Numerical and experimental estimation of global gas holdup in a bubble column using computational fluid dynamics (CFD)

Bubble column bioreactors can provide adequate heat and mass transfer, rapid mixing and good suspension of solids. The influence of the lift force in square cross-sectional bubble columns is being studied in order to evaluate its importance in CFD simulations. In this work, the global gas holdup ((alpha) over bar (G)) was analyzed experimentally and numerically using CFD. Euler-Euler model was applied for the gas-liquid multiphase simulations. Different specific air flow rates (1.0-5.0 vvm) were simulated in order to evaluate the inclusion of lift interfacial force in the modeling and the effect of air flow rate in this analysis. The simulations considering lift force effect showed greater agreement between the experimental data and those estimated by computational fluid dynamics, with the highest values of (alpha) over bar (G) found for the higher specific air flow rate (5 vvm) and the minor bubble diameter (4 mm) analyzed in this study.