacuum conditions; and collecting valuable operator feedback for continuous improvement.
The controls architecture for the CMDS is based on one Programmable Logic Controller (PLC) integrated into EPICS through the controls network, and distributing commands and notifications via Profinet to a total of 46 PLCs responsible for the cryogenic controls of the valveboxes and cryomodules in the LINAC. This type of integration allows for the remote operation from the control room and the necessary interaction of the control system with other related systems and EPICS services like archiving, alarms, and save-and-restore.Speaker: Emilio Asensi Conejero (European Spallation Source ERIC) -
343
Development of whole-body cryochambers based on a mixed-gases Joule-Thomson refrigeration cycle
Abstract
Whole-body Cryotherapy (WBC) or cryostimulation stands as a prevalent and extensively employed recovery modality in the realms of sports and exercise medicine, especially post strenuous training and competitions. This practice involves brief exposures, usually lasting between 2 to 4 minutes, to extremely cold air, reaching temperatures of −110 °C and below. Individuals undergoing WBC are minimally dressed and positioned within cryogenic chambers. Initially employed within clinical contexts for alleviating symptoms associated with diverse rheumatic diseases, WBC is claimed to diminish pain, edema, and inflammation.
Whole-body cryotherapy equipment gained popularity in the 1970s. Over the past few decades, these devices have been heavily reliant on liquid nitrogen. Cryotherapy at low temperatures inevitably necessitates frequent liquid nitrogen supply, which is challenging to obtain or permit in many urban areas. There are also potential risks associated with oxygen consumption and the need for exhaust system installation. Electrically powered equipment eliminates the need for liquid nitrogen supply, requires less maintenance compared to liquid nitrogen devices, and is considered safer. However, electric cryotherapy chambers face challenges in competing with liquid nitrogen cryochambers concerning temperature control, especially in hot climates, cooling dynamics, and hourly processing capacity. The electric cryotherapy chambers simplify logistics and maintenance, but most commercial electric cryochambers currently use multi-stage cascade refrigeration for cooling, which imposes a limitation on treatment temperatures, typically reaching around -110℃.
The Joule-Thomson refrigeration, based on the real gas Joule-Thomson effect, stands as one of the oldest refrigeration methods, experiencing a resurgence with the utilization of multicomponent mixed gases in recent decades. Various refrigeration cycle configurations have been proposed for diverse applications. Commercialized applications based on mixed-gases Joule-Thomson refrigeration technology include low-temperature cryogenic preservation chambers, cryogenic water traps for high vacuum applications, and natural gas liquefiers. The majority of these applications operate at temperatures around -150℃, signifying the considerable potential for applying Joule-Thomson refrigeration in whole-body cryochambers.
In this paper, both single-person and double-person electric-powered cryochambers were developed utilizing a mixed-gas Joule-Thomson refrigeration system, allowing for treatments at temperatures as low as -140℃. The single-person cryochamber achieves a reduction to -120℃ within 90 minutes, employing a 12 kW compressor unit dedicated to freezing the entire cryochamber. Simultaneously, the double-person cryochamber achieves -120℃ within 50 minutes and can even reach temperatures as low as -140℃ within 90 minutes under significant thermal loads, facilitated by a 28 kW compressor unit. The cooling capacities of the two compressor units in distinct temperature zones were determined, and the mole fraction of the mixed refrigerants was optimized to enhance overall cooling efficiency.
In addition to the refrigeration unit design, concerning the design of cryotherapy cabins, the individual cold therapy cabin has a volume of 1.3 cubic meters, while the double-type cold therapy cabin measures 3.2 cubic meters. The cabins facilitate self-circulation of air, ensuring a high oxygen concentration. Moreover, a glass viewing window is installed on the door, allowing continuous observation of the cabin conditions.
Finally, an economic analysis of the proposed system was conducted, revealing that the electric-powered whole-body cryochamber exhibits superior economic performance when contrasted with devices heavily reliant on liquid nitrogen. The economic advantages become increasingly apparent with each successive use.Acknowledgments
This work is financially supported by the National Natural Sciences Foundation of China (No. 52036010), QingDao CASFuture Research Institute CO., LTD. (21–8–1–1-qy), and the China Postdoctoral Science Foundation (2023M733584).Speaker: XIAN WANG (Technical Institute of Physics and Chemistry) -
344
Flywheel type uninterruptible power supply using high temperature superconducting induction machine
This paper studies, experimentally and analytically, on the characteristics of fly-wheel type uninterruptible power supply (FW-UPS) using high-temperature superconducting (HTS) induction machine (HTS-SIM). This study assumed that the SIM is iron-cored and composed of Cu wire stator windings and HTS rotor windings. The rotor windings consist of HTS wires embedded in iron rotor core and connected to HTS end-rings. The entire assemble of the rotor windings are placed in a rotor cryostat and cooled at cryogenic temperature, with no electric connections to the rotor. The stator is at room temperature. When AC currents are applied to the stator windings by an AC power supply to start the SIM, the HTS rotor windings are subject to AC magnetic field. Initially, no rotating torque is produced as the rotor windings are superconductive. However, when subjected to AC magnetic field, the AC losses are generated in the rotor windings raising the winding temperature. Simultaneously, the AC shielding currents is induced to expel the magnetic flux. When the shielding currents exceed the critical currents of the HTS rotor wires which are lowered by the temperature rise, the HTS rotor becomes resistive. As a result, the magnetic fluxes penetrate in the rotor windings, generating the rotating torque. When the revolution speed of the rotor becomes close to the synchronous speed, the shielding currents and the temperature of HTS wires of the rotor decrease due to the reduction of resistive and AC losses, and the rotor wires regain the superconductive state. Then, the rotor is pulled into the synchronous speed by the trapped magnetic fluxes. The back electromotive voltages induced by the trapped magnetic flux are maintained even when the SIM is disconnected from the power supply. Therefore, by inserting an SIM combined with a fly-wheel between a power line and electric loads, electric power to the load is sustained even when the power from the line is lost. When the power from the line is recovered, the SIM-FW-UPS recovers idling state automatically. There is no need for a device to synchronize the SIM-FW-UPS to the power line frequency.
The authors made 3kW class SIM to study fundamental characteristics of HTS-SIM and investigate feasibility of application to FW-UPS. The authors also conducted numerical simulation to study dynamic characteristics of 3MVA class SIM-FW-UPS for industrial use.Acknowledgements
This work was based on results obtained from Grant-in-Aid for Scientific Research (C) [19K04356] from the Ministry of Education, Science and Technology, JapanSpeaker: Hanzawa (Yokohama National University) -
345
Innovative cryogenic systems for cooling superconducting wind turbine electrical generators in the 20-65 K temperature range
As part of the energy transition, the off-shore wind power market is booming with many very large-scale projects emerging or already in operation in Europe, Asia and America. Wind farms are commonly made up of several dozen turbines, the power of which has steadily increased in recent years, now exceeding more than 10 MW each, or soon even beyond.
Installed more than 150 meters above the waves, the nacelles housing the electric generators nowaday weigh more than 400 tonnes. This includes in particular several tons of rare earths used in electromagnets that operate at room temperature.
By cooling the electromagnets located in stators or rotors down to cryogenic temperatures, a superconducting state can be achieved, where electrical conductors do not oppose any resistance anymore. The weight of the generator and therefore that of nacelles might then be reduced by several dozen tons, while the mass of necessary rare earths in classical permanent magnets (PM) might be reduced by two or even three orders of magnitude.
Indeed, literature about superconducting wind power generators shows about 7 tons of rare earths are needed for classical PMs in a 10 MW-scale generator working at room temperature, while market prospects for offshore wind power show about 1200 gigaWatts of generating capability might be installed worldwide before 2050. This would increase demand for rare earths by almost 1 million tonnes over the next two decades, putting this market in competition with other applications, such as ground-based electric mobility, thus straining supply chains, not to mention geopolitical tensions.
This paper will first present an existing single-stage turbo-Brayon cooler able to provide up to 17 kW of cooling power at 65 K, which could go down to about 40 K. Being an extremely compact and standalone cryocooler, it would be well suited for cooling large superconducting electrical power generators aboard offshore wind turbines working in this range of temperatures.
Then the paper will present an innovative cryocooling concept based on the same industrially-proven turbo-Brayton technology using several-stage turbomachines that is able to provide about 1 kW of cooling power in the 20-30 Kelvin temperature range (or 5-6 KW at 65 K), enough for cooling a 10 MW-scale wind turbine generator. Other versions in the future might operate at 4 K. It is based on Air Liquide’s extensive experience on the mature reverse turbo-Brayton refrigeration technology (from the International Space Station, HTS ground applications to LNG ship carriers) and on large superconducting systems for scientific instruments (CERN-LHC, ITER, SLAC, etc…).
A compact, hermetic and extremely reliable system, this standalone cooler is composed of a few small turbomachines and heat exchangers mounted on a unique plate. An internal manifold distributes the cold gas to the various magnets using closed loops. The complete system can cool down either stators or be mounted onto a direct drive rotor to rotate with it.
Superconductivity is now a mature technology that has been demonstrated on the field for wind turbines. A game-changer, these extremely compact and powerful cryocoolers working in a wide range of temperatures and powers pave the way to a new era in offshore wind power, reducing the demand in critical raw materials while improving the LCOE of wind turbines.
Speakers: Guillaume Delautre (Air Liquide), Pierre Barjhoux (Air Liquide Advanced Technologies), pierre crespi -
346
Investigation of Liquid Nitrogen/Fluorocarbon Mixture for HTS Apparatus
Liquid Nitrogen/Fluorocarbon mixture would be an effective coolant and insulating medium of high-temperature superconducting (HTS) magnets and power devices, which may provide a cryogenic environment in the wide temperature range of 50 to 100K and serve as a liquid dielectric. In this paper, the gas-liquid-solid phase equilibrium, boiling heat transfer and insulation characteristics of the LN2/CF4 mixture were discussed firstly, and then its applications in the fields of superconducting electrical technology, such as superconducting energy pipeline, superconducting fault current limiter, superconducting reactor/magnetic energy storage, and superconducting magnetic resonance instrument are presented with an emphasis focused on their electromagnetic characteristics and thermal stability compared with those devices cooled by other means.
Speaker: Qingquan Qiu -
347
Numerical investigation on the dispersion characteristics of cryogenic helium vapor cloud in confined space
Helium cryogenic system has been widely used in large-scale scientific engineering fields utilizing superconducting technology, such as nuclear fusion, high-energy accelerator, and high-energy particle detector. Once suffering from vacuum insulation failure, magnet quenching, material defect, mechanical fatigue, external impact, electrical joint failure, etc., the protective devices and key components of helium cryogenic system could rupture and fail. The cryogenic helium will then leak into surrounding environment, posing severe threat to the safety of personnel, equipment, and building. Previous studies mainly evaluated the potential hazards of extremely low temperature, hypoxia, and overpressure induced by the accidental leakage of cryogenic helium into confined space from macroscopic perspective, while rarely focused on the dispersion characteristics of cryogenic helium vapor cloud in confined space. In the present work, CFD numerical model predicting the leakage and dispersion of cryogenic helium in confined space is developed firstly. Then, the spread and evolution laws of cryogenic helium cloud, the helium concentration distribution characteristics, and the cloud turbulent disturbance characteristics are investigated from microscopic perspective. The work provides guidance for the prediction and safe protection of the leakage and dispersion of cryogenic helium in confined space, which helps to improve the safety of helium cryogenic system further.
Speaker: Yuanliang Liu (Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences) -
348
Safety at HL-LHC IT String during construction, commissioning, and operation
The HL-LHC IT String, a test facility for the major components of the HL-LHC Inner Triplet, is currently in its construction and commissioning phases in a surface building at CERN. The primary motivation of the HL-LHC IT String is to study and validate the collective behavior of its different subsystems which include mainly: the inner triplet superconducting magnets and their correctors, a novel superconducting link, the cryogenics infrastructure for the cooling and quench recovery, the powering and quench protection systems, and the remote alignment system.
Over the past two years, the HL-LHC IT string project has made progress in the installation of general infrastructure and hardware components. It has initiated a series of individual system tests focused on the powering systems and the cryogenic supply infrastructure. By the year 2025, the following objectives are foreseen: gradually and securely finalize the hardware installation and perform the required individual system tests of the warm and cold powering systems in preparation of the HL-LHC IT String Validation Program due to start in the second half of 2025. This program aims at fully validating the collective behavior and performance of the HL-LHC IT region before installation in the LHC tunnel.
The HL-LHC IT String is a multi-disciplinary project that integrates novel superconducting technologies and requires the contribution of multiple stakeholders. Throughout the construction and commissioning It involves a significant number of co-activities that must be safely managed, considering the safety and operational requirements of neighboring testing facilities located in the same buiding. During its operation, multiple failure modes can occur for which a detailed risk assessment has been conducted to address and mitigate them.
The safety aspects of the HL-LHC IT String are of key importance and have been duly addressed. In this paper we will first introduce the HL-LHC IT String facility. Subsequently we will then focus on methodologies employed for safety assessments and explore how safety measures are implemented during the different phases of design, construction, commissioning, and operation of the cryogenic and superconducting systems.Speaker: Davide Bozzini (CERN) -
349
Vaporization of cryogenic liquid stored in damaged vacuum-insulated tank
Abstract
Vacuum insulation is commonly used in cryogenic liquid storage, in the ground applications, because of its excellent insulation performance. However, the accidental loss of insulating vacuum might result in significant boil-off of the stored liquid. The loss of the stored liquid through boil-off not only impacts energy efficiency but also poses a serious safety concern. The hazards associated with the storage of cryogenic liquids must be thoroughly considered to protect humans, assets, and the environment. Quantitative risk assessment (QRA) is an essential tool for evaluating the risks. As a critical step in QRA, the consequence estimation process requires the evaluation of the boil-off rate of the liquid in the case of vacuum failure to analyze incident outcomes. In this study, the boil-off rate of liquid nitrogen stored in a double-walled vacuum insulated tank in the case of vacuum loss was numerically and experimentally investigated. Heat sources for the liquid boil-off included solar radiation and convection from the ambient air. A numerical model was developed to take into account all heat transfer phenomena between the liquid and the surroundings. Significantly, the convection of air in the gap between the inner and outer tank walls was carefully considered. Besides, a physical model was built and experiments were conducted for both intact and damaged vacuum insulation cases. The surface temperature of the outer tank wall and the boil-off rate of the liquid were measured. The model proved its excellent accuracy through the validation against the experimental data. Significantly, it was observed that the boil-off rate decreased approximately linearly over time. The findings of this study are expected to enhance the understanding of the boil-off behavior of cryogenic liquids in the case of the failure of vacuum insulation and also provide an efficient numerical tool for analyzing the incident outcomes for consequence estimation as a part of QRA.Keywords: Cryogenic liquid; storage; vacuum insulation; boil-off; quantitative risk assessment.
Acknowledgments
This research was supported by a research program funded by the Ministry of Trade, Industry and Energy of the Republic of Korea and Korea Institute of Energy Technology Evaluation and Planning (Grant number: 20215810100020).Speaker: Le-Duy Nguyen (Korea Institute of Machinery and Materials)
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337
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Thu-Po-3.3: Large Scale Cryogenic Systems 6 Poster area
Poster area
Convener: Benjamin Bradu (CERN)-
350
Analysis and optimization of helium liquification process utilizing the turbo Brayton refrigerator as the pre-cooling stage
A helium liquefication process utilizing a turbine Brayton refrigerator instead of liquid nitrogen is proposed as the pre-cooling stage, and a thermodynamic system cycle flow is built up. Turbine Brayton refrigeration has the advantages of high efficiency, low maintenance costs, contact-free, and low noise. The closed-cycle Turbine Brayton refrigerator applied in the pre-cooling stage of helium liquefiers, the liquefication can avoid the continuous supply of liquid nitrogen and improve the adaptability of helium liquefiers. More importantly, we can adjust the motor’s speed to match the load and operating conditions. We utilize genetic algorithms for component optimization and conduct thermodynamic research on the system under design conditions. The results indicate that the proposed system has better cyclic performance and can provide a reference and basis for practical engineering applications.
Speakers: Jin Zhen Wang (Technical Institute of Physics and Chemistry, CAS), Jihao Wu (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
351
Application, development and future of helium compressor in large-scale cryogenic engineering
Liquefaction or refrigeration cycle with helium as working medium was the main thermodynamic process in large-scale cryogenic engineering. In the process of realizing thermodynamic cycle, helium compressor and expander were two core moving parts, which play the roles of providing power and expanding refrigeration respectively. Helium compressor had experienced the evolution process of piston and screw in helium liquefaction technology. Oil-injection screw compressor skillfully used the sealing effect and atomization cooling effect of oil film to solve the technical problems caused by easy leakage of small molecular weight gas and high compression heat of helium gas respectively. In order to improve the compression efficiency of helium gas, the profile of screw rotor was continuously optimized according to different working conditions and developed into the latest asymmetric streamline. The new processing and manufacturing technology also played a great supporting role in the realization of the new rotor profiles. In order to cooperate with the application of oil injection screw compressor, oil-gas separation and ppb high-precision oil removal technology had also made progress. With the accumulation of running time, it was difficult to avoid the accumulation of oil in low-temperature components, which would lead to engineering accidents. In order to completely solve the ultimate problem of oil pollution, centrifugal compression technology based on magnetic bearing would also expected to become the future development trend.
Keywords: Helium; Compressor; Cryogenic engineering; Screw; Centrifugal compressorSpeakers: Jingyu Li (University of Chinese Academy of Sciences, Beijing 100049, China), zhongjun Hu (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China) -
352
Automated operation modes for the ESS cryogenic moderator system
The European Spallation Source (ESS) will provide long-pulsed cold and thermal neutron fluxes at exceptionally high brightness. Spallation neutrons generated at a rotating tungsten target are transformed into lower-energy cold and thermal neutrons through a thermal water pre-moderator and two liquid hydrogen moderators, which was designed to optimize the brightness of the cold neutron beams for scientific experiments, meeting the requirement of a parahydrogen fraction exceeding 99.5%. Upon injection of the proton beam, a rapid liquid hydrogen temperature rise occurs due to nuclear heating, which is estimated to be 6.7 kW for the proton beam power of 5 MW. The temperature rise propagates downstream of the moderator and induces pressure fluctuations. The cryogenic moderator system (CMS) was designed to supply subcooled liquid hydrogen at 17 K and a parahydrogen concentration of over 99.5% at a flow rate of 0.5 kg/s, to satisfy the moderator requirements. An ortho-para hydrogen catalyst vessel is placed into the loop and an in-situ ortho-to-parahydrogen fraction measurement system have been integrated. Pressure fluctuations caused by abrupt nuclear heating are mitigated by a pressure control buffer with a volume of 65 liters, while the CMS pressure is adjusted by recondensing vapor in the buffer tank through another small heat exchanger. The heat load is removed through a plate fin heat exchanger by a large-scale 20 K helium refrigerator with a cooling capacity of 30.2 kW at 15 K, referred to as the Target Moderator Cryoplant (TMCP).
An automated operation control system for the CMS has been developed, featuring seven operational modes: cooldown mode, steady-state mode, energy-save mode, beam injection mode, warm-up mode, quick warm-up mode and ortho-to-parahydrogen measurement mode. The CMS cooldown process was divided into three phases (vapor state, condensation state, and liquid state). The operational procedures and parameters were optimized based on CMS cooldown simulations and TMCP commissioning results. The cool down operation mode is expected to be completed within 27 hours before transitioning to the steady-state or energy-save mode.
During proton beam operation, the beam injection mode mitigates the pressure fluctuations resulting from beam injection or trip while providing thermal compensation for the nuclear heating using a TMCP valve box and a heater in the CMS. The warm-up mode is also divided into three modes, similar to the cooldown mode. CMS temperature is increased to 40 K by adjusting the feed helium temperature of the TMCP, while one of the two cold turbines is in operation. Moreover, the quick warm-up mode aiming to release liquid hydrogen within 10 minutes is integrated. The CMS installation was completed in February 2024. Preliminary CMS commissioning, excluding the moderators, is currently underway using nitrogen and helium. Hydrogen operation for the CMS is scheduled to start Q3 2024. The automated operational control system will have been completed by the beam-on-target.Speaker: Attila Zsigmond Horváth (European Spallation Source) -
353
Design of a 10 ton/day air liquefaction system for liquid air energy storage
To achieve carbon neutrality, the contribution of renewable energy to electricity generation is growing. However, renewable energy sources may exhibit significant output fluctuations depending on weather conditions. As a result, there is a gradual rise in demand for high-capacity energy storage systems to ensure grid stability. The Liquid Air Energy Storage (LAES) system is an energy storage system that liquefies air using surplus electricity for storage and then, when power is needed, pressurizes and vaporizes the liquid air to generate electricity through power turbines. The energy storage by liquid air at ambient pressure is safe and echo-friendly. It enables a large amount of energy to be stored. In this study, a 10 ton/day air liquefaction system was designed as a pilot plant for liquid air energy storage. It is based on the Claude cycle with some variations for air liquefaction. A cold stream, which utilizes cold thermal energy recovered during a power generation process, is added to the cycle. The cold stream also branches out to improve cycle efficiency. The basic and detailed designs were performed for the cycle. Additionally, a cold box was designed for the liquefaction system. The design results, such as the process flow, system configurations, and details for the cold box, are presented and discussed in this study.
Acknowledgment
This research was supported by a grant of the Basic Research Program funded by the Korea Institute of Machinery and Materials (grant number : NK249E).Speaker: Sehwan In (Korea Institute of Machinery and Materials) -
354
Design of cold box for air liquefaction with capacity of 10 ton/day
The cold box for the cryogenic liquefaction process of the liquid air energy storage (LAES) device is a facility that produces cryogenic liquid air by introducing gas at high pressure/room temperature. Inside the cold box, various devices such as heat exchangers, cryogenic valves, filters, expansion turbines, and phase separators are installed, and each component must be optimally designed for high efficiency operation. Especially, expansion turbines are high speed rotating machines and require components such as filters and expansion joints to prevent mechanical damages. The various internal components of cold boxes are connected by process piping, and the cold box piping system must have sufficient structural strength to withstand high pressure and minimizes pressure loss of working fluid, as well as considering thermal deformation of the piping system due to cool-down operation. In this study, thermal and structural analysis were performed to design a process piping system for the cold box with a liquefaction capacity of 10 tons/day. Through analysis, the structural robustness of the pipe as well as the force / moment acting on the nozzle of the heat exchanger and the pipe support were evaluated. Additionally, pressure losses in the pipe were evaluated. Finally the detailed design of a cold box for the LAES was completed.
Acknowledgment : This work was supported by a grant of the Basic Research Program funded by the Korea Institute of Machinery and Materials (grant number : NK249E).
Speaker: Yong-Ju Hong -
355
Development of a Hardware-In-the-Loop (HIL) simulation system for a 3000L/h helium liquefier
ABSTRACT: A 3000L/h Helium Liquefier has been designed and is being assembled in China by the Technical Institute of Physics and Chemistry, CAS. A dynamic simulation of this helium liquefier has been performed to evaluate the heat transient performance. To verify the control system program before the commissioning of this liquefier, a Hardware-In-the-Loop (HIL) Simulation System has been developed. This HIL simulation system consists of three parts, namely, simulation model of this helium liquefier performed by EcosimPro, NI Veristand to deploy the encapsulated simulation model, a real PLC control system to run control program and human machine interface. Control signals from real PLC and process parameters from simulation model have been interchanged between PLC hardware and simulation model through NI inputs and outputs hardware. The performance of this HIL simulation system proves that this HILS improves and verifies the control system design and will reduce the time for system commissioning on site.
Speakers: Gang Zhou (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences), Jing Li (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
356
Development of Cold Box for Upgradable Helium Refrigerator Plant of 200W at 4.5 K
The cold box for helium refrigerator plant of cooling power ~200 W at 4.5 K is being developed at IPR, Gandhinagar, India. Helium compressor system, which gives helium flow ~60 g/s at 14 bar will be used for this plant. The cold box of the plant is made using a vertical vacuum chamber, within which all cold components are assembled. The thermodynamic process used is a modified Claude Cycle. This cold box has 7 plate-fin heat exchangers, 3 turbo-expanders, an 80 K helium purifier and a JT valve. All 3 turbines are of aerodynamic bearing with eddy-current brake type and these are fitted vertically at the top dish end of the vacuum chamber. All seven plate-fin heat exchangers are made using serrated fins of Al-alloy and are vacuum-brazed. LN2 pre-cooling is used to ensure 80 K before the helium purifier. Turbine-1 and 2 are warmer ones and are connected hydraulically in series and helium outlet from turbine-2 is connected to the low pressure line of the cycle. The 3rd turbine is colder one and is in series with JT valve. Later, based on the detailed process analysis and optimization, it is found that if only 7th heat exchanger, the coldest one, is replaced by a higher capacity, cooling power of the plant can be improved significantly. Hence, provision has been kept for future up-gradation to a plant of higher capacity. Appropriate provisions to upgrade the plant from only-refrigerator to refrigerator-cum-liquefier and for LHe extraction have been included. This refrigerator plant has been designed to handle high air impurity up to ~500 PPM. The component and piping layout within the cold box has been done considering thermal, structural and hydraulic aspects for different operations and future up-gradations. The architecture of this layout has been developed and implemented indigenously. Sufficient instruments and data acquisition have been included to diagnose troubles easily, as, such helium plant is being made at IPR 1st time. Details of the design concept of the cold box and experiences of initial operations will be discussed in this paper.
Speaker: Ananta Sahu (Institute for Plasma Research) -
357
Efficiency increase of cryoplants by retrofitting with state-of-the-art turbine technology
Linde Kryotechnik AG is known as a supplier of high quality products in the field of cryogenics. This results in the fact, that still many users are operating helium liquefaction and refrigeration systems that are 30 years and older. Technology has developed and the efficiencies of todays cryogenic plants have increased. Instead of replacing the entire cryogenic plant an upgrade of only dedicated components might be already a benefit and does not involve too high cost.
The most effective method to increase efficiency and consequently improve performance by considering the restrictions of space and accessibility is the use of state-of-the-art turbines.
The new approach presented here combines existing infrastructure with state-of-the-art turbine technology by means of a special adapter. The adapter allows a modification of the turbines without the need to change the inner design of the cold box.
