可控直流对于单级脉管制冷机的影响研究

脉管制冷机中气体工质为交变流动,当制冷机中引入一个环路时,便有形成直流的可能。采用引入可控直流的方法予以研究,实验结果发现,一定量的直流可以提高脉管制冷机的性能。在理想气体的温区,制冷机的COP相比于无直流情况最大可提升2.2%,进而初步研究提升制冷效率的机理。同时研究发现,液氮温区在正向直流量相对于交流量变化量大约小于3.5‰的范围内,制冷效率相对于无直流的工况并未降低,说明脉管制冷机具有允许一定直流量的特性。

Study on controllable DC flow in a single-stage pulse tube cryocooler

The flow in the pulse tube cryocooler is a kind of alternating-current(AC) flow.However,whenever a closed-loop flow path forms,there is a potential for a direct-current(DC) flow.Some theoretical studies have shown that any direction in ideal temperature range will deteriorate the cooling efficiency.However,these researches has not been experimentally verified,for this reason the controllable DC flow is introduced to study this phenomenon.Experiment results the performance of the pulse tube cryocooler can be improved by imposing a certain amount of the DC flow.The COP of the refrigerator gets a maximum improvement of 2.2% in the ideal gas temperature range in our single-stage pulse tube cryocooler working wth 4He.Furthermore,the mechanism of refrigeration efficiency improving is preliminarily studied.Meanwhile,this study find that if the amount of positive DC flow is less than approximately 3.5‰ of AC flow in liquid nitrogen temperature range,the cooling efficiency won’t be reduced compared with the working condition without DC flow,which means pulse tube refrigerator has the characteristic of allowing a certain amount of DC flow.