(178h) Mitigating Gas-Liquid Segmented Flow Instabilities in Microchannel Systems with High-Speed Actuation

Segmented flow, a flow regime in microchannels, has attracted significant research interest due to its enhanced mixing, superior mass transfer, and other advantages. However, generating and maintaining a stable segmented flow remains challenging. Traditional methods, such as passive T-junctions and flow-focusing techniques, rely heavily on fixed geometries and fluid properties, often resulting in limited operational flexibility and unstable performance at elevated flow rates. Alternative approaches, such as modifying junction or system pressure, typically involve bulky setups that hinder broader application.

In this study, the stable operating window of gas-liquid segmented flow in microchannels is expanded by simply employing a high-speed valve to manipulate gas behaviour across a wide range of liquid flow rates. Experimental results demonstrate that the valve effectively broadens and stabilizes the formation of gas-liquid segmented flow, enabling operation under more diverse conditions and prolonging stable flow patterns before interruptions occur. Additionally, tuning the valve frequency results in more controllable segment length compared to cases without valve control. This approach opens new possibilities for achieving efficient and precise synthesis in microreactors.