BigBen2K:
I think that LN2 COULD be used as a refigerant HOWEVER it would not be a very viable solution compaired to a standard phase exchange refrigerant.
Freon (which used to be the main source for phase exchange refrigerant) is similar to LN2 however it can be compressed easier and "boils" at a much higher temerature than LN2.
LN2 is created by either freezing nitrogen gas to (I think) -164C or compressed to more than say 2000psi (correct me if I am off on my figures) Freon condenses (AKA goes from a gas to a liquid) at say -60C or 200psi. Obviously freon is easier to work with because the requirements to get the gas back into a liquid is much less than that of LN2.
What I am trying to say is that LN2 could possibly be used as a refigerant but you would need a MASSIVE compressor to create the 2000+psi required to convert the gas back into a liquid. Just not fisable.
BTW, my father is a big Do-It-Him-Selfer and build many large phase exchange systems by himself with me being his "go-for" helper
ALSO if anyone is SERIOUSLY interested, we have some industrial Phase exchange Compressors sitting in our backyard waiting for a home
from 1Ton to 10Ton compressors
