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Several light hydrocarbons seem like perfectly good alternatives. Propane is another one. And there's also quite a lot of use of ammonia for refrigeration as we

Several light hydrocarbons seem like perfectly good alternatives. Propane is another one. And there's also quite a lot of use of ammonia for refrigeration as well. It's not clear to me why these simpler, non-chlorinated, non-fluorinated compounds are so grossly undesirable that we keep chasing more-complex alternatives. Is it really that people are simply horribly afraid of their flammability?

SoftTalker 4y ago
Ammonia is quite toxic. Some bad outcomes from leaky ammonia air conditioning in the past. Ok for industrial chillers with good leak detection systems.
- VLM 4y ago
  Texas state code requires machine rooms for ammonia systems to get 30 air exchanges per hour, same state building code requires houses to be under 1/3 air exchanges per hour. I'm a little fuzzy about the later, pretty sure about the former, and most people don't have the privilege of living in Texas (not sure if I'm kidding or not?), but it demonstrates the safety issue that ammonia cooling needs about a hundred times as much ventilation as a normal kitchen. And insert the usual quotes about building codes being written in blood so they aren't demanding a hundred times the ventilation just for fun.
VLM 4y ago
People are scared of the sealed container explosion. An external butane leak would be about as harmful as a leaking cig lighter. Internal leak? A perfect mixture of butane and air the size of fridge would certainly take out a wall, maybe an entire house if it knocks out a load bearing wall. The worst part about the internal explosion is its almost certain to happen when the owner is standing right in front and opens the door and the light kicks on along with maybe anti-frost heaters or whatever else is in there. I have seen some ideas proposed such as using the "smart" in a smart fridge for good not evil and locking the door if the system pressure drops below "X". Much more likely the "smart" in a smart fridge will never be permitted to be used for anything other than advertising and marketing, which is sad. Energy content of hydrocarbons is about the same (to one sig fig or less LOL) and just one gram of gasoline can blow a piston rod clean thru an engine block under perfectly bad conditions (already shattered bearings, etc) so a couple hundred grams under worst possible case in a confined sealed fridge could take out a house, most likely. (Edited to add: I have a better analogy: A perfect stochiometric mix of air and diesel the size of my coffee cup can blow the engine head clean off a diesel engine, IIRC that's how one of the brothers who invented the Diesel engine died in a lab accident a century ago. And that was just a little coffee cup sized engine cylinder. So imagine a sealed container the size of a fridge instead of a coffee cup... that'll take out a house for sure... neighbors will "probably" live but I wouldn't bet on it...)
- gabereiser 4y ago
  I had an internal explosion of my gas grill. I apparently forgot to turn the gas off so it filled the chambers under the grill plates and when I went to light it, it sent the top and the grill plates through the lanai and 40ft into the air. I lost my eyebrows for a few months.
- ilyt 4y ago
  locking might not even be necessary, just power off the device if pressure of refrigerant drop. Having some way to ventilate the gas (so you don't just get "a box full of flammable gas" situation on slow leak) without reducing performance too much might help also
- ajb 4y ago
  I get your point, but we already have methane pumped to our houses. Are these worse?
  - VLM 4y ago
    Yes, sealed container vs open air. If we stored natgas in scuba tanks that could get exciting... ironically there are people considering powering auto engines with compressed natgas... must be very exciting in a fire LOL.
- zbrozek 4y ago
  Yet we plumb methane in houses all the time. Also, at least for HVAC, it's perfectly reasonable to keep all of the refrigerant outdoors and use water as a heat transfer medium to the interior.
  - amluto 4y ago
    And it’s not a great idea, especially given the proliferation of appliances that burn it in room air. And methane has the convenience property of being less dense than air. I’m not sure, but I expect that the heavier hydrocarbon gasses might be more likely to accumulate indoors.
carnot 4y ago
A3 refrigerants (hydrocarbons) have very low charge quantity limits that basically make them infeasible systems with even modest capacities. Split type air conditioners or heat pumps predominately used in the US have several times the allowable limit of charge in the liquid line alone. Building codes have only recently (and incompletely) been revised to allow mildly flammable refrigerants (A2L) inside most buildings for space conditioning. Amending these for A3 refrigerants is an uphill battle. Ammonia is mildly flammable, toxic, and electrically conductive. Good luck finding/building a hermetically sealed compressor that is anywhere near affordable. CO2 in a refrigeration cycle goes transcritical at even moderately warm temperatures, making the system very inefficient without adding several (typically expensive) changes to the cycle. Manufacturers would struggle to build a CO2 air conditioner that meets minimum efficiency standards at anywhere near current equipment costs.

