Enhancement and mechanistic elucidation of thermal and electrochemical performance for proton exchange membrane fuel cells with wavy integrated cooling configurations under diverse coolant flow conditions

Suboptimal cooling flow field configurations hinder efficient thermal management in proton exchange membrane fuel cells (PEMFCs), limiting performance and durability. To address this, integrated cooling configurations are proposed, along with their wavy integrated (WICs) and hybrid integrated variants. Parallel, tri-serpentine, and serpentine cooling channels are embedded into blocked reactant flow field, with alternating reactant-coolant flow configuration as a benchmark. Employing a three-dimensional multiphase PEMFC model, the thermal and electrochemical performance of these configurations is investigated across coolant temperature differences (Δ T ). Theoretical resistance analysis and voltage loss decomposition are used to clarify how these designs improve heat transfer and thus electrical output via gas–water transport effects. Results indicate that, by regulating coolant flow and heat conduction patterns at Δ T = 3 K, WICs improve temperature uniformity relative to basic integrated configurations. Through full rib-width coverage with wavy structures, they also exhibit lower average temperature than hybrid setups and benchmark. This enhanced thermal performance shifts water phase equilibrium, promoting membrane hydration and vapor condensation, thereby elevating proton and oxygen availability, and cutting ohmic and concentration losses by approximately 0.05 V. Across varied Δ T levels, WICs consistently deliver optimal thermal and electrical performance, with greater uniformity advantages but diminished output gains as coolant flow rate rises. Balancing output gain against parasitic consumption, serpentine WIC proves optimal for Δ T of 10 K and 6 K, tri-serpentine for 3 K, and parallel for 1 K, yielding net power increases of 3.61%, 2.92%, 2.60%, and 1.96%, respectively, over the conventional parallel design. This work provides design insights into compact PEMFC cooling-unit development.