Proposal of a proton exchange membrane fuel cell-based hybrid system: Energy, exergy and economic analyses and tri-objective optimization

Abstract

This article presents energy, exergy and economic analyses and tri-objective optimization of a hybrid system that comprises a proton exchange membrane fuel cell and a recuperative-regenerative organic Rankine cycle. The novelty of this study is the utilisation of a recuperative-regenerative organic Rankine cycle rather than the basic configuration of the organic Rankine cycle to recover waste heat from the fuel cell. The simulation results showed that the proposed system generates a net power of 1195.6 kW, with an exergy efficiency of 44.37% and a product cost rate of 160.78 $/h at the base condition. The hybrid system is found to be more efficient and cost-effective as compared to a standalone fuel cell with 15.05% and 15.06% improvements in energy and exergy efficiencies, respectively, and a 9.28% decrement in unit product cost. The fuel cell is the component with maximum exergy destruction rate of 636.72 kW, accounting for 90.62% of the total exergy destruction. Further, it is also observed that the fuel cell accounts for 89.2% of the total levelized cost rate of the hybrid system. Then a tri-objective optimization is carried out on the system using Pareto Envelope-based Selection Algorithm-II with net power output, exergy efficiency, and product cost rate as the objective functions. The optimization results showed that the proposed system generates a net power of 1271.52 kW, with an exergy efficiency of 49.48% and a product cost rate of 152.62 $/h. It implies that at the optimal conditions, the hybrid system's net power and exergy efficiency increased by 6.35% and 11.51%, respectively, and the product cost rate was reduced by 4.98%. Finally, this study showed that the inclusion of recuperative-regenerative organic Rankine cycle as compared to other organic Rankine cycle layouts improved the performance of the suggested hybrid system compared to similar other systems reported in the literature.