Effects of vapor superheat and condensate subcooling on laminar film condensation

Nusselt's model is employed to illustrate the effects of vapor superheat an d condensate subcooling on laminar film condensation occurring under simult aneous actions of gravity and interfacial shear. The vapor superheat affect s the condensation kinetics in cooperation with heat transfer in both phase s. Under comparable conditions, the condensate film is thinner and the heat transfer coefficient larger for superheated than for saturated vapor. The heat flux on the cooling surface arising from the sensible heat of condensa te increases as the critical point of the condensing substance is approache d and, at this point, the Nusselt condensation model gives the single-phase boundary layer solutions.