A 50 mm diameter pipe of circular cross section and with walls 3 mm thick is covered with two concentric layers of lagging, the inner layer having a thickness of 25 mm and a thermal conductivity of 0.08 W/m-K, and the outer layer a thickness of 40mm and a thermal conductivity of 0.040 W/m-K. What is the rate of heat loss per metre length of pipe if the temperature inside the pipe is 550K and the outside surface temperature is 330K? A. 62.7 W/m B. 74.7 W/m C. 82.5 W/m D. 98.3 Wlm

A plane wall has a thermal conductivity of 20 W/(m-K) and generates heat at 0.5 MW/m3. The wall is 0.2 meters thick and is perfectly insulated on one side. The other side is exposed to fluid at 100 °C. The convective heat transfer coefficient between the wall and the fluid is 400 W/(m2 K). Determine the maximum temperature in the wall.

An experiment to measure the thermal conductivity of food formulations was carried out by measuring the surface temperature of the food formulations which were formed into flat plates with a thickness of 10 mm. It is found that at steady-state conditions, there is a temperature difference of 40 ° C between the two surfaces, the heat transfer rate per unit area of 4700 W / m2 is measured near the center of the two surfaces. Calculate: the thermal conductivity of the product, = AnswerW / m ° C

Steel pipe (outer diameter 100 mm) is covered with two layers of insulation. The inner layer, 40 mm thick, has a thermal conductivity of 0.07 W / (m K). The outer layer, 20 mm thick, has a thermal conductivity of 0.15 W / (m K). Pipes are used to deliver steam with a pressure of 700 kPa. The temperature on the outer insulation surface is 24 ° C. If the pipe is 10 m long, determine the following: (assuming that the conduction heat transfer resistance of the steel pipe and the vapor convection resistance are negligible). a. Heat loss per hour. = AnswerkJ / hour. b. Temperature between insulation layers. = Answer° C.