SoftTalker 4y ago

Ammonia is quite toxic. Some bad outcomes from leaky ammonia air conditioning in the past. Ok for industrial chillers with good leak detection systems.

VLM 4y ago
Texas state code requires machine rooms for ammonia systems to get 30 air exchanges per hour, same state building code requires houses to be under 1/3 air exchanges per hour. I'm a little fuzzy about the later, pretty sure about the former, and most people don't have the privilege of living in Texas (not sure if I'm kidding or not?), but it demonstrates the safety issue that ammonia cooling needs about a hundred times as much ventilation as a normal kitchen. And insert the usual quotes about building codes being written in blood so they aren't demanding a hundred times the ventilation just for fun.

VLM 4y ago

People are scared of the sealed container explosion. An external butane leak would be about as harmful as a leaking cig lighter. Internal leak? A perfect mixture of butane and air the size of fridge would certainly take out a wall, maybe an entire house if it knocks out a load bearing wall. The worst part about the internal explosion is its almost certain to happen when the owner is standing right in front and opens the door and the light kicks on along with maybe anti-frost heaters or whatever else is in there. I have seen some ideas proposed such as using the "smart" in a smart fridge for good not evil and locking the door if the system pressure drops below "X". Much more likely the "smart" in a smart fridge will never be permitted to be used for anything other than advertising and marketing, which is sad. Energy content of hydrocarbons is about the same (to one sig fig or less LOL) and just one gram of gasoline can blow a piston rod clean thru an engine block under perfectly bad conditions (already shattered bearings, etc) so a couple hundred grams under worst possible case in a confined sealed fridge could take out a house, most likely. (Edited to add: I have a better analogy: A perfect stochiometric mix of air and diesel the size of my coffee cup can blow the engine head clean off a diesel engine, IIRC that's how one of the brothers who invented the Diesel engine died in a lab accident a century ago. And that was just a little coffee cup sized engine cylinder. So imagine a sealed container the size of a fridge instead of a coffee cup... that'll take out a house for sure... neighbors will "probably" live but I wouldn't bet on it...)

gabereiser 4y ago
I had an internal explosion of my gas grill. I apparently forgot to turn the gas off so it filled the chambers under the grill plates and when I went to light it, it sent the top and the grill plates through the lanai and 40ft into the air. I lost my eyebrows for a few months.
ilyt 4y ago
locking might not even be necessary, just power off the device if pressure of refrigerant drop. Having some way to ventilate the gas (so you don't just get "a box full of flammable gas" situation on slow leak) without reducing performance too much might help also
ajb 4y ago
I get your point, but we already have methane pumped to our houses. Are these worse?
- VLM 4y ago
  Yes, sealed container vs open air. If we stored natgas in scuba tanks that could get exciting... ironically there are people considering powering auto engines with compressed natgas... must be very exciting in a fire LOL.
zbrozek 4y ago
Yet we plumb methane in houses all the time. Also, at least for HVAC, it's perfectly reasonable to keep all of the refrigerant outdoors and use water as a heat transfer medium to the interior.
- amluto 4y ago
  And it’s not a great idea, especially given the proliferation of appliances that burn it in room air. And methane has the convenience property of being less dense than air. I’m not sure, but I expect that the heavier hydrocarbon gasses might be more likely to accumulate indoors.

carnot 4y ago

A3 refrigerants (hydrocarbons) have very low charge quantity limits that basically make them infeasible systems with even modest capacities. Split type air conditioners or heat pumps predominately used in the US have several times the allowable limit of charge in the liquid line alone. Building codes have only recently (and incompletely) been revised to allow mildly flammable refrigerants (A2L) inside most buildings for space conditioning. Amending these for A3 refrigerants is an uphill battle. Ammonia is mildly flammable, toxic, and electrically conductive. Good luck finding/building a hermetically sealed compressor that is anywhere near affordable. CO2 in a refrigeration cycle goes transcritical at even moderately warm temperatures, making the system very inefficient without adding several (typically expensive) changes to the cycle. Manufacturers would struggle to build a CO2 air conditioner that meets minimum efficiency standards at anywhere near current equipment costs.