6.9 Refrigerator

6.9 Refrigerator

Refrigerator is a device which maintains the temperature of a body below that of its surrounding. It operates in a cyclic process but in reverse as that of the heat engine as shown in Fig. 6.10. A refrigerator absorbs heat from a cold reservoir and gives it off to a hot reservoir. This shows that in a refrigerator, the work is done on the system while in a heat engine work is done by the system.

A refrigerator works on the basis of Clausius statement of second law of thermodynamics, i.e., a heat engine is operating in reverse. Heat $Q_{C}$ is drawn from Low Temperature Reservoir (LTR) $T_{1}$, by compressor and is thrown into High Temperature Reservoir (HTR) $T_{2}$ with the help of external work done. The heat rejected to HTR ($Q_{H}$) is given by:

The main purpose of refrigerator is to extract as much heat $Q_{C}$ as possible from LTR with the expenditure of as little work $W$ as possible.