The rate of heat transfer through a pipe wall is given by, q = 2? k (Ti- T0)/ln (ri /r0). For cylinder of very thin wall, q can be approximated by
A)q = [2? k (Ti + T0)/2]/ln (ri /r0)
B)q = 2? ri k (Ti- T0)/(r0/ri)
C)q = 2? k (Ti- T0)/(r0/ri)
D)q = 2? k (Ti- T0)/[(r0 + ri)/2]

Question

Quizplus · Accepted Answer

For a cylinder of very thin wall, the logarithmic term ln(ri/r0) in the original equation can be approximated by the difference (ri - r0) divided by the average radius [(ri + r0)/2], simplifying the expression to the form given in option D.

The Rate of Heat Transfer Through a Pipe Wall Is