Awell-insulated 2 m x 5 mx 6 m room initially at 8 °c is heated by the radiator of a steam heating system. the radiator has a volume of 80 l and is filled with superheated vapor at 500 kpa and 400°c. at t = 0 minutes both the inlet and exit valves to radiator are closed. a 40 w fan is used to distribute the air in the room. at t = 45 minutes, the pressure of the steam has dropped to 200 kpa because of heat transfer to the room. assuming constant specific heats for air at room temperature, determine the average temperature of air at t = 45 minutes. assume the air pressure in the room remains constant at 100 kpa.