Characteristics of liquid slugs in gas-liquid Taylor flow in microchannels

The hydrodynamics of liquid slugs in gas-liquid Taylor flow in straight and meandering microchannels have been studied using micro Particle Image Velocimetry. The results confirm a recirculation motion in the liquid slug, which is symmetrical about the center line of the channel for the straight geometry and more complex and three-dimensional in the meandering channel. An attempt has also been made to quantify and characterize this recirculation motion in these short liquid slugs (L-s/w< 1.5) by evaluating the recirculation rate, velocity and time. The recirculation velocity was found to increase linearly with the two-phase superficial velocity U-TP. The product of the liquid slug residence time and the recirculation rate is independent of U-TP under the studied flow conditions. These results suggest that the amount of heat or mass transferred between a given liquid slug and its surroundings is independent of the total flow rate and determined principally by the characteristics of the liquid slug. (C) 2011 Elsevier Ltd. All rights reserved.