A simple multiple flow regime modeling approach of induced flow in external loop airlift reactors

• A novel method for modelling the induced flow in airlift reactors is presented. • The homogeneous flow model is upgraded by capturing lower scale phenomena. • The model was tested over multiple flow regimes and reactor geometries. • While remaining simplistic, the error of the model is below 10%. • The model can be used both with a theoretical or experimental fitting approach. Accurate treatment of heat and mass transfer processes inside airlift reactors requires accurate velocity field information. This study presents a novel one-dimensional model forecasting induced liquid flow within an external loop airlift reactor across diverse flow regimes. The approach is grounded on homogeneous flow assumption, augmented by a novel correction term derived through modeling of turbulence-induced pressure losses behind gas structures, employing the separated flow model (Lockhart-Martinelli). The model was assessed by comparing the results with purpose-provided experimental data utilizing air and demineralized water. The gas and liquid superficial velocities ranged from 0.001-0.6 m/s and 0.2–1.1 m/s, respectively. Within ± 10 %, an agreement between the novel model and experimental data was observed for both bubbly, separated, and intermediate flow regimes. A similarly robust agreement was confirmed through comparisons with five published experimental datasets. The distinctive feature of this model is its ability to accommodate multiple flow regimes in a unified manner. It circumvents the necessity for specific regime modeling by introducing a correction term with a complexity marginally surpassing that of the conventional homogeneous flow approach. Beyond its primary application in airlift reactors, the model provides a unified framework for modeling two-phase flow hydrodynamics in thermal applications, particularly in flow boiling and bubble-induced convective heat transfer systems. The model’s simple yet effective structure also allows for integration into higher-fidelity heat transfer simulations, making it valuable for boiling heat transfer studies, enhanced cooling strategies, and industrial multiphase flow applications.