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Bunslow t1_j19zc1y wrote

Reply to comment by quintus_horatius in Why do we use phase change refrigerants? by samskiter

well i dont know what mine is, but i'd always assumed it was a heat pump exactly since it is indeed 2-4x more efficient than simply dumping a whole bunch of power into heat thru a resistor. but it could be resistive heating for all i know.

and if there are indeed heat pumps with 400% heating efficiency (or CoP or whatever we want to call it), then probably 300% is a very achievable number for even "merely" residential purposes, one would assume?

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quintus_horatius t1_j1a6369 wrote

You only have a few options for heat, and only one that can exceed 100% efficiency - a heat pump.

A typical heat pump exceeds 2.5, a good heat pump exceeds 3.0, and a fantastic heat pump approaches 4.0.

The latter generally show up in highly specialized applications like geothermal, where you can tailor your working fluid to a narrow, predictable temperature range.

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Bunslow t1_j1ajqfp wrote

cool, so 2.5-3 is totally achievable for residential/end consumer purposes. is that what residential air conditioners achieve as well?

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seven_tech t1_j1assin wrote

Mine almost does.

It uses a maximum of 1.9kW of electricity to move up to 5.2kW of heat in best circumstances. That's a CoP of 2.74. And it's definitely not as efficient as they get.

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samskiter OP t1_j1co3h0 wrote

There are residential heat pumps with SCOP (seasonal cop) of 5.

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bluesam3 t1_j1b6eed wrote

Yes, 3.0 is a very achievable number for a residential heat pump in a mild-ish climate.

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