A 0.10 m thick wall with k=0.50 W/(m K), area 8.0 m2, and face temperatures 120 and 30 degrees C conducts heat at a rate most nearly:
- (A)3600 W
- (B)4320 W
- (C)5400 W
- (D)7200 W
Show worked solution
Answer: (A)
Fourier conduction gives Q=kA delta T/L=3,600 W.
One-dimensional steady wall conduction is proportional to area and temperature difference.
The temperature difference is 90 K.
FE Reference Handbook — Heat Transfer: Plane-Wall Conduction
Why the other choices appear
- (B)Applying an unsupported 20% final scaling overstates the result obtained from the governing relation.
- (C)Applying an unsupported 50% final scaling overstates the result obtained from the governing relation.
- (D)Using half the wall thickness doubles heat rate.