质子交换膜燃料电池多孔介质中水的两相迁移

Two-Phase Transport of Water in Porous Medium of Proton Exchange Membrane Fuel Cells

在混合流动模型的基础上,建立了一个新的二维两相流模型来研究质子交换膜燃料电池内水分的传递规律和分布状态,在该模型中,催化剂层作为一个有厚度的实体包含在电极中.模型耦合了质子交换膜燃料电池电极中的流动方程.组分方程、催化剂层和质子交换膜中的电势和电流密度分布方程,可以应用在质子交换膜燃料电池的阴极,也可以使用在阳极.同时,模型还考虑了相变引起的液相和气相间的动量变化,重点模拟了水分在燃料电池的阴极、阳极和质子交换膜中的传递规律及其分布状态.模拟结果显示:升高加湿温度、提高电流密度和降低电池温度都会使电池质子膜中的水分含量增大,质子传导率升高,也会使阴极中液态水含量增加,阴极浓差极化加剧.

A new two-dimensional, two-phase flow model based on the mixture flow model was developed to investigate the water transport and distribution in the proton exchange membrane （PEM） fuel cell. The model couples the flows, species, electrical potential, and current density distributions in the cathode and anode fluid channels, gas diffusers, catalyst layers, and membrane, respectively. The catalyst layers are now included in the respective unified domains for the cathode and anode. Furthermore, the two-phase flow model was also used in the anode side, and the momentum transfer between the liquid and gas phases due to phase change was taken into consideration. The model was used to study water transport and its distribution in the cathode, the anode, and the membrane of PEM fuel cell. simulation results show that the increase of humidification temperature and current density, or the decrease of fuel cell temperature makes the increase of water content in membrane, leading to the increase of ionic conductivity and overpotential of concentration difference in cathode attributed to flooding.