Microstructural Evolution and Fluid Transport in Gas Diffusion Layers under Compression: A Micro-CT Based Study

This study investigated the microstructural evolution and mass transfer performance of Toray TGP-H-060 carbon paper gas diffusion layer (GDL) under pristine, uniform compression (2 MPa), and offset compression (2 MPa, 0.5 mm displacement) conditions. High-resolution microcomputed tomography (Micro-CT) combined with filtered backprojection (FBP) reconstruction techniques was employed to quantitatively analyze changes in pore structure, fiber geometry, and volume fraction. Adaptive thresholding and iterative gray scale adjustment ensured the reconstructed model’s porosity matched the original sample (78%). Compared to statistical reconstruction methods, the FBP-based approach better preserves submicron connectivity and anisotropy, enabling precise pore-scale CFD simulations. Uniform compression reduced porosity by 15.4% and increased local flow velocity by 25%, while offset compression misalignment triggered more significant porosity fluctuations (61%–82%), fiber rearrangement, and peak flow rates nearing 6 m/s, indicating irregular flow channels and mass transfer losses. This validation-oriented 3D reconstruction framework quantitatively reveals how compression patterns and structural heterogeneity influence gas diffusion layer permeability and flow field distribution, thereby guiding fuel cell component optimization.