Coefficient of performance of the cooling machine

A cooling machine is a machine that takes heat from a low-temperature place, then transfers it to a high-temperature area. For this process to happen, the machine must do the work, because the heat naturally flows from high temperature to low temperature. This is by Clausius’s statement:

It is impossible for a cooling machine to transfer heat from a low-temperature place to a high-temperature place, without work (Second law of thermodynamics – Clausius statement).

The machine works (W) to transfer heat, from low temperature (Q

L) to high temperature (QH). Based on conservation of energy, QL + W = QH.

If the heat engine uses the term efficiency, then the refrigerant uses the term coefficient of performance (CP). The coefficient of performance (CP

) of refrigerant is the ratio between heat transferred from low temperature (QL) to work (W), which is done to transfer heat.

Coefficient of performance cooling machine 1

Ideal cooling machine’s coefficient of performance :

Coefficient of performance cooling machine 2
TL = low temperature, TH = high temperature