Conveners
C2Po1E: Components IV: Heat Exchangers
- John Jurns (NIST)
In order to improve the heat transfer and pressure drop performance of plate-fin heat exchanger in helium cryogenic system, a new type of perforated-serrated fin is proposed by combining traditional serrated and perforated fins. A series of numerical simulations are carried out with well-validated 3D models. Because the flow in the channel should be in a turbulent state, the RNG k-ε turbulence...
The recuperative heat exchanger is a key component of the new pulse tube expansion type cryogenic refrigerator, which is tasked with the periodic heat exchange of cold and hot helium, and the thermodynamic efficiency of the entire machine is directly impacted by its heat exchange efficiency. A simulation study is carried out to investigate the heat transfer characteristics of the intermittent...
The cryogenic heat sink attached to the cold head of the cryogenic cooler is used to cool cryogenic fluids such as helium, neon, and hydrogen. The performance of the heat sink involves the pressure drop, the heat transfer area, and the overall size. In order to improve the thermal-hydraulic performance of the heat sink within a limited size, it is necessary to reduce the pressure drop and...
The self-pressurization and pressure control in a zero boil off tank partially filled with liquid nitrogen is investigated numerically. This research analyzes the influence of phase change and forms of the heat exchanger for cryogenic liquid storage in zero boil of tank using numerical method. The phase change model in simulation comes from the Schrage equation which to describe the mass...
A novel gas thermal switch is designed and tested in this paper. This thermal switch would be considerably useful in the cryogenic devices with cryocooler, especially for the helium free devices. It can cut off the conduction path with a simple and low cost design. It has an active operation mechanism driven by normal gas. The fine calculated switch gas type and amount can drive the thermal...
Heat switches are widely used in cryogenic systems and play an important role in controlling thermodynamic cycles and accelerating the cooling of cryogenic components, etc. Among them, the active gas-gap heat switch (AGGHS), as one of the mainstream heat switches, mostly uses activated carbon as the adsorption material. It desorbs/adsorbs helium, by heating/cooling the activated carbon, to...
