Model based analysis of forced and natural convection effects in an electrochemical cell

Abstract

High purity copper, Suitable for electrical applications, Can only be obtained by electro-winning. The hallmark of this process is its self-induced natural convection through density variations of the electrolyte at both anode and cathode. In order to accelerate the process, first its full dynamic complexity needs to be understood. Thus, an OpenFoam®-based 2D model has been created. This finite-volume multiphysics approach solves the laminar momentum and copper-ion species conservation equations, as well as local copper-ion conversion kinetics. It uses a Boussinesq approximation to simulate the species-momentum coupling, namely natural draft forces induced by variations of the spatial copper concentration within the fluid. The model shows good agreement with benchmark-cases of real-life electrochemical cells found in literature. An additional flow was imposed at the bottom of a small-scale electrochemical cell in order to increase the ionic transport and thereby increase the overall performance of the cell. In a small-scale electrochemical cell in strictly laminar flow, the overall performance could be increased and stratification decreased.