A boundary layer analysis for determination of the limiting current density in an electrodialysis desalination
| Autor: | Yoshihiko Sano, Akira Nakayama, Xiaohui Bai, Kenji Tado |
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| Rok vydání: | 2017 |
| Předmět: |
Work (thermodynamics)
Chemistry Mechanical Engineering General Chemical Engineering Analytical chemistry Limiting current 02 engineering and technology General Chemistry Mechanics Electrodialysis 021001 nanoscience & nanotechnology Boundary layer 020401 chemical engineering Stack (abstract data type) General Materials Science 0204 chemical engineering Electric current 0210 nano-technology Porous medium Water Science and Technology Voltage |
| Zdroj: | Desalination. 404:41-49 |
| ISSN: | 0011-9164 |
| Popis: | A general ion-transport equation has been derived eliminating the electrophoresis term from the set of Nernst-Planck equations for cations and anions, under the local electro-neutrality assumption. Boundary layer solutions were obtained for the two asymptotic cases of sufficiently short and long channels, respectively, when the electric current is applied uniformly across the channels. A local volume averaging theory for porous media was also introduced to describe the cases of electrodialysis stacks with spacers. The results obtained for both with and without spacers are compared against available experimental data. The predicted limiting current density and stack voltage based on the asymptotic solutions for sufficiently short channels agree well with those of measurements for both cases with and without spacers, revealing the validity of the present analysis based on the local electro-neutrality assumption. It has been clearly shown that the spacers work to delay possible depletion of the ions on the dilute side of the membrane, thus increasing the limiting current density. |
| Databáze: | OpenAIRE |
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