The turbine adapter technology can be used for liquefiers and refrigerators as well as different process mediums like helium or hydrogen.Speaker: Marco Muehlegger (Linde Kryotechnik AG) -
358
Integrated design of an 18kW@4.5K/4kW@2K helium cryogenic refrigeration system for CiADS
Large cryogenic refrigeration systems are the only means to achieve a low-temperature environment for large scientific devices. As an important part of the China Initiative Accelerator Driven System (CiADS), an 18kW@4.5K/4kW@2K large helium cryogenic refrigerator is mainly used to cool down superconducting magnetic cryostats. It has been designed by Technical Institute of Physics and Chemistry, Chinese Academy of Sciences at the end of last year in 2023. This is the largest self-developed helium cryogenic refrigerator in China. This paper gives an overview on the performance characteristics and working principle of the 18kW@4.5K/4kW@2K large helium cryogenic system. And introduces the integrated design of this helium cryogenic refrigerator. And now the overall engineering layout design of it based on the experimental building in Zhongshan Institute of Advanced Cryogenic Technology has been completed. The design result has been used to guideline the engineering and manufacturing phase. Its commissioning tests will be carried out and completed at the end of this year.
Speakers: Shaoqi Yang (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences), Xiujuan Xie (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
359
LBNF/DUNE nitrogen refrigeration system update
The Deep Underground Neutrino Experiment (DUNE) is supported by the infrastructure of the Long Baseline Neutrino Facility (LBNF). The central feature of DUNE is the liquid argon filled cryostats, which house the neutrino detector components. In order to maintain the argon in a liquid state, heat must be continuously removed. Argon condensers will remove this heat, and liquefy the argon, through the evaporation of liquid nitrogen. The supply of liquid nitrogen relies heavily on a near-industrial scale nitrogen refrigeration/liquefaction system. The nitrogen system will be a closed loop, in which the liquid nitrogen is supplied to users and, after being vaporized, is recycled to the nitrogen liquefaction units to be liquefied again. The system will also include nitrogen generation, to increase inventory in the closed loop, as well as to make up for losses. All of this will be installed nearly one mile underground (1.5km) on the 4850 level of the Sanford Underground Research Facility (SURF). The final DUNE vision requires 400kW of liquid nitrogen cooling capacity. Based on the operation modes and phased installation of the experiment, modularity of this cooling capacity is required. Nitrogen liquefaction will occur in four units which will afford a wide operational range of production (nominally 100kW each). Due to the experiment’s location deep underground in an inactive gold mine, there are unique and challenging constraints. These include limited access, footprint, and utilities. This contribution will provide a description of the engineering effort, an overview of the refrigeration system, and how the constraints are being addressed. The design includes a unique compressor arrangement which will be covered in detail. Pictures and models will be included where possible to help visualize the system, and how the constraints referenced above were managed.
Speaker: Markus Graf (Fermilab) -
360
MITICA Cryoplant
Authors: G Kouzmenko1, J D Dupuy1, N. Besse3, L.Perrot3, M. Valente2
Coauthors: J. Beauvisage3, JM. Bernhardt3, M. Bigi2, P. Bravais3 ,R. Capobianco2, P. Dauguet3, Y. Fabre3, D. Faisandier3, O. Fraisse3, J. Legrand3, A. Luchetta2, A. Machefel3, E. Mardani3, C. Urban3.1Fusion for Energy, C/ Josep Pla 2, Torres Diagonal Litoral, 08019 Barcelona, Spain
2Consorzio RFX, Corso Stati Uniti, 4 – 35127 Padova (Italy)
3Air Liquide Advanced Technologies, 2, rue de Clémencière, BP 15, 38360 Sassenage, FranceGrigory.Kouzmenko@f4e.europa.eu
Jose.Dupuy@f4e.europa.euAbstract. The ITER Neutral Beam Test Facility (NBTF), called PRIMA (Padova Research on ITER Megavolt Accelerator), is hosted in Padova, Italy and includes the MITICA experiment – a full-scale prototype of the ITER heating neutral beam injector (HNB). The large cryopump is intended to absorb the gas used to neutralize the high energy beams of the MITICA experiment. The cryopump is cooled by a dedicated cryoplant based on a Helial refrigerator by Air Liquide Advanced Technologies. The plant delivers up to 800 W of cooling power at 4.5 K. A specifically designed Auxiliary Cold Box (ACB) is capable to provide a He flow of 220 g/s at 81K & 40 g/s at 4.6K to the thermal shields and the cryosorption panels respectively. This cryoplant has a high grade of versatility needed to cope with the highly variable heat loads as well as with the different modes of operation.
This paper presents the design of the cryoplant and highlights the various stages of the installation, commissioning and final acceptance tests.
Speakers: Grigory Kouzmenko (F4E), Jose Daniel Dupuy Exposito -
361
nEXO Underground LN2 Plant at SNOLAB
nEXO is a tonne scale neutrinoless double beta decay experiment which will use 5,000 kg of Xenon-136 as its target fluid. nEXO will need to cool the liquid xenon (LXe) down to 165 K (-108.15 °C) for ten years of continuous operation. nEXO will be located at SNOLAB, in its facility 2 km underground in Vale’s Creighton nickel mine.
A 12,000-litre liquid nitrogen (LN2) plant will be required for maintaining the experiment temperature +/-0.1 K over ten years of operation. nEXO also requires a LXe recovery system, which needs a large volume of bulk cooling to be able to condense the LXe exterior to the detector.
SNOLAB’s underground environment imposes severe spatial limitations, and designing an efficient LN2 plant within these confines requires creative solutions. Compactness becomes paramount, necessitating detailed layouts that maximize every square meter.
Maintaining the LN2 plant requires robust cooling power, the system must handle the experiment’s transient heat load generated during: (1) condensation of GN2 to LN2, (2) the cooling the hydrofluoroether (HFE), and (3) condensation of GXe to LXe into the experiment’s central volume. The plant design of 8 kW cooling capacity ensures sufficient margin during phase changes and losses in the system.
The system will circulate LN2 to two heat exchangers: one for LXe and one for the HFE. The HFE is used to maintain a stable temperature within the experiment’s inner volume while being surrounded by a vacuum space in the outer vessel to maintain the HFE temperature.
nEXO requires high-purity LN2; the nitrogen plant will provide 99.999% pure nitrogen. Maintaining this purity throughout the system is essential for experiment background considerations. Any impurities could affect data integrity and compromise the scientific goals of the experiment. Rigorous quality control testing will ensure that the LN2 meets stringent purity standards.
Operating a LN2 plant underground provides usual safety concerns a unique twist. Ventilation systems must accommodate large volumes of boil-off nitrogen gas, which could displace breathable air. A safety challenge lies in ensuring efficient gas dispersion and supplying sufficient makeup air. In an underground environment, Oxygen Deficiency Hazards are of critical importance. Therefore, designing fail-safes to prevent accidental exposure to LN2/GN2 are always the highest priority.
SNOLAB is a global leader in low background astroparticle physics research and underground science. Having a dedicated LN2 plant located in the underground facility to supply nEXO’s cooling needs without interruption shows SNOLAB’s commitment to support world class science.
Speaker: Tristan Hillier (SNOLAB) -
362
PRELIMINARY design of a new Helium liquefaction system at LBL
A new high efficient helium liquefaction system with high capacity is under design and will be built at Lawrence Berkeley National Laboratory in the next couple of years to replace a current 43 years old liquefier. The new liquefaction system will provide at least a mixed 80 liter per hour liquefaction rate and 35 W refrigeration capacity at 4.5K without liquid nitrogen pre-cooling, or a mixed 140 liter per hour liquefaction rate and 35 W refrigeration capacity at 4.5 K with liquid nitrogen pre-cooling. It can be operated mainly at two modes, liquefaction mode and liquefaction/refrigeration mixing mode. As a core element, the new liquefaction system will significantly improve the capability and efficiency of the magnet testing system at LBL in developing and testing novel magnet configurations. The system shall be designed and built with the capability to be further expanded to 1.8 K to 2 K by adopting a warm pumping system, as well as to furthermore enable future integration of helium recovery and purification capability. The new liquefaction system will be critical to deliver on LBL’s commitments to the US Magnet Development Program (MDP) and to support the High Energy Physics (HEP) Program at LBL. This paper describes the preliminary design of the new LBL’s liquefaction system including its performance, operation modes, functional analysis, main components, layout plan and piping route and so on.
Speaker: Li Wang (Lawrence Berkeley National Lab) -
363
Proven cryogenic solutions for large power under 4.5K by ALAT
Since the end of the last decade, projects requiring a high refrigeration power below 4.5K are flourishing around the world. This increase in refrigeration capacities at temperatures close to 2K represents a real challenge for cryogenic plants design and operation. In a few years Air Liquide Advanced Technologies supported customers in not less than six major new projects ranging from 900W up to 4.2kW power at 2K. The particular operation of the 2K cavities necessitates a high flexibility in terms of operation range but also a high reliability cryogenic plant to ensure smooth and long term operation. Therefore during conceptual phases, one of the key factors is the right selection of the process scheme to optimize the proposed solution.
The aim of this paper is to present the advantage of the selected solutions and to give an overview of the critical design aspects focusing on the last references.Speakers: Jean-Marc Bernhardt (Auteur), Nicolas chantant, Pascale Dauguet (Auteur), Yannick Fabre (Auteur) -
364
System integration and commissioning of helium liquefier
With the development of science and technology, the application of cryogenic technology is more and more extensive. Liquid helium, as one of the cryogenic liquid, is popular in many fields. The acquisition of liquid helium may be of interest to many people. Therefore, system integration and commissioning of helium liquefier are introduced in this paper. In order to meet the conditions of helium liquefaction, the integrated process of helium liquefier was investigated. According to the studied Integrated process, a helium liquefier was built. And then the commissioning of helium liquefier was presented. The test results are shown that the liquefier meets the design requirements.
Speaker: Bingming Wang -
365
The Failure Analysis of the Turbine for Helium Cryogenic System at Taiwan Light Source
There are two helium cryogenic system with maximum 450W cooling capacity, which were installed for five superconducting magnets and one superconducting RF cavity at Taiwan Light Source (TLS). One of these two helium cryogenic system was shut down due to the failure of first stage turbine, as called as T1. The T1 was replaced twice and failure just in the beginning with the attempt to produce liquid helium. Most of the failures for the turbine were caused by gas purity or material fatigue. The major reason for our case may not only cause by the above reasons, since the analyzer shows good purity of the helium gas. There’s one auxiliary component may introduce the damage of the T1, because of the relevant parameters indicated the abnormal phenomena before T1 damage. This paper was aimed to present the study of the failure of T1 and the relevant operation parameters. The test of the auxiliary component of T1 was also presented and discussed.
Speaker: Huang-Hsiu Tsai (National Synchrotron Radiation Research Center) -
366
The influence of the UA ratio between heat exchangers on the temperature distribution
In the design of large scale helium refrigerators, it has been found that the UA ratio between the heat exchangers will influence the temperature distribution, which will be required in some special applications, such as the temperature before the expansion or some set temperatures. In this paper, a 2000W@20K helium refrigerator without Nitrogen precooling is described, which need a 70K temperature for cooling the radiation shields and a 20K temperature for cooling the heat load. The calculation showed the relationship between the UA ratios and the temperature between the heat exchangers, which proposes some requirements to the design and produce the heat exchangers.
Speaker: Gang Zhou (Techincal Institute of Physics and Chemistry, CAS)
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350
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Thu-Po-3.4: Thermal Properties Poster area
Poster area
Convener: Maciej Chorowski-
367
A GUI Based Property Package for Thermo-physical Properties of Cryogenic Fluids
Thermo-physical and transport properties of fluids at cryogenic temperature deviate significantly from their room temperature properties. The cryogenic fluid properties like density, specific heat, thermal conductivity, viscosity, etc. show non-linear behavior at supercritical regions. Hydrogen, Helium, and Neon being a quantum fluid do not follow the laws of corresponding states and require special attention. The developed correlations are based on the experimental data, which is scarce and limited to certain pressure and temperature ranges. Most of the time, one must rely on commercial property packages like REFPROP®, GASPACK®, HEPAK®, etc. for accurate cryogenic fluid properties. These property packages use various correlations, which provide accurate fluid properties at different ranges of pressure and temperatures e.g. helium properties up to 2.17 K are available in REFPROP [1], the most reliable data source based on the NIST database. CoolProp [2], an open-source property package, is widely used to obtain cryogenic fluid properties during process simulations performed on non-commercial platforms e.g. DWSIM etc. However, in a few cases, these property packages don’t provide transport properties e.g. thermal conductivity, viscosity, etc. for certain fluids e.g. p-Hydrogen, Deuterium, Neon, etc. and thermal conductivity data for n-Hydrogen shows the inaccuracy of ~ 20 % in the temperature range of 15 K to 30 K.
Therefore, there is a need for a cryogenic property package that is robust, accurate, and applicable over a wide range of temperatures and pressures. A new property package “CryoProp” has been developed on the Python platform for cryogenic fluids and inaccuracy in thermal conductivity data is improved to 2-4 % in the temperature range of 15 K to 30 K. A Graphical User Interface (GUI) has also been developed to use the “CryoProp conveniently”.
The poster will summarize the approach for developing a fluid property package and highlight its limitations. A comparison of the property data obtained with the standard database is also represented, which shows a good agreement.Speakers: Hitensinh Vaghela, Nitin Shah, Parthasarathi Ghosh -
368
Cryogenic contact resistance and material conductivities in astronomic instrumentation: an experimental characterization.
