Performance prediction, optimization and economic analysis of a combined PEMFC-ORC system

Proton exchange membrane fuel cells (PEMFC) are considered as highly promising solutions for both stationary and mobile applications. However, the constraint of recovering waste heat from PEMFCs is still a challenging task. In this context, the present paper is devoted to prediction of the performance of a combined system, consisting of a proton exchange membrane fuel cell integrated with an organic Rankine cycle (PEMFC-ORC). The PEMFC waste heat is recovered by an ORC system for electricity generation. Here, a validation study was conducted by comparing the obtained results with a literature-based case. Simulation comparisons of the combined system performance were made using five different organic working fluids. The R123 exhibited the best improvement in terms of power and efficiency. It improved the net power and overall efficiency of the combined system by 13.76% and 5.19%, respectively, compared to the PEMFC system. It was also outlined how stack operating pressures and temperatures affect the system performances. Moreover, an optimization study was performed to select the operating parameters values that maximize the system's power output. Accordingly, the net electrical output and overall efficiency of the system using the basic working fluid R123 have been improved by 16.17% and 5.47%, respectively. The investigations were completed by an economic analysis, where payback period and net cumulative profit of the system were predicted.