The Flow Of Liquid Droplets In The Interface Between The Gas Diffusion Layer And The Gas Flow Channel

Gas diffusion layers(GDLs)are the important component of proton exchange membrane fuel cells(PEMFCs).As an important flow pathway for gas reactants and water generated,its internal structure properties are very important to fluid flow and have received increased research attention lately.In this work,the mathematical model of the GDL structure is obtained by random structure reconstruction and XCT tomography reconstruction methods.The properties of void fraction,void distribution,geometric tortuosity,and hydraulic tortuosity have been studied.Lattice Boltzmann method(LBM)was used to study the flow behaviour of gas and liquid in GDLs,and related to pore properties.The results show that the structure with a larger void,the greater the gas flow rate is.In addition,the more the fiber direction tends to be parallel to the paper surface,the greater the obstruction to gas flow and the smaller the gas flow rate.A void with a large pore radius is not necessarily the place with a larger gas flow rate,and the distribution of other surrounding voids also shows an impact on this.It is easier to form a liquid flow passage in a void with a large hydrophobic aperture and smaller anisotropic(The fiber is less selective in the paper level).Large hole radius is conducive to water transfer,while the penetration of liquid from a large pore to small pores is reduced by the hydrophobic boundary,so that small pores can contain liquid water.With a decrease in the anisotropy parameters,the tendency of void distributed in the horizontal direction becomes lower,the flow of liquid water does not need to flow on the horizontal direction,but tends to penetrate through the GDL.