Fouling Factor

A fouling factor is an added thermal resistance applied in heat-exchanger design to account for deposits — scale, sludge, biofilm — that build up on heat-transfer surfaces over time. It de-rates the clean performance to a realistic in-service value.

No heat exchanger stays clean in service; layers of mineral scale, corrosion products, dirt or biological growth insulate the surface and cut heat transfer. Designers include a fouling factor — an extra resistance term in the overall heat-transfer coefficient — so the exchanger is sized with enough surface to still meet duty when dirty. Tracking the rising fouling factor over time also signals when cleaning is due.

Related terms

Heat Exchanger · Log Mean Temperature Difference (LMTD) · Cycles of Concentration