微孔间距和孔径对PEMFC气体扩散层表面液滴流动传输特性的影响

Analysis on Influence of Micropore Spacing and Size on Droplet Flow Transport Characteristics on Gas Diffusion Layer in PEMFC

质子交换膜燃料电池(PEMFC)被认为是最具潜力的新能源汽车动力装置之一,其性能受到气体扩散层(GDL)表面液滴的形成及动态传输特性的影响。本文以格子Boltzmann方法(LBM)的伪势模型为基础,对液滴从GDL表面浮现、生长和脱落等动态过程进行了仿真模拟,详细分析了微孔间距和孔径对气体扩散层表面液滴动态特性以及流道内压降的影响。研究结果表明在双进水孔的情况下,两个微孔小于某一个微孔间距时,两个液滴会发生融合,融合后的液滴会增大气流通道内的压降,缩短液滴排出的时间,当两个微孔孔距足够大时,两个液滴之间几乎没有相互影响,液滴排除时间相等,且流道内压降随着微孔间距的增加而降低。不同孔径的液滴在GDL表面的运动主要受气体作用剪切力的影响,与下游孔径大于上游孔径液滴的运动周期相比,上游孔径比下游孔径大时,液滴的运动周期更短。

Proton exchange membrane fuel cell(PEMFC)is considered as one of the most promising power devices for new energy vehicles,whose performance is affected by the droplet formation and dynamic transport properties on the surface of the gas diffusion layer(GDL).In this paper,based on the pseudo-potential model of the lattice-Boltzmann method(LBM),the dynamic processes of droplet emergence,growth,and shedding from the GDL surface are simulated,and the effect of micro pore spacing and micro pore size on the dynamic characteristics of droplets on the surface of the GDL as well as the pressure drop in the flow channel are analyzed in detail.The research results show that in the case of dual inlet holes,when the distance between two micropores is less than a certain value,the two droplets will merge.The merged droplet will increase the pressure drop in the airflow channel and shorten the time for droplet discharge.When the two micropore spacing is sufficiently large,there is almost no interaction between the two droplets,with the same droplet exclusion time,and the pressure drop inside the flow channel decreases with the increase of the micropore spacing.And the pressure drop in the flow channel decreases with the increase of micropore spacing.The motion of droplets with different micropore sizes on the surface of GDL is mainly affected by the gas-actuated shear force,and the motion period of droplets with upstream micropore size larger than downstream micropore size is shorter compared to the motion period of droplets with larger downstream micropore size.