Non-isothermal evaporation in a sessile droplet of water-salt solution

Abstract

Experimental data on nonisothermal evaporation of sessile droplets of water-salt solutions (LiBr + H2O; CaCl2+H2O) were obtained. Evaporation of droplets of volatile liquids occurs with almost constant evaporation rate, and the problem is solved in a stationary approximation. High-temperature evaporation of water-salt solutions leads to significant difficulties at modeling the heat and mass transfer. In this case, the evaporation rate substantially decreases with time. With the growth of salt concentration in the solution from 11% to 60%, the partial pressure of water vapor at the interface falls by an order of magnitude. In this work, we have performed simulation, considering diffusion in solutions, a non-isothermal character, and the Stefan flow, and proposed a simple method for calculating the mass flow. The resulting technique can qualitatively and quantitatively predict the solution behavior with a significant change in the external boundary conditions in time.