关键词: 空冷型PEMFC, 电流密度-电压特征曲线, 电压分布

Abstract: In this work, the self-adaptive characteristics of self-humidifying air-cooled PEMFC stack was investigated. The performance and the unit-cell voltage distribution of the stack were measured and analyzed through the unit-cell I-V curve fitting. The operating conditions for this experimental study were set as follows: hydrogen pressure at the anode was 2 bar, the fan power used for the reactant oxygen feed and stack cooling was at 0.3 W, and the duration and time gap of water purged from hydrogen chamber were 1 s and 10 s, respectively. The experimental results showed that the self-humidifying air-cooled PEMFC stack used for this work could be in stable operation with a certain fan power, e.g., 0.3 W, at self-adaptive mode without the requirement of external control circuit. The unit voltage distribution of the air-cooled PEMFC stack was highly affected by the load current. Under the operation with higher current density, the unit-cell voltage distribution of the stack was less uniform due to the difference in the internal resistance of the unit-cells and the excessive temperature existed in the stack. Based on the data analyses, an approximate exponential relationship was found between the voltage fluctuation rate and the load current density.

Key words: air cooled PEMFC, I-V curve, voltage distribution