Gas-liquid Two-phase Mass Transfer Under Taylor Flow In Microchannel

The significant process intensification effect of microreactor and monolithicreactor has made gas-liquid two-phase flow inside capillary become the focus ofrecent research. In this paper, the flow and mass transfer properties under gas-liquidtwo-phase Taylor flow have been investigated by both CFD simulation andexperiment. The aim of this paper is to reveal the mass transfer characteristic and themechanism of intensification of gas-liquid Taylor flow in capillary.Computational fluid dynamics (CFD) was adopted to simulate the gas-liquidtwo-phase Taylor flow inside capillary. In simulation, Taylor bubble was assumed tohave an ideal shape. Under two-dimensional、axisymmetric coordinate, the effects ofgas bubble velocity, liquid phase diffusivity、liquid film thickness, Taylor unit length,liquid film length and capillary diameter on the flow and mass transfer wereinvestigated in simulation. According to the simulation results, it is found that thecirculation inside liquid slug is mainly determined by the gas bubble velocity andliquid property；Two-phase mass transfer rate decreases with the increase of masstransfer time；The increased gas bubble velocity and liquid phase diffusivity enhancetwo-phase mass transfer and the grown channel diameter and Taylor unit lengthreduce the two-phase mass transfer. While the effects of liquid film length and liquidfilm thickness on two-phase mass transfer change with the mass transfer time.CO2-H2O system was used in Experiment. The gas-liquid absorption experimentwas carried out in four capillaries with different length. The influence of two-phasesuperficial velocity on gas bubble length、liquid slug length and unit length wasinvestigated by observing the two-phase distribution. Through the analysis of CO2absorption in capillary, the effects of two-phase superficial velocity and Taylor unitresident time on two-phase mass transfer were studied. Experimental results show thatthe gas bubble length and liquid slug length increase with the increased superficialvelocity of gas and liquid phase, respectively. The liquid phase volumetric masstransfer coefficient decrease with the increase of unit resident time, the more theresident time is, the little change of the liquid side volumetric mass transfercoefficient is. Base on the results of simulation and experiment, several correlations weregiven to predict the gas-liquid two-phase mass transfer under Taylor flow in capillary.