Low stoichiometry operation of a polymer electrolyte membrane fuel cell employing the interdigitated flow field design

Fuel cell operation on dry reactant gases under low stoichiometry conditions employing the interdigitated flow field is investigated using a multi-fluid model. It is assumed that the MEA contains a water uptake layer which facilitates water absorption to the membrane and hence prevents the anode gas phase from drying out. It is shown that the membrane humidity level increases with decreasing stoichiometric flow ratios to values of lambda approximate to 7. Operating the cathode side at a stoichiometric flow ratio of xi(c) = 1.2 appears feasible under steady state conditions, while our simulations suggest that the anode stoichiometry may even be as low as xi(a) = 1.05. The effect of operation pressure and temperature on the membrane water content is studied. Finally, experiments are suggested to determine the kinetic absorption coefficient and the specific surface area of the electrolyte inside the catalyst layers.