CFD-DEM study of residence time, droplet deposition, and collision velocity for a binary particle mixture in a Wurster fluidized bed coater

An approach that combines computational fluid dynamics with the discrete element method is applied to investigate the residence time and collision velocity in different processing zones of a Wurster fluidized bed. Ideal and nonideal circulating motions of particles are distinguished to evaluate distributions of cycle times. Solid-like droplets are injected and simulated inside a predefined spray zone to study the droplet deposition rate. The simulation, conducted for a binary mixture of small and large particles, predicts the ideal cycle times and the residence times of both particle sizes in the Wurster tube are in good agreement to the available experimental results.