Question

A composite plane wall consists of a Li = 50 mm thick layer of insulation (ki = 0.05 W/m.K) and a Ls = 25 mm thick layer of siding (ks = 0.10 W/m.K). ​The inner temperature of the insulation is 20oC. The outer temperature of the siding is -10oC.​Steady state conditions apply.

​Determine the temperature at the interface between the two layers, in oC, and the rate of heat transfer through the wall, in W per m2 of surface area.
1/ The rate of one-dimensional conduction heat transfer per unit area through a wall is proportional to the:
A. average temperature.
B. wall thickness.
C. absolute temperature.
D. temperature gradient.

Answer 1

The rate of heat conduction through a wall is proportional to the temperature gradient.

Step-by-step explanation:

The rate of one-dimensional conduction heat transfer per unit area through a wall is proportional to the temperature gradient. Therefore, the correct option is D. temperature gradient.

The temperature gradient is determined by the difference in temperature between the two surfaces of the wall divided by the thickness of the wall.