Lattice Boltzmann modeling of coupled multi‐phase reaction processes in the proton exchange membrane fuel cells

The multi‐phase reaction processes within the proton exchange membrane fuel cells (PEMFCs) are critical for optimizing water management, reducing platinum loading, and improving cell performance. However, it is a great challenge to study these complex processes through visualization experiments. To reveal the coupling mechanism between multi‐phase flow and reaction, a 3D Lattice Boltzmann Method (LBM) model is proposed. It achieves bidirectional coupling of flow and reaction while maintaining computational efficiency and accuracy. Based on the established model, the water transport, oxygen concentration, and reaction performance are systematically studied. The results reveal a strong interplay between water production and current density: excessive water accumulation floods active sites, whereas rapid drainage favors higher current density. The minimum porosity yields both higher water production and higher current density. High overpotential readily induces flooding. Platinum loading exhibits a similar trade‐off mechanism, where an optimum value must be identified to balance reaction and water management.