A room contains 60 kg of air at 100 kPa and 15°C. The room has a 250-W refrigerator (the refrigerator consumes 250W of electricity when running), a 120-W TV, 1-kW electric resistance heater and a 50-W fan. During a cold winter day, it is observed that the refrigerator, the TV, the fan and the electric resistance heater are running continuously but the air temperature in the room remains constant. The rate of heat loss from the room that day is
- A. 3312 kJ/h
- B. 4752 kJ/h
- C. 5112 kJ/h
- D. 2052 kJ/h
Answer: C. 5112 kJ/h
Explanation: Energy in = Energy out. Total Power In = 250 + 120 + 1000 + 50 = 1420 W = 1.42 kW. Heat Loss = 1.42 kJ/s = 1.42 * 3600 kJ/h = 5112 kJ/h.