Modeling of Particle Formation during Spray Drying

A mathematical model for the evaporation of a single droplet, subjected to convective drying in a spray dryer was developed to study the transient phenomena of particle formation. During the constant-rate drying period, the governing equations and boundary conditions were transformed into a form containing Peclet number, Pe, as the main controlling parameter. A numerical solution was developed to solve the diffusion equation in spherical coordinates with a moving boundary (Stefan Problem). The solution provides the concentration fields in a droplet as a function of time and space. This information enables the prediction of the tendencies of droplet to form hollow or solid particles as well as structure composition and morphology.