Tertiary current and potential distribution including laminar/turbulent convection, diffusion, and migration by the finite volume method using OpenFOAM

Abstract

A numerical tool is presented under a finite volume framework, implemented in the open-source package OpenFOAM, to calculate concentrations and current and potential distributions in electrochemical systems composed of two-dimensional electrodes with a monopolar connection. The convection, diffusion, and migration of species in electrochemical systems are considered in coupling the potential and concentration fields together with the hydrodynamics under laminar or turbulent conditions. Multiple reactions with any kind of kinetic control (charge-transfer, mass-transfer, mixed, or special cases) are permitted at both electrodes. The algorithm allows calculations for a given local potential at the working electrode (potentiostatic control) or for a fixed cell potential difference and also for a current flowing through the cell (galvanostatic operation). The model was verified by using analytical expressions and simplified numerical implementations. Moreover, a new test reaction is proposed in order to study the effect of ionic migration and validate the model. A good match between experimental results and predicted calculations was obtained. This computational tool can be employed to optimize both cell stack design and system operation conditions. Furthermore, the algorithm can also be used to check, for a given geometrical configuration and reaction environment, the validity of some assumptions such as tertiary current distribution without migration, mass-transfer-controlled reactions, or primary-secondary current distributions.