Numerical Simulation of Mass Transfer Characteristics of Gas–Liquid Bubble Columns and an Improved Mass Transfer Model

This study aims to achieve an accurate prediction of the mass transfer characteristics of bubble columns under various conditions. First, numerous simulation cases are conducted to explore the appropriate numerical models and bubble sizes for accurately predicting gas holdup of air–water bubble columns operated with superficial gas velocity in the scope of 0.01 to 0.23 m/s. Second, suitable approaches are employed to evaluate the accuracy of some developed aspect ratio models and mass transfer models. Lastly, an improved model considering the residence time distribution is developed, and the effects of bubble shape and bubble swarm on mass transfer are deeply analyzed. This work provides a comprehensive insight into the mass transfer characteristics across different regions of gas–liquid bubble columns operated at various regimes, and offers references for precisely predicting gas–liquid mass transfer rates as well as designing and optimizing bubble columns.