Transient analysis of proton electrolyte membrane fuel cells (PEMFC) at start-up and failure

A two-dimensional, transient, single-phase computational model, incorporating water transport in the membrane and the flow and transport of species in porous gas diffusion electrodes is developed to evaluate the transient performance of a PEMFC with interdigitated gas distributors. The co-flow and counter-flow of the anode and cathode reactants are discussed to address their effects on PEMFC performance and transients. The important role of water transport in the membrane on the transients is demonstrated. The membrane's water intake or outtake determines the duration of the transients. The effect of the operating conditions on steady state and transient performances is outlined. Overshoots and undershoots are observed in the average current density, due to a step change in the cell voltage and the cathode pressure under start-up conditions. Simulation results are used to address the role of auxiliary components in the failure modes of the PEMFC.