Clausius Statement of the Second Law of thermodynamics is the following: It is impossible to construct a device that operates in a cycle and produces no effect other than the transfer of heat from a lower-temperature body to a higher-temperature body. In order to accomplish heat transfer from cold to hot – you need a device, like a heat pump or refrigerator, which consumes work: Energy from the surroundings in the form of work or heat has to be expended to force heat to flow from a low-temperature media to a high-temperature media. Thus, the coefficient of performance of a refrigerator or heat pump must be less than infinity. For a refrigerator it is equal to: