A two-phase model to predict the enhanced mass transfer by bubble-induced convection in parallel-plate electrochemical reactors

Abstract

This study introduces a two-phase model (Euler-Euler) designed to predict mass transfer enhancement resulting from electro-generated bubbles under varying conditions. Considering parameters such as bubble size, current density, turbulence, and fluid properties, the model aims to provide a comprehensive understanding of the relationship between bubble dynamics and mass transfer enhancement. The methodology for constructing the model, the incorporation of empirical correlations for bubble-liquid interactions, the validation against experimental data, and a sensitivity analysis are discussed. The model proves valuable in simulating mass transfer behaviour under bubble-induced convection, allowing for the straightforward exploration of the effects of different parameters. It is inferred that the exponent in the Schmidt (Sc) number in correlations for gas-evolving electrodes should be 0.5. Incorporating two dimensionless numbers, Reynolds (Reg) and Galileo (Ga), in a correlation is essential to fitting experimental results, accounting for the hydrodynamics of the two-phase system. Finally, the model facilitates the prediction of cell voltage during galvanostatic operations and the total current for a fixed cell potential difference. This capability enables the calculation of figures of merit, such as space time yield and specific energy consumption, offering practical insights for engineering scale-up and optimization.