Mass transfer in the homogeneous flow regime of a bubble column

Abstract

A model for the evaluation of the mass transfer coefficient in bubble column reactors in the homogeneous regime is proposed. This approach combines three-dimensional two-phase flow simulations using OpenFOAM with mass transfer models in order to evaluate the average mass transfer coefficient in the reactor. The accuracy and limitations of the simulations are discussed based on comparisons with existing experimental data and correlations from the literature. Radial gas holdup and velocity profiles at different operating conditions are in reasonable agreement at low gas velocities. A sensitivity analysis was performed to determine the best interfacial force model among several possibilities. Schiller-Naumann’s drag force model appeared to be the most appropriate, a swarm correction has a limited impact. Overall, the predicted global mass transfer coefficients fell within the range of values obtained from existing correlations in the literature. The level of accuracy of the proposed approach is, however, difficult to estimate as the predictions from the correlations in the literature varied over a 5-fold range. Despite the limitations of the proposed model (e.g., low gas velocities), the approach could be used to estimate the mass transfer in columns with internal packings, baffles or inserts, for which no correlation exists in the literature.