(292f) Predicting emulsion coalescence: Multi-scale simulation techniques

In optimizing industrial solvent extraction performance, a throughput-limiting process is the efficient separation of raffinate and loaded organic phases via coalescence of dispersed droplets. New research findings are needed in order to quantify the physical and chemical regimes that favour coalescence, which will aid in the design and optimization of hydrometallurgical processing equipment; with both economic and environmental benefits. Coalescence remains difficult to model due to the disparate length scales involved: a successful model must simultaneously capture both droplet and film-scale dynamics. While multiphase flows have been well simulated by interface-capturing methods, the detail of thin-film drainage is difficult to
simultaneously resolve using these techniques alone.

This study demonstrates the predictive power of a multi-scale simulation method, in which droplet-scale interface-capturing techniques are coupled to a lubrication analysis of thin-film drainage. The developed multi-scale interface-capturing (MSIC) method was applied to binary droplet interactions in emulsion systems. Depending on the droplet diameter ratio used, the MSIC method can discriminate between bouncing and coalescence outcomes. The present results support the development of physically based coalescence relations for application in unit-scale population balance models.