Heat Transfer in Condensers:

In a water-cooled condenser the heat transfer is described by the Equation given below

              ...3.18

Here U indicates the overall heat transfer coefficient depends on the surface area A of the condenser and ?t indicate the overall temperature difference. Given figure illustrate the components of the heat-transfer resistance in a water-cooled condenser, like as the outside metal wall, refrigerant film, scaling on water-side surface & inside- water film. The whole resistance is attained by adding all the resistances that are in series.

    Thermal Resistance in Water-Cooled Condenser

Here

U₀ = Overall heat-transfer coefficient depend on the outside surface area

h₀= Condensing film coefficient of heat transfer

A₀ = Outside or refrigerant-side area

k = Thermal conductivity of the tube material

A_m = Mean tube surface area

h_f = Coefficient of heat transfer through the scale

A_i = Inside or water-side area

h_i= Water-side coefficient of heat transfer.

Therefore the overall heat-transfer coefficient may be found out from the above Equation 3.19 after determining the individual resistances.