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An improved MRT lattice Boltzmann model for calculating anisotropic permeability of compressed and uncompressed carbon cloth gas diffusion layers based on x-ray computed micro-tomography
journal contribution
posted on 2012-10-02, 11:04 authored by Yuan Gao, Xiaoxian Zhang, Pratap Rama, Rui Chen, Hossein Ostadi, Kyle JiangThe gas diffusion layers (GDLs) in polymer proton exchange membrane fuel cells are
under compression in operation. Understanding and then being able to quantify the
reduced ability of GDLs to conduct gases due to the compression is hence important in
fuel cell design. In this paper, we investigated the change of anisotropic permeability of
GDLs under different compressions using the improved multiple-relaxation time (MRT)
lattice Boltzmann model and X-ray computed micro-tomography. The binary 3D X-ray
images of GDLs under different compressions were obtained using the technologies we
developed previously, and the permeability of the GDLs in both through-plane and inplane
directions was calculated by simulating gas flow at micron scale through the 3D
images. The results indicated that, in comparison with the single-relaxation time (SRT)
lattice Boltzmann model commonly used in the literature, the MRT model is robust and
flexible in choosing model parameters. The SRT model can give accurate results only
when using a specific relaxation parameter whose value varies with porosity. The simulated
results using the MRT model reveal that compression could lead to a significant
decrease in permeability in both through-plane and in-plane directions, and that the relationship
between the decreased permeability and porosity can be well described by both
Kozeny-Carman relation and the equation derived by Tomadakis and Sotirchos (1993,
“Ordinary and Transition Rdgime Diffusion in Random Fiber Structure,” AIChE J., 39,
pp. 397–412) for porosity in the range from 50% to 85%. Since GDLs compression takes
place mainly in the through-plane direction, the results presented in this work could provide
an easy way to estimate permeability reduction in both through-plane and in-plane
directions when the compressive pressure is known.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Aeronautical and Automotive Engineering
Citation
GAO, Y. ... et al, 2012. An improved MRT lattice Boltzmann model for calculating anisotropic permeability of compressed and uncompressed carbon cloth gas diffusion layers based on x-ray computed micro-tomography. Journal of Fuel Cell Science and Technology, 9 (4), 041010, 10pp.Publisher
© ASMEVersion
- NA (Not Applicable or Unknown)
Publication date
2012Notes
This article is closed access.ISSN
1550-624XPublisher version
Language
- en