On the condensational growth of a multicomponent droplet

The growth of a well-mixed droplet due to multicomponent condensation has been analysed focusing on the quasi-steady evolution of droplet composition and temperature. For supersaturated vapour mixtures, the composition and temperature will stabilize at final values depending essentially on ratios of mass fluxes. This allows a mathematically novel formulation of the problem, since the droplet composition can be algebraically solved for and even the explicit temperature dependence can be excluded. However, the numerical solution of the full set of initial differential equations for the composition and temperature is equally simple in practice. The growth of a droplet composed of five alcohols forming an ideal mixture is predicted. Simulations reveal a strong enchancement in the growth rate of ethanol if other alcohols are present. More volatile alcohols promote the growth most. The theoretical approach can be applied for systems with relatively slow transfer rates (e.g. atmospheric particles), not for those with strongly non-steady behaviour (e.g. in combustion) or significant gaseous vapour-vapour interactions (small fraction of an inert carrier gas). (C) 1997 Elsevier Science Ltd.