Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
We propose a simple diffusion model of a PEM fuel cell and
perform its thermodynamic analysis. Our description is based
on a set of two mass balance equations involving water and
proton transport through the membrane coupled with two reaction
equations describing the electrochemical reactions at the
electrodes. Equations for the water and proton flux densities are
constructed in a linearized form suitable for the analysis from
the point of view of irreversible thermodynamics. In terms of
our simplified model, relations for the characteristic thickness
of a PEM membrane is derived, and the maximum efficiency
of a fuel cell is evaluated, both as functions of the transport
properties of the PEM material.