In a mechanical refrigerator, the low temperature coils are at a temperature of -23°C and the compressed gas in the condenser has a temperature of 27 °C. The theoretical coefficient of performance is:

Coefficient of performance of refrigerator is given asK=T2T1−T2, where T1 is absolute temperature of condenser and T2 is absolute temperature of coil.⇒K=(273−23)(273+27)−(273−23)⇒K=250300−250=25050=5Hence, coefficient of performance of refrigerator for given condition is 5.