MLP-based cascaded optimization of a novel combined power and steam system for collaborative recovery of waste heat and pressure energy from fuel cells

As a zero-carbon carrier with high energy density, the efficient utilization of hydrogen is a key pathway for achieving deep industrial decarbonization. This urgently requires the synergistic conversion of chemical and thermal energy within a multi-energy complementary framework. This study proposes a novel combined power and steam system that couples a PEMFC with a flash heat pump. The system utilizes the pressure energy from the cathode exhaust to drive a turbine for auxiliary power generation and recovers the waste heat from both the anode and cathode exhausts to preheat the reactant gases. Simultaneously, the heat pump recovers the waste heat from the cooling channel, achieving internal energy cascade utilization through an economizer and a preheater. Furthermore, a cascaded optimization method integrating data-driven modeling, feature attribution analysis, and multi-objective decision-making is established to identify the system operating conditions. The results indicate that the coefficients of determination for the surrogate models all approach 1.00, verifying the high reliability of the data-driven approach in predicting the performance of the cogeneration system. Feature attribution analysis further indicates that the current and stack temperature show the highest relative importance for the power generation efficiency and cost distribution of the PEMFC, whereas the compressor discharge pressure and make-up water flow rate act as the primary factors influencing the heating capacity and economic performance of the heat pump. The case study demonstrates that under the selected operating conditions, the cogeneration system delivers 76.96 kW of net power and 390.92 kg/h of high-temperature steam, achieving a comprehensive energy efficiency of 0.89. Moreover, the LCOE for the PEMFC and the LCOH for the heat pump are reduced to $476.75/MWh and $1.32 × 10 -2 /kg, respectively. Consequently, the proposed method effectively bridges operating variables and performance indicators to trade-off energy efficiency and economic viability, thereby providing theoretical guidance for low-grade PEMFC waste heat cascade utilization and advanced cogeneration system development.