Verlag des Forschungszentrums Jülich
JUEL-4182
Arends, Gesine
Mathematische Modellierung von Niedertemperatur-Brennstoffzellenstapeln
122 S., 2005
The simulation tool presented in this work develops descriptions of the most
relevant processes in polymer electrolyte fuel cells into a model of a complete
fuel cell stack. Using a finite volume method, the fluxes of mass, heat and charge
across the electrolyte membrane are modelled in an integral form. The model
includes several mechanisms for water transport in the membrane, gas-phase mass
transport limitations in the diffusion layers as well as gas flow distributions in cell
and stack. The water transport model was compared to measurements performed
on a laboratory cell.
The simulation results show that the current density distribution is determined
mainly by membrane water content, superimposed by oxygen depletion. The model
is used to examine the influences of flow patterns, pressure, gas concentrations
and membrane properties as well as flow field and manifold geometries. Temperature
distribution is most important, since even slight temperature differences
have a strong influence on water management. Superposition of temperature effects
and non-uniform gas flow distribution can cause local minima in current
density.
Comparison with a current density distribution determined experimentally shows
that the model predicts current density distributions well even for large, technically
relevant cell sizes.
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