(170a) Investigation of Gas-Liquid Slug Formation in a Microchannel T-Junction

Gas-liquid two-phase flow in a microfluidic T-junction with nearly square microchannels of 113 μm hydraulic diameter was investigated experimentally and numerically for applications to microreactors and micro heat exchangers. Air and water were used as the working fluids and their superficial velocities were 0.018?0.791 m/s and 0.042?0.757 m/s, respectively. Three-dimensional modeling was performed with computational fluid dynamics (CFD) package FLUENT and the volume-of-fluid (VOF) model. 3D modeling resolved surface tension effects more accurately than 2D simulation. Slug flow (snapping/breaking/jetting) and stratified flow were observed experimentally. From numerical results void fraction was found to follow a linear relationship with the homogeneous void fraction; two-phase frictional pressure drop agreed with the Lockhart-Martinelli correlation with a Chisholm constant of 5; and the contact angle value affected the shape and size of gas slugs and determined the occurrence of liquid film and corner flow. Correlations were developed for prediction of flow parameters. Higher experimental velocity slip caused by gas inlet pressure build-up can result in deviation from numerical predictions.