Characterization of dynamics of gas-liquid flows in rectangular bubble columns

Gas-liquid flow in bubble columns is inherently unsteady. The unsteady fluid dynamics influences mixing and other transport processes occurring in bubble column reactors. In this work, we have characterized dynamics of gas-liquid flows in rectangular bubble columns using wall pressure and voidage fluctuations. The low-frequency oscillations caused by meandering bubble plume were characterized using the plume oscillation period. Experiments were carried out to study the influence of superficial gas velocity, sparger configuration, and liquid height-to-width (H/W) ratio on the low-frequency oscillations. The dimensional analysis based on analogy between buoyancy-driven thermal and bubbly flows was carried out to relate low-frequency oscillations to various design and operating parameters. This analysis was able to correlate present as well as previously published experimental data. We have further demonstrated the importance of establishing such a quantitative relationship for validation of computational fluid dynamics (CFD)-based models by carrying out CFD simulations of gas-liquid flow in rectangular bubble columns. The importance of bubble-scale information obtained using conductivity probes in validating Eulerian-Lagrangian models is also demonstrated.