Evaporation and heat and mass transfer of a sessile drop of aqueous salt solution on heated wall

Abstract

The droplets evaporation of water and aqueous salt solution were experimentally studied. The impact of various key factors on the evaporation has been estimated. Typically when considering evaporation of droplets, only the diffusive vapor-gas transfer and the molecular heat conduction are taken into account. However, vapor-gas convection plays an important role at droplets evaporation. The qualitative behavior of gas convection for water and aqueous salt solution is substantially different. The neglect of gas convection in the prediction leads to manifold underestimation of the evaporation rate compared with the experimental data. With a growth of salt concentration with time, the influence of the convective component first increases, reaches an extremum and then significantly decreases. The evaporation at nucleate boiling in the liquid drop is divided into several characteristic time intervals.