A 4-m 5-m 7-m room is heated by the radiator of a steam-heating system. The steam radiator transfers heat at a rate of

A 4-m × 5-m × 7-m room is heated by the radiator of a steam-heating system. The steam radiator transfers heat at a rate of 10,000 kJ/h, and a 100-W fan is used to distribute the warm air in the room. The rate of heat loss from the room is estimated to be about 5000 kJ/h. If the initial temperature of the room air is 10oC, determine how long it will take for the air temperature to rise to 20oC. Assume constant specific heats at room temperature.

5000 kJ/h 4 m x5 m X 7 m 10,000 kJ/h Steam pw FIGURE P4-65