Thermal resistance due to fouling deposits (general)


Often during their use, heat exchangers collect a layer of fouling on the surface which, in addition to potentially contaminating a stream, reduces the effectiveness of heat exchangers. In a fouled heat exchanger the buildup on the walls creates an additional layer of materials that heat must flow through. Due to this new layer, there is additional resistance within the heat exchanger and thus the overall heat transfer coefficient of the exchanger is reduced. The relationship shown here is used to solve for the heat transfer resistance with the additional fouling resistance.

Related formulas


Ufoverall heat transfer coefficient for a fouled heat exchanger (W/m2*K)
Pperimeter of the heat exchanger (m)
Uoverall heat transfer coefficient for an unfouled heat exchanger (W/m2*K)
RfHfouling resistance on the hot side of the heat exchanger (m2*K/W)
PH perimeter of the hot side of the heat exchanger (m)
RfCfouling resistance on the cold side of the heat exchanger (m2*K/W)
PCperimeter of the cold side of the heat exchanger (m)