CFD–PBM Simulation of Liquid–Liquid Dispersions in a Pump-Mixer

The approach coupling computational fluid dynamics and a population balance model (PBM) was adopted to simulate the hydraulic performance of liquid–liquid dispersions in a pump-mixer. Behaviors of the drop breakage and coalescence were considered in the PBM. To validate simulation methods and strategies, simulated drop size distributions were compared with experimental data and a good agreement was obtained. Flow structures in the pump-mixer were analyzed and two recirculation loops were observed. Holdup profiles reveal that the dispersed phase is unevenly distributed in space, which is more obvious at lower rotating speeds. Simulation results show that breakup regions are mainly located near the impeller where high energy dissipation rates exist, while coalescence regions were observed in the whole mixer. Distributions of the drop mean diameter were displayed. It indicated that the drop size is uniformly distributed in space at higher rotating speeds.