MEASUREMENT AND INTERPRETATION OF GROWTH OF BINARY DROPLETS SUSPENDEDIN A WATER-N-PROPANOL-NITROGEN MIXTURE BY MEANS OF A PISTON-EXPANSION-TUBE

We generate a cloud of monodisperse binary droplets in a piston-expans ion-tube by homogeneous nucleation and subsequent growth in a supersat urated vapor. By Mie light scattering we measure the growth rate of th e droplets in the radius range from 0.16 to 3 mu m. We investigate the water-n-propanol system because the growth behavior of the pure subst ances is very well known from previous studies. Our model calculations are an extension of a successful unary model to the binary case inwhi ch the droplet composition is treated as a variable. The calculation s tarts at the nucleus, passes through the transition zone about Knudsen number one and extends to the final droplet/vapor equilibrium which i s only reached when vapor depletion and heat release are taken into ac count. The model is in good agreement with the experimental data. (C) 1997 Elsevier Science Ltd.