A cold storage room has walls made of 0.23 m of brick on the outside, 0.08 m of plastic foam, and finally 1.5 cm of wood on the inside. The outside and inside air temperatures are 22C and -2C, respectively. If the inside and outside heat transfer coefficients are respectively 29 and 12 W/m^2K, and the thermal conductivities of brick, foam and wood are 0.98, 0.02, and 0.17 W/mK, respectively, find
(a)the rate of heat removal by refrigeration if the total wall area is 90 m^2
(b)The temperature of the inside surface of the brick.
To solve this problem, draw a schematic diagram, clearly define different symbols for the different thickness, show these in your schematic diagram, define symbols for the conductivities, the heat transfer coefficients (inside and outside), the temperatures inside, outside, and intermediate points etc. Write down all equations necessary for this in a symbolic fashion. Finally substitute the valuesand find the heat transfer rate.