PEMFC中水的饱和蒸汽压力与其中多孔介质特征关系研究

Relationship Between Saturated Water Vapour Pressure and Characteristics of Porous Medium in PEMFC

质子交换膜燃料电池(PEM FC)水管理是电池能否良好运行的关键.根据催化层微观结构模型,分析了其中电化学反应生成水的传递方式;又据催化层、扩散亚层和扩散层多孔介质材料的亲水性和憎水性,计算了多孔材料中孔径对饱和蒸汽压力的影响.认为电化学反应生成的水可能是气态也可能是液态;材料亲、憎水性和孔径对饱和蒸汽压力有巨大的影响.为了在PEM FC中更精确地构造反应物和生成物的流通通道,微观上研究水的相变和二相流是必须的,因此应构造新的相变和二相流模型.

Water management of PEMFC is a key factor for its successful operation. Based on the microstructure model of the catalyst layer, the transfer manner of the water produced in the electrochemical reaction is analysed. According to the hydrophilic and the hydrophobic characteristics of the porous medium of the catalyst layer, sub-diffusion layer and the diffusion layer, the effect of the diameter of the pore in the porous medium on the saturation water vapour pressure is calculated, and hence conclusion is made that the produced water by the electrochemical reaction can be either vapour or liquid, depending upon the environment where it exists. Hydrophilicity, hydrophobicity and the diameter of the pore in the porous medium have great effect on the saturation water vapour pressure; when water phase change and two-phase flow is studied in pore level, the factors mentioned above must be considered.