Q145
A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100°C and leaves at 60°C. A cold fluid enters the heat exchanger at 40°C. The mean temperature difference between the two fluids is
A.
20°C
AnswerB.
40°C
C.
60°C
D.
66.7°C
Answer: Option A
Solution
Answer: Option A
Solution:
tm = mean temperature difference between the two fluids for counter flow heat exchangertm = th1 - tc2 = th2 - tc1
tm = th2 - tc1 = 60 - 40 = 20.