Question

The inner and outer surfaces of a 4-m x 10-m brick wall of thickness 20 cm are maintained at temperatures of 168C and 48C, respectively. If the rate of heat transfer through the wall is 1250 W, determine the rate of entropy generation within the wall.

Answer 1

Answer: Rate if entropy generated is 1.06W/K

Explanation: The rate of entropy generation can be determined from the rate of heat lost by the inner wall and the heat gained by the outer wall

S= Q[1/Tout - 1/Tin]

S is the entropy generated

Q is the heat

Tout is the temperature of outer wall = 48+273=321K

Tin is the temperature of inner wall= 168+273=441K

S=1250[ 1/321 - 1/441]

S= 1.06W/K