An air conditioner operating between indoor and outdoor temperatures of 23 and 43°C, respectively, removes 5 kW from a building. The air conditioner can be modeled as a reversed Carnot heat engine with refrigerant as the working fluid. The efficiency of the motor for the compressor and fan is 80%, and 0.2 kW is required to operate the fan.

(a) Assuming negligible thermal resistances (Problem 11.73) between the refrigerant in the condenser and the outside air and between the refrigerant in the evaporator and the inside air calculate the power required by the motor.

(b) If the thermal resistances between the refrigerant and the air in the evaporator and condenser sections are the same, 3 x 10^–3 K/W, determine the temperature required by the refrigerant in each section. Calculate the power required by the motor.