ABSTRACT

Film wise condensation prevails generally on wettable surfaces where a stable condensate removal mechanism is provided. It is well known that drop wise condensation is more efficient in heat transfer than its counterpart of Film wise condensation. When the nucleation takes place on entrained particulate matter in a vapour environment or on a cold solid surface, the process is called heterogeneous nucleation. There are basically two forms of heterogeneous condensation: drop wise and Film wise condensation. Drop wise condensation occurs on surfaces that are hard to wet. Condensation in circular tubes is strongly affected by the vapour inlet velocity and the orientation of the tube. Heat transfer correlations for condensation in a horizontal tube with an annular flow pattern were first addressed by E. P. Ananiev et al. for single-component pure vapour and smooth tubes. In most of the condensation processes, non condensables are usually present such as air for those operating in the atmospheric environment.