Question

The overall heat transfer coefficient of a counter current heat exchanger based on clean
w
surface is 800
After 5 years, a scale is formed on the surface so that the heat
m'.°c
transfer rate is reduced to 75% of its original value based on clean surface. Assume that
the change in heat transfer area due to scale formation is negligible Calculate the fouling
factor​

Answer 1

The fouling factor can be calculated using the formula:

Fouling factor = (1/Uo - 1/Ui) x Ai

where Uo is the overall heat transfer coefficient based on a clean surface, Ui is the overall heat transfer coefficient based on fouled surface, and Ai is the heat transfer area.

Given that Uo = 800 m'°C/W and the heat transfer rate is reduced to 75% of its original value based on a clean surface, Ui can be calculated as:

Ui = Uo / 0.75 = 1066.67 m'°C/W

Assuming that the heat transfer area is constant and negligible, the fouling factor can be calculated as:

Fouling factor = (1/800 - 1/1066.67) x A

Fouling factor = 0.00066667 A

Therefore, the fouling factor is directly proportional to the area and can be calculated if the area is given.