Hello everyone,

I am trying to design a refrigeration system which has about 20 Watts cooling capacity at -140 degree Celsius. The ambient temperature is 25 degree Celsius. I think it should be a three-stage cascade system. What I am concerning is the last stage. Does someone have any experience on such a low temperature application? Which company provides suitable compressors for this application? What kind of refrigerant I should use? What kind of compressor oil I could use in such a low temperature?

Any comments and suggestions are appreciated.

Thanks
Vincent