Vaporization of Small Spherical Drops in a Gas

The process of vaporization of a small (compared to the free path of molecules in the medium) spherical liquid drop in an infinite nonabsorbing gaseous medium is considered. Analytical expressions for the time dependence of the drop radius are derived under assumption that vaporized molecules escape from the drop in the asymptotic diffusion regime, and the thermal energy flux toward the vaporizing drop is formed as a result of collisions of vaporized and gas molecules. It is demonstrated that consideration of unsaturated vapor at the surface of the evaporating drop increases the estimated vaporization time of submicron drops by several orders of magnitude compared to the Maxwell classical model.