Lifetime and efficiency analysis and optimization of PEMFC-based combined heat and power system with auxiliary heating for battery

This paper proposes a proton exchange membrane fuel cell (PEMFC) based combined heat and power (CHP) system model, comprising a PEMFC aging model, a battery aging model, and subcomponents model. In low temperature environments, heat production of PEMFC stack is utilized to provide auxiliary heating for lithium-ion storage battery, greatly slowing down its capacity degradation rate. Several parameters' (PEMFC operating current, PEMFC temperature, battery temperature and battery initial capacity) effects on lifetime and efficiency of entire system are investigated. To improve system lifetime and efficiency, these parameters are optimized using non-dominated sorting genetic algorithms (NSGA-Ⅱ) and the optimal solution is selected by technique for order preference by similarity to ideal solution (TOPSIS). The results show that the auxiliary heating for battery not only increases the system lifetime by 5.15%, but also improves the energy utilization of the PEMFC-based CHP system by 6.53% compared with system without auxiliary heating for battery. Under initial battery capacity of 40 Ah, the optimized parameters can further extend system life by 4.87% and increase efficiency by 4.48%, with optimized lifetime of 7749 h and efficiency of 80.44%. The optimized PEMFC stack's power is increased by 42 W with current density of 0.76 A/cm², which prolongs its aging time and stabilizes battery temperature at 25.09 °C. The present study provides guidance for the enhancement of PEMFC-CHP system's lifetime and efficiency.