Further Developments of Dropwise Condensation Theory

Abstract

The high rates of heat transfer of dropwise condensation as well as its limits are explained on the basis of the behaviors of submicroscopic active drops. The expression for the substantial growth rate of a single drop valid down to the thermodynamic critical size is incorporated into a set of basic equations from [8] whose capability to describe the process of coalescence and growth of drops in dropwise condensation has been demonstrated in [9]. Consideration of the nondimensionalized forms of the basic equations with the aid of numerical analysis results in an expression of the Nusselt number for dropwise condensation in terms of a few characteristic parameters. Comparison of the predicted Nusselt numbers with available experimental data suggests that the condensation coefficient of water is around 0.2 provided the nucleation site density is infinitely high. Otherwise, if the condensation coefficient should be unity, we have to accept that the nucleation sites are fairly scattered.