Analysis of inlet and gap effect in hydrodynamics and mass transport performance of a multipurpose electrochemical reactor: CFD simulation and experimental validation

CFD simulation of mass transfer in electrochemical reactor with mesh cathode for higher phenol degradation

Cathode, where electro-catalytic oxidation barely took place, could exert a significant influence on electro-catalytic efficiency, whereas little investigation has been focused on this effect. In this study, the effect of cathode configuration on electro-catalytic activities was investigated with phenol as model pollutant, and the mechanism was revealed from the perspective of mass transfer with computational fluid dynamics (CFD) simulation. Compared with the planar Ti cathode, the electro-catalytic reactor with mesh Ti exhibited 1.21-1.26 times faster phenol degradation rate under various testing inlet flow rates. CFD simulation revealed the higher velocity distribution both in the reactor and on anode surface when meshed Ti cathode was used, which benefited faster fluid flow so that the pollutant transfer was accelerate especially at higher inlet flow rate. Excellent agreement of mass transfer between CFD simulation and experimental analysis was achieved, the mass transfer coefficient with mesh Ti was 1.40-1.55 times of the case with planar cathode under various inlet flow rates. The enhanced mass transfer performance was mainly ascribed to the rhombic pores of mesh cathode where hydrogen bubbles generated on would escape timely and randomly at various directions, leading to the disturbance of fluid flow around the anode. This study highlighted mesh cathode played a key role in improving pollutant degradation, and CFD, as a versatile and convenient tool to analyze the hydrodynamic behavior of electro-catalytic reactor, showed a strong persuasion to guide the optimization of electrode configuration.

Pressure drop analysis on the positive half-cell of a cerium redox flow battery using computational fluid dynamics: Mathematical and modelling aspects of porous media

Description of electrolyte fluid dynamics in the electrode compartments by mathematical models can be a powerful tool in the development of redox flow batteries (RFBs) and other electrochemical reactors. In order to determine their predictive capability, turbulent Reynolds-averaged Navier-Stokes (RANS) and free flow plus porous media (Brinkman) models were applied to compute local fluid velocities taking place in a rectangular channel electrochemical flow cell used as the positive half-cell of a cerium-based RFB for laboratory studies. Two different platinized titanium electrodes were considered, a plate plus a turbulence promoter and an expanded metal mesh. Calculated pressure drop was validated against experimental data obtained with typical cerium electrolytes. It was found that the pressure drop values were better described by the RANS approach, whereas the validity of Brinkman equations was strongly dependent on porosity and permeability values of the porous media.