Flow and mass transfer characteristics of Newtonian/non-Newtonian liquid-liquid flow in a microreactor

The online mass transfer characterization technology was used to study the liquid-liquid two-phase mass transfer process of Newtonian/non-Newtonian fluid with polyacrylamide (PAAm) solution as the dispersed phase in the microchannel. The flow patterns were analyzed first. A unique sussage slug flow was observed and the effects of PAAm concentration on the flow patterns (slug flow, sussage slug flow and annular flow) were investigated. The research reveals that the mass transfer in both the Newtonian and non-Newtonian slug droplets was dominated by the convection and diffusion. However, the shear-thinning characteristics of the non-Newtonian fluid lead to significant change in the vortices and concentration distribution. The convection inside the slug droplets was affected by the flow rate, droplet length and capillary number. Based on the penetration theory, a modified correlation by relating the flow rate ratio and capillary number was proposed, which shows excellent prediction performance. © 2024 Materials China. All rights reserved.