Question

A solid concrete wall 4.0 m by 2.4 m and 30 cm thick, with a thermal conductivity of 1.3 w/(m·k), separates a basement at 18°c from the ground outside at 6°c. how much heat flows through the wall in one hour?

Answer 1

THE AREA OF THE ROOM IS :A=4*2.4=9.6 m^2
THICKNESS t=0.30 m
DIFFERENCE IN TEMPERATURE dT=18-6=12
q=kAdT/dx=kA*dT/t
q=1.3(9.6)(12)/0.30=4992 W=499.2 J/s
In 1 hour or 3600 sec
P=q*T=(499.2 J/s)(3600 s)=1797120 J=1.8 MJ
1.8MJ OF HEAT FLOWS HTROUGH THE WALL IN ONE HOUR