One-dimensional Model of Oxygen Transport Impedance Accounting for Convection Perpendicular to the Electrode

Autor: G. Maranzana, Jérôme Dillet, J. Mainka, Sophie Didierjean, Olivier Lottin, A. Thomas
Přispěvatelé: Laboratorio Nacional de Computação Cientifica [Rio de Janeiro] (LNCC / MCT), Laboratoire Énergies et Mécanique Théorique et Appliquée (LEMTA ), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
Rok vydání: 2012
Předmět:
Zdroj: Fuel Cells
Fuel Cells, Wiley-VCH Verlag, 2012, 12 (5), pp.848-861. ⟨10.1002/fuce.201100193⟩
ISSN: 1615-6846
1615-6854
DOI: 10.1002/fuce.201100193
Popis: International audience; A one-dimensional (1D) model of oxygen transport in the diffusion media of proton exchange membrane fuel cells (PEMFC) is presented, which considers convection perpendicular to the electrode in addition to diffusion. The resulting analytical expression of the convecto-diffusive impedance is obtained using a convectiondiffusion equation instead of a diffusion equation in the case of classical Warburg impedance. The main hypothesis of the model is that the convective flux is generated by the evacuation of water produced at the cathode which flows through the porous media in vapor phase. This allows the expression of the convective flux velocity as a function of the current density and of the water transport coefficient a (the fraction of water being evacuated at the cathode outlet). The resulting 1D oxygen transport impedance neglects processes occurring in the direction parallel to the electrode that could have a significant impact on the cell impedance, like gas consumption or concentration oscillations induced by the measuring signal. However, it enables us to estimate the impact of convection perpendicular to the electrode on PEMFC impedance spectra and to determine in which conditions the approximation of a purely diffusive oxygen transport is valid. Experimental observations confirm the numerical results.
Databáze: OpenAIRE
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