A Methodology for the Design Optimization of Bipolar Plates of PEM Fuel Cells

Polymer Electrolyte Membrane Fuel Cells (PEMFCs) recently received a relevant interest as an electric power generation technology in Fuel Cells Electric Vehicles (FCEVs) to decarbonize hard-to-abate sectors alongside Battery Electric Vehicles (BEVs). However, the massive requirements of power and durability indicate the urgent need to develop higher-than-ever power density cell designs with minimum internal gradients responsible for accelerated degradation, thus requiring a methodology able to disregard sub-optimal concepts since the early design stage. Starting from the outcomes of a first study, confirming that for industry-relevant PEMFCs the parallel channels flow field was the best solution to jointly minimize the pressure losses and to limit super-saturation at high current density, still several degrees of freedom exist for the cell designer. In this study, the research of the optimal PEMFC design is fine-tuned using CAE-guided design exploration, exploring candidate solutions using an optimization software for the simulation of the coupled mass/heat/charges transport processes in PEMFCs. The study aims at identifying designs maximizing the current density or the uniformity in membrane water content. The investigated input variables are the width of bipolar plates ribs, and the height of the gas diffusion layers, independently evaluated at cathodic and anodic side. The methodology shown in this paper leverages the scalability of parametrized 3D-CAD models and of multi-dimensional 3D-CFD simulation, and it is applied to an elementary cell unit. Starting from a conventional baseline design, two optimized configurations are identified that maximize the current density under the same voltage (+10%) and the uniformity of the membrane water content (+13%), respectively, showing the entity of performance gain made possible by the wise use of optimization methods in the field of PEMFC engineering.