Question

Thermodynamics

A 29-L electrical radiator containing heating oil is placed in a 41-m3 room. Both the room and the oil in the radiator are initially at 10°C. The radiator, with a rating of 1.8 kW, is now turned on. At the same time, heat is lost from the room at an average rate of 0.35 kJ/s. After some time, the average temperature is measured to be 20°C for the air in the room, and 50°C for the oil in the radiator. Taking the density and the specific heat of the oil to be 950 kg/m3 and 2.2 kJ/kg.°C, respectively, determine how long the heateir has been on. Assume that the room is tightly sealed, so that no air infiltrates or leaks out during the process. Room 10°C Radiator

Answer 1