Enhanced solvent extraction in a serial converging-diverging microchannel at high injection ratio

Abstract

A microchannel with serial converging–diverging geometries, inspired by porous structures of rock, was designed to enhance the cross-interfacial mass transfer of two-phase flow at a high phase injection ratio up to 200:1. It was experimentally demonstrated that the design enhanced mass transfer coefficient by approximately four times compared to classic microchannel design. The superior performance of the microchannel was attributed to the retention of dispersed fluid before the converging geometry due to the capillary pressure barrier that resulted in velocity contrast between the two fluids and reduced the effective mass-transfer distance in continuous phase. Additionally, the deformation and dispersal of droplets at the diverging geometry further increased the interfacial area. The flow patterns in this geometry were experimentally identified. The serial converging–diverging design can be used for high phase ratio extraction applications.