Pore-Scale Study of Two-Phase Flow in the Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells: The Impact of Polytetrafluoroethylene Content and Gradient Distribution

The polytetrafluoroethylene (PTFE) is commonly used to improve the hydrophobic of the gas diffusion layer (GDL). In this study, impacts of PTFE content and piecewise/linear gradient distributions on the transport behavior of liquid water were numerically studied by using a multiphase lattice Boltzmann method. A two-dimensional microstructure of the GDL was reconstructed by stochastic algorithm. The two-phase flow in the GDLs with PTFE contents of 0, 10, 20, 30 and 40wt% were evaluated and compared. The liquid water transport process can be greatly affected by the PTFE content and the best water drainage performance was provided by the GDL with PTFE content of 30wt%. Subsequently, the GDLs with PTFE piecewise/linear gradient distributions were designed and investigated. It was found that the water drainage performance can be further improved when the PTFE content is well distributed. This study can provide guidelines for design of GDL for high performance proton exchange membrane fuel cells.