Modelling of heterogeneities inside polymer electrolyte fuel cells due to oxidants

In present study, the influences of oxidants (concentration and stoichiometry factor) on the heterogeneities inside the polymer electrolyte fuel cells (PEFC) are analysed and modelled. In situ current density mapping technique is adopted to evaluate the heterogeneities. Heterogeneity factor is being introduced in present study to investigate the effects of the oxidants on the local performances. Local and mean performances of the fuel cells are analysed and modelled as a function of the air stoichiometry factor. It is observed that the minimum values of stoichiometry factors required for maintaining heterogeneities inside the fuel cells at the minimum level increase with the mean current density. Based on the experimental results, a model is being developed for determining the optimum values of air stoichiometry factor to maintain the heterogeneity inside the fuel cell at minimum level. The local performances of the fuel cells are investigated as a function of oxygen concentration at the cathode inlet. It is observed that the heterogeneities inside the fuel cell do not always increase with the decrease in the oxygen concentration at the cathode inlets. However, the heterogeneity factor always increases with the decrease in oxygen concentration.