Gas-liquid hydrodynamics with different liquid viscosities in a split-and-recombine microchannel

Split-and-recombine (SAR) technology has shown great potential in the passive intensification of mass transfer. However, the gas-liquid flow is rarely encountered in the SAR microdevices. In this work, the flow regime, void fraction, and pressure drop of gas-liquid flow were experimentally studied in a common SAR microchannel designed with a curved divergence-convergence channel and rectangular obstacles. Parameter studies were conducted by varying the flow rates of nitrogen/glycerol aqueous solutions and glycerol contents. Four flow regimes, namely, total breakup, partial breakup, abnormal breakup, and annular flow are observed with a highspeed camera. The flow map and correlations to predict the regime transitions are presented based on the liquidphase Capillary number (0.0022-1.016) and gas/liquid rate (0.5-5). Furthermore, the modified frictional factor is correlated with Capillary and Reynolds numbers based on the flow regimes. Overall, the SAR microchannel is a promising candidate as the high-efficient gas-liquid contactor in terms of mass transfer rate, product selectivity, and energy efficiency for highly viscous liquids. A reasonable match of bubble length and the number of SAR units for the total breakup of bubbles is required. This study can contribute to the design, optimization, and regulation of the SAR microchannel for gas-liquid flows.

Automated summary

The flow regime, void fraction, and pressure drop of gas-liquid flow in a SAR microchannel were experimentally studied. Four flow regimes were observed, and correlations to predict regime transitions were presented. The SAR microchannel shows potential as an efficient gas-liquid contactor for highly viscous liquids.