Effects of Various Physical Conditions on Heat Transfer of the Free Convection Film Condensation

Abstract

In this chapter, the film condensation of saturated water vapor is taken as an example for analyzing the effects of various physical conditions on heat transfer. The effects of four physical conditions including Boussinesq approximation (i.e. ignoring variable physical properties), shear force at the liquid–vapor interface, inertia force of the condensate film, and the thermal convection of the condensate film on the heat transfer coefficient of the film condensation are deeply investigated. It is found that the variable physical properties and thermal convection cause larger effect on heat transfer of laminar free convection film condensation, meanwhile, the effect of the variable physical properties is even larger than that of the thermal convection. It follows that it is necessary to consider variable physical properties for investigation on heat transfer of free film condensation. Compared with the variable physical properties and thermal convection, the effect of the Interfacial shear force and inertia force will be much smaller on heat transfer of laminar free convection film condensation, meanwhile, the effect of the inertia force is little bit smaller than that of the interfacial shear force.