A theory of dropwise condensation at large subcooling including the effect of the sweeping

 The effect of sweeping by the departing droplets on the heat transfer coefficient in dropwise condensation is studied analytically here. Using basic principles, an analytical model for dropwise condensation is devised, which takes into account the elementary processes that make up the dropwise condensation cycle. The analysis is divided into two parts: in the first part, the heat transfer as a result of nucleation and coalescing of the droplets is considered. In the second part, the effect of sweeping is introduced. The results are presented as the variation of nondimensional heat flux versus the distance from the upper edge of the condenser surface at various surface subcoolings. Calculations show that the variation of heat flux with surface subcooling is linear only at small values of subcooling. As the subcooling is increased the slope of the mean heat flux versus subcooling curve decreases, and for a sufficiently high body force passes through a maximum. Received on 12 August 1999 / Published online: 29 November 2001