Thermal Resistance Due To Fouling Deposits
Surface coatings can build on heat transfer surfaces during heat exchanger operation due to fouling. These add extra thermal resistance to the wall and may noticeably decrease the overall heat transfer coefficient and thus performance. (Fouling can also cause other problems.)
The additional thermal resistance due to fouling can be found by comparing the overall heat transfer coefficient determined from laboratory readings with calculations based on theoretical correlations. They can also be evaluated from the development of the overall heat transfer coefficient with time (assuming the heat exchanger operates under otherwise identical conditions). This is commonly applied in practice, e.g. The following relationship is often used:
- =
where
- = overall heat transfer coefficient based on experimental data for the heat exchanger in the "fouled" state,
- = overall heat transfer coefficient based on calculated or measured ("clean heat exchanger") data,
- = thermal resistance due to fouling,
Read more about this topic: Heat Transfer Coefficient
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