Numerical Investigation of Tapered Flow Field Configurations for Enhanced Polymer Electrolyte Membrane Fuel Cell Performance

A tapered flow field configuration (FFC) is proposed to improve the oxygen transport, water removal and performance of polymer electrolyte membrane fuel cells. By performing a three-dimensional multiphase fuel cell model, the influence of the tapered FFC on the internal physicochemical process and overall cell performance are numerically investigated in this study. The tapered FFC without and with consideration of the electric contact resistance (ECR) between bipolar plates and gas diffusion layers are comparatively evaluated. Compared with the conventional FFC, for the tapered FFC without considering the ECR, an increased ratio of the side length for the inlet to that for the outlet (LI/O) enhances oxygen transport, water removal and cell performance. However, for tapered FFCs considering the ECR, an increased ratio of LI/O initially increases and then weakens oxygen transport, water removal and cell performance. Nevertheless, regardless of the tapered FFC with or without considering the ECR, a decreased ratio of LI/O degrades the overall cell performance. In comparison with all tapered FFC designs, the optimal tapered FFC design with an LI/O of 1.2 exhibits a more uniform reactant and current density distributions, which reduces the coefficient of variation of the current density and oxygen molar concentration by approximately 21.4% and 8.5%, thereby improving overall cell performance.