A small building that shelters a water supply pump measures 4 m Times 6 m Times
ID: 988516 • Letter: A
Question
A small building that shelters a water supply pump measures 4 m Times 6 m Times 2.4 m. It is constructed of wood (1-cm thick) with a thermal conductivity of 0.126 W/m-K. The inside walls must be maintained at 10 degreeC. When the outside temperature is -18 degree C, how much heat must be supplied each hour to maintain the desired inside temperature? How much heat must be supplied if the walls are lined with 10 cm of glass wool insulation with a thermal conductivity of 0.0377 W/m K? You may neglect the contribution of the wood layer for this calculation.Explanation / Answer
7. a. heat supplied/h = Area x thermal conductivity x dT/thickness
Area = 4 x 6 x 2.4 = 57.6 m^3
thickness = 1 cm = 0.01 m
thermal conductivity = 0.126 W/m.K
we get,
heat required to be supplied = 57.6 x 0.126 x (-18 - 10)/0.01 = -2032
b. The total heat required to be supplied in this case, using the same formula as above,
heat supplied = 57.6 x 0.0377 x (-18 -10)/0.1 = -608.02