Numerical Study Of Liquid-liquid Slug Flow Behavior In Microchannels

Due to its perfect performance of heat and mass transfer, the microreactor hasbeen focused in industrial and scientific applications recently. And the slug flowregime also provides uniform and stable interfacial area for the transportation. In thisstudy, we manipulated the CFD method to investigate the behaviors ofhydrodynamics、mass transfer and chemical reaction existing in liquid-liquid slugflow microchannels.The free surface tracing approach was used to simulate the process of sluggeneration. We analyzed flow field within slugs and proved the existence of internalcirculation and the rotate mode of vortexes. By refining the mesh in the vicinity ofwall, we acquired the wall film between the dispersed slug and wall and obtaineddifferent flow and pressure fields from the majority of slugs. Comparing with the slugvelocity, the flow rate ratio could manifestly affect the size of slugs. We switched thewettability of wall and got the flow regime that dispersed and continuous slugsexchange their positions, which validated the feasibility of this method.A fixed interface approach was applied to study the coupling of mass transfer andchemical reaction within slugs. The transfer trail of species in the aqueous slugobviously indicated the circulation path of internal vortexes. By defining theenhancement factor, we analyzed the intensification of mass transfer quantitatively.We simulated different types of reactions and acquired the trend from intrinsickinetics limited to mass transfer limited. We investigated the influences of operatingparameters on the process and explained the intensification mechanisms. On thewhole, the coupling results of mass transfer and chemical reaction obtained bysimulation are in accordance with those reported in literature previously.