1561. Fouling factor for a heat exchanger is given by (where, U₁ = heat transfer co-efficient of dirty surface U₂ = heat transfer co-efficient of clean surface) September 7, 2025 by Admin U₁ – U₂ 1/U₁ – 1/U₂ 1/U₂ – 1/U₁ U₂ – U₁ ✅ The correct answer is option B.
