Numerical Investigation into Effects of Gas Sparger and Horizontal Baffles on Hydrodynamics of Flat Bubble Column

Computational fluid dynamics (CFD) was used to investigate influence of different gas sparger configurations and the presence of horizontal baffles on hydrodynamic characteristics in a flat bubble column. CFD results of time-averaged local and global gas holdup, liquid axial velocity, and Sauter mean diameter were experimentally validated. Subsequently, the validated CFD model was extended to investigate the effects of different gas sparger configurations, i.e., S1, S3, S4, S5, S8, and S72, and baffles arrangements, i.e., Config-A and Config-B on overall hydrodynamics at different superficial gas velocities (Ug = 0.0014 m/s and 0.0073 m/s). CFD results demonstrated significant influence of both sparger and Ug. Gas holdup and interfacial area increased with smaller, more numerous sparger openings, such that S72 achieved ~1.55 times higher holdup and ~2 higher interfacial area than that of S1. Spargers with fewer and larger openings induced stronger turbulence, which intensified early breakup and coalescence and broadened the bubble size distribution. Results revealed that spargers with many small openings (S72) produced the narrowest distribution, retaining a high fraction of bubbles of initial size (5 mm), whereas spargers with fewer larger openings (S1) generated broader distributions with significant coalescence, especially at higher Ug. The inclusion of baffles enhanced liquid circulation and gas–liquid mixing and contact. However, intensified turbulence below each baffle significantly increased coalescence, producing larger bubbles and resulting in only marginal changes in interfacial area despite increased gas holdup.