On the experimental verification of an electrodialysis simulation model for optimal stack configuration design through solver software

Abstract

Electrodialysis (ED) is well known as a desalination method. In the ED process, anions and cations are transported respectively through anion and cation conductive membranes, while applying an electric field. Specific process membrane stack parameters are determining the ion transport, making ED a relatively complex process. Mathematical modeling is reported in literature, enhancing the insight in the phenomena and allowing the optimization of the stack design and process conditions for a specific application. A comprehensible software based design procedure, using such a mathematical model, is therefore interesting for the industrial ED user. As a result, a selected model was implemented in a solver software. An experimental verification of the software was then performed, using an ED pilot with an industrial type of stack and sodium chloride model solutions. Prior to this, limiting current densities were measured in a small stack. The large stack was used to verify the ohmic region and to obtain basic stack model parameters. In a next step, limiting current density conditions in the large stack were theoretically evaluated in the model calculations for design purposes and correlated with the experimental results. These verifications showed that the software approach is relevant for the estimation of an optimal stack geometry. A number of model restrictions are however indicated as well and some recommendations are made with respect to the expansion and fine tuning of the selected model.