A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of_________________?

Question

Accepted Answer

2. The film heat transfer coefficient is proportional to the square root of the mass flow rate. Since a two-pass unit effectively increases the total air passage area or residence time compared to a single pass for the same overall conditions, the ratio is expected to be 2.