Comprehensive optimization of PEMFC hybrid propulsion systems for regional aircraft: Design, sizing, and operational strategy

The development of zero-carbon smart cities requires efficient hydrogen deployment, with regional aviation emerging as a critical application for infrastructure integration. Conventional approaches that optimize component design, system sizing, and operational strategy separately often lead to excessive system mass and infeasible control under high altitude conditions. To overcome these limitations, this study proposes a coupled three-level optimization framework for PEMFC–battery hybrid regional aircraft that integrates component design, system sizing, and operational strategy. Component-level optimization of the centrifugal compressor and hydrogen storage tank achieves significant mass reduction and efficiency improvements. Incorporating these refined component parameters into system-level optimization and optimizing the sizing of fuel cell and battery collectively reduce total propulsion mass by 3.25%. At the operational level, and informed by these precise system parameters, a Dynamic Programming-based strategy reveals a critical altitude dependency in the optimal cathode pressure ratio. This coupled approach reduces hydrogen consumption by 7.88% compared to rule-based methods. Furthermore, a life cycle cost optimization strategy incorporating component degradation reduces total operating costs by 52% through an optimized trade-off between hydrogen efficiency and component durability. Robustness analysis confirms that the proposed strategy maintains near-optimal performance under stochastic power demand perturbations, with a deviation of only 0.85%. By overcoming the lack of synergy and suboptimal performance inherent in isolated design methodologies, this study provides a highly viable and practical framework for developing scalable hydrogen infrastructure in the aviation sector of zero-carbon urban ecosystems.