Effects of solid volume fraction on bubble characteristics under four flow regimes in a quasi-2D gas–liquid–solid bubble column

Abstract This study investigates the influence of solid volume fraction ( V s = 0.03–0.30) on bubble characteristics across various flow regimes in a three-phase bubble column, comparing the effects for two solid particle sizes (48 μm and 150 μm). Bubble size distribution, area distribution, number, shape, and Sauter mean diameter ( d 32 ) are analyzed. At the smaller particle size (48 μm), increasing V s consistently shifts the bubble size distribution towards smaller diameters across all regimes, indicating a particle stabilizing effect on small bubbles; bubble coalescence under these conditions is primarily driven by increasing gas velocity ( U g ). Conversely, at 150 μm, elevating V s broadens the bubble size distribution at all tested gas velocities. These contrasting results demonstrate that while more adhering 48 μm particles stabilize small bubbles, increased concentrations of 150 μm particles promote bubble coalescence. Furthermore, higher V s reduces bubble numbers across all flow regimes due to increased flow resistance. For 48 μm particles, increased V s also enhances the longitudinal stretching deformation of bubbles. The d 32 results quantitatively reflect the observed changes in bubble size distributions. This work provides fundamental data elucidating particle effects on hydrodynamics in gas-liquid-solid bubble columns.