Select fouling factor, clean overall heat-transfer coefficient, or fouled overall heat-transfer coefficient and enter the other two values. Use the same area basis and comparable operating conditions. Imperial resistance is measured in h·ft²·°F/Btu.

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Use overall heat-transfer coefficients on the same area basis under comparable operating conditions.

Fouling Factor Formula

The following formula is used to calculate the fouling factor:

FF = (1) / (Uf) - (1) / (Uc)

Variables:

  • FF is the fouling factor (m²K/W)
  • Uf is the overall heat-transfer coefficient when the surface is fouled (W/m²K)
  • Uc is the overall heat-transfer coefficient when the surface is clean (W/m²K)

To calculate the fouling factor, subtract the inverse of the clean overall heat-transfer coefficient from the inverse of the fouled overall heat-transfer coefficient.

What is a Fouling Factor?

The fouling factor is a parameter used in the design and operation of heat exchangers. It accounts for the resistance to heat flow caused by the accumulation of fouling materials on the heat transfer surfaces. Fouling can be caused by various factors such as corrosion, scaling, biological growth, or sedimentation. The fouling factor is critical for ensuring that heat exchangers operate efficiently and for predicting the need for maintenance or cleaning.

How to Calculate Fouling Factor?

The following steps outline how to calculate the Fouling Factor.

  1. First, determine the clean heat transfer coefficient (Uc) in W/m²K.
  2. Next, determine the fouled heat transfer coefficient (Uf) in W/m²K.
  3. Next, gather the formula from above: FF = (1/Uf) – (1/Uc).
  4. Finally, calculate the Fouling Factor (FF) in m²K/W.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Clean heat transfer coefficient (Uc) = 1500 W/m²K

Fouled heat transfer coefficient (Uf) = 1000 W/m²K