Two-phase flow pattern and pressure drop in silicon multi-microchannel with expansion-constriction cross-section

Gas-liquid two-phase intermittent flow pattern and frictional pressure drop in new silicon multi-microchannel were investigated experimentally by means of the IDT high-speed camera mounted together with a Nikon microscope. Each test section consisted of 10 parallel microchannels with 0.1 mm wide and 0.2 mm deep in constant cross-section segment and each microchannel consisted of an array of periodic reentrant cavities. The major two-phase flow pattern observed was intermittent in the test sections, and the intermittent sub regimes in the new microchannels were different from those displayed in the rectangular straight microchannel. Using nitrogen and deionized water as working fluids, the intermittent sub regime maps for the new multi-microchannel were obtained. Meanwhile, the pressure drops were compared with several existing correlations based on the homogeneous or separated mixture assumption. Results show that the homogeneous flow model cannot predict the two-phase pressure drop data well, while the separated flow model is proposed to provide a better prediction of the two-phase frictional pressure drop. Among the separated flow models investigated, the best two correlations of C value can provide mean deviations within less than 16% for all the three microchannels and all the predictions lie in the bound of ±30%.