Here are the step-by-step workings to solve this problem:
Given:
Outside temperature is 15°C
Inside temperature is 22°C
Window area is 75 m x 0.5 m = 37.5 m^2
Wind speed through window is 1.2 m/s
We want to find the thermal power transfer out of the room.
We use the heat transfer equation:
Q = UAΔT
Where:
Q is the heat transfer rate (power)
U is the heat transfer coefficient
A is the area
ΔT is the temperature difference
The heat transfer coefficient for natural convection and an open window is ~ 8 W/(m^2K)
U = 8 W/(m^2K)
The window area is 37.5 m^2
A = 37.5 m^2
The temperature difference is 22°C - 15°C = 7 K
ΔT = 7 K
Plugging into the equation:
Q = UAΔT
Q = (8 W/(m^2K)) * (37.5 m^2) * (7 K)
Q = 2100 W
Therefore, the thermal power transfer out of the room is 2100 W.
The key steps are:
Using the heat transfer equation Q = UAΔT
Finding the relevant values for U, A, and ΔT
Plugging those values into the equation to calculate Q, the heat transfer rate
Hope this helps! Let me know if you have any other questions.