A small building that shelters a water supply pump measures 2 m x 3 m x 2.4 m hi
ID: 1826501 • Letter: A
Question
A small building that shelters a water supply pump measures 2 m x 3 m x 2.4 m high. It is constructed of 1- cm thick wood having a thermal conductivity of 0.126 W*m^-1*K^-1. The inside walls are to be maintained at 10 degrees C when the outside temperature is -18 degrees C. How much heat must be supplied to maintain the desired temperature? How much heat must be supplied if the walls are lined with 10cm of glass-wool insulation having a thermal conductivity of 0.0377W.m^-1? Assume there is no heat loss through the floor. Ignore the wood in the second calculation.Explanation / Answer
Q=KA(dT/dx)
Area = Top panel + 2 Side panel + 2 Side Panel
= 2*3 + 2*2.4*2 + 2*3*2.4 = 30m^2
dT= (10-(-18) = 28 C
Thick Wood Q= 0.126*30*28/0.01= 10584J
Glass Wool Q = 0.0377*30*28/0.1 = 316.68J