Experimental And Numerical Study Of Liquid-liquid Slug Flow In Microchannel

Liquid-liquid slug flow in the capillary microreactor is truly a noble techniquewith great promise in enhancing heat and mass transfer in liquid-liquid reactions. Wellunderstanding of hydrodynamics and mass transfer behavior for microreactor isnecessary to design it properly. In this paper, the mass transfer behavior of slug flowwas investigated in PTFE microchannels with diameters of0.6mm、0.8mm and1.0mm, respectively. The hydrodynamics behavior of slug flow was simulated withVOF model.The slug length was determined through the photographic snapshot method, andthe interfacial area was calculated accordingly. The mass transfer performances ofmicrochannel were studied by the hydrolysis of n-butyl acetate with aqueous sodiumhydroxide, and overall volumetric mass transfer coefficient was determined. Theresults show that the slug length of aqueous phase and organic phase both decreasedwith increasing the slug velocity or decreasing the channel diameter, and so do theinterfacial area. The range of interfacial area and overall volumetric aqueous sidemass transfer coefficient are840⁴100m²/m³and0.002⁰.37s^-1, respectively.The2D geometry and structured grids were generated using the pre-processorGAMBIT, and the liquid-liquid slug flow generation of T-junction in microchannelswas investigated numerically by FLUENT. The result shows that the simulation ofslug flow corresponds with the phenomenon observed in experiments. Then, the staticpressure and wall wetting behavior in slug flow were investigated, and the resultshows that the length of dispersed phase decreases with worse wall adhesion. Finally,UDF （user defined function） was utilized with VOF model to compute the interphasemass transfer while the slug flow developing for the first time.