Anode purge management for hydrogen utilization and stack durability improvement of PEM fuel cell systems

Proton exchange membrane fuel cell (PEMFC) is one of the most promising power sources for vehicle applications. However, improving efficiency has always been the focus of researches for PEMFCs. To improve the hydrogen utilization and protect the stack of PEMFC systems, a general anode purge scheme is proposed in this paper. Firstly, based on a typical topology of the hydrogen delivery subsystem, the water management of the anode loop is introduced to decouple the performance degradation caused by nitrogen accumulation from water flooding. For the purge strategy, an accurate and fast anode nitrogen concentration observer is established to determine the purge interval. Then, the purge duration is determined by the simulation analysis. Finally, the effectiveness and reliability of the proposed anode purge scheme are verified by testing a new and an aged commercial PEMFC stack. Experimental results show that the proposed anode purge strategy increases the hydrogen utilization rate of the actual PEMFC system to 99% (with considering the hydrogen crossover loss) and greatly prolongs the purge interval based on the real-time estimation of the anode nitrogen concentration.