Mechanical Engineering - Heat transfer - Heat Exchanger :What the value of effectiveness of very long concentric tube heat exchanger in counter flow ????????

Answer:

Why counter flow heat exchanger is more effective?

Counter flow heat exchangers are inherently more efficient than parallel flow heat exchangers because they create a more uniform temperature difference between the fluids, over the entire length of the fluid path. ... For example, one fluid may make 2 passes, the other 4 passes.

Explanation:

How do you calculate the effectiveness of a heat exchanger?

The effectiveness (ϵ) of a heat exchanger is defined as the ratio of the actual heat transfer to the maximum possible heat transfer. Qmax is the minimum of these two values i. e.