Abstract
Mass transfer phenomena in polymeric electrolyte membrane fuel cells (PEMFC) electrodes has already been analyzed in terms of the interactions between diffusive and forced flows. It was demonstrated that the whole phenomenon could be summarized by expressing the Sherwood number as a function of the Peclet number. The dependence of Sherwood number on Peclet one Sh(Pe) function, which was initially deduced by determining three different flow regimes, has now been given a more accurate description. A comparison between the approximate and the accurate results for a reference condition of diluted reactant and limit current has shown that the former are useful for rapid, preliminary calculations. However, a more precise and reliable estimation of the Sherwood number is worth attention, as it provides a detailed description of the electrochemical kinetics and allows a reliable comparison of the various geometrical arrangements used for the distribution of the reactants.
Highlights
In a previous work [1], attention was paid to the gas-phase mass transfer occurring on polymeric electrolyte membrane fuel cells (PEMFC) electrodes according to the different flow arrangements used
The various possible diffusive regimes were highlighted and the interaction between diffusive and forced flows was defined in terms of Peclet numbers, so that the overall diffusive resistance could be expressed in terms of a Sherwood number as a function of a Peclet number
A local description of the hydration condition of the membrane allows a reliable prediction of cell performance [2,3,7,10,11,18] and the simulation of different flow fields indicates that the interdigitated flow channel gives in general better results than the serpentine flow channel configuration [11,18]
Summary
In a previous work [1], attention was paid to the gas-phase mass transfer occurring on polymeric electrolyte membrane fuel cells (PEMFC) electrodes according to the different flow arrangements used ( parallel, serpentine, and totally or partially interdigitated). The present work will demonstrate that these approaches are substantially significant and useful for rapid, preliminary and correct calculations the errors in these latter approximate solutions are not fully negligible: only a more precise and reliable estimation of the Sherwood numbers can provide detailed and accurate correlations for the local electrochemical kinetics. This estimation can lead to a useful comparison of the various geometrical arrangements used for the distribution of the reactants. Could be considered as promising steps in the right direction
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