TY - JOUR EP - 341 AV - public VL - 80 N2 - Circulation patterns and mixing characteristics within water plugs in liquid/liquid segmented flow were investigated by means of micro-Particle Image Velocimetry. Experiments were carried out in a glass microchannel with circular cross-section of 100 ?m radius using [C4mim][NTf2] ionic liquid as the carrier fluid. A T-junction was used as inlet, while mixture velocities varied from 0.0028 m/s to 0.0674 m/s. Two main circulation vortices were found within the plugs while at intermediate mixture velocities two additional secondary vortices appeared at the plug front. The mixing rate was locally quantified by means of the non-dimensional circulation time, which was calculated across the plug length. Consistently with the circulation patterns, the non-dimensional circulation time was found to have a profile along the direction of the flow that mirrors the shape of the plug, with a minimum at the axial location of the vortex cores (where the circulation velocity is maximum at the channel centre) while it tended to infinity towards the liquid/liquid interfaces. For all the experiments the minimum value of the circulation time fell within the range of 1.00?1.75. For increasing mixture velocities (i.e. increasing Ca) and sufficiently long plugs (?IL=0.4) a general decrease (i.e. higher mixing rate) of the circulation time minimum was found, although the behaviour was rather complex. On the other hand, the circulation velocity linearly increased as the Ca number (mixture velocity) increased. KW - Multiphase flow KW - Microfluidics KW - Mixing KW - Liquid-liquid KW - Ionic liquids KW - PIV UR - http://dx.doi.org/10.1016/j.ces.2012.06.030 A1 - Dore, V A1 - Tsaoulidis, D A1 - Angeli, P SN - 0009-2509 JF - Chemical Engineering Science TI - Mixing patterns in water plugs during water/ionic liquid segmented flow in microchannels N1 - This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. SP - 334 ID - discovery1349518 Y1 - 2012/10/01/ ER -