Question 7.52: A food refrigerator is to provide a 15,000 kJ/h cooling effe......

The cooling effect and the rate of heat rejection of a refrigerator are given. The COP of the refrigerator is to be determined.

Assumptions The refrigerator operates steadily.

Analysis Applying the first law to the refrigerator gives

\dot{W}_{\text {net,in }}=\dot{Q}_{H}-\dot{Q}_{L}=22,000-15,000=7000 \mathrm{~kJ} / \mathrm{h}

Applying the definition of the coefficient of performance,

\mathrm{COP}_{\mathrm{R}}=\frac{\dot{Q}_{L}}{\dot{W}_{\text {net,in }}}=\frac{15,000 \mathrm{~kJ} / \mathrm{h}}{7000}=\mathrm{2 . 1 4}