Question

Estimate the rate of heat loss through a glass window of area 2m^2 and thickness 3mm when the temperature of the room is 20 degree celcius and that of air outside is 5 degree celsius

Answer 1

Answer:

See below.

Explanation:

We can calculate the rate of heat loss by assuming that the heat is loss to the surroundings ( outside the room ) by conduction.

In this case, the thickness of the window becomes the length of the conductor. We use the expression,

$\begin{aligned}H=KA\dfrac {dT}{dx}\\ =KA\dfrac {\left( T_{2}-T_{1}\right) }{l}\end{aligned}$

Where H is the rate of heat transfer. The thermal conductivity ( K ) of glass is 0.96 W/m/K. Plugging the values,

$\begin{aligned}H=\left( 0.96\right) \left( 2\right) \dfrac {\left( 20-5\right) }{3\times 10^{-3}}\\ =0.96\times 10^{4}\\ =9.6\times 10^{3} \ W \ m^{-1} \ K^{-1}\end{aligned}$