Astronomic instrumentation requires working at cryogenic temperatures and a high stability. It is crucial to understand the properties of materials and contacts among components within the cryostat to be able to achieve the thermal goals in astronomical applications.
To enhance instrument cold structure designs, there's a growing need to perform accurate Finite Element Method (FEM) analyses. Consequently, we conducted an experimental investigation to understand the properties of materials which we frequently employ in astronomical instrumentation at “Instituto de Astrofísica de Canarias“ (IAC). The data will be used as an input to our Finite Element Models in order to minimize uncertainties.
This paper presents an experimental study focused on cryogenic contact resistance and material conductivities vital for the advancement of astronomical instrumentation. The investigation is focused on the characterization of contact resistance and conductive properties at low temperatures, specifically for Copper, Stainless Steel and Aluminum (for conduction), and Nylon and PTFE (for insulation).
Through in site experimentation, we explore the behavior of materials under cryogenic conditions, providing valuable knowledge for optimizing the performance and reliability of astronomical devices and the way of designing contacts inside a cryostat.
Speakers: Antonio Zamora-Jiménez (INSTITUTO DE ASTROFÍSICA DE CANARIAS), Eduardo David González-Carretero (INSTITUTO DE ASTROFÍSICA DE CANARIAS), Haroldo Lorenzo-Hernández (INSTITUTO DE ASTROFÍSICA DE CANARIAS) -
369
Cryogenic emissivity testing apparatus for insulating materials cooled by a cryocooler
The emissivity of low-temperature materials exhibits variations with changes in temperature. Currently, measuring low-temperature emissivity often includes the use of cryogenic liquids like liquid nitrogen and liquid helium, which presents challenges such as handling inconvenience and limited adaptability to a broad temperature range. Furthermore, materials like aluminum-coated polyester films exhibit surface emissivity levels lower by several orders of magnitude compared to materials like copper and stainless steel, presenting significant challenges in achieving high-precision measurements. In this study, a low-temperature emissivity testing apparatus based on a pulse tube cryocooler has been developed. The measurement temperature range extends from 50 K to room temperature, and with the option to change the cryocooler, measurements at even lower temperatures, such as 4 K to room temperature, can be achieved. The measurement principles and crucial structural elements of the developed testing apparatus, specifically designed for low emissivity samples, will be introduced. Additionally, experimental measurement results for various samples at different temperatures will also be presented.
Speaker: Liubiao Chen -
370
Development of a Machine Learning-Based Model for Cryogenic Film Boiling Flow Pattern Prediction During Transfer Line Chill-Down Operation
The transfer of vapor-free liquid cryogen through fluid systems in low-temperature applications demands achieving thermal equilibrium between the channel wall and the flowing liquid. This transient cool-down phase, known as transfer line chill-down, poses challenges due to associated complex two-phase heat and mass transfer phenomenon. Accurate modelling of the same is necessary for optimizing cryogen usage during this phase as well as to make sure the safety of the system from severe fluid transients.
The traditional approach in predicting cryogenic flow film boiling heat transfer has relied heavily on empirical and semi-empirical correlations, which are often limited in their ability to capture the intricate non-linearities inherent in heat transfer phenomena during flow boiling. Machine learning presents a promising alternative by offering the capability to decipher complex relationships among fluid flow parameters and heat transfer. This allows for the accurate calculation of wall-fluid heat transfer coefficients, a critical aspect in optimizing cryogenic transfer line operations. Despite the success of artificial neural networks in conventional flow boiling scenarios, there exists an unexplored realm in cryogenic feed line chill-down boiling.
Available research findings have indicated that film boiling is prevalent during most of the feed line quenching process, underscoring the pivotal role of an appropriate constitutive model for the same in ensuring the accuracy of numerical models for chill-down. This study aims to pioneer a machine learning-based model tailored for chill-down film boiling heat transfer prediction. The film boiling regime in chill-down exhibits various flow patterns, including Inverted Annular Film Boiling (IAFB), Inverted Slug Film Boiling (ISFB), and Dispersed Flow Film Boiling (DFFB). Hence, one of the critical aspects in numerically solving the conjugate heat transfer during cryogenic quench flow boiling is the identification of the prevailing flow pattern and then to use appropriate wall-fluid heat transfer correlation. Building upon prior empirical correlations developed by the Cryogenic Engineering Centre IIT Kharagpur, this study explores the potential of machine learning to autonomously identify specific flow patterns during cryogenic flow film boiling, potentially involving classification problems.
Initially, an Artificial Neural Network (ANN) was selected for analysis. Following a preliminary dataset-cleaning process, various feature selection methods were employed, including Mutual Information, Maximal Information Coefficient, Principal Component Analysis (PCA), correlation matrix visualization, and decision trees. Notably, the outputs from Mutual Information and Maximal Information Coefficient exhibited consistent performance. Consequently, the ANN model training commenced utilizing features selected through these methods. The architecture comprised 15 input nodes, one hidden layer with 8 nodes utilizing the Rectified Linear Unit (ReLU) activation function, and three output nodes with SoftMax activation. This configuration yielded a training accuracy of 94.48% and a testing accuracy of 48.33%. Attempts to enhance the model by adjusting the number of hidden layers and nodes did not improve the results. Further iterations involved dataset modifications and strategies to mitigate overfitting, resulting in improved training accuracy of 97.64% and a testing accuracy of 97.79%. Subsequent attribute analysis revealed three non-significant parameters, leading to their removal and achieving a training accuracy of 95.74% and a testing accuracy of 98.51%. Subsequently, a non-dimensional dataset approach was explored, undergoing similar preprocessing steps and feature selection. Various architecture configurations were tested, with the optimal setup comprising two hidden layers with 32 and 64 nodes, respectively, resulting in a peak accuracy of 90.25%. The dataset was also utilized to train a Support Vector Machine (SVM) model using the same 15 input features as in ANN model. Basic hyperparameter tuning through GridSearchCV yielded a test accuracy of 79%.
In conclusion, this research contributes to understanding of cryogenic feed line chill-down phenomena and establishes a foundation for accurate numerical modelling based on machine learning. This study proposes an optimization tool for cryogenic transfer line operations, impacting various applications such as space technologies, LNG transport, clean energy systems, food processing, and cryosurgery. The promising results thus far indicate the potential for machine learning to revolutionize our ability to predict and optimize heat transfer in cryogenic systems.Speaker: Parthasarathi Ghosh (IIT Kharagpur India) -
371
Experimental study of enhanced cryogenic cool-down performance in metal pipe with polymer coating on the inside
Cryogenic fluids such as liquid oxygen, hydrogen and nitrogen are used in rockets and superconducting applications. Boiling heat transfer occurs between the liquid and solid interface during initial cooling from room temperature to cryogenic temperature. Boiling heat transfer performance has a significant impact on the cooling speed. The largest heat flow occurs in nucleate boiling, but has a short range in the cool-down process, while film boiling has a relatively small heat flow due to the vapor film, but has a long range in the cool-down process. Previous research has confirmed that polymer coating on a metal surface increases cooling speed by reducing the film boiling process within pool boiling, but understanding of flow boiling is limited. Flow boiling is a complex effect caused by vapor-liquid flow as well as the liquid-solid interface. Therefore, it is greatly influenced by the pressure, flow rate, and type of two phase flow.
In this paper, liquid nitrogen was used to experimentally analyze the cool-down performance of horizontal stainless steel pipe with polymer coating on the inside according to the coating material, coating thickness, and flow conditions. The polymer coating significantly improved heat transfer efficiency and reduced cool-down time. The proposed pipe with polymer coating on the inside presents a competitive method for accelerating rapid fueling and rapid pipeline cool-down operation for future cryogenic mobility application.*This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT)(No. 2019R1A5A8083201) and the Basic Research Program funded by the Korea institute of Machinery and Materials (grant number : NK237B).
Speaker: Youngjun Choi (Changwon National University, Department of Smart Manufacturing Engineering, Changwon, South Korea) -
372
Heat transfer characteristics analysis of the large-scale cold storage solution based on moving bed
Large-scale cold storage plays a crucial role in future net-zero emission scenarios. It is expected to drive advancements in technologies such as liquid air energy storage (LAES) and liquid nature gas (LNG) cryogenic energy utilization, with promising commercial prospects. To eliminate the use of flammable, explosive, and potentially polluting liquid-phase storage mediums, packed bed cold storage emerges as a promising solution. However, the inclined thermocline effect within the packed bed can compromise the quality of cold energy, leading to reduced efficiency. To address this challenge and develop an efficient, safe, and environmentally friendly cold storage technology, this study proposes a cold storage solution based on the moving bed technology. It utilizes quartz sand as the storage medium and employs gas-solid direct contact heat transfer to increase the heat transfer area and minimize the heat transfer temperature difference. The study establishes a gas-solid coupling heat transfer model and conducts heat transfer analysis, investigating the impact of different design parameters on heat transfer performance. The results highlight the outstanding performance of the moving bed-based cold storage technology, achieving an exergy efficiency of cold storage exceeding 90%, making it a highly competitive large-scale cold storage solution.
Speaker: Xiaoyu Fan (Key Laboratory of Cryogenic Science and Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
373
Model and dynamic simulation of the liquid hydrogen distribution by trailer
Liquid hydrogen (LH2) is gaining attention as a low-carbon energy vector and fuel in the clean energy sector. This has led to a significant growth in the worldwide production and distribution of LH2 in recent years. Today, the distribution of LH2 from the liquefier facility to the user is almost entirely performed by road trailers. In the future, the LH2 distribution via rail cars, the transport on ships, and the usage as fuel in heavy duty mobility will become more important. LH2 transfer processes used for filling and unloading of these tanks play a substantial role in the efficiency of the overall LH2 distribution chain. To minimize the losses in today’s LH2 supply chain, as well as for efficient transfer operations in emerging LH2 systems, it is essential to understand the thermodynamic processes occurring in the tanks. Studying the current LH2 distribution by trailer enables the development of models that can support the planning of an efficient future LH2 infrastructure.
In this work, the LH2 distribution by trailer is explained and the different process steps occurring are defined. In the ullage of the LH2 trailer gaseous hydrogen is present above the loaded liquid. During the different process steps, depending on the magnitude of the phase transition, vapor-liquid equilibrium can be reached between the phases, or non-equilibrium can be induced whereupon superheated gas is present above subcooled liquid. The work shows the significant influence that this phase transition has on the efficiency of the process steps in the LH2 distribution chain. In the study, a thermodynamic model is developed using MATLAB with thermodynamic property data from REFPROP. With the model, a generic LH2 trailer route is simulated and the influence of the phase transition is investigated. The study suggests ways to minimize losses in the LH2 distribution chain by purposely adjusting the phase transition to target vapor-liquid equilibrium or non-equilibrium in the LH2 trailer.Speaker: Christian Wolf (Linde GmbH, Clean Energy Technology R&D, Pullach/Germany; Technical University of Munich, TUM School of Engineering and Design, Department of Energy and Process Engineering, Institute of Plant and Process Technology) -
374
Modelling heat ingress in LH2 containment systems – benchmarking improved thermal resistance network models against the finite element method
Hydrogen is projected to play an important role in the decarbonization of industries that are not readily electrifiable, such as aviation, shipping, and high-energy process industries [1]. To this end, effective solutions for hydrogen transport and storage are needed at a scale far exceeding current capacity. As the hydrogen value chain expands, a wide range of computational modelling tools are required to ensure that the deployed technology is satisfactory in terms of thermo-dynamic efficiency, economic profitability, and safety. In the present work, we discuss and compare two modelling tools designed to predict heat ingress and boil-off generation in liquid hydrogen containment systems.
In the first tool, the finite element method (FEM) is used to solve the steady heat equation on a tetrahedral mesh that accurately represents the geometry of the containment system. This tool, which we have implemented using the open-source NGSolve library [2], provides high predictive accuracy, but it is also computationally intensive. These characteristics imply that the tool is most suited for detailed assessments of the containment system in isolation, as computational cost is then not a critical concern.
For more comprehensive studies, where several value chain components are considered simultaneously, the computational cost of modelling each component must be kept at a minimum. Then, an alternative to the FEM-based tool is desirable. This motivates the second modelling tool we consider: a state-based thermal network model that exploits the analogy between electrical and thermal conduction [3]. In this model, the various components of the containment system are represented by nodes connected by thermal resistances that are computed, e.g., using exact solutions of the heat equation for simple geometries, such as spherical shells and cylinders. With this approach, some local information about the temperature field within the system is lost, but high-level performance indicators such as total heat ingress can still be predicted with reasonable accuracy.
In this work, we present novel augmentations of the network model that significantly improve the model's predictive accuracy without any adverse increase in model complexity. One such augmentation is a semi-analytic estimate of the temperature field surrounding the cold spot at the intersection between the support structure and the outer tank. We also discuss how to handle geometrically complex support structure components such as a connection between a support skirt and the inner tank. The FEM tool is used to provide empirical error bounds for the network model across a range of material choices and support structure geometries. Based on these bounds, we establish that the augmented network model is sufficiently accurate for use in more comprehensive studies of liquid hydrogen carrier ships, including optimization of ship design and reliquefaction capacity. Results from a case study on 40 000 m3 capacity LH2 tanks – conducted in the LH2 Pioneer project (Research Council of Norway grant 320233) – will be presented in order to demonstrate the efficacy of the modelling tools discussed.
