Question

The thermal conductivity of a sheet of rigid, extruded insulation is reported to be k=0.029 W/m∙K. The measured temperature difference across a 20 mm thick sheet of the material is T1− T2=10 ℃. (a) What is the heat flux through a 2m×2m sheet of the insulation? (b) What is the rate of heat transfer through the sheet of insulation?

Answer 1

Answer:

a. 14.5 W/$m^{2}$

b. 58 W

Explanation:

Thermal conductivity k = 0.029 W/m∙K

Temperature difference ΔT = 10 ℃

Thickness of sheet x = 20 mm = 0.02 m

area of sheet = 2m x 2m = 4 $m^{2}$

a. heat flux q = k x (ΔT/x)

q = 0.029 x (10/0.02)

q = 0.029 x 500 = 14.5 W/$m^{2}$

b. Rate of heat transfer through the sheet  Q = heat flux x area

Q = 14.5 x 4 = 58 W