Problem Set #10 - Radiation Heat Transfer 1. A 3m-diameter biomass boiler is operating in an enclosed room 15m x 15m. The height of the boiler is 3m, and the height of the room is 5m. The surface temperature of the boiler is 200 C, and the surface temperature of the walls of the room is 30 C. If the boiler walls are made out of painted steel (& = 0.95), and the room walls are painted brick (& = 0.85), calculate the heat lost due to radiation. Note: neglect heat transfer from the top and bottom surfaces of the boiler T2 T, = 200"C Note : surface area of a 15 m T 2 = 30 "C cylinder = Trah boiler E , = 0,95 *- 3m E, = 0.85 A = Tidh - 5 - boiler height = 3 m - 15 m room height = 5 m 2. To reduce the heat loss from the boiler in Problem #1, a thermal radiation shield is installed around the boiler. The shield is a cylinder with a diameter of 5m and a height of 5m. It is made of polished aluminum with & = 0.05. Calculate the heat lost due to radiation, and the reduction in heat loss due to the thermal radiation shield. T 2 T , = 200 C shield T2 = 30 " C 15 m boiler E , = 0.95 Ez = 0. 85 Eshield = 0,05 * 5 m boiler height = 3 m * 15m room height = 5 m shield height = 5 m 37