References
[1] IPCC, 2022: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926
[2] J. Schoeberl, C++11 implementation of finite elements in NGSolve, Vienna University of Technology - Institute for Analysis and Scientific Computing, (2014).
[3] A. Majumdar, T. Steadman, J. Maroney, J. Sass, J. Fesmire, Numerical modeling of propellant boil-off in a cryogenic storage tank, in: AIP Conference Proceedings, Vol. 985, American Institute of Physics, (2008), pp. 1507–1514Speaker: Sindre Stenen Blakseth (SINTEF Energy Research / Norwegian University of Science and Technology) -
375
Numerical modelling of cavitation-induced water hammer in cryogenic fluid management systems with finite volume method
A water hammer is a pressure surge that occurs when a liquid in motion within a pipe is suddenly stopped, often due to a rapid closing of the valve or shutting down of the pump. This abrupt change in momentum creates a powerful pressure wave that can cause severe damage to pipes, pumps, and other components and also leads to reduce the efficiency of the components. Whenever the amplitude of the pressure wave reaches below its vapour pressure, it can lead to the rupture of fluid, and a vapour cavity will form and collapse when localized pressure becomes high due to the dynamic nature of the pressure wave. This is known as cavitation during water hammer. Because of the cavitation, an additional pressure is added to the generated wave.
In cryogenic fluids, however, water-hammer becomes even more complex due to its unique and peculiar thermophysical properties at low temperatures. Here, the phenomenon differs due to the 'thermal suppression effect'. This effect occurs because of the reduction in localized vapour pressure during the formation of a vapour bubble that makes cavitation harder. This alters the way the pressure wave behaves compared to water hammer in non-cryogenic fluids. Hence, understanding and predicting the dynamics of the cavitation-induced fluid hammer in cryogenic fluids becomes crucial for optimizing the design and operation of various engineering applications. Numerical modelling is employed to predict and understand this intricate behaviour.
The investigation utilizes a Finite Volume Method (FVM) approach to analyze the water hammer phenomenon. Initially, the model is developed for water, leveraging its well-defined properties and the abundance of existing experimental data. This serves as a baseline for understanding and validating the model. The water model is then adapted to accommodate the unique thermophysical properties of cryogenic fluids, allowing the exploration of the complex behaviour of cavitation-induced water hammer for cryogenic fluids. Finally, the modified model has been validated against available experimental data specific to cryogenic fluids to ensure its accuracy.Keywords: Cryogenics, Cavitation, Numerical modelling, Water Hammer, Thermal suppression.
Speaker: Arjun Garva (Indian Institute of Technology Kharagpur, India) -
376
Research on transient measurement of thermal conductivity of ultra-low temperature frozen soil
This paper designed a detachable cryostat. The cooling capacity is obtained by GM refrigerator and transferred to the test chamber through the copper cold chain. The test chamber is filled with low temperature helium, and the sample is installed in the test chamber. Finally, the temperature of the sample is controlled by adjusting the temperature of the helium atmosphere. The cryostat above has the advantages of flexible sample changing and no need to repeat vacuum pumping, which result in short sample changing time. By recording the temperature change of the plane heat source probe with time, the transient plane heat source method (hotdisk) can measure the thermal properties of the tested sample, and has the characteristics of accuracy and efficiency. Here, the cryostat is combined with the transient plane heat source method to measure thermal conductivity of frozen soil, and the temperature test range of hotdisk method is extended to the liquid hydrogen temperature range of 20K. The thermal conductivity of 304 stainless steel and epoxy resin G10 has been measured in 20K-300K. The values are in good agreement with the thermal conductivity values provided in the literatures, thus verifying the reliability of the measuring device. On this basis, the thermal conductivity of different kinds of frozen soil under 70K has been measured, and the variation rule of thermal conductivity values has been obtained: frozen soil with 3.8% salt content and 19% water content > frozen soil with 20% water content > frozen soil with 9% perlite content and 45% water content > frozen soil with 77% water content, 17% peat content and 6% perlite content > frozen soil with 37% water content and 11% peat content. Finally, the calculation model of thermal conductivity of frozen soil was given. The thermal conductivity of frozen soil can be predicted by temperature and water content of frozen soil. The thermal conductivity of cryogenic frozen soil in this study can provide data support for cryogenic liquid underground storage projects.
Speaker: pengfei zhao (Zhongshan Institute of Advanced Cryogenic Technology) -
377
Strange Behavior of Boiling Around Wire Heater at The Pressure Condition Very Close to The Lambda Point
It was found in our past microgravity experiments that the bubble size was much smaller than the prediction in the vicinity of the lambda point, and the bubbles had unstable interfaces. However, no experimental reports like this anomalous feature of He II boiling at the vicinity of lambda point were shown. Therefore, in this study, we focused on the boiling experiments around wire heater in He II very close to the lambda point were. The 50-micron wire heater of manganin were set horizontally on the height adjustable rod in He II glass Dewer. The heater temperatures were calculated by the calibration curve of correlation between electric resistance and temperature. The heater power and the resistance were measured by the four-terminal method. The immersion depth was changed to investigate the effect of small subcooling due to gravity. Under the several saturated vapor pressure conditions b, 35.5, 36.0, 36.5, 37.0 and 40 torr, the boiling curves were compared. In the comparison between boiling curves the new findings were not appeared.
At the pressure condition very close to lambda point, the precise pressure control is quite difficult. Thus, the pressure was raised up very slowly around the lambda temperature at the fixed heat flux to obtain quasi-steady state. The heater temperature had been changing many times with the inflection point with the audible noise during raising pressure though silent boiling mode should be occur in this region. In the saturated pressure condition, the two modes were known in He II. One is the noisy film boiling mode, another one is silent film boiling mode. The silent film boiling mode has stable vapor film with no-audible noise. And it is found that the boiling heat transfer coefficient just above lambda point is higher than that just below lambda point.Speaker: Shinji Hamaguchi -
378
Thermal analysis of a conduction-cooled superconducting quadrupole for ILC Main Linac with large temperature margin
The Main Linac of the International Linear Collider (ILC) includes superconducting quadrupole (SCQ) packages that are located between the superconducting RF cavities, with one SCQ within each of the Type-B cryomodules. This combined-functioned, splittable superconducting magnet focus and steer the electrons and positrons. The magnet is required to be cryogen free, and conductively cooled down via thermal links. This links should be connected to the outer surface of the transfer line that supplies liquid helium to the RF cavities. Additionally, to address the large heat deposition expected in the superconducting coils due to beam-induced dark currents, the use of Nb3Sn strand is advocated for the coil, given their superior thermal margin related to NbTi.
This paper depicts a numerical analysis of the thermal behaviour of the impregnated Nb3Sn quadrupole coils and proposes a conduction-cooling strategy for these coils. The anisotropic behaviour of the coil has been thoroughly examined. A highly conductive casing for the coil has been designed and high purity aluminium sheets have been integrated to significantly improve thermal management.Speaker: Oscar Duran Lucas (CIEMAT - Centro de Investigaciones Energéticas Medioambientales y Tec. (ES)) -
379
Thermal conductance measurement of electrically insulated joints for cryogenic applications
One of the important aspects of any cryogenic design is to achieve good thermal performance by minimizing the temperature gradient at different contact regions of the thermal mass. In some cases, electrical isolation may be required at contact regions. Different combinations of the thermally conductive and at the same time electrically insulated joints have been characterized using a GM cryocooler based conduction-cooled test rig (CCR). A two stage CCR has been used to cool sample stacks down to 4 K with measured temperature differences across the sample stack up to 110 K, by increasing the 2nd stage temperature. Different types of ceramics and polyimide (Kapton sheet) have been used as an electrical insulator, stacked in between copper blocks and a 2nd stage copper bus bar. Ceramic materials have been coated on copper blocks with surface roughness (roughness average, Ra) that varies from 9 to 14 µm for different ceramics measured, using chromatic white light profilometry (CWLP), whereas bare copper blocks for samples and the 2nd stage copper busbar show a milled finish roughness average of Ra = 1.6 to 3.2 µm. We present a detailed, comparative study of novel thermal contact conductance measurements by using different material combinations.
Speaker: Vijay Soni (GE HealthCare Technology and Innovation Center, Niskayuna, NY 12309, USA) -
380
Thermodynamic scaling analysis of cavitation-induced fluid transients in a cryogenic environment
Fluid transients resulting from rapid flow acceleration or deceleration can pose a significant risk to the structural strength of fluid handling networks, such as those in cryogenic rocket propulsion systems, LNG transport systems, powerplant flow systems, household water systems and many others. Additionally, due to its oscillating behaviour, fluid transients can lead to the formation and subsequent collapse of vapour cavities in the high-pressure regions, leading to cavitation that may potentially damage equipment if not adequately addressed. The complexity of cavitation-induced fluid transient is heightened in cryogenic fluids due to significant variations in thermophysical properties and the presence of a thermal delay effect, an outstanding phenomenon for cryogenic fluids resulting in cavitation suppression through a reduction in the localized vapour pressure.
Cryogenic liquids, operating at extremely low temperatures, require increased maintenance and additional safety precautions. Also, the cryogenic fluids operate near the critical temperature, making them prone to cavitation. In such a situation, experiments using cryogenic fluid become challenging and expensive. Therefore, non-dimensional thermodynamic scaling analysis emerges as a valuable tool, facilitating the substitution of cryogenic fluid with a preferred alternative while maintaining comparable fluid dynamics and thermodynamic characteristics, accounting for the thermal delay effect.
This article presents a scaling analysis of the cavitation-induced fluid transient within a fluid network consisting of a fast-closing valve at the downstream end. The study employs cryogenic fluid and hot water at a temperature corresponding to the same thermodynamic parameter, using various scaling models. A comprehensive comparative assessment of the cavitation-induced fluid transient behaviour in cryogenic fluid and hot water is conducted to ascertain the similarity in flow conditions. The similarity approach based on this thermodynamic scaling will be used for a proposed scaled-down experimental setup to study the cryogenic fluid transients at IIT Kharagpur.
Keywords: Cryogenic, Cavitation, Fluid transients, Thermodynamic scaling, Thermal delay effect
Speaker: Arjun Garva (Indian Institute of Technology Kharagpur, India) -
381
Unusual thermal properties of the nonsuperconducting PrBCO cuprates at low temperatures
The data of the linear thermal expansion (α) and specific heat (Cp) are combined for the study the thermal and magnetic properties of PrBa2Cu3O6+x (PrBCO6+x or PrBCO) ceramic samples in two different oxygenation states: an underdoped (UN) with x = 0.44 and an optimally doped (OP) with x = 0.95. The temperature dependences of the ratio (α/Cp) as well as the effective Grüneisen parameter (Γeff), and the Pr magnetic contribution deduced using the (Δα(T)/T) and (ΔCp(T)/T) representations on the basis on the following differences ∆α = α(PrBCO6+x ‒ α(YBCO6+x) and ∆Cp = Cp(PrBCO6+x) ‒ Cp(YBCO6+x) have been calculated. Anomalies are detected at the Néel temperature TN = 9 and 14 K respectively for x = 0.44 and 0.95 due to the Pr antiferromagnetic (AFM) ordering. Below TN, there is evidence for some possible transitions at the spin reorientation temperature T2 = 6.75 K and 10.25 K, respectively for UN and OP states and close to the same low-critical point Tcr(x) = 4‒5 K. They are compared to the Schottky anomaly due to the crystal field splitting of the Pr3+ ground state in the OP state determined by numerical analysis and to earlier ∆Cp(T)/T-data obtained on an overdoped PrBCO7 ceramic sample [1]. The results show that below TN, the effect of the Pr-Cu(2) magnetic interaction to both AFM Pr and Cu(2) systems appears with more evidence as the key for a better interpretation of the unusual thermal properties of these nonsuperconducting PrBCO cuprates.
[1] Hilscher G, Holland-Moritz E, Holubar T, Jostarndt H.-D, Nekvasil V, Schaudy G, Walter U, Fillion G, “Valence of praseodymium in PrxY1−xBa2Cu3O7−δ: Inelastic-neutron-scattering, specific-heat, and susceptibility study,” Phys. Rev. B, vol. 49 (1994) 535.Speaker: Mahieddine Lahoubi (Badji Mokhtar Annaba University) -
382
Volume calculation and heat transfer performance simulation of a helical tube
To study the performance of the intermittent flow cold storage surface heat exchanger in the experimental system, the volume selection of the helical tube and its heat transfer characteristics play a crucial role in ensuring the continuous and stable operation of the entire experimental setup. A method for calculating the volume of the helical tube based on the gas vessel dynamics model is proposed. Additionally, a three-dimensional simulation model of the helical tube was developed. The simulation focused on analyzing the flow and heat transfer process of low-temperature helium within the helical tube under constant wall temperature conditions. This research provides a scientific foundation for the volume selection of helical tubes to optimize the overall performance of the experimental system.
