Discriminating Trickle-Flow Hydrodynamic Models:  Some Recommendations

The forecasting ability of five one-dimensional (1-D) two-fluid phenomenological models for liquid holdup and two-phase pressure drop in trickle-flow reactors was evaluated using the most comprehensive trickle-flow regime database. All of these models, namely, the permeability model, the slit model, the extended slit model, the 1-D CFD model, and the double-slit model can be used to predict liquid holdup. Among them, the permeability and the slit models, because of a much simpler structure, are recommended. The extended slit model based on Iliuta et al. (Ind. Eng. Chem. Res. 1998, 37, 4542) shear and slip constitutive relationships can be employed for two-phase pressure drop predictions. When the knowledge of wetting efficiency becomes essential at very low liquid flow rates, the double-slit model is recommended.