Experimental determination and mathematical modeling of the drying kinetics of a single droplet of colloidal silica

摘要

Colloidal silica has been used frequently as a model material of drying in the past two decades. Several models of single droplet drying have been validated against the sole experimental evidence by Nei and Vodnik (Kinetics of droplet evaporation. Chemical Engineering Science1991, 46(2), 527-537), in which relatively scattered experimental data on drying of single droplet of colloidal silica were provided. Due to the importance of this sort of data, the drying of single droplet of colloidal silica was determined more accurately under more extensive conditions in this work. The effect of air temperature on the drying of single droplet of colloidal silica was probed as well as the evolution of particle morphology. The droplet of colloidal silica was found to shrink irregularly during drying due to uneven exposure of droplet surface to air stream. The moisture within the droplet appears to transfer freely to the surface, keeping the surface highly moist. For a large part of drying process, drying of single droplet of colloidal silica is similar to the evaporation of water droplet, which can be predicted well using a simple mathematical model.