## Heat Transfer in Condensers

**Introduction:**

The overall heat-transfer coefficient can be determined after estimating the individual resistances.

**Description:**

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

where U is the overall heat transfer coefficient based on the surface area A of the condenser and Δt is the overall temperature difference. Figure shows the

components of the heat-transfer resistance in a water-cooled condenser, viz., the outside refrigerant film, metal wall, scaling on water-side surface and insidewater film. The overall resistance is obtained by adding all the resistances which are in series.

**Figure : Thermal Resistance in Water-Cooled Condenser**

where

U0 = Overall heat-transfer coefficient based 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

Am = Mean tube surface area

hf = Coefficient of heat transfer through the scale

Ai = Inside or water-side area

hi= Water-side coefficient of heat transfer.

Thus the overall heat-transfer coefficient can be determined from the above Equation after estimating the individual resistances.