Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.
Proton exchange membrane fuel cells (PEMFC) are
considered a key future technology for both automotive and
stationary applications. At high current densities the
performance curve of a PEMFC deviates from the linear region
where the cell losses are dominated by the ohmic resistance,
and the cell performance deteriorates rapidly. This phenomenon
has often been assigned to mass transport losses because
conventional fuel cells rely on diffusion of the reactants to
reach the catalyst layers. This study will investigate the role of
thermal properties on expected cell performance in general and
on the membrane hydration level in particular. The two key
thermal properties that have been investigated in detail in this
study are the thermal conductivity of the porous gas diffusion
layers k, and the thermal contact resistance between the gas
diffusion layer and the bipolar plates. At a high current density
of 1.0 A/cm2 the difference in the average predicted membrane
hydration level varies from = 8.92 for the best case to a value
down to = 7.73 for the worst case. The difference in the
predicted maximum temperature in the cell is more severe. The
main conclusion is that it is highly recommended to use dense
gas diffusion media with lower porosity but higher thermal
conductivity when employing the interdigitated flow field.
