Gas-liquid slug flow (also termed as Taylor flow) is a flow pattern characterized by the alternate movement of elongated bubbles and liquid slugs. Gas-liquid slug flow operation in microchannels has been found important implications in the enhancement of gas-liquid reactions due to its advantages such as easy control

uniform bubble and slug size

narrowed residence time distribution as well as enhanced radial mixing. This review presents the basic conceptions and recent research progress on flow and mass transfer characteristics during the gas-liquid slug flow in microchannels. The gas bubble formation mechanisms

the corresponding bubble and liquid lengths

and mass transfer during bubble formation are summarized. For regular slug flow in the main section of microchannels

several important aspects are addressed including bubble cross-sectional shape and liquid film profile

internal liquid recirculation and leakage flow through the gutters

gas-liquid mass transfer coefficients and coupling phenomena between flow and mass transfer in physical and chemical absorption processes. Finally

an outlook is given for future research directions in this field.