Analytical Modeling of PEM Fuel Cell Gas Diffusion Layers Deformation under Compression: Part 2 - Nonlinear Behaviour Region

Abstract

In the Proton exchange membrane PEM fuel cell stack, the porous gas diffusion layer (GDL) provides mechanical support for the membrane assembly against the compressive loads imposed by bipolar plates. In this paper, using assumption of existing gap between the fibers in the GDL micro-structure, an analytical model proposed in first part of this study for linear region is extended to predict the GDL nonlinear mechanical behaviour in low compressive pressures. The present unit cell model covers salient microstructural parameters and properties of the fibrous porous medium including: carbon fiber diameter, elastic modulus, pore size distribution, gap size distribution between fibers. A comparison between the present model and the GDL stress-strain data shows that the assumption of closing gap between the fibers during compression can accurately describe the GDL nonlinear behaviour. The proposed model also provides useful information about the microstructural properties of the GDL during compression such as gap distribution between fibers that can be used in the GDL transport properties prediction.