Dr Yanjie Liu (Technical Institute of Physics and Chemistry CAS)
Key Laboratory of Space Energy Conversion Technologies of TIPC, CAS has developed a 4.5K Joule-Thomson (J-T) refrigerator precooled by a three-stage pulse tube cooler. In this paper, special attention is paid to the characteristics of the J-T cycle, so a commercial two-stage GM cryocooler is used to provide precooling for the J-T cycle for the purpose of shorten experimental time. The analysis of the system performance results at different operating conditions are presented and discussed in detail. When only the power consumption of J-T compressors is considered, the COP (coefficient of performance) of the refrigerator is calculated to evaluate the performance of J-T cycle. Influence of charge pressure on cooling capacity is analyzed. Then experimental research is carried out to validate the theoretical result and cooling capacity of 12mW is gained at 4.5K. Orifice of different diameters is also studied to explore the effect of throttling resistance on the performance of J-T cooler. In order to increase pressure ratio, two compressors are used in J-T cryocooler, but experimental results of one stage compression is also demonstrated to confirm the necessity of the second stage compressor.
Dr Yuexue Ma (Technical Institute of Physics and Chemistry CAS)