Speaker
Description
Krypton has been identified as a candidate cooling fluid for the temperature range below the usable range of CO2. Krypton has a critical point of -63.7°C @ 55.3 bar and a normal boiling point of -153°C. In between this range Krypton can be used as 2-phase evaporative cooling, and above the critical point as a super critical single phase cooling. The CERN EP-DT-DC cooling group together with NTNU in Trondheim (NO) have built a Krypton demonstrator system proving the concept of Krypton in both super critical and sub critical operation. The demonstrator was built with standard CO2 refrigeration components and has demonstrated cooling performance on a typical detector cooling tube (D=2mm x L=1m) down to -82°C at 450 Watt.
Krypton is gas at room temperature, and therefore a new cycle type was developed. The new cycle is a compressor driven cycle with an ejector to obtain low quality liquid conditions needed in the detector. Krypton pressures are similar to those of CO2, this means that typical CO2 components have the potential to be used.
The demonstrator was built with a single stage compressor and was therefore limited in low temperature. A 2-stage compressor system should have the potential to go as low as -140°C and can serve detectors like Silicon Photomultipliers giving a cheaper and more efficient alternative to cryogenic LN2 cooling.