A simulation of the tertiary current density distribution from a chlorate cell - I. Mathematical model

Numerical modeling is becoming an integral part of all research and develop ment within the field of electrolytic systems. A numerical model that calcu lates the current density distribution and concentration profiles of a chlo rate cell is presented here, The results are shown as functions of electrol yte velocity and exchange current density. The model takes into account the three transport mechanisms; diffusion, migration, and convection by consid ering the development of the flow velocity vector through the channel. It w as seen that the developing velocity profile influences the concentration o verpotentials, which in turn influences current density distributions. Resu lts from the model show that the total current density decreased along the length of the anode, and that this distribution varied more at lower veloci ties. In addition, it was seen that migration contributes significantly to species transport, even within the diffusion layer. Finally, the model indi cates that the hypochlorite ion is the main participant in the principal si de reaction producing oxygen, and not the hypochlorous acid molecule. The r esults are useful as they increase knowledge of the chlorate process, and c an be used to simulate future systems with a wide range of varying paramete rs such as cell geometry, flow, electrolyte composition, and electrode mate rials. The aim of the model is to use it as a tool for identifying the sour ces that contribute to the overpotential in the cell. This article concentr ates on the concentration overpotential, which is one of the phenomena that can actually be influenced, (C) 2001 The Electrochemical Society.