Constructing region-specific porous flow field to enhance heat, mass and charge transports in proton exchange membrane fuel cells

Abstract

The pursuit of ever-improving performance in proton exchange membrane fuel cells (PEMFCs) requires more appropriate flow field design to reduce the electrode polarizations. Herein, a region-specific porous flow field (rs-PFF) that simultaneously enhances the heat, mass and charge transports is proposed, of which gas permeability and heat conductivity are respectively higher in marginal region and central region than those of the conventional uniform porous flow field (u-PFF). A three-dimensional non-isothermal PEMFC model that considers the multi-phase multi-species transfer is adopted to elucidate the impacts of the rs-PFF. It is demonstrated that the oxygen concentration in weak flow regions is increased by 26.3 % while the temperature in main flow region is decreased by 2.14 K, thus yielding a 5.5 % increase in peak power density. The rs-PFF is effective to reduce reactant supply, thereby saving the system energy consumption. Additionally, even the lower humidified rs-PFF-based PEMFC shows the better performance than the fully humidified u-PFF-based PEMFC. This region-specific design strategy has the potential to be applied to other types of flow field design for improving cell performance.