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

• Published in: Electrochimica acta 2024-09, Vol.498, p.144606, Article 144606
• Main Authors: Colli, A.N., Bisang, J.M.
• Format: Article
• Language: English
• Subjects: Bubble-induced convection; Electrochemical reactors; Gas-evolving electrodes; Gas-liquid flow; Mass transfer enhancement; OpenFOAM; Two-phase hydrodynamics
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2024.144606

•A hydrodynamic model simplifies exploration of parameter effects in bubble-induced mass transfer.•Incorporating dimensionless numbers improves correlation accuracy for experimental results.•Theoretical inference of Schmidt number exponent aligns with literature measurements.•A correlation including Reynolds and Galileo numbers is crucial for accurate predictions. 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.