Performance assessment and multi-objective optimization of a novel vehicular power system integrating a direct borohydride fuel cell with an organic Rankine cycle

In this study, a novel vehicular direct borohydride fuel cell (DBFC) power system integrated with an organic Rankine cycle (ORC) is proposed. The ORC subsystem recovers the waste heat generated by the onboard DBFC stack to produce additional electrical power. Given the limited engineering maturity of vehicular DBFC systems and low-temperature ORCs, the proposed system is investigated through steady-state theoretical and numerical analyses. The principal contribution of this work is the development of a DBFC-ORC system-level framework for vehicle-oriented power assessment, incorporating comprehensive 4E evaluation and multi-objective trade-off analysis in terms of energy, exergy, economic, and environmental performance.Numerical results show that the integration of the ORC subsystem effectively enhances system performance. At operating temperatures of 70, 75, and 80 °C, the maximum net output power of the integrated system is increased by 9.0%, 8.5%, and 8.0%, respectively, compared with that of the standalone DBFC stack. Moreover, the parametric analysis reveals that the 4E performance indicators cannot be simultaneously optimized through parameter adjustment alone. Therefore, multi-objective optimization is performed to obtain the Pareto-optimal solution set and the corresponding optimal operating parameters. Compared with the baseline case(current density of 10500 A/ m 2 , an operating temperature of 353.15 K, a NaBH4concentration of 1 mol/L, an inlet pressure of 2 atm, anode stoichiometric ratios of 1.2 and cathode stoichiometric ratios of 1.2), the selected Pareto-optimal solution yields an 18.22% increase in net output power, a 14.52% reduction in the levelized cost of energy, and a 97.27% increase in exergy efficiency. These results are instructive for the design and implementation of DBFC as a power source for automotive applications.