Performance evaluation and optimization of a distributed generation system integrating high-temperature proton exchange membrane fuel cell and recuperative-regenerative Organic Rankine Cycle

Improving the electrical efficiency of distributed generation systems based on high-temperature proton exchange membrane fuel cells (HT-PEMFC) is essential for its promotion. This paper proposes a distributed generation system that uses the recuperative-regenerative Organic Rankine Cycle (RR-ORC) to recover waste heat from the HT-PEMFC for electricity generation. To further increase the evaporation temperature of the RR-ORC, it innovatively utilizes organic fluid to replace conventional coolants for stack cooling. The energy, exergy, and economic analysis method is adopted to evaluate the system performance comprehensively. The results suggest that toluene is an optimal organic fluid. Under the typical condition, the total cost per hour, the net power, and the energy efficiency of this novel system are 44.86 $/h, 119.66 kW, and 49.48 %, respectively. Compared with the conventional system integrating HT-PEMFC and ORC, the system net power can be improved by 7.55 %. Moreover, the parameterization results suggest that the current density, fuel cell temperature, cathode stoichiometry, and pinch point temperature difference of the condenser can significantly affect the system performance. On this basis, the optimal design parameters under which the total cost per hour and the system exergy efficiency are 44.88 $/h and 53.87 %, respectively, have been obtained through a two-objective optimization.