Evaporation and condensation of large droplets in the presence of inert admixtures containing soluble gas

Abstract

In this study the mutual influence of heat and mass transfer during gas absorption and evaporation or condensation on the surface of a stagnant droplet in the presence of inert admixtures containing noncondensable soluble gas is investigated numerically. The performed analysis is pertinent to slow droplet evaporation or condensation. The system of transient conjugate nonlinear energy and mass conservation equations was solved using anelastic approximation. Using the material balance at the droplet surface the authors obtained equations for Stefan velocity and the rate of change of the droplet radius taking into account the effect of soluble gas absorption at the gas-liquid interface. The authors also derived boundary conditions at gas-liquid interface taking into account the effect of nonisothermal gas absorption. It is demonstrated that the average concentration of the dissolved species in a droplet strongly depends on the relative humidity (RH) for highly soluble and for slightly soluble gaseous atmospheric pollutants. Therewith the difference between the average concentration of the dissolved species in water droplets attains tens of percent for different values of RH. © 2007 American Meteorological Society.