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nti in ework #l-Heat transfer basics (conduction) Due: Wednesday Sep 12 1.(40 po

ID: 717879 • Letter: N

Question

nti in ework #l-Heat transfer basics (conduction) Due: Wednesday Sep 12 1.(40 points) Find the thermal conductivity of common brick at 300 K. Provide the source (Table number and authors). 2. (60 points) The wall of a house is constructed from uninsulated 6-inch-thick common brick. Measurements made during a winters day reveal temperatures of 80 °F and 20 °F at the inner and outer surfaces, respectively. What is the rate of heat loss through the wall given that is 30 feet wide and 10 feet high assuming one dimensional heat transfer.

Explanation / Answer

Ans 2

From the Fouriers law of heat conduction

Q = - kA(T2 - T1) /t

k = thermal conductivity of common brick = 0.72 W/m-K

A = Area = 30 ft x 10 ft x (0.305m/1ft)2

= 27.91 m2

Thickness t = 6 in x 1m/39.37in = 0.152 m

Inner Temperature T1 = (80°F + 459.67) x 5/9

= 299.8 K

Outer temperature T2 = (20°F + 459.67) x 5/9

= 266.48 K

Rate of heat loss

Q = - 0.72 x 27.91 x (266.48 - 299.8) / (0.152)

= 4405 W