A well-insulated 4 - m 4-m 5-m room initially at 10C is heated by the radiator of a steam heating system. The radiator

A well-insulated 4 - m × 4-m × 5-m room initially at 10°C is heated by the radiator of a steam heating system. The radiator has a volume of 15 L and is filled with superheated vapor at 200 kPa and 200°C. At this moment both the inlet and the exit valves to the radiator are closed. A 150-W fan is used to distribute the air in the room. The pressure of the steam is observed to drop to 100 kPa after 30 min as a result of heat transfer to the room. Assuming constant specific heats for air at room temperature, determine
(a) The average temperature of room air in 24 min,
(b) The entropy change of the steam,
(c) The entropy change of the air in the room, and
(d) The exergy destruction for this process, in kJ. Assume the air pressure in the room remains constant at 100 kPa at all times, and take T0 = 10°C.

10c Steam radiator FIGURE P8-105