Electric-thermal-gas synergistic dynamics in PEMFC-LIB hybrid systems for hydrogen ships: A multi-scale evaluation framework

As maritime transportation continues to dominate global trade, Proton Exchange Membrane Fuel Cell (PEMFC)-Lithium Battery (LIB) hybrid power ship systems (HPSS) present an effective solution for reducing carbon emissions and improving efficiency. This study employs one-dimensional-plus (1D+) modeling and heat current methods to analyze the multi-physics coupling of electrical, thermal, and gas flow responses in HPSS under different operating conditions. A coupling response evaluation system based on the Relative Variability Index (RVI) quantifies system performance. Electrical response analysis reveals high synchronicity between load current and power output, indicating strong sensitivity. Thermal analysis reveals a temperature rise of 10.88 K in the cathode catalyst layer during overshoot load conditions, with the cathode flow channel showing substantial thermal variations, highlighting the need for focused thermal management. Gas flow rate evaluation indicates that curvature values increase by 61.8 %, reflecting a strong correlation between gas flow and load current. Coupled response evaluations indicate that electrical responses are more sensitive compared to thermal and gas flow responses. The RVI values show that thermal responses are dominant, with maximum values of 1.5 for thermal, 1.14 for electrical, and 0.92 for gas flow, indicating that thermal effects surpass electrical and gas dynamics in certain conditions. Moreover, pure PEMFC operation ensures stable power with minimal thermal fluctuations but is constrained by load capacity, joint operation facilitates load sharing yet amplifies thermal and gas flow variations, while LIB power compensation effectively regulates SOC but introduces additional thermal and electrical transients. This study advances maritime carbon reduction and efficiency.