CFD modeling of the mixing of water in oil emulsions

A computational fluid dynamics (CFD) model was developed for the mixing of water in oil emulsion in a lab-scale mixing tank equipped with a Rushton turbine impeller. Multiple reference frames (MRF) technique, k–ɛ model, and Eulerian–Eulerian approach were employed to model the impeller rotation, turbulence, and multiphase flow, respectively. The droplet size distribution within the mixing tank was estimated by means of the population balance approach, which employs the discrete method to describe coalescence and breakage of water droplets. To validate the CFD model, the cumulative probability size distribution computed using the model was compared with the experimentally determined values reported in the literature. This validated CFD model was then utilized to explore the effects of the impeller speed, oil type, and volume fraction of water on the cumulative probability droplet size distribution, number density, and distribution of local volume fraction of the dispersed phase.

► The mixing of water in oil emulsions was simulated using computational fluid dynamics.
► The population balance equations were coupled with the multiphase transport equations.
► The discrete method was employed to describe the breakage and coalescence phenomena.
► The CFD results were in very good agreement with the experimental data.
► The effects of different operating conditions on the drop size distribution were explored.