Question

Consider a 20 cm thick granite wall with a thermalconductivity of 2.79 W/m·K. The temperature of the leftsurface is held constant at 50°C, whereas the right face isexposed to a flow of 22°C air with a convection heat transfercoefficient of 15 W/m2·K. Neglecting heat transfer by radiation, find the right wall surface temperature and the heat fluxthrough the wall.

Answer 1

Answer:

Q= 231.88 W/m²

Explanation:

Given that

L= 20 cm

K= 2.79 W/m·K

T₁=50°C

T₂= 22°C

h=15 W/m₂·K

The total thermal resistance

$R=\dfrac{L}{KA}+\dfrac{1}{hA}$

Now by putting the values

$R=\dfrac{L}{KA}+\dfrac{1}{hA}$

$R=\dfrac{0.2}{2.79A}+\dfrac{1}{15A}$

R= 0.138  K/W      ( for heat flux A= 1 m²)

Heat flux Q= ΔT/R

Q= (50-22)/0.138 = 32/0.138 W

Q= 231.88 W/m²