Investigating the pressure loss associated with two-phase flow in a rectangular microchannel suddenly expanding into a manifold

This study focuses on the experimental investigation of the two-phase pressure loss occurring as air-water flow exits a microchannel to a larger manifold. The microchannel has dimensions of 3.23 mm wide by 0.304 mm high by 164 mm long and expands into an exit manifold of 1.4 cm diameter oriented ${90}^{°}$ relative to the flow direction. The expansion results in an additional 150–400 Pa pressure loss. Visualization of the flow illustrates water accumulation at the channel exit with varying behavior, resulting in the range of the pressure loss. Using the sudden expansion model of Abdelall et al. resulted in a mean absolute percent error of 96%. Treating the pressure loss as a result of the ${90}^{°}$ bend, the model of Paliwoda produced a mean absolute percent error of 81%. The combined influence of the models of Abdelall et al. and Paliwoda predicted the experimental measurement with a mean absolute percent error of 78%.