When a heat pump is used to cool we call it a refrigerator or perhaps
an air-conditioning system depending on the circumstances. For such a system
our main concern is to remove heat from the system we wish to cool and
so we define the efficiency of a refrigerator as follows
The process is no different from that described above only the definition of efficiency
is different. Correspondingly we get a slightly lower efficiency for cooling. The most efficient
refrigerator is based on the Carnot cycle and has an efficiency
