F-12 Improved Use of Fouling Allowances in Heat Exchanger Design

J. W. Palen

Arbitrary specification of fouling factors can lead to significantly oversized heat exchangers, resulting in unnecessary cost and poor operation. This report reviews the present use of fouling factors and recommends a fouling factor selection system using improved HTRI methods, which have reduced the need for design safety factors. While we recognize that a safety factor is still necessary to provide flexibility and to account for unforeseen problems, this report recommends that such factors be specified directly rather than being hidden in unrealistic, and often unnecessary, fouling resistances. As a result of these recommendations, informational messages are provided to be included in HTRI software to help users specify fouling allowances.