Continuous turbulent liquid-liquid emulsification using open-cell solid foams: Experimental investigation and modelling

Abstract

The study investigates the efficiency of liquid-liquid emulsification using three types of open-cell solid foams. Initially, the pressure drop profiles revealed the non-negligible impact of the inertial term at a low viscosity of the continuous phase, with profiles becoming more linear at higher viscosities. The Darcy-Forchheimer model effectively predicted pressure drops with a maximum mean relative error of 14%. Emulsification performance (seen as a decrease in the droplet size) was then evaluated by varying dispersed phase viscosity, superficial fluid flow velocity and foam insert packing length, comparing results with structured static mixers (SMX+). The droplet size of the dispersed phase rapidly decreased within the first foam inserts before stabilizing at a length of 175 mm. Under the same superficial velocity, the mean droplet diameter is correlated to the foam's mean pore size. SMX+ mixers exhibited emulsification capability comparable to solid foam with the largest pores, while medium and small pore foams produced smaller droplets. Finally, the Middleman's correlation with viscosity correction accurately predicted mean droplet size at equilibrium and across various scenarios.