Parallel Plate Electrochemical Reactor Model: Material Balance Closure and a Simplification

A material balance closure calculation is presented to test the consistency of a previously published model of a parallelplate electrochemical reactor. New expressions are used in this procedure to calculate the average concentration of species i and the average current density for reaction j from the predicted concentration and potential distributions. Also, the previously presented model equations are simplified by assuming that the axial concentration gradient for species i can be approximated by a step change from the known feed concentration to the unknown outlet concentration. This one-step model provides a qualitative evaluation of cell performance and adds insight into understanding of the previous model, while providing substantial savings in computer time. The models are compared using a hypothetical case of the electrowinning of copper from a chloride solution. For a small aspect ratio (S/L), the models show that a set of independent variables consists of the cell potential (Ecell), the surface area of an electrode per unit of cell volume(1/S), and the residence time (L/avg) when the feed concentrations (ci,feed) are fixed