-120C low temp refrigerator

[Lc_shi]

One of my friends ask me how to build a -120C low temp refrogerator (cooling capacity 100W ,reach -120C in 60mins,single stage compressor). I've no idea. Pls give me some help.

rgds
LC

[Brian_UK]

Sounds like a trick question. ;)

[lowcool]

100 watt cooling capacity had me stuffed,not that im well versed in ultra colds anyway.

[Brian_UK]

I suppose liquid nitrogen could be used for a quick result.

[DEVITG]

I have the need to build a test chamber to -60°C , and load is just 150 W . sensible heat , a device operating at 50 VDC 3 Amp .
Maybe I can do it in 2 stages or cascade
But it is my first time on such topic, the 2 stages.