Hydrodynamics And Mass Transfer Of Gas-Liquid Two-Phase Flow In Tree-Shaped Parallel Microchannels

As an effective approach for process intensification,the micro-chemical technology has received increasing attention due to its efficient mass transfer,precise controllability,and convenient experimentation.Gas-liquid systems are widely encountered in various chemical processes,such as reaction,separation and purification.Therefore,the study on the hydrodynamics and mass transfer of gas-liquid two-phase flow in microchannel is indispensable for the application of micro-chemical technology.In this study,the tree-shaped scale-up strategy of the microchannel and its influence on the hydrodynamics and mass transfer of gas-liquid two-phase flow are studied:The flow and mass transfer performance of gas-liquid two-phase flow in a single microchannel are investigated under different gas-liquid two-phase flow rates and absorbent concentrations.It is verified that the mass transfer performance in the microchannel is higher than that in the traditional macroscopic column.The hydrodynamics and mass transfer of gas-liquid two-phase flow in treeshaped parallel microchannels are investigated.The results show that the uniformity of flow distribution is jointly affected by bubble length at T-junction and the hydrodynamic feedback of the downstream channels.Meanwhile,the uniform flow distribution facilitates the mass transfer performance.There exists a critical ratio of gasliquid flow rate to attain ideal flow distribution and optimal mass transfer performance.Beyond the critical point,the flow pattern becomes different with before,the change of hydrodynamics could cause the remarkable deteriorations in flow distribution and mass transfer efficiency.Furthermore,the correlations for predicting the volumetric mass transfer coefficient are proposed.The flow distribution and mass transfer of gas-liquid two-phase flow in two treeshaped microchannels with typical dimensions are studied.The operating range in the halving-width microchannel is significantly narrower than the constant-width microchannel,and the flow distribution has a large difference between two microchannels,resulting the remarkably different mass transfer performance.Considering the mass transfer and pressure drop comprehensively,the performance ratio is adopted to evaluate their mass transfer performances.The performance ratio of the halving-width microchannel is generally higher than the constant-width microchannel.A novel pressure drop model of gas-liquid flow with mass transfer in tree-shaped microchannels is proposed based on the gas-liquid flow without mass transfer in single microchannel.The evolution of the length of the bubble along the microchannel is divided into the body shortening stage and the cap shrinking stage.A new calculation method for the number of gas-liquid units based on time scale is proposed,and the pressure drop model of gas-liquid units is revised.Subsequently,the pressure drop model of the gas-liquid flow with mass transfer in the tree-shaped microchannels is proposed by jointly considering the effects of the dynamics and the absorption.