An ideal, reversible refrigerator keeps food in the freezer portion at −15°C and dumps excess heat into the kitchen, whose temperature is 20°C. What is the refrigerator's coefficient of performance under these conditions?
A) 7.4
B) 4.0
C) 8.4
D) 2.1

Question

Quizplus · Accepted Answer

The coefficient of performance (COP) for a refrigerator is given by the formula COP = T_c / (T_h - T_c), where T_c is the absolute temperature of the cold reservoir and T_h is the absolute temperature of the hot reservoir. Converting the temperatures to Kelvin, T_c = 258 K and T_h = 293 K. Thus, COP = 258 / (293 - 258) = 7.4.

An Ideal, Reversible Refrigerator Keeps Food in the Freezer Portion