Speaker: Meimei Zhang
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367
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Thu-Po-3.5: Cryocoolers 2 Poster area
Poster area
Convener: Delio Ramos (CERN)-
383
A helium isotope separation system with an optimized entropy filter
A helium isotope separation system has been established which consisted of a 2K cryostat and a cryogenic separation device with an entropy filter. The 2K cryostat could reach 1.5K, providing a low-temperature environment for the separation device especially the entropy filter. The entropy filter, the core component of the cryogenic separation device, was made of Al2O3 powder which could selectively allow the passage of superfluid. In this paper, the structure of different cryogenic separation devices and the ideal separation conditions have been studied. The resulting entropy filter demonstrated a helium leak rate as low as Pa·m3/s, which was suitable for helium isotope separation. The system could continuously operate to separate helium isotope. The 3He concentration of the entropy filter inlet and the outlet were measured using Helix SFT™ Mass Spectrometry. The concentration of 3He in the feed helium is 3.3E-8 while the 3He concentration of the helium filtered by the system is 2.41E -10. The results indicate that the concentration of 3He separated decreases by two orders of magnitude and this system could separate these two helium isotope with a good performance.
Speaker: Liguo Wang (University of Chinese Academy of Sciences) -
384
Conduction Cooling Test Facility for Superconducting Model Coils
A conduction cooling test facility to perform the characterization of superconducting model coils has been designed based on the use of a Gifford-McMahon cryocooler with a maximum of 1.8 Watt cooling capacity at 4.2 K. This facility will allow to test prototype coils as well as determine thermal properties of their components at a wide range of controllable temperatures. Such functionality is especially valuable when aiming to design and manufacture magnets at non-standard working conditions, for instance profiting from the temperature margins of the superconducting materials rather than their high critical fields, in which case, allowing to work at higher temperatures than those provided by cryogen bath based facilities is a necessity. A major challenge is presented when aiming to design and construct a test facility for cooling down and keeping temperature values stable and homogeneous while keeping the heat load below the cooling capacity of the cryocooler at the working temperature. The detailed design of the vacuum vessel, shields, current leads and cold mass supports are here presented together with preliminary heat load calculations.
Speaker: Luis Antonio Gonzalez Gomez ((CIEMAT - Centro de Investigaciones Energéticas Medioambientales y Tec. (ES))) -
385
Cryocooler-based conduction cooling technology development for 1.3 GHz Nb3Sn superconducting radio frequency cavity
Superconducting radio frequency (SRF) cavities are, along with superconducting magnets, indispensable technologies for modern particle
accelerators. The current cooling method for SRF cavities is immersion in liquid helium, which is ideal in terms of cooling because the entire outer surface of the cavity is maintained at liquid helium temperature.
On the other hand, while superconducting magnets such as MRIs have been converted from immersion cooling with liquid helium to conduction cooling with cryocoolers to reduce costs and difficulties related liquid helium, conduction cooling for SRF cavities are still in the development stage. In particular, considering the recent rise in the price of helium, the conduction-cooled SRF cavity technology with cryocoolers will obviously be essentially important in the future.
In order to operate SRF cavities with conduction cooling by 4K cryocoolers, it is desirable to adopt Nb3Sn (Tc~18.3 K) cavities instead of conventional Nb (Tc~9.2 K) cavities. This is to lower the BCS resistance and reduce heating when RF power is applied. Also, a cryocooler with a large cooling capacity and high electrical efficiency is desirable. In KEK, conduction cooling of Nb3Sn cavities has been performed using two types of cryocoolers, GM (1.8-2W at 4.2K ) and new GM-JT (9-10W at 4.2K) cryocoolers developed by Sumitomo Heavy Industries, Ltd. In this presentation, the current status of cryocooler-based conduction cooling technology development in KEK will be reported.Speaker: Tomohiro Yamada (High Energy Accelerator Research Organization) -
386
DESIGN AND COMMISSIONING OF THE NITROGEN CRYOGENIC SYSTEM FOR THE HEPS
High Energy Photon Source (HEPS) is a high-performance and high-energy synchrotron radiation light source with a beam energy of 6GeV and an ultra-low emittance of better than 0.06nm×rad. The HEPS is mainly composed of accelerator, beamlines and end-stations. No less than 90 high performance beamlines and end-stations are capable to be built around the storage ring. The HEPS is scheduled to be put into operation in 2025 at Institute of High Energy Physics in China. A large nitrogen cryogenic system will support a liquid nitrogen cryogenic environment temperature for the HEPS. The nitrogen cryogenic system is crucial for creating and maintaining operational conditions of the thermal shield of superconducting radio frequency cavity cryomodules, precooling a 2.0kW@4.5K helium refrigerator, cooling photon beamline crystats and cryogenic inserts in the HEPS. The nitrogen cryogenic system has an average capacity about 50kW at 80K in the HEPS phase I. The nitrogen cryogenic system is mainly included of a large scale nitrogen cycle refrigerator, two liquid nitrogen tanks and a cryogenic fluid distribution tube network. The nitrogen cryogenic system project engineering implementation has started at June 2019. In this paper, the Schematic diagram, status and recent commissioning of the nitrogen cryogenic system are described.
Speaker: Ma Changcheng (Institute of High Energy Physics Chinese Academy of Sciences) -
387
Development of a cryogen-free test cryostat for a superconducting CCT short magnet
In the framework of the ISOLDE Superconducting Recoil Separator (ISRS) project, a short and straight CCT magnet demonstrator (MAGDEM) has been designed, comprising a dipole and a quadrupole. The final ISRS spectrometer is intended to consist of 12 units of this CCT magnet arranged in a ring configuration. Additionally, this type of magnet could potentially be used for proton therapy gantry systems. A cryogen-free test cryostat has been developed for the MAGDEM, taking into account the space constraints related to the installation of the spectrometer at ISOLDE. The magnet will be conduction cooled using cryocoolers in order to be independent of any liquid Helium supply. In order to speed up the cool down time, a liquid nitrogen pre-cooling system has been included. This work mainly focuses on the design of the cryostat, encompassing descriptions of the different components, an optimization study of the current leads, and an analysis of the cool down time. A prototype of the MAGDEM and its cryostat will be built and tested at Huelva University in the forthcoming years.
Speaker: Arthur IZIQUEL (Accelerators and Cryogenic Systems) -
388
Development of a high-capacity single-stage 20K GM cryocooler
This poster discusses the development of a new single-stage 20K Gifford-McMahon (GM) cryocooler by Sumitomo Heavy Industries, Ltd. The new cryocooler will have been released in this April. Its main features and the potential applications will be highlighted.
The new cryocooler is an upgraded version of the existing RDK-500B model, with no changes to its interface. It can be used for High-Temperature Superconductivity (HTS) applications. In addition, use for liquid hydrogen (LH2) recondensation and its small amount generation could be other potential applications. One of the key improvements in the new cryocooler is its enhanced cooling capacity, particularly below 30K. The cooling capacity at 20K is improved by over 10% compared to the existing model. It has achieved a cooling capacity of over 50W at 20K when the compressor is operated at 60Hz. In addition to the improved cooling capacity, the lifetime of the cryocooler has also been enhanced compared to the existing model. This means that the new cryocooler can provide reliable and efficient cooling for longer durations.
This poster also highlights the potential applications of the new cryocooler briefly. It can be utilized in HTS applications, which require cryogenic temperatures for optimal performance. It is also expected that it can be used in hydrogen recondensation and small amount LH2 generation, which are crucial to store and to produce of LH2.Overall, this poster presents the main features and advancements of the new single stage 20K GM cryocooler developed by Sumitomo Heavy Industries, Ltd. Its potential applications in HTS systems and in hydrogen recondensation and small amount generations will also be addressed.
Speaker: Yoshinori Fujii (Sumitomo Heavy Industries, Ltd.) -
389
Development of two-stage Stirling cooler for simultaneous cooling at 100 K and 50 K
A two-stage Stirling cryocooler for cooling at temperatures of 100 K and 50 K is designed and its performance is experimentally validated. In the development process of the Stirling cryocooler, we firstly designed and evaluated the performance of a single-stage Stirling cryocooler operating at 100 K to calibrate the numerical model. The results revealed that the cooling performance of the single-stage Stirling cryocooler was lower than the design target, primarily due to the smaller dynamic pressure. The heat transfer in the cylinder spaces and the leakage within the linear compressor contribute to the reduced dynamic pressure. Building upon the improved numerical analysis, the two-stage Stirling cryocooler is designed and fabricated. Stainless steel mesh #400 is used for the regenerator matrix, and the stepped displacer is made of phenolic tubes having different diameters. Flexure bearing, providing the restorative force to the displacer, is designed and manufactured through finite element method (FEM) analysis, with the spring constant of the flexure bearings matching the design values within a 10% error. The slit-type heat exchangers are utilized as the aftercooler and the cold-end heat exchangers. The detailed development steps and the performance analysis are discussed in the present paper. This study provides comprehensive insights into the enhancement of numerical models for designing Stirling cryocooler and the development process of Stirling cryocooler.
Speaker: Bokeum Kim (KAIST) -
390
Experimental study of silver powder sintering for optimization of sintered heat exchanger in dilution refrigerator
Abstract:
With the development of quantum computing and other scientific fields, dilution refrigerator, as a major ultra-low temperature refrigeration equipment, is required to greater cooling capacity. The silver powder sintered heat exchanger is an essential component of the dilution refrigerator, as it determines its minimum temperature. This study examines the sintering of silver nano powder samples with particle sizes of 50 nm, 100nm, and 200 nm, sintering pressures of 0.4 MPa, 0.7 MPa, and 1.0 MPa, and sintering temperatures of 220°C and 200°C. The porosity and specific surface area were measured, and the 200 nm silver powder was found to have the best performance under the conditions of 1.0 MPa and 220°C, with a specific surface area of 2.3m²/g. It was successfully applied to a dilution refrigerator and achieved a minimum temperature of 19 mK and a cooling capacity of 300 μW at 100 mk. This experiment will effectively improve the cooling capacity of the dilution refrigerator and provide guidance for the design of the dilution refrigerator.Keywords: dilution refrigerator, silver powder sintered heat exchanger, ultra-low temperature, high cooling power
Speaker: Lingjiao Wei (Technical Institute of Physics and Chemistry, CAS) -
391
Investigation of the stand-alone cryomodule for the 3rd harmonic cavity of the synchrotron light source
Superconducting accelerators currently rely on central refrigeration systems and complex piping system for distributing liquid helium and nitrogen. The proposed stand-alone cryomodule can be an attractive solution for both scientific and industrial applications. It offers the the simpler applicability in facilities lacking cryogenic equipment and expertise, and is particularly useful in scenarios where the development of additional cryogenic systems is impractical. The technical challenge lies in minimizing heat losses to incorporate a commercially available helium ZBO (Zero-Boil-Off) system by the embedded cryocoolers on cryomodule. This presentation introduces the design proposal for a stand-alone cryomodule intended for bunch lengthening cavity applications at synchrotron light sources which the design employs a normal conducting cavity as the primary RF system, elimination the need for bulky cryogenic refrigeration units. The development of low-heat load peripheral components contributes to cost reduction and broadens the applicability of such a system. The primary challenge in implementing an SRF cryomodule with a cryocooler for particle accelerator applications lies in effectively suppressing vibrations and reducing heat loads.
Speaker: Junho Han (Kiswire Advamced Technology Co. Ltd.) -
392
Numerical investigation of free piston Stirling cooler with annular regenerator for moderate cryogenic temperature applications
Stirling coolers are a highly promising technology in the field of low temperature production due to their exceptional efficiency and reliability. Stirling coolers, one which employs helium as the working fluid, offer an alternate choice for those looking for a cooling system that offers both ecological friendly and energy-efficient. Stirling cooler, appropriate for producing temperature ranges of 100 K to 200 K applications used in this design, prototyping and investigation. Free piston coolers avoid the difficulties usually occur in crank driven mechanism also provides better robustness and eliminate side forces. The application levels of this type of devices encompass a wide range of functions, including deep freezing, medical preservation, and vaccine chilling. These kinds of coolers have the capacity to generate a cooling effect that can range from a few watts to 100 W, depending on the levels of application and temperature range.
The system and preliminary conceptual design of a beta-type free piston Stirling cooler were carried out by using SAGE software. The important system components comprise the compression space, expansion space, regenerator and heat exchangers were interconnected through the application of distinct boundary conditions, including pressure, mass flow, and heat flow. The resonating mechanism of the cooler is achieved by a moving magnet type linear compressor and spring-mass system. In this work, the regenerator, hot and cold heat exchangers are modelled as porous media. The analysis of the cooler takes into account several crucial characteristics, including the porosity of the regenerator, the heat exchangers for both hot and cold temperatures, the clearance of the piston seal, the gap in the displacer appendix, and the losses in the gas spring, all of which have an impact on the cooler's performance. The designed cooler can produce varying cooling loads in the 100K to 200 K range nearly with linear temperature gradient curve. The second stage of the study focused on the design of a linear motor drive mechanism with the help of SAGE and Ansys Maxwell software by which the piston moves in axial direction to provide the Simple Harmonic Motion. The important parameters considered for the analysis the size and material of magnet, optimum magnetic gap and the core sizes. Final part of the study includes the energy loss calculation in given prototype with varying parameters for better performances.Speaker: Biju T. Kuzhiveli (National Institute of Technology, Calicut, India) -
393
PRELIMINARY design of a LH2 target cooling system at LBL
In order to study nuclear structure at the limits of stability through a program of targeted measurements at the Facility for Rare Isotope Beams (FRIB), a thick liquid-hydrogen target and vertex tracking detector system specifically optimized to be coupled to the Gamma-Ray Energy Tracking Array (GRETA) for fast beam measurements at FRIB is under development. The LH2 target-cell and windows will be made of thin Mylar. The target thickness is around 10~15 cm with an effective diameter of order 50~60 mm. A cryocooler-based hydrogen cooling system is under design to cool down the target, liquefy gas hydrogen, deliver and maintain liquid hydrogen in the target. The cooling system primarily consists of a cryocoole-cooled cryostat, a gas hydrogen and gas nitrogen storage and handling sub-system including safety devices, as well as instrument rack and PLC control system. The hydrogen is liquefied in the cryostat using a two-stage GM cryocooler at 20 K. The vaporized hydrogen is re-liquefied in the condenser attached to the second stage of the cold head and the liquefied hydrogen flows into the target through its gravity-driven thermos-syphon cooling circuit. A thermal radiation screen at around 30-40 K is mounted on the first stage of the cold head to protect the cold mass at 20 K from the 300K radiation. The safety design of the hydrogen cooling system is carefully taken into account. This paper presents the preliminary design of the LH2 target cooling system at LBL.
