in Wiley InterScience (www.interscience.wiley.com).In this work, the flow of immiscible fluids in a PMMA microchannel 300 mm wide and 600 mm deep was investigated experimentally. Dyed de-ionized water and kerosene were selected as the test fluids. Flow patterns were observed by using a CCD camera and were identified by examining the video images. Flow patterns obtained at the T-junction and in the microchannel are presented. Superficial velocities varied between 9.26 Â 10 À4 ; 1.85 m/s for water and 9.26 Â 10 À4 ; 2.78 m/s for kerosene. The formation mechanism of slug, monodispersed droplet and droplet populations at the T-junction was studied. Weber numbers of water and kerosene, We KS and We WS , were used to predict the flow regime transition and the flow patterns map. The experimental data of volume of dispersed phase were successfully correlated as a function of We KS , We WS , and hold-up fraction. Considering the uncertainty associated with experimental quantification of the process, the results are in satisfactory agreement over the wide range of 1.90 Â 10 À3 < We WS < 30.43 and 5.90 Â 10 À6 < We KS < 0.13 with average absolute deviation of only 16.18%.

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In this work, the mass transfer characteristics of immiscible fluids in the two kinds of stainless steel T-junction microchannels, the opposing-flow and the cross-flow Tjunction, are investigated experimentally. Water-succinic acid-n-butanol is chosen as a typical example of liquid-liquid two-phase mass transfer process. In our experiments, the mixture velocities of the immiscible liquid-liquid two phases are varied in the range from 0.01 to 2.5 m/s for the 0.4 mm microchannel and from 0.005 to 2.0 m/s for the 0.6 mm microchannel, respectively. The Reynolds numbers of the two-phase mixture vary between 19 and 650. The overall volumetric mass transfer coefficients are determined quantitatively in a single microchannel, and their values are in the ranges of 0.067-17.35 s 21 , which are two or three orders of magnitude higher than those of conventional liquid-liquid contactors. In addition, the effects of the inlet configurations, the fluids inlet locations, the height and the length of the mixing channel, the volumetric flux ratio have been investigated. Empirical correlations to predict the volumetric mass transfer coefficients based on the experimental data are developed.