A refrigerator used for cooling food in a grocery store is to produce a 10,000 \mathrm{~kJ} / \mathrm{h} cooling effect, and it has a coefficient of performance of 1.35 . How many kilowatts of power will this refrigerator require to operate?
The cooling effect and the COP of a refrigerator are given. The power input to the refrigerator is to be determined.
Assumptions The refrigerator operates steadily.
Analysis Rearranging the definition of the refrigerator coefficient of performance and applying the result to this refrigerator gives
\dot{W}_{\text {net,in }}=\frac{\dot{Q}_{L}}{\mathrm{COP}_{\mathrm{R}}}=\frac{10,000 \mathrm{~kJ} / \mathrm{h}}{1.35}\left(\frac{1 \mathrm{~h}}{3600 \mathrm{~s}}\right)=\mathrm{2 . 0 6} \mathrm{k W}