First Investigations of Local Current Density Distribution over the Flow Field Channel and Rib

摘要

In this work experimental methods are presented,that investigate the effects of local current conduction through the gas diffusion layer (GDL) and flow field as well as the influence of reactant gas diffusion in the GDL on local current generation.The project's final goal is to determine the inhomogeneous current density distribution over the flow field's channel and rib,in order to evaluate the errors by assumptions made in modeling as well as to minimize the bipolar plates voltage drop by finding an optimum in rib ratio and size,regarding the flow field geometry.The presented experimental methods aim to backcalculate the current density distribution from locally resolved measurements of the voltage drop under flow field channel and rib.Therefore,the anisotropic conductivity of the backing layer and the occurring contact resistances have to be determined under specific operating conditions.Results show,that the difference in current density under channel and rib is measurable and the inhomogeneities leave considerable room for optimization.