Question

A window has a glass surface of 2907 cm2 and a thickness of 5.6 mm. Find the rate of energy transfer by conduction through this pane when the temperature of the inside surface of the glass is 71◦F and the outside temperature is 81 ◦F. Assume the thermal conductivity of window glass is 0.8 J/s · m · ◦ C . Answer in units of kW

Part BFind the rate of energy transfer for the same inside temperature and an outside temperature of 0◦F.

Answer 1

2.30714 W

-16.38071 W

Step-by-step explanation:

k = Heat conduction coefficient = 0.8 W/(m·°C)

A = Area = 2907 cm²

l = Thickness = 5.6 mm

`T_2` = Outside temperature

`T_1` = Inside temperature

Rate of heat transfer is given by

`Q=(kA(T_2-T_1))/(l)\\\Rightarrow Q=(0.8* 2907* 10^(-6)* (81-71)* (5)/(9))/(5.6* 10^(-3))\\\Rightarrow Q=2.30714\ W`

The rate of energy transfer is 2.30714 W

`Q=(kA(T_2-T_1))/(l)\\\Rightarrow Q=(0.8* 2907* 10^(-6)* (0-71)* (5)/(9))/(5.6* 10^(-3))\\\Rightarrow Q=-16.38071\ W`

The rate of energy transfer is -16.38071 W