Liquid-liquid Two-phase Flow Patterns And Mass Transfer Characteristics In Microchannel

Microreactor has the characteristics of process intensification, reaction safety,easily controlled, quantity amplification and so on for the micro size effect, andattracted researchers‘enormous attention. Microchannel is the core part ofmicroreactor, the process of flow, mass transfer and heat transfer for microreactor arealmost take place in microchannel. In my paper, through the experimental study of theflow patterns and mass transfer process of liquid-liquid two-phase flow system, theinfluence of dimensionless numbers on flow patterns, and the influence of flowpatterns and superfacial velocity on the mass transfer process of liquid-liquid twophase flow system are analysised. In addition, active carbon is added in to the organicphase to study its influence to liquid-liquid two-phase flow pattern and mass transfer.In this paper, the working system,30%TBP (in kerosene)-water is used toobserve the flow patterns of liquid-liquid two-flow flow in a microchannel with thediameter of924μm. The main equipment used is CCD high speed camera. Flowpatterns observed under different superfacial velocity and flux ratio of the two liquidphases are: droplets flow, slug flow, parallel flow, annular flow, slug-annular flow,churn flow and irregular flow. The characteristics of those flow patterns are analyzedin this paper, and the generate mechanism of those flow patterns are analysed throughthe introducing of Reynolds number, Webber number and Capillary number, conbinedwith the flow patterns map. Through the analysis we concluded that every flowpattern‘s formation is mainly determined by the relative size of interfacial tensionandinertia force.30%TBP (in kerosene)–acetic-water is used to determine the overall volumetricmass transfer coefficient in microchannel in this paper, conbined with the using ofacid-base titration principle. The influence of flow patterns and flow velocity onliquid-liquid two-phase flow mass transfer coefficient are analysised. For every flowpattern, the mass transfer coefficient grows as the increase of velocities of two liquidswhile the flux ratio is constent, but it‘s reversed for irregular flow. Through theanalysis we found that the main factors for mass transfer are interfacial area andsuperficial velocity. The higher of the interfacial area result the higher overall masstransfer coefficient. What‘s more, for droplets flow and slug flow, the inner circle flow generated in droplets will intensify the mass transfer process.Active carbon is added in the organic phase to study its influence to liquid-liquidtwo-phase flow pattern and mass transfer. Study found that active carbon couldincrease the slug length for slug flow and have negative effect for liquid-liquidtwo-phase flow mass transfer.