Hydrodynamics of a bubble passing through a Kelvin cell in microchannel with shear-thinning fluid

Abstract

Open cell solid foams (OCSF) show great potential for process intensification in heterogeneously catalyzed reactions due to their favorable properties regarding heat-mass transfer, pressure drop and specific surface area (SSA). As one of the most ideal OCSF structure, Kelvin cell (KC) exhibits a fundamental importance in fully understanding the complex flow and transport properties of these reactions, but the research involving gas-liquid two-phase flow is still missing. In this work, the hydrodynamics of a bubble through a representative elementary volume with KC model in minichannel with sodium carboxymethyl cellulose aqueous solution are investigated by coupled level-set and volume-of-fluid method. The regime of bubble penetration into KC is elucidated. The specific surface area and permeability of bubble are studied by systematically analyzing the influences of solution concentration, liquid velocity, KC's porosity and contact angle, as well as fluid type. Four penetration regimes of approaching stage, engraving stage, extruding stage, and deviating stage are identified, and a typical curve of SSA of bubble in terms of flow time is acquired accurately. It is found that the drastic changes in SSA and permeability are closely related to the engraving and extruding stages. The average SSA in two involved stages increases with solution concentration, decreases with KC's porosity. The maximum permeability corresponding to the transition point between two stages, decreases with solution concentration, increases slightly with KC's porosity. However, liquid flow velocity and KC's contact angle have no significant effect on both the average SSA and the maximum permeability. Compared with water, a small SSA tends to be obtained and the permeability climbs slowly but reaches a high peak in CMC solution.