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0 pointsjabl3y ago0 comments

In Europe, and I think in much of the rest of the world except the US, isopropane or butane is used in common household refrigerators. Recently EU regulations were changed to allow these to be used in small split AC's as well, provided some flammability precautions are taken in the design and installation of the units.

In principle you could also go without phase change refrigerants with the reverse Brayton cycle, essentially running gas turbine cycle in reverse. But AFAIU these are not competitive with phase change refrigerants in the usual temperature ranges used for AC's and refrigerators.

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6 comments · 1 top-level

SoftTalker3y ago· 5 in thread

Yes a propane/isobutane blend works well, it's basically a drop-in replacement for R-12 in air conditioners. Straight propane replaces R-22 in freezers.

The only drawbacks are that it's flammable, and that for the blend, if there is a a slow leak, the blend ratios change due to different partial pressures of the two gasses. So to recharge, you basically have to vacuum the system and refill with the proper blend.

Ammonia also works for industrial applications (the local ice rink uses it) but due to its toxicity it's not ideal for household applications.

Gibbon13y ago

I did a quick search on how much refrigerant is in a household refrigerator. Internet says 30 to 180 grams.

I wouldn't be very concerned with 100 grams of propane. Your kitchen has probably 20kg of air. You ain't going to get even close to the flammability limit releasing a 100gm of propane into it.

bombcar3y ago

Which is about 5000 BTUs or about the same amount as 3/4 a cup of gasoline, if I did the math right.

So not nothing, but not very worrisome either.

jjeaff3y ago

R22 is also flammable. But probably not as much as propane. But you aren't going to get anything dangerous with the small amounts used in HVAC. It would need to be a propane/pure oxygen mixture to even approach danger.

mh-3y ago

It would be useful to be able to (easily) smell a refrigerant leak, too.

happyopossum3y ago

That smell you're thinking of is an additive - propane and butane are relatively odorless without it.

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