|dc.description.abstract||Until now, water management is an important issue on the performance of proton exchange membrane fuel cells (PEMFC). Especially, at high cell load or low gas flow rate, the two-phase transport of reactants and products constitutes an important limit in performance of PEMFC. In the two-phase region, product water obstructs the open pores of the cathode gas diffusion layer (GDL) and micro-porous layer (MPL) and limits the reactants transport to the active catalyst sites.
In this study, we establish the two-dimensional, steady state, isothermal two-phase model according to two-phase theory. The occurrence of liquid saturation in what sites of GDL, MPL and catalyst layer can be anticipated in this model. Via this two-phase model, we discuss the effect on PEMFC performance and liquid saturation with different porosity and thickness of GDL and MPL. In another way, we study the proton behavior and the influence on current density, liquid saturation distribution in catalyst layer via this two-phase model、Bulter-Volmer equation and Nernst-Planck equation.
Result shows that by increasing the porosity of porous medium, increasing the cell performance due to enhance the reactants transport and render them more active for electrochemical reaction surface. When the proton exchange membrane can hold more protons in unit volume and increase proton diffusion coefficient in the electrolyte, the PEMFC performance will be increased.||en_US|