에너지 보존 기반 저위발열량 운전을 통한 연료전지 시스템 순 효율 최적화

초록

Physics-based, reduced-order fuel cell system models are developed to optimize net efficiency through energy-conservation-based heating-value prediction. The stack model predicts cell voltage, gross power, and outlet water state, while the auxiliary models calculate parasitic power. The heating value is determined from an energy conservation analysis. The numerical models are validated against published experimental data and show good agreement, with relative errors of 1.9% and 4.7% for the estimated stack and system power, respectively. Results show that the proposed lower heating value (LHV) strategy maintains saturated outlet gas without liquid-water formation. In contrast, the baseline strategy with fixed inlet humidity induces liquid-water formation above 0.6 A/cm² and increases both the heating-value input and cooling demand. Therefore, the proposed strategy achieves higher net system efficiency in the high-current-density region. Furthermore, a quasi-steady analysis using a representative vehicular load profile predicts a maximum net efficiency improvement of 9.3%. These results provide a physical basis for energy-efficient LHV operation of vehicular fuel cell systems.

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