Flow regime transition for cocurrent gas–liquid flow in micro-channels

Experimental investigations of gas–liquid two-phase flow regimes in micro-channels were carried out in this work. Four distinctive flow patterns of slug flow, slug-annular flow, annular flow and parallel stratified flow were captured by a digital video recording (DVR) system and the transitions among different flow regimes were studied. The effect of fluid properties and wetting properties of the channel wall on the flow regime and flow pattern transition were studied as well. Novel empirical correlations for predicting flow pattern transitions during the steady gas–liquid flow in micro-channels have been developed with the fluid properties and the wetting properties of micro-channels incorporated, whereas the traditional flow criteria were based on gas and liquid superficial velocities only. The predictions of the present empirical models agree well with the experimental data.

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► Experiments were conducted to reveal gas–liquid flow pattern transitions in micro-channels.
► Slug flow, slug-annular flow, annular flow and parallel stratified flow were observed.
► A flow map based on the coordinates of Ca and ReG/ReL is firstly established.
► Novel empirical correlations for predicting flow pattern transitions were developed.
► Effects of fluid properties and wetting properties of channel wall on flow patterns were studied.