Modeling and simulation of solid-containing droplet drying and different-structure particle formation

The formation of solid and hollow particles from solute precipitation of a liquid droplet was investigated using a simulative approach. The simulation model describes the evolution of the solute concentration, temperature gradient, and size change of the droplet and includes the vapor concentration and temperature gradient in the air surrounding the droplet. The volume of fluid (VOF) method was adopted to capture the gas–liquid–solid interface. The entire drying process was analyzed using a sodium chloride aqueous droplet as an example. The influence of ambient temperature on the final structure of the precipitate particle was studied. Two distinct particle structures were discussed. The droplet solidifies into a solid particle when the ambient temperature is low, and into a hollow shape when the ambient temperature is high. The mechanisms underlying these two particle structures were discussed.