Effect of cathode recirculation on high potential limitation and self-humidification of hydrogen fuel cell system

Abstract

The high potential at the start and stop of the stack, as well as the flooding and film drying phenomena that occur during operation, will seriously cause the performance degradation of PEMFC. In this study, the effects of the cathode cycle on the high-voltage limiting strategy and water management characteristics of the hydrogen fuel cell system under different operating conditions was measured using the orthogonal test and the AC impedance measurement methods. The experimental results show that by reducing the fresh airflow and increasing the amount of air recirculation, the oxygen concentration can be reduced and the single piece voltage can always be kept below 0.8 V under a small load. Air recirculation improves the relative humidity at the cathode inlet close to the humidifier, thereby improving the output performance of the stack and having better dynamic characteristics. Furthermore, air recirculation can also enhance the water removal capacity of the stack outlet under high power operation with less pump power, thereby significantly improves the consistency of the distribution of oxygen along the flow channel and increasing the durability of the stack. The conclusion can provide more specific guidance for fuel cell performance improvement and control optimization.