Computational optimization of heat recovery in a combined Proton Exchange Membrane Fuel Cell (PEMFC) and Organic Rankine Cycle (ORC) system using zeotropic fluids with Non-Dominated Sorting Genetic Algorithm II (NSGA-II)

This study presents a bi-objective optimization approach to maximize net power output by integrating Proton Exchange Membrane Fuel Cell (PEMFC) and Organic Rankine Cycle (ORC) systems. The research emphasizes the role of zeotropic working fluids in recovering waste heat from the PEMFC and converting it into additional electrical power through the ORC cycle. The study begins with validating the electrochemical model of the PEMFC by comparing simulated polarization curves with experimental data. Subsequently, three working fluid combinations—R245fa/R227ea, R245fa/R123, and Isobutane/R227ea—are evaluated for the ORC system. Among these, R245fa/R227ea exhibits the highest efficiency in combined PEMFC-ORC performance and is selected for further analysis. Under optimized conditions, the integrated system achieves an 18.91% increase in net power, alongside a 7.38% improvement in the overall efficiency compared to a standalone PEMFC without heat recovery. Additionally, a notable reduction in residual heat from both the PEMFC and ORC is observed while maintaining consistent hydrogen consumption. The ORC heat release is minimized for a zeotropic mixture of 65% R245fa and 35% R227ea, making it a key criterion for selecting working fluids in PEMFC-ORC applications.