(d) Explain why a heat pump is better than an electric furnace, which simply converts electrical work directly into heat. (b) What relation among Q h, Q c, and W is implied by energy conservation alone? Will energy conservation permit the COP to be greater than 1 ? (c) Use the second law of thermodynamics to derive an upper limit on the COP, in terms of the temperatures T h and T c alone. T h = temperature inside building T c = temperature outside Q h = heat pumped into building in 1 day Q c = heat taken from outdoors in 1 day W = electrical energy used by heat pump in 1 day (a) Explain why the "coefficient of performance" (COP) for a heat pump should be defined as Q h / W. Let us define the following standard symbols, all taken to be positive by convention: In other words, it's the same as a refrigerator, but its purpose is to warm the hot reservoir rather than to cool the cold reservoir (even though it does both). A heat pump is an electrical device that heats a building by pumping heat in from the cold outside.
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