Evaporation Rate and Lifetimes of Clouds and Sprays in Air—The Cellular Model

Abstract

A simple, yet effective, mathematical model based on the cellular method is proposed for the study of the evaporation rate of liquid droplets in assemblages in air. It has been found that the modified cellular model is adequate for the determination of the rate of evaporation, the saturation point, and the lifetime of a monodisperse system of droplets. All characteristic properties of the droplet system can be expressed in terms of known parameters in closed form. Correction for submicron droplets is also given. Numerical results obtained for various droplet systems of water and n-dibutylphthalate indicate that both the droplet radius and the degree of dilution have important effects on the evaporation rate of clouds and sprays. Several possibilities are suggested for further refinement of the theory and improvement on the model in order to account for the influence of dispersion and diffusion of droplets in air and the effect of polydispersity of the cloud itself.