Dynamic changes in gas-liquid mass transfer during Taylor flow in long serpentine square microchannels

Taylor bubble length shrinks and subsequently plateaus out along the flow direction from the T-junction, resulting in the decrease in Taylor bubble velocity. kLa in a unit cell gradually decreases along the serpentine microchannel, and increases as the channel cross-sectional area decreases. As the gas flow rate increases under a given liquid flow rate, a critical point is found for the evolution of kLa and kL (that is the liquid phase mass transfer coefficient). The results indicate that the contribution of the circulation in the liquid slug to kL is dominant before the critical point compared to the leakage flow in the liquid film. All these findings in this work give important information to understand the dynamic change in gas-liquid Taylor flow mass transfer within microchannels. They will serve as basis for designing and optimizing gas-liquid multiphase microreactors in the future.