Heater temperature 227 C. Determine the efficiency of an ideal motor and the temperature of the refrigerator

Heater temperature 227 C. Determine the efficiency of an ideal motor and the temperature of the refrigerator if, for every kilojoule of energy received from the heater, the motor performs 350 Joules of mechanical work.

Data: Тн (engine heater temperature) = 227 ºС (500 К); Qн (heat from the heater) = 1 kJ = 1000 J; A (perfect work) = 350 J.

1) The efficiency of the motor used: η = A / Qн = 350/1000 = 0.35 (35%).

2) Refrigerator temperature: η = 1 – Тх / Тн, whence we express: Тх = (1 – η) * Тн = (1 – 0,35) * 500 = 325 К (52 ºС).

Answer: The motor used has an efficiency of 35%, the refrigerator has a temperature of 325 K (52 ºC).