Remarkable reduction of microbubble size by constructing a flexible interaction region in a T-junction microchannel

High-efficiency reduction of the microbubble size is important for bubble-based microflow processes but has hitherto required high-energy-consumption methods. This study designed a new T-junction microchannel with a flexible interaction region exhibiting apparent superiority in producing smaller bubbles with high energy-utilization efficiency, and for the first time breaks the limitation of the flow pattern in the ordinary T-junction microchannel. The results indicate that under the given two-phase working conditions, the microbubble size was greatly reduced in the new T-junction microchannel compared to that in the ordinary one. The microbubble formation mechanism in the new microdevice is analyzed via a simulated liquid velocity field. Importantly, the bubbly flow pattern appeared rapidly under a higher gas flow rate, which is totally opposite to the expectations in the ordinary T-junction. Finally, via interface analysis, the importance of the gas velocity on the viscous shearing force was clarified, and a new bubble size-prediction model was developed.