A porous-rib flow field for performance enhancement in proton exchange membrane fuel cells

Abstract

Concentration loss under solid rib induced by oxygen starvation and water flooding in conventional solid-rib flow fields (sr-FFs) limits the cell performance. Herein, a porous-rib flow field (pr-FF) is proposed for proton exchange membrane fuel cells (PEMFCs) to improve the gas transport and water removal under the ribs. The multi-physical processes and cell performance are investigated via a three-dimensional multi-phase PEMFC model. Numerical results show that the limiting current density and peak power density for the pr-FF-based PEMFC are increased by 15% and 9% respectively, while the pressure drop is reduced by 38%. A higher oxygen concentration and a lower liquid saturation under the porous ribs are obtained, in addition to the improved uniformities of oxygen concentration and current density. The pr-FF-based PEMFC is suggested to operate under a fully humidified condition for yielding a higher performance, where the peak power density is increased by 14% corresponding to the increase in cathode inlet humidity from 0.5 to 1.0. More interesting, the porous-rib design can enhance the cell performance regardless of the porosity. The proposed pr-FF provides an alternative solution for performance enhancement of PEMFCs by enhancing under-rib mass transport without increasing pumping power.