Three-dimensional numerical study of a cathode gas diffusion layer with a through/in plane synergetic gradient porosity distribution for PEM fuel cells

This study proposes a through-plane (TP) and in-plane (IP) synergetic (SYN) gradient porosity distribution (GPD) in the cathode gas diffusion layer (CGDL) to enhance the mass transfer and water removal of a polymer electrolyte membrane (PEM) fuel cell. The novel SYN-GPD CGDL is comparatively evaluated with TP-GPD, IP-GPD and uniform porosity distribution (UPD) CGDL by implementing a three-dimensional multiphase fuel cell model. The results show that a higher porosity within CGDL near the cathode flow channel (CFC) for TP-GPD CGDL, however, a higher or lower porosity near the cathode outlet for IP-GPD CGDL improves the mass transfer and water removal within fuel cell, which benefitting the uniform distributions of oxygen and current density, and the cell performance. Additionally, as compared with the TP-GPD, IP-GPD and UPD CGDL, the SYN-GPD CGDL has a greater advantage in the enhancement of mass transfer and water removal, consequently resulting in much more homogeneous internal physical quantity profiles and a higher overall cell performance. Ultimately, the optimal SYN-GPD CGDL improves the maximum power density by 6.73%, while reducing the coefficient variations (CVs) of the oxygen mass fraction and current density by approximately 10.24% and 40.69%, respectively, compared with those of the UPD CGDL. (c) 2022 Elsevier Ltd. All rights reserved.