A Numerical Solution to Dropwise Evaporation

Abstract

A numerical solution is presented for spray evaporation on the surface of a spray evaporator. Excess temperatures below the Leidenfrost transition temperature are considered along with the nonisothermal wall condition. The combination of a high thermal conductivity and low heat capacity for the evaporator wall material, as well as the time-dependent boundary conditions, dictates a quasi-steady-state solution to this evaporator phenomenon. A numerical solution to the conduction equation and boundary conditions is given. A dimensionless evaporation time is computed, and from this a flooding index is developed. The flooding index is shown to be related exponentially to the droplet diameter and wetting ratio. The functional correlation between the heat transfer coefficient for the spray and the wetting ratio is verified from previously published experimental data.