Exergy-guided multiphysics analysis of transport irreversibilities in PEMFC flow-field architectures

Transport-induced thermodynamic irreversibilities remain one of the primary factors limiting the efficiency and high-load performance of proton exchange membrane fuel cells (PEMFCs). However, the complex interactions among flow-field architecture, coupled transport phenomena, electrochemical reactions, and exergy destruction are not yet fully understood. This study presents an exergy-guided three-dimensional multiphysics framework that integrates electrochemical kinetics, multicomponent species transport, heat transfer, two-phase flow, membrane hydration, and entropy-generation analysis to investigate transport irreversibilities in hierarchical PEMFC flow-field architectures. The developed framework establishes direct quantitative relationships between flow-field geometry, local transport behavior, and exergy destruction mechanisms under realistic operating conditions. The results show that total exergy destruction increases from 0.14 to 1.10 W cm^-2 as current density increases, while exergy efficiency decreases by approximately 40–50 because of intensified mass-transport limitations. The optimized multiscale flow-field architecture improves net power density by up to 19 and exergy efficiency by 24, while simultaneously reducing pressure losses by 20–25 and increasing oxygen concentration by 6–8 compared with the conventional design. Furthermore, transport-related irreversibilities become dominant above approximately 1.5 A cm^-2, where mass-transfer resistance and viscous dissipation together account for more than 30–35 of the total exergy destruction. These findings demonstrate that the proposed exergy-guided multiphysics framework provides a physically consistent strategy for identifying dominant transport-loss mechanisms and optimizing PEMFC flow-field architectures for enhanced electrochemical and thermodynamic performance. Copyright © 2026 Alrwashdeh.