Critical Review of Gas–Liquid Mixing Using Gas-Inducing Impellers: Modeling, CFD Simulation, and ANN Applications

Abstract

This manuscript provides a comprehensive overview of gas-inducing reactors (GIRs) and identifies areas for further investigation. It examines the gas induction systems available in the literature, categorizing them into conventional types of 11, 12, and 22, and highlights the importance of focusing on double-impeller systems as a practical solution for large-scale GIRs. The work includes a thorough review of applied models and correlations for estimating critical impeller speed ( N C ), induced gas flow rate ( Q G ), influence of fluid’s physical properties, power consumption ( P G ), gas holdup (ε G ), and gas–liquid mass transfer coefficient ( k L a ). Furthermore, it discusses the necessity for further research in understanding non-Newtonian flow behaviors, the impact of fluid physical properties across a broad range of fluids, the interdependence of variables, the identification of key parameters, and stability analysis in large-scale reactors. Additionally, the manuscript addresses the challenges and limitations in experimental techniques, equipment utilization, scale-up processes, and the application of modeling tools such as artificial neural networks (ANN) and computational fluid dynamics (CFD) in the context of gas induction.