Compound Freezer too cold?
I have been looking into making liquid nitrogen and I have found one DIY method. It uses a small cryocooler. I wondered if it would be possible to use multiple stages of coolers like those used in a freezer. So basically you take all the stuff off of a two or three freezers, or more, and you use them in a series to get progressively colder. The first compresses the coolant which is then decompressed cooling the hot side of the next step down to freezing temperatures. Is this possible with your everyday freon which is already in these systems, or do you need to get a better coolant, and will this even get cold enough to liquify nitrogen?