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Assuming a standard domestic refrigerator that uses R134a, I can see only two reasons a vapor-compression cycle wouldn't work. Either the ambient temperature is so low that the R134a freezes in the condenser spiral. Or the target temperature inside the refrigerator is higher than the ambient temperature. Am I wrong? The pump might not work properly in low temperatures, but that seems unlikely.

I was very surprised by the following page, which sounds wrong to me: "Refrigeration systems rely on the boiling of refrigerant under pressure and heat. When the ambient temperature is below 60ºF, it takes more energy to make the refrigerant boil and change into a vapor. And the energy consumption increases with the decreasing temperature until at 32ºF, there’s no cooling capacity at all."

https://www.davesappliance-wi.com/blog/does-room-temperature-affect-my-refrigerator/

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    $\begingroup$ All you need to do is choose a fluid which has suitable temperatures of boiling and condensing, this is why some systems run on propane etc $\endgroup$
    – Solar Mike
    Feb 24 at 8:39
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    $\begingroup$ Have a look at: uri.com/INTERSHOP/static/BOS/URI-URIUS-Site/-/… $\endgroup$
    – Solar Mike
    Feb 24 at 8:52
  • $\begingroup$ Thanks @SolarMike, that is how see it too. So the above quote from that website is incorrect? $\endgroup$ Feb 24 at 9:09
  • $\begingroup$ At a temperature where you will not need a refrigerator in the first place. $\endgroup$
    – RC_23
    Feb 24 at 19:33
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    $\begingroup$ We're engineers, and we tend to pay attention to theory, ship product, and lose track of what actually happens in practice. Technicians like Dave tend to have their noses ground into practice, and they make up theory on the fly, or they get one of those partial truths that are enough to get by on, but aren't "true". If Dave the Refrigerator Guy tells you that they don't work in unheated garages, that's because he continually gets calls to fix broken refrigerators that live in garages -- listen to that part. But be very leery of basing any design mods on his exposition of theory. $\endgroup$
    – TimWescott
    Feb 25 at 18:35

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The refrigerant "boils" inside the box - room temperature has nothing to do with it. It condenses in the room temp environment.

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  • $\begingroup$ I agree that the evaporation side has no limitation. The condenser side is where there can be a limitation. This is on the outside in contact with the ambient temperature, and this is where the gas condenses into a liquid. If the ambient temperature is low enough the liquid will solidify (freeze) och block the spiral. $\endgroup$ Feb 24 at 17:41
  • $\begingroup$ While Dave the refrigerator guy is correct that it takes more energy to evaporate refrigerant at lower temperatures, luckily this happens in the evaporator, not as he says in the condenser. But he is right that the oil is probably the problem. At low enough temperatures the oil becomes extremely viscous and does not return to the compressor. So it’s possible with extreme low condenser temperatures the oil will stay in the condenser and the compressor will burn out due to lack of lubrication, or it may return as a “slug” of oil which the compressor cannot handle - it will destroy the valves. $\endgroup$
    – Rich
    Mar 25 at 15:45
  • $\begingroup$ This will happen at much higher temperatures than the refrigerant freezing. The temperature inside the box being lower than ambient is no problem. Your refrigeration system will work much more efficiently in this case! $\endgroup$
    – Rich
    Mar 25 at 15:45

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