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Accurate analytical model for determination of effective diffusion coefficient of polymer electrolyte fuel cells by designing compact Loschmidt cells

Izadmehr, M ; Sharif University of Technology | 2017

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  1. Type of Document: Article
  2. DOI: 10.1016/j.fuel.2017.03.017
  3. Publisher: Elsevier Ltd , 2017
  4. Abstract:
  5. Effective diffusion coefficient is an important parameter which needs to be determined in different fields of study, such as cathode catalyst layers of PEM fuel. For this purpose, a Loschmidt diffusion cell can be used. When a porous medium is placed in Loschmidt apparatus, the effective gas diffusion coefficient (EGDC) of this section must be correlated by diffusion coefficient in absence of a porous medium. In the previous researches studying the Loschmidt diffusion cell, a simplifying infinite-length assumption was used in the analytical solution. Therefore, the solution is only applicable for a short time range, and this can result in high error. In order to overcome this challenge, the length of cell should be quite long. This requirement is not experimentally and economically easy to achieve. In this study, a new analytical solution is proposed by applying Fick's second law and separation of variables technique. This model does not use simplifying assumptions such as infinite length and equivalent diffusivity coefficient. The results of the new analytical solution are verified with the experimental measurements, as well as numerical finite element simulation. In order to analyze the reliability of previous methods, a new characteristic time is defined based on diffusion wave propagation in the system. Finally, a sensitivity analysis on thickness of porous media and EGDC is conducted and it is shown that previous models can predict diffusion coefficient with high deviations. © 2017 Elsevier Ltd
  6. Keywords:
  7. Effective diffusion coefficient ; Finite element simulation ; Loschmidt cell ; Mass transport ; Polymer electrolyte membrane fuel cells ; Diffusion ; Electrolytes ; Finite element method ; Fuel cells ; Mass transfer ; Polyelectrolytes ; Porous materials ; Proton exchange membrane fuel cells (PEMFC) ; Sensitivity analysis ; Solution mining ; Wave propagation ; Cathode catalyst layers ; Diffusivity coefficient ; Effective diffusion coefficients ; Finite element simulations ; Loschmidt cells ; Polymer electrolyte fuel cells ; Separation of variables ; Simplifying assumptions ; Solid electrolytes
  8. Source: Fuel ; Volume 199 , 2017 , Pages 551-561 ; 00162361 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S0016236117302909