Numerical study of a three-dimensional ramp flow field for proton exchange membrane fuel cells (PEMFC)

Abstract

The Proton Exchange Membrane Fuel Cells (PEMFC) are regarded as a key technology for alleviating resource constraints and addressing environmental challenges. To enhance the output power and mass transfer characteristics of PEMFC, this study developed a 3D model of a PEMFC featuring a wedge-shaped flow field plate using CFD methods. The study focused on analyzing the flow behavior and hydrothermal management of reactants, as well as examining the water removal capacity and mass transfer characteristics across various angular channel configurations. The results indicated that different inlet methods combined with ramped flow channels affected the mass transfer within the fuel cell. The polarization curves showed greater consistency for reacting gases flowing both downstream and countercurrent. When the reacting gas flowed countercurrent, it did not favor the uniform distribution of the gas, despite its strong water removal capacity and mass transfer characteristics. The greatest impact on the performance of PEMFC was observed when the reaction gases flowed convectively. At a tilt angle of 18° and a voltage of 0.25 V, the maximum current density reached to 19,547 A/m², representing a 24.7% increase over the conventional parallel flow channel. Under these conditions, the reactive gases were more uniformly distributed within the PEMFC, and the water removal capability was significantly enhanced. The results demonstrated that the new wedge-shaped flow field plate of PEMFC can generate high current densities at larger angles and lower voltages, enhancing oxygen distribution and facilitating the efficient removal of liquid water.