Compact Refrigerators

How cheap and small can a cryogenic fridge be made these days?

If you want to liquefy air at home, (temperature minus 200 degrees Celsius or so), how small can the equipment be made, how much does it cost and how does it work? I'm disappointed that this question has received no answers at all. I'd really like an answer because so many portable devices requiring cryogenics would be useful. Please all you Silicon Valley engineers give it a thought.

Public Comments

1. A "fridge" in the sense you are speaking isn't realistic. If you really want something that cold, get some liquid nitrogen and go nuts. It's not as cold as, say, liquid helium... but oxygen in the air will nicely dissolve into liquid nitrogen, and you don't have to keep it under any pressure. If you want to create a fridge, the best way would be to create a vacuum on the inside and line it with copper (silver plated, ideally) pipes all over the place (for conduction). Cycle the liquid nitrogen through a compressor and through the pipes. But why? This would likely cost 3 or 4 grand to get something that actually works.
2. I'm assuming that what you really want to ask is why aren't we able to cryogeniocally freeze things in our homes for personal use or how come inventors have not come up with something portable for the home. First of all, laws forbid you to have these stuff because they are highly dangerous. At least for now, there is no need to cryogenically freeze things in the home or for personal use. Until such time, we can just make use of the freezer compartments in our refrigerators. Do you plan to cook your meat five years after you bought it? hehehehe Anyway, for your info, the simplest freezing containers can be found in sperm banks. Sperm banks have containers where sperm in tubes may be frozen in time. They look like ordinary stainless steel milk containers (just like the ones that come from the farms). Liquid nitrogen is poured into the containers and the tubes are immersed into it.