Two-phase flow in coupled gas diffusion layer and patterned wettability metal foam flow field in PEM fuel cells

This study reconstructs the 3D structures of the gas diffusion layer (GDL) and metal foam flow field (MFF) in proton exchange membrane fuel cells (PEMFCs) using X-ray computed tomography. The innovation lies in applying the phase-field lattice Boltzmann method (a mesoscopic approach) to simulate two-phase flow in the GDL-MFF coupling region. Results show that, compared to hydrophobic metal foam (HMF), a patterned wettability metal foam (PWMF) with a hydrophilic region contact angle of 5° and a diameter of 0.3 mm improves several performance aspects. These include reducing liquid water coverage at the GDL-MFF interface (below 2 %), enhancing vertical gas convection in the GDL, lowering and stabilizing pressure in the MFF, and achieving a more uniform gas velocity distribution. However, improper PWMF design can slow liquid water transport from the GDL to the MFF, increasing water saturation in the GDL and reducing drainage rates. A contact angle of around 65° in the hydrophilic region of PWMF enhances PEMFC performance, increasing vertical gas convection by 67 % compared to HMF, without reducing liquid water transport. When the diameter of the hydrophilic region exceeds the MFF's average pore size, vertical convection in the GDL improves by 40 %, while maintaining liquid water transport.