压缩气体扩散层微观结构中氧气传输过程的研究  

Investigation of Oxygen Transport in the Microstructures of the Compressed Gas Diffusion Layer

作　　者：杜青[1] 李雅楠 牛志强 周侠 包志铭 焦魁[1] Du Qing;Li Yanan;Niu Zhiqiang;Zhou Xia;Bao Zhiming;Jiao Kui(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《天津大学学报（自然科学与工程技术版）》2020年第11期1175-1182,共8页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(51976138);国家重点研发计划资助项目(2018YFB0105500).

摘　　要：气体扩散层(gasdiffusionlayer,GDL)是实现质子交换膜燃料电池电极内有效气体传输的关键部件.在实际电池中,GDL所承受的装配压力会引起其内部结构较大的变形,尤其是脊下受压部位变形显著.然而,目前国内外相关研究主要集中在未受压GDL上,针对GDL局部受压后的变形对GDL内氧气传输过程的影响方面的研究相对较少,受压GDL内的传质机理尚不清楚.为阐明装配压力所引起的GDL微观结构变形对内部氧气传输过程的影响规律,本文基于有限单元法(finiteelementmethod,FEM)和GDL微观结构随机重构算法建立了压缩GDL孔尺度氧气扩散模型,针对4种装配压力(1.4 MPa,2.8 MPa,4.2 MPa,5.6 MPa)下GDL孔隙内的氧气传输过程进行了详细研究对比.同时,本文研究了孔隙率、纤维直径和GDL厚度等结构参数对压缩GDL内氧气传输特性的影响.结果表明:随着装配压力的增大,GDL内的最小氧气浓度值在逐渐减小,同时流道和脊下氧气浓度分布均匀性变差;随着纤维直径减小、孔隙率增大,在GDL平面方向,压缩GDL中的氧气扩散能力增加;在GDL厚度方向,流道和脊下的氧气浓度同时增加,且脊下氧气浓度上升较多,流道和脊之间氧气浓度梯度增加.GDL孔隙率对压缩GDL中氧气扩散影响较大,且随着GDL孔隙率的增加,GDL内的最小氧气浓度值也增加.当氧气在GDL平面内传输时,随着GDL厚度的减小,横向氧气传质阻力增大,GDL内最小氧气浓度值减小.同时,本文也发现纤维直径对压缩GDL中氧气扩散的影响较小.A gas diffusion layer(GDL)is a key component for achieving efficient gas transport in the electrodes of a proton exchange membrane fuel cell.In an actual battery,the assembly pressure experienced by the GDL causes severe deformation of its internal structure,especially the compressed portion under the ridge.However,related research in China and elsewhere has mainly focused on uncompressed GDLs,with relatively little work conducted on the oxygen transmission process in a GDL subject to deformation under local compression.The mass transfer mechanism in a compressed GDL is also unclear.To clarify the influence of microstructural deformation of the GDL on the internal oxygen transport process due to assembly pressure,in this study,we established a compressed-GDL porescale oxygen diffusion model based on the finite element method(FEM)and a GDL-microstructure random reconstruction algorithm.We made a detailed investigation of the oxygen transfer processes in the GDL pores at four levels of assembly pressure(1.4 MPa,2.8 MPa,4.2 MPa,and 5.6 MPa).In addition,we studied the effects of structural parameters such as porosity,fiber diameter,and GDL thickness on the oxygen transport characteristics in compressed GDLs.The results show that with increases in the assembly pressure,the minimum oxygen concentration in the GDL gradually decreases and the uniformity of the oxygen concentration distribution in the flow channel and ridge worsens.As the fiber diameter decreases and the porosity increases,across the GDL plane,the oxygen diffusion capacity in the compressed GDL increases.In the thickness direction of the GDL,the oxygen concentrations in the flow channel and ridge increase simultaneously,with the oxygen concentration in the ridge increasing more,and the oxygen concentration gradient between the flow channel and ridge also increasing.The porosity of the GDL has a significant effect on the diffusion of oxygen in a compressed GDL;as the GDL porosity increases,the minimum oxygen concentration in the GDL increases.When oxygen i

关 键 词：质子交换膜燃料电池 气体扩散层重构 装配压力 氧气传输 有限元 

分 类 号：TK448.21[动力工程及工程热物理—动力机械及工程]