A furnace wall consists of 120 mm thick refractory brick and 120 mm thick insulating fire brick separated by an air gap. The outer wall of the furnace after the insulating fire brick is covered with 12 mm thick plaster. The inner surface of the furnace wall (refractory brick layer) is at 1090˚C and the room temperature is 20˚C. The heat transfer coefficient from the outside wall surface to the air in the room is 18 W/m2˚C, and the resistance to heat flow of the air gap is 0.16 K/W. If the thermal conductivities of the refractory brick, insulating fire brick, and plaster are 1.6 W/mK, 0.3 W/mK and 0.14 W/mK, respectively. Sketch the thermal resistance network. Calculate: Rate at which heat is lost per m2 of the wall surface Each interface temperature Temperature of the outside surface of the wall.
