A furnace of 70- by 60- by 90-cm inside dimensions is constructed of a material having a thermal conductivity of 1.05 kJ/kg °C. The wall thickness is 15 cm. The inner and outer surface temperatures are 500 and 100 °C, respectively. Calculate the heat loss through the furnace wall.

.240mm steam main pipe, 210m long is covered with 50mm of high temperature insulation (k-0.092 W/m °C) and 40mm of low temperature insulation (k-0.062 W/m °C). The inner and the outer surface temperature as measured are 390 °C and 40 °C respectively. Calculate: 1- The total heat loss per hour. 2- The temperature between two layers of insulation.

An industrial cold room has four 200 mm thick walls made of concrete. The walls are insulated on the outside with a layer of foam 60 mm thick. Cladding with a thickness of 15 mm protects the foam on the outside from the elements. The composite wall surface temperatures are –3 °C on the inside and 18 °C on the outside of the room respectively. The thermal conductivities of concrete, foam and cladding are 0.75, 0.35 and 0.5 W/m K respectively. a) Assuming perfect thermal contact between the layers of the composite walls, draw the typical temperature distribution across the layers and determine the heat energy gained per hour through all 4 walls of the room with a total surface area of 20 m2 . What does this heat energy represent in terms of the refrigeration system of the cold room?

In a multi-layered square wall, the thermal resistance of the first layer is 0.005 ° C / W, the resistance of the second layer is 0.4 ° C / W, and the third layer is 0.1 ° C / W. The overall temperature gradient in the wall is multilayered from one side. to the other side is 60 ° C. a. Determine the heat flux through the walls. = Answerwatt / m2. b. If the thermal resistance of the second layer is changed to 0.2 ° C / W, what is the effect in% on heat flux, assuming the temperature gradient remains the same? = AnswerAnswer%.

4. A bilayer polymer slab (1.2m long, 1.4m wide, 5 cm thick) is placed on a hot plate, which keeps the side of the slab touching the hot plate at 105C. The thermal conductivity of Layer 1 (2 cm thick) is 0.44 W/mK and the thermal conductivity of Layer 2(3 cm thick) is 0.67 W/m K. If the air surrounding the slab is 27 C and the convective heat transfer coefficient between the top of the slab and the air is 20 W/m²K. What is the rate of heat transfer from the side of the slab touching the hot plate to the air?