Re:Air-conditioners do great good, but at a high environment...
by kragen on Tuesday August 28, 2018 @03:26PM
(#17862056)
This is backwards; while it's true that a resistor is less mechanically complicated than a compressor-expander-condenser heat pump like an air conditioner, the coefficient of performance for a resistor is limited to 1 (and is very nearly 1, say 0.9999), while the coefficient of performance for such heat pumps is 2–6. That is, for every joule of energy you burn up in the compressor, you transfer 2–6 joules out of your living space into the outdoors.
I know, that sounds crazy, and sometimes the CoP is given as an "efficiency", which makes it sound even crazier — a CoP of 2.0 is "200% efficient"! But it's not science fiction; it's a simple consequence of the Carnot cycle being reversible and the Carnot efficiency of heat engines at ordinary temperatures being quite low.
I know, that sounds crazy, and sometimes the CoP is given as an "efficiency", which makes it sound even crazier — a CoP of 2.0 is "200% efficient"! But it's not science fiction; it's a simple consequence of the Carnot cycle being reversible and the Carnot efficiency of heat engines at ordinary temperatures being quite low.