Subtopic: Steady state heat transfer in conduction, convection and radiation
Question Statement:
In the design of sanitary tubular heat exchangers for processing liquid dairy products, the overall heat transfer resistance $\frac{1}{U}$ accounts for fouling layers via the expression:
Thermal resistances in series are additive: total resistance is the sum of inside convective film resistance ($1/h_i$), inside milk fouling fouling resistance ($R_{f,i}$), tube wall conduction resistance ($x_w/k_w$), outside fouling resistance ($R_{f,o}$), and outside convective resistance ($1/h_o$).