There is nothing really new about using explosive gasses like propane as a refrigerant medium to produce cooling in domestic electric refrigerators. The reason that refrigerants such as Freon became so attractive is that unlike poisonous refrigerant gases like ammonia or explosive gases that can go bang and burn your house down, Freon is inert and not poisonous.

You can be sure that any "new" version of a refrigerator will be surrounded with patents and regulations in the USA to keep out the riff-raff old syle stuff using much the same scenario as was used when the Freon 12 patent expired. Or the "long life" mercury cfls which somehow were more "environmental" than the inoffensive banned no patent light bulbs. The mercury bulbs were supposed to fill the gap pending the time the new hugely expensive patented photonic bulbs were in production, but the best laid plans .......

I've been a member of refrigeration-engineer.com for years.

Search using these words
: refrigerant types

Here are some results

http://www.comfort.uk.com/refrigerants.htm

http://en.wikipedia.org/wiki/Refrigerant
and in there is a list of types
http://en.wikipedia.org/wiki/Refrigerant#Blends
e.g.
R-401A
R-404A
R-406A
R-407A
R-407C
R-408A
R-409A
R-410A
R-500
R-502

Conclusion: nothing new in the OP.