Chemical Engineering Research & Design, Vol.126, 153-160, 2017
Free convection and vapor diffusion of droplet aqueous solutions
Evaporation of drops of water and aqueous solutions of salts LiBr and CaCl2 have been studied experimentally. The impact of various key factors on the evaporation has been estimated. The behavior of convection significantly differs in drops of water and salt solution. The contribution of gas convection changes with an increase in salt concentration. With increasing salt concentration in a drop, the role of the convective component first increases, reaches an extremum and then decreases with time. Usually when modeling droplet evaporation, the only considered are the diffusive vapor transport and the molecular heat conduction in liquid. The neglect of gas convection in the simulation leads to essential (manifold) underestimation of the evaporation rate compared with the experimental data. Gas convection may be neglected at intensive bubble boiling in a water drop. The process of drop boiling is divided into 4-5 characteristic time stages with a significant change of both the rate of evaporation and the role of convection. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.