Heat is lost through a plane wall steadily at a rate of 750W. If the inner and outer surface temperatures of the wall are 50C and 15C respectively the rate of entropy generation within the wall is.

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Solution

Definitions and Equations:
Entropy = S
Heat Flow = Q =
Temperature = T
S = Q/T

Entropy Generated = ΔS = S_Out - S_In

Q = 750 W

T_In = 50^oC = 323K

T_Out= 15^oC = 288K

Caclculations:

S_In = Q/T_In = 750 W/ 323K = 2.322 W/K

S_Out = Q/T_Out = 750 W / 288K = 2.604 W/K

Therefore....

ΔS = S_{Out -} S_{In = (2.604 - 2.322) W/K = ......}