Are these statements about the heat exchangerstrue?
Statement 1: In parallel flow, the temperature difference between the two fluids is large at the entrance end, but it becomes small at the exit end.
Statement 2: The log mean temperature difference is greater for parallel flow.
a) True, False
b) True, True
c) False, True
d) False, False

Answer: a
Explanation: In parallel flow, both the fluids enter at one end and exit at the other end.the temperature difference between the two fluids is large at the entrance end, but it becomes small at the exit end. The log mean temperature difference is greater for counter flow. So the surface area of the parallel flow heat exchanger should be larger than for a counter flow heat exchanger.