球形团聚物模型在质子交换膜燃料电池过程模拟中的应用

Application of spherical agglomerate model in PEMFC process simulation

在建立直通道质子交换膜燃料电池(PEMFC)的二维全电池数学模型中,将球形团聚物模型应用至两极的催化剂层。通过调节团聚物中质子传导介质的比例和催化层孔隙率,预测了基准供气状态下单电池的极化曲线,与文献报道的实验数据吻合良好。研究了电池运行过程中,膜电极内各化学组分和电流密度的分布情况及流向,比较了不同供气压力、催化剂铂颗粒尺寸等参数对电池性能的影响。计算结果表明,在阴极及时排出反应产生的水,并在阳极对燃料气进行加湿是保证单电池正常运行的前提,提高阴极的氧化剂气体压力,可显著改善PEMFC单电池性能,特别是在受浓差极化影响较大的大电流密度区;在催化剂铂载量相同的情况下,减小铂颗粒的尺寸可以提高电池的性能。

A two-dimensional full cell mathematic model for PEMFC with conventional parallel flow field was developed.In this model,the transport of the two charged species,electrons and ions,as well as that of the chemical species in MEA was considered.The model treated the catalyst layers as spherical agglomerates of polymer electrolyte coated catalyst particles.Different parameters for polymer electrolyte content in agglomerate and catalyst layer porosity were employed under different cell voltage.The polarization curves predicted at base case by the model agreed well with the published experimental data.Profile of chemical species and current density within MEA in running state was investigated respectively.The influences of pressure and sizes of Pt particles in catalyst on the fuel cell performance were also investigated.The simulation results showed the mass transport and reaction phenomena in MEA,suggested that water draining at cathode and gas humidification at anode is important to maintain the performance of single cell.The results indicated that high pressure of cathode inlet gas was good for PEMFC single cell performance,especially running under low cell voltage.It also indicated that within the same Pt loading,the fuel cell performance is better at smaller Pt particle size.