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 m^2. What does this heat energy represent in terms of the refrigeration system of the cold room? b) Without any calculations, how would you expect the internal and external air temperatures to be relative to the wall surface temperatures?c) How do you expect the heat gain calculated in question 1a) above to change if you take into account the floor and the ceiling of the cold room?

Question

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 m^2. What does this heat energy represent in terms of the refrigeration system of the cold room?

b) Without any calculations, how would you expect the internal and external air temperatures to be relative to the wall surface temperatures?

c) How do you expect the heat gain calculated in question 1a) above to change if you take into account the floor and the ceiling of the cold room?