How is it that a machine (like a heat pump) can consume 1kw of power and produce an amount greater than that of heat? What am I misunderstanding?
In: 320
Efficiency is (what you get)/(what you put in). In this case, what you get is hotter air, and what you put in is work. There is also heat input from the cold air, but we aren’t “paying” for that and so it isn’t included in the efficiency metric.
When the heat pump is operating steadily, the energy input to the cycle matches the energy output. This means the heat out to the hot room will be equal to the heat input from the cold outdoors plus the work input from electricity. This means the efficiency fraction as defined above must be bigger than 1.
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