Modeling the Dynamic Behavior of Proton-Exchange Membrane Fuel Cell

Abstract

A two-phase transient model that incorporates the permanent hysteresis observed in the experimentally measured capillary pressure of GDL has been developed. The model provides an explanation for the difference in time constants between membrane hydration and dehydration observed in the HFR experiments. When there is liquid water at the cathode catalyst layer, the time constant of the water content in the membrane is closely tied to that of liquid water saturation in the cathode catalyst layer, as the vapor is already saturated. The water content in the membrane will not reach steady state as long as the liquid water flow in the cathode catalyst layer is not at steady state. Also, increased resistance to proton transport in the membrane is observed when the cell voltage is stepped down to a low value, with a corresponding large increase in current.