With the lowest refrigeration temperature and the cooling power at 20K, the openings of needle valves have been optimized, respectively. The power cooling curves and the coefficients of performance (COP) for the two cases are compared.

• 同时实现了压力和温度的计算机数据自动采集系统,分别针对无负荷制冷温度(液氦温区)和20 K温区制冷量优化了各调节阀的开度,并进行了功率曲线以及制冷系数(COP)的比较。