Question

2.1Consider a solid cylindrical rod of length 0.15 m and diameter 0.05 m. The top and bottom surfaces of the rod are maintained at constant temperatures of 20oC and 95oC, respectively, while the side surface is perfectly insulated. 2.1.1 Draw a diagram to represent the situation described above. (3) 2.1.2 Determine the rate of heat transfer through the rod if it is made of copper, k = 380 W/m? oC. (4) 2.1.3 Determine the rate of heat transfer through the rod if it is made of steel, k = 18 W/m? oC. 2.1.4 Determine the rate of heat transfer through the rod if it is made of granite, k = 1.2 W/m? oC. (2) 2.1.5 Comment on the answers you calculated for the rate of heat transfer for copper, steel and granite. (2) 2.2A 2 m x 1.5 m section of wall of an industrial furnace burning natural gas is not insulated, and the temperature at the outer surface of this section is measured to be 80oC. The temperature of the furnace room is 30oC, and the combined convection and radiation heat transfer coefficient at the surface of the outer furnace is 10 W/m2 ? oC. It is proposed to insulate this section of the furnace wall with glass wool insulation (k = 0.038 W/m? oC) in order to reduce the heat loss by 90%. Assuming the outer surface temperature of the metal section still remains at about 80oC, determine the thickness of the insulation that needs to be used

Answer 1