Speaker: Li Wang (Lawrence Berkeley National Lab) -
394
Study on the performance of liquid helium re-liquefier for superconducting chip test
A liquid helium re-liquefier system has been designed for superconducting chip test. The cold source of the system is a PT420 GM type Pulse tube cryocooler. On this base, the precooling structure and recondensation structure has been designed. Besides, composite magnetic shielding structure was used to ensure the chip working in an extremely low magnetic environment. With a special designed mechanical interface and PID control system, the chip could be replaced when the cryocooler is on. Experiment shows that the cooling time of the system is about 8h, and the cooling capacity is 1.15W, which could ensure the working of superconducting chip with hundreds of channels. Residual magnetism of the working chamber is below 5nT. Automatic control module could ensure the system working without people. In order to extend the holding time when unexpected power outage occurred, a special cooling capacity recovered structure has been added to the system to utilize the cooling capacity of the cold helium gas.
Speaker: Guopeng Wang (Technical Institute of Physics and Chemistry, CAS) -
395
Cryocooler development for superconducting applications
ABSOLUT SYSTEM has developed an industrial CRYOCOOLER, for superconducting applications.
Our cryocooler is based on Reverse Turbo-Brayton technology (RTB), allowing to deliver cold powers from 20K to 80K. It is composed with turbomachinery also designed and developed by Absolut System: compressors and turbine.
In addition, Absolut System specify and incorporate the necessarily exchangers, piping, controlling devices and highly insulated cryostat. Every part of the equipment is assembled and tested by our teams as well as the global performances.
Our equipment is a compact and autonomous skid (about 10m²/100ft²), making it easy to freight, unload and integrate in a larger system anywhere in the world: it will only need to be connected to the customer’s utilities (water, electricity, exhausts, liquid nitrogen if needed for the application) to be functional.
As we master each component and each part of the conception, the cryocooler can be adapted to suit with many superconductor devices i.e., cold powers/temperature: superconducting motors for ships or plane, superconducting magnets, regular or high temperature superconducting (HTS) cables… With our cryocooler, superconducting cables can also be cooled with liquid hydrogen, for a combination of hydrogen and electricity transportation.
Also, thanks to special designs options on our turbomachinery with contactless bearings, maintenance will be reduced, and the longevity is increased.
The validation tests of this machine are planned early 2024.Speaker: Louise Terrien (Absolut System)
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383
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Thu-Po-3.6: Superconductors, AC Loss & Stability Poster area
Poster area
Convener: Alexey Dudarev (CERN)-
396
Characteristics of the Critical Current Capabilities of an Stepped Grooves Structure Superconducting Conductor with Stacked REBCO Tapes
In order to improve the transmission capability of the second generation REBCO tape, many structures of superconducting strand/cable stacked with REBCO tapes were proposed. In this paper, a compact twisted stack tape conductor (TSTC) with stepped grooves was performed. The stepped groove is divided into long groove and short groove with different number of tapes, and a long copper plate is sandwiched between the two stacking tapes to improve stability, while contributing to distribute fault current. Numerical studies of current-carrying capability and magnetic behavior of these conductors have been carried out by employing a T-A formulation model and a H-homogenized formulation model. The effect of the quantity of grooves and tapes on the critical current is studied by the finite element method, respectively. With 20+10 superconducting tapes configuration, the engineering current density of three stepped grooves structure reaches 1.28×108 A/m2 in an area of 75.51 mm2, which is a significant increase over the usual single-groove stacked cables. Then, the sample of HTS TSTC conductor with three stepped grooves was fabricated, and the critical current was measured at liquid nitrogen temperature and self-field. The test results correspond with simulation.
Speaker: Junfeng Yang (Beijing Jiaotong University) -
397
Design and Electromechanical Properties of HTS Twisted Stacked-Tape Conductor with Three Stepped Slots
The high temperature superconducting (HTS) twisted stacked tape conductor (TSTC) is one of the methods to improve the current-carrying capability of a superconducting conductor. A three stepped slots with twisted stacked YBCO tapes is presented in this paper. The YBCO tapes embedded in the stepped grooves of two different lengths. A 2D finite-element model is used to computes the magnetic field and current distribution. The current carrying characteristics under 2 T background magnetic field are studied. The minimum critical current of 4108 A is measured under the perpendicular field, and maximum of 4535 A for parallel. The correlation between the maximum von Mises stress of the conductor and the external field angle is also studied. A 20+10 tapes in each single groove configuration conductor of YBCO was fabricated using the twisted stacked-tape method, and the bending test of the samples at 77 K in self-field are performed to verify the electromechanical characteristics.
Speaker: Junfeng Yang (Beijing Jiaotong University) -
398
Field-induced phase transition, weak ferromagnetism, and metamagnetic transition in the underdoped PrBCO cuprate
We report anomalous magnetic properties in high DC magnetic fields H up to 16 T on an underdoped PrBa2Cu3O6.44 insulating ceramic sample of cuprate family. Significant magnetic-field effects are revealed in the derivative dM(T)/dT of the magnetization M(T) versus T using two sets of values of H selected in the range of 2.5-9.5 T. Anomalies are observed in the region of Tcr ~ 4.5 K, T2 ~ 6.5 K and TN = 9 K, which are respectively the well-known low-critical point, the spin reorientation phase transition temperature, and the Néel temperature of the antiferromagnetic (AFM) ordering of the Pr3+ sublattice [1]. Using Arrott plot analysis, we identified at 1.35 K weak field-induced phase transitions at two critical fields, Hcr1 ~ 3.3 T and Hcr2 ~ 7.5 T, whose associated transition lines appear temperature-independent as T increases up to T2, and seem to vanish in the vicinity of TN. Between TN and 20 K, the curves of the derivative dM(H)/dH of the magnetization M(H) versus H show a slight increase when H is taken in the low-field range of 0.7 T < HS < 1.2 T. The field HS being the specific field above which the weak ferromagnetic (WFM) part settles in the Pr AFM regime as well as in the AFM state of the Cu(2) spins which takes place in the region of room temperature. As T decreases, HS increases monotonically, while dM(H)/dH exhibits a high-speed increase below Tcr. The M(H) curves obtained with a high accuracy, show obviously a linear field dependence in the range of HS-Hcr1, so, they may be represented by the equation MS(T) + χd(T)H. The spontaneous magnetization MS(T) and the differential magnetic susceptibility χd(T) are obtained by extrapolation to zero-field from the linear part of the M(H) curves in the low-field range (HS < H < 2 T). MS(T) decreases as the inverse of T, like for paramagnetic systems with a shape change when crossing TN and survives above TN. Whereas χd(T) has a behavior practically analogous to that of AFM materials and shows a shape change when crossing Tcr, T2, and TN. The M(H) - χd(T)H versus H curves present a metamagnetic-like field-induced transition at a threshold field Ht for H lower than 0.15 T. These anomalous features observed at low temperatures and surviving above TN, are taken as evidence for an additional weak ferromagnetic-like component. The results are compared with previous neutron-scattering study [2] and discussed in terms of the significant role of the Pr-Cu(2) coupling which appear to continue well above TN.
[1] M. Lahoubi, Physica B 536 (2018) 12.
[2] A. T. Boothroyd et al., phys. Rev. Lett., 78 (1997) 130.Speaker: Mahieddine Lahoubi (Badji Mokhtar Annaba University) -
399
Improvement in Jc of KIT-CERN (KC4) REBCO tapes through a study of growth defects
The KIT-CERN Collaboration on Coated Conductors (KC4) was established as a research facility for the development of novel long-length Coated Conductor samples. This production line, originally established by Bruker, has been used to produce REBCO CCs since last year after its assembly at the Institute for Technical Physics (ITEP, Karlsruhe Institute of Technology). Recent measurements of the self-field inductive Jc show quite good values of 300 A/cm (width) at 77K, and there is potential for further improvement. Here we will discuss how higher Jc values can be achieved through the study of the growth defects of these REBCO tapes, which will help in extending the manufacturing e.g. towards wider tapes essential for High-Field HTS magnets.
Speaker: Sukanya Baruah (ITEP, Karlsruhe Institute of Technology) -
400
Investigating the Electromechanical Performance of REBCO Tapes for High-Field Magnet Applications
Rare-earth barium copper oxide (REBCO) coated conductor tapes hold immense promise for high-field magnet applications due to their exceptional critical current (I_c) at cryogenic temperatures. However, during magnet manufacturing and operation, REBCO tapes experience strain and fatigue, potentially affecting their I_c and compromising performance. This study investigates the interplay between I_c, strain, and fatigue in REBCO tapes at cryogenic temperature to optimize their usage in magnet design and construction. Various REBCO tapes from different manufacturers are subjected to controlled tensile strain at 77 K in a dedicated cryogenic testing setup. Ic will be measured simultaneously using a four-probe technique. I_c variations under controlled tensile strain are measured and analyzed at 77 K. Identification of the critical strain limits beyond which Ic degradation becomes irreversible are reported. REBCO tapes are also exposed to cyclic tensile loads at 77 K and their Ic is monitored over extended cycles to evaluate fatigue resistance and potential degradation. This study develops a comprehensive understanding of how strain and fatigue influence I_c in REBCO tapes at cryogenic temperatures. The results will also provide valuable data for magnet designers to optimize coil winding procedures and mitigate I_c losses. This study will contribute significantly to advancing the application of REBCO tapes in high-field magnets for various scientific and technological applications.
Speaker: Aniket Ingrole (National High Magnetic Field Laboratory (NHMFL), Florida State University) -
401
Investigation of the emittance properties of multilayer insulation used in cryogenic applications
Multilayer insulation (MLI) is a critical material used to control radiative heat transfer in cryogenic systems. MLI consists of alternate layers of reflective aluminized mylar, separated by low thermal conductivity spacers. The thermal emissivity of the MLI layer plays a critical role in minimizing the radiative heat transfer through its layers. The formation of native oxide is inevitable in any aluminized coating. Any long-term atmospheric exposure of aluminized surfaces can affect the nature of native oxide formation. This native oxide layer can affect the emittance of the reflective layer depending on its nature and thickness. The exact microstructure and elemental composition of the native aluminium oxide is highly uncertain, and it is commonly identified as an amorphous combination of different oxides and hydroxides. It is essential to characterize the material and measure the emittance of the reflective surface of MLI before its application in cryogenic systems. This work aims to characterize the reflective surface of MLI structurally and functionally. This paper reports on the functional and structural characterization of aluminized mylar used in multilayer insulation. In this work, the emissivity of the reflective layer of multilayer insulation was measured experimentally, and the relation between emissivity and surface resistivity was demonstrated successfully. Grazing incidence x-ray diffraction result gives the diffraction peaks corresponding to polyethylene terephthalate (PET), which is the substrate (at 2θ = 26°), and aluminium, which is the conductive coating material (at 2θ = 38.47° and 44.74°). Scanning electron microscopy (SEM) analysis shows that the surface is uniform, while elemental analysis through energy dispersive spectroscopy (EDS) indicates the presence of only Al, O, and C. Atomic force microscopy (AFM) shows that the MLI surface is smooth with a surface roughness (Ra) of ~ 4.7 nm. The total hemispherical emissivity is measured as per ASTM C 1371 standard using a portable emissometer at room temperature and found to be 0.03 ± 0.01 and is compared with the estimated value from measuring the sheet resistivity of MLI using the Hagen-Rubens relation. While native oxide formation in aluminium is inevitable, the measured results show that the reflective layer of MLI maintains its low emissivity due to the minimal thickness of alumina.
Keywords: Multilayer insulation; Emissivity; Sheet resistance; Aluminum coating; Oxide thicknessSpeaker: Uday Kumar (ITER-India, Indian Institute of Technology Madras) -
402
Modelling the effect of anisotropic elasticity of REBCO on the mechanics of high field magnets with screening currents
The development of high temperature REBCO superconducting (HTS) REBCO tapes are promising for high field magnets. However, the mechanical properties of these tapes are transversally isotropic a special case of anisotropy, where the elastic behavior is determined largely by the thickness of the Hastelloy substrate and the electroplated copper stabilizer. Furthermore, for such high magnetic field applications, there are high electro-mechanical forces which can lead to possible damage and thus concern for mechanical degradation. Also, the magnet design is not straightforward due to complex interplay of large screening currents. In this workarticle, we present a novel 2D axisymmetric finite element tool programmed in MATLAB. The stack of pancakes and the large number of REBCO tapes turns are approximated as anisotropic bulk hollow cylinder. Here, we study the following configuration.Firstly, the current is ramped up to a value below the critical current and we calculate the screening currents and the magnetic forces that they cause using the MEMEP model . This electromagnetic model can now takeallows to take into account non-insulated and metal insulated high field magnets into account. With this method, we study REBCO HTS inserts for 32 T magnets under a the background magnetic field of a low-temperature superconducting (LTS) outsert of 19 T. In particular, we study the effect of anisotropic REBCO laminated tape and on the mechanical quantities. We show that the stresses within the HTS magnet coil can be decreased by increasing the thickness of the stabilization layer of REBCO tapes within a realist range. The total tape thickness is kept constant by reducing the thickness of the substrate layer. We then, take these different tape configurations and calculate hoop strains, radial stresses, and hoop stresses. The study show that stresses generated in the magnet depends on an anisotropic factor κ (ratio of radial, , to circumferential , elastic modulus). We have also calculated the self-heating effects during ramp and the thermal stresses due to quench. In conclusion, the numerical analysis shows that by adjusting the thickness of stabilizer and of substrate in a realistic range the mechanics of HTS magnet specifically stress generated can be controlled. The presented modelling method is suitable for multi-physics design of high-field magnets.
