ABSTRACT
Condensation and evaporation heat transfer occurs in many engineering applications, such as in power condensers, boilers, and steam generators, which are all important components in conventional and nuclear power stations. In the design of these condensers and evaporators, proper correlations must be selected to calculate the condensing and boiling heat transfer coefficients. The most common type of condensation involved in heat exchangers is surface condensation, where a cold wall, at a temperature lower than the local saturation temperature of the vapor, is placed in contact with the vapor. During film condensation in tube bundles, the conditions are much different than for a single tube. In the absence of vapor velocity, as condensate flows by gravity onto lower tubes in a bundle, the condensate thickness around the lower tubes should increase and the condensation heat transfer coefficient should decrease. During condensation inside horizontal tubes, different heat transfer models are used, depending on whether vapor shear or gravitational forces are more important.
