Numerical Investigation of Mass Transfer with Two-Phase Slug Flow in a Capillary

W. Han, and B.H. Dennis
University of Texas, Arlington, TX, USA

The multiphase flow of two immiscible liquids in a microchannel was investigated numerically. A Y-shape micromixer was designed to produce a pattern of slugs from the flowing liquids. The mass transfer characteristics of this flow pattern are of primary interest in this study. A simple neutralization titration reaction was chosen as the basis. The liquid-liquid two phase slug flow was formed during the mixing. The mixing was quantified for different volume flow rates of the reactants. It was shown that the residence time required for reaction completeness was dominated by the flow rate for this type of micro mixer. Furthermore, a parametric two-dimensional model was implemented with COMSOL Multiphysics to investigate the mixing phenomenon within the slugs. The COMSOL model allows for rapid analysis of different microchannel geometries and flow rates. The results show a dramatic intensification of the reaction as the channel diameter is decreased.