空冷型PEMFC电堆的单电池特性研究

Voltage Distribution of Self-Humidifying Air-Cooled PEMFC

本文对实验室自制的自增湿空冷型PEMFC电堆进行了自适应特性研究,并分析了各单电池的性能以及各电池的电压分布情况.实验中设定操作条件为:阳极工作压力为2 bar,阴极风扇功率0.3 W,氢气室每隔10 s排水1 s.从实验结果可以看出,空冷型PEMFC的电压分布与负载电流的大小具有一定的联系,大电流负载下电池的电压分布会出现明显的不均匀现象,根据分析结果可以看出,电堆的单体电压波动率与负载电流之间存在近似的指数关系分布,且各单片电池间内阻的差异与大电流下过高的电堆温度都会造成电压分布不均匀的现象.

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.