A Carnot refrigerator is operated between two heat reservoirs at temperatures of 320 K and 270 K. (a) If in each cycle the refrigerator receives 415 J of heat energy from the reservoir at 270 K, how many joules of heat energy does it deliver to the reservoir at 320 K? (b) If the refrigerator completes 165 cycles each minute, what power input is required to operate it? (c) What is the coefficient of performance of the refrigerator?

Solution 17E Step 1: Data given Temperature T = 120 K Temperature T = 270 K 2 Heat received at T_1 Q =1415J Number of cycles per minute = 165 cycles Step 2 : We need to find heat received at temperatureT 2 This is obtained as Q 1 T1 Q = T 2 2 Substituting we get 415 J 320 K Q = 270 K 2 Solving for Q 2 Q 2 1.185 K × 415 J Q = 492 J 2 This can be approximated to 492 J