Speaker: Anang Dadhich (Slovak Academy of Sciences) -
403
Performance investigation of multilayer insulation structures with variable metal coating
Multi-layer insulation (MLI) is a passive insulation technology, which is known as "super insulation" due to its excellent insulation performance in cryogenics engineering field. The traditional multi-layer insulated reflective layer often uses a single aluminum metal coating, ignoring the influence of temperature change on the metal emissivity. On this basis, this paper proposes a variable metal coating MLI (VM-MLI) using aluminum, gold and copper as reflective layer materials. In this research, the layer-to-layer model is employed to theoretically analyze the performance of VM-MLI. The total heat leakage of the MLI and the VM-MLI under the same conditions are calculated, and the effects of layer density, spacer layer material, air pressure and thermal boundary temperature on the total heat leakage of the VM-MLI are analyzed. The calculation results show that the VM-MLI can significantly reduce the total heat leakage, and the thermal insulation performance of the newly designed insulation structure is about 55% higher than that of the traditional single aluminum metal coating MLI.
Speaker: wenjie zhou -
404
Research and development of 650 MHz superconducting cavity for CEPC
The 650 MHz superconducting radio-frequency (SRF) cavities used for the Circular Electron Positron Collider (CEPC) were studied to achieve high accelerating gradient (Eacc) and high intrinsic quality factor (Q0). The 650 MHz single-cell cavities were subjected to a combination of buffered chemical polishing (BCP) and electropolishing (EP), and their Eacc exceeded 40 MV/m. Such a high Eacc may result from the cold EP with more uniform removal. BCP is easy, cheap, and rough, whereas EP is complicated, expensive, and precise. Therefore, the combination of BCP and EP investigated in our study is suitable for surface treatments of mass SRF cavities. Medium temperature (mid-T) furnace baking was also conducted, which demonstrated an ultrahigh Q0 of > 8E10 at 22 MV/m, and an extremely low BCS resistance of ~ 1.0 nΩ was achieved at 2.0 K. Moreover, nitrogen doping was carried out, which also enhanced Q0 of 650 MHz SRF cavities. This study may benefit SRF community, which has been referenced by PIP II.
Speaker: Peng Sha (IHEP) -
405
RF response of REBa2Cu3O7-x coated conductors under high magnetic fields
Our recent investigations have highlighted REBa2Cu3O7-x (RE = rare earth) Coated Conductors (CCs) as promising candidates to replace copper (Cu) as low surface-impedance coatings in high-energy physics (HEP) RF applications operating under very-high magnetic fields [1, 2, 3].This contribution provides a thorough demonstration of why REBCO CCs as promising solutions for the HEP community, specifically addressing the need for low-surface impedance materials in the GHz range under very high magnetic fields. This study pioneer’s advancement in characterizing the surface impedance (Zs) of Coated Conductors (CCs) using a novel Hakki-Coleman dielectric-loaded resonator. The resonator is optimized for TE011, TE012, and TE013 modes, resonating at frequencies of 6.5GHz, 8.1GHz, and 10GHz, respectively. The study is conducted over a broad range of cryogenic temperatures and magnetic fields strengths up to 16T. The results highlight the resonator's pivotal role in ensuring precise multi-frequency measurements, providing crucial insights into vortex dissipation phenomena such as vortex creep. The results underscore that CCs outperform Cu in the desired high-temperature (H-T) region crucial for HEP applications. Additionally, high-frequency vortex parameters are extracted from the Coffey–Clem model, utilizing surface resistance and reactance data, and they are used to extrapolate results under working conditions not accessible via experiments.
References:
[1] T. Puig et al, Supercond. Sci. Technol. 32 (2019)
[2] A. Romanov, et al. Scientific reports 10 (2020)
[3] J. Golm, et al. IEEE Trans. App. Supercon. 32 (2022)Speaker: IRFAN AHMED Not Supplied -
406
Superconductor – Insulator Transition in Sputtered ZrNxOy Thin Films Induced by Tuning RF Power
Varying the sputtering power during magnetron reactive sputtering deposition simultaneously affects the sputtering yield of the target atoms and the degree of disorder in the films. This greatly tunes the physical properties of transition metal oxynitrides films ($TMN_xO_y$), resulting in the emergence of various interesting physical phenomena such as metal-insulator transition (MIT) and superconductor-insulator transition (SIT). In this work, a series of $ZrN_xO_y$ thin films were deposited by adjusting the rf power. Scanning Electron Microscopy (SEM) characterization of the cross-sectional and planar morphologies revealed that higher rf power led to denser film growth. The electrical transport properties of the films were measured from 300 K to 2 K using the van de Pauw (vdP) geometry configuration. Increasing rf power resulted in lower room temperature resistivity and higher deposition rates. Meanwhile, the SIT was observed with decreasing rf power. As temperature decreased, the conduction mechanism transited from metal edge conduction of MIT to Mott’s variable range hopping (Mott-VRH) mechanism. The transition temperature on the three superconducting samples increases from 2.9 K to 3.4 K with increasing rf power. Using the w function (the logarithmic derivative of T - dependent R), the dominant temperature range of the conduction mechanism for films with different sputtering powers was identified. Analysis of magnetoresistance (MR) at 2 K and 4.2 K revealed that within 9T, films exhibiting insulating characteristics displayed negative MR behavior, whereas samples undergoing SIT transition exhibited saturated positive MR, with varying saturation field strengths. This study successfully controlled the electrical transport properties of thin films by varying the sputtering power. This study could contribute to the understanding and optimization of $TMN_xO_y$ thin films for various applications, such as electronic devices and sensors.
Speaker: Zhen Geng (Technical Institute of Physics and Chemistry, Chinese Academy of Sciences) -
407
Temperature uniformity characterization in heat treatment of the Nb3Sn coils for nuclear fusion
Burning plasma Experimental Superconducting Tokamak (BEST) is a full superconducting coil tokamak. The heat treatment of the Nb3Sn coils of the BEST is carried out by using atmosphere atmosphere-protected heat treatment furnace. The temperature uniformity throughout the coil becomes a crucial problem due to the large size of the cross-section of the coil. In this study, the temperature uniformity characterization experiment of the Nb3Sn coils was carried out to simulate the actual coil heat treatment condition. The test results show that the temperature gradient of the cross-section of the coil is within 3℃, which provides data for further optimization of heat treatment of the coils of BEST.
Speaker: Bingkun Lyu (Songshan Lake Materials Laboratory) -
408
Thermal conductivity of REBCO tapes with different stabilizers at 4.2 – 200 K
REBCO coated conductor is a HTS material that is promising for a wide range of applications. One of them is the application for current leads of magnet systems. In the design of current leads, it is important to minimize its thermal conduction while maintain the superior electrical conduction of the superconductors.
In this study, we fabricated 4 mm wide REBCO tapes stabilized with different materials of different thicknesses. Then we measured the effective thermal conductivity of these tapes between 4.2 K and 200 K using the thermal transport option of a physical property measurement system (PPMS). The electrical conductivity of these stabilizers was also characterized by residual-resistance-ratio (RRR) measurements and correlated with the thermal conductivity. Our results confirm that the thermal conductance of these samples is dominated by that of the stabilizer layer. Our data showed that the sample with Ag-Au alloy as the stabilizer has significantly lower thermal conductivity than that with a copper stabilizer. The effect of the stabilizer thickness on electrical stability and thermal performance will also be discussed.Speaker: Jun Lu -
409
Understanding AC losses in state-of-the-art superconducting cables: Physics insights from 2D to 3D computational modelling
Producing accurate computational models that forecast the alternating current losses associated with cold-dielectric conductors is pivotal for power grid investors, what in turn can influence the designing and manufacturing of lightweight superconducting cables aspiring to reach high engineering current densities whilst maintaining a compact structure. By utilizing the so-called H-formulation of Maxwell’s equations with different critical current density approaches, such as a constant Jc model equivalent to the classical but widely successful critical-state model for type-II superconductors, or tailored Jc (B) functions similar to the acclaimed Kim’s model for non-isotropic superconductors, and the most realistic approaches considering the magneto-angular anisotropy Jc (B, θ) of commercial superconducting tapes, we present an extensive electromagnetic analysis for practical cold dielectric conductors, including single phased multi-layer powered cables, triaxial cables, and the state-of-the-art Conductor on Round Core (CORC) and Twisted Stacked-Tape Cables (TSTC) designs. All cables are simulated either within two- or three-dimensional approaches depending on the availability of proper experimental data considering transversal applied magnetic fields and transport currents in the fully assembled cables. Computational results are duly validated by straight comparison with experimental measurements of AC losses, providing further insight on the cumbersome coexistence of magnetization and transport currents inside the superconducting tapes within hysteretic conditions, whose physics can only be resolved within the H-formulation at the expense of increased computational costs. Remarkably, features such as the need to unbalance the current phase distribution in triaxial cables achieve near zero magnetic leakages, as shown without the need for recurring to 3D formulations, whilst physically meaningful distributions of current density for both CORC and TSTC cables are shown within our 3D models. Distinctively, CORC cables shows distributions of current density characteristic of Bean’s model with well-defined loops of magnetisation currents turning across the thickness of the superconducting tapes, whereas the TSTC cables exhibit distinctive slab-like profiles due to the twisting of stacked tapes, which also reduces the magnetic flux coupling and consequently its AC losses. In conclusion, this paper serves as a benchmark for comparing the electromagnetic performance and actual physics behind different HTS cabling techniques, offering valuable insights for future development.
Acknowledgement:
H.S.R. and M.C. acknowledge the support of the Engineering and Physical Sciences Research Council (EPSRC) through its DTP programme with the University of Leicester (UoL) . H. Al-S. thanks to the Iraq’s Higher Committee for Education Development (HCED) for their funding support. All authors acknowledge the use of the High-Performance Computing Cluster Facilities (ALICE) at UoL. Networking support provided by the European Cooperation in Science and Technology, COST Action CA19108 (Hi-SCALE), is also acknowledged.Speaker: Matthew Clegg
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396
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15:30
Coffee & Tea break Exhibition & Posters area
Exhibition & Posters area
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Thu-Pl-5: Superconductivity for Aircraft (plenary 5) Room D
Room D
Convener: Francois Millet (CEA)-
410
Electrification of Aviation Propulsion – Cryogenic Technologies that enable the Next Generation of Propulsion Systems
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Speaker: Rod Badcock
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410
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Thu-Pl-6: Cryogenics for Energy (plenary 6) Room D
Room D
Convener: Maciej Chorowski-
411
Cryogenics for power and energy: a winning ticket?
For 60 years, the Air Liquide group has worked on major international industrial and scientific programs using cryogenics, which have enabled the development of technologies and skills today serving the energy transition.
For example, the Ariane rocket program has developed a mode of space transport using liquid Hydrogen as an energy vector, for which we have produced all the Hydrogen, Oxygen and Helium tanks. This mastery naturally led us to get involved in other sectors of mobility, such as charging stations for land transport and liquid Hydrogen tanks for trucks, planes and ships.
“Big Science” is also participating to this energy transition, with facilities like the LHC at CERN or the ITER fusion reactor, which use enormous superconducting magnets cooled with liquid Helium. The large Hydrogen liquefiers necessary for the energy transition are now directly derived from these Helium liquefiers, while the use of superconductivity appears more and more attractive to generate and transport electrical energy in an increasingly electrified society.
This plenary conference will present several examples of the latest cutting-edge cryogenic technologies used for space, aeronautics, terrestrial mobility, and large scientific experiments.
It will also provide an insight on potential medium and long-term markets for the use of high temperature superconductivity for fusion reactors and energy transportation, as well as various uses of liquid Hydrogen.
The industry is now on the path to carbon neutrality and cryogenics will play an instrumental role in energy production, transport, and storage. The global cryogenics community is nowadays able to provide practical, efficient, and reliable industrial cooling systems over a wide power and temperature range that are game changing. This will pave the way to a more sustainable industry and great scientific experiments.Speaker: Pierre Crespi (Air Liquide)
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411
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412
Conference Closing: Numbers, Acknowledgements and Next conference in Korea Room D
Room D
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18:30
Cocktail and Conference Banquet in Town Restaurant (Fairmont Hotel)
Restaurant
Fairmont Hotel
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08:30
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Technical visits to CERN CERN
CERN
Convener: Marta Bajko (CERN) -
12:45
End of conference
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