A novel cathode flow field for PEMFC and its performance analysis

Abstract

A good flow field design is important to the proton exchange membrane fuel cell (PEMFC) performance, especially under a high current density region, which is dominated by concentration polarization. Motivated by the variable cross-section channel idea, in this study, a novel flow field containing a converging-diverging (C-D) pattern is proposed. A three-dimensional multiphase model is established to study its performance. The numerical results show that it outperforms the conventional straight channel and only depth-variant channel. In the novel flow field the enhanced under land cross flow and higher effective mass transfer coefficient both improve the reactant transport. The effects of operating conditions, like stoichiometric ratio and operating pressure, on cell output performance are studied. It is found that a higher promotion rate can be obtained by increasing the stoichiometric ratio, but increasing the operating pressure has little effect. The droplet dynamic behavior in the C-D channel and straight channel are studied, and the results prove the better drainage capability of the novel flow field.