ANALYTICAL METHODS TO CALCULATE CONDENSATION RATES OF A MULTICOMPONENT DROPLET

The multicomponent condensational growth and/or evaporation of a dropl et in the continuum and transition regimes are considered. Analytical expressions are derived for the mass fluxes by eliminating the particl e surface temperature from the quasi-steady-state multicomponent mass and heat transfer equations, This requires approximating the temperatu re dependence of the saturation vapor pressures and the coupling of th e mass fluxes by series expansion. The approximation errors involved i n deriving the equations are studied by comparing the methods to each other and to previously published models, The growth of a droplet comp osed of five alcohols forming an ideal mixture is predicted. The impor tance of the accurate method to calculate the droplet temperature is r evealed. The derived analytical model for condensation/evaporation flu xes is convenient to use in a numerical general dynamic equation solut ion routine, where nucleation, condensation, coagulation, deposition a nd gas-phase chemistry have to be solved simultaneously, and obviously not very much computing time can be consumed in any of the subprocess es. (C) 1998 Elsevier Science Ltd. All rights reserved.