Regulating bubble specific surface area and pressure drop in microchannels via embedded obstacles

Abstract

Gas-liquid flow hydrodynamics are essential for controlling multiphase transport processes and reaction properties in the microreactors. In this work, gas-liquid two-phase flow is regulated effectively by arranging obstacle array in microchannels using a coupled Level Set and Volume of Fluid (CLSVOF) method. The numerical model is validated against experimental data, confirming its reliability for capturing interface dynamics. Through analysis of Nitrogen bubble evolution, the flow regime during bubble-obstacle interaction is clarified, and five distinct transition stages are identified. The effects of key parameters, including liquid velocity, glycerol concentration, surfactant concentration, obstacle spacing, and gas-liquid velocity ratio, on the average bubble specific surface area (SSA) and system pressure drop are systematically quantified. The results show that SSA and pressure drop increase with liquid velocity, glycerol concentration, and surfactant concentration, but decrease with obstacle spacing. The most significant enhancement occurs in 60% glycerol solutions. Increasing the gas-liquid velocity ratio raises pressure drop while reducing SSA, with both trends saturating at higher ratios. Based on the systematic investigation of various factors, a novel and more accurate pressure-drop correlation for both straight and obstacle-laden microchannels is developed, which outperforms existing models when tested against literature data.