Numerical investigation and experimental validation of water condensation in the gas diffusion layer with different properties

Liquid water in porous media hinders the transport of reactant to catalyst layer, where the electrochemical re -actions occur, which in turn, reduces performance and lifetime of a proton exchange membrane fuel cell (PEMFC). In this study, two types of gas diffusion layer (GDL) materials are used to study the two-phase satu-ration distribution in a PEMFC. The correlations between the effective and anisotropic transport properties and porosity of the two GDLs are solved by the pore scale model. In addition, the anisotropic liquid water perme-ability and the relationship between saturation pressure and capillary pressure is determined by using the Lattice-Boltzmann method. Fuel cell performance as well as liquid water distribution in the GDL using neutron radiography are obtained for validation. Under wet conditions, the cell with Freudenberg GDL performs better than that using Toray GDL, especially at high current densities. The results of the two-phase model simulation show that the peak water saturation for Toray GDL occurs in the catalyst layer and can reach 40%, while the peak water saturation for Freudenberg GDL occurs inside the GDL directly under the ribs and only reaches 25% saturation. The combined results provide key insights to enable high power density operation of a PEMFC through GDL material optimization.

Automated summary

This study investigates the saturation distribution of two types of gas diffusion layer (GDL) materials in a proton exchange membrane fuel cell (PEMFC). The relationships between the effective and anisotropic transport properties and porosity of the two GDLs are determined using a pore scale model. The anisotropic liquid water permeability and the relationship between saturation pressure and capillary pressure are determined using the Lattice-Boltzmann method. Neutron radiography is used to validate the fuel cell performance and liquid water distribution in the GDL. The results show that the Freudenberg GDL performs better than the Toray GDL, especially at high current densities.