The role of liquid mixing in evaporation of complex multicomponent mixtures: modelling using continuous thermodynamics

Abstract

This paper investigates the part played by internal mixing in the evaporation of droplets of mixtures with large numbers of components. Continuous thermodynamics—the use of probability density functions rather than discrete components to represent composition—is applied as the mixture model, and continuous mixture formulations of the liquid phase transport equations and diffusivities are developed. Sample calculations are presented for a mixture with a single distribution function as well as for mixtures with two widely separated distributions (“dumbbell” mixtures, composed of very light and very heavy fractions). The calculations show that internal mixing generally has a smaller influence on droplet behaviour for a mixture with a large number of components than it does for a binary mixture, and give some guidance as to when a well-mixed droplet model may—or may not—be a good approximation for practical work.