On the Limitations of Volume-Averaged Descriptions of Gas Diffusion Layers in the Modeling of Polymer Electrolyte Fuel Cells. (24th August 2017)

• Record Type: Journal Article
• Authors: García-Salaberri, Pablo A.; Gostick, Jeff T.; Zenyuk, Iryna V.; Hwang, Gisuk; Vera, Marcos; Weber, Adam Z.
• Is Part Of: ECS transactions. Volume 80:Number 8(2017)
• Page Start: 133
• Page End: 143
• Publication Date: 2017-08-24
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/08008.0133ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

Abstract : Understanding of the coupled transport processes that occur in thin gas diffusion layers (GDLs) is necessary to develop improved designs. The traditional technique used to model GDLs is the volume-averaged approximation. However, the applicability of this approach has been long questioned, and the error in the results is unclear. In this work, the limitations of GDL volume-averaged models are examined under single-phase conditions. The lattice Boltzmann method is combined with tomography images of carbon-paper GDLs to assess the existence of a representative elementary volume (REV) in terms of various effective properties. Then, the predictions of GDL volume-averaged and pore-scale formulations are compared by using a CFD model of a differential cell. The results show that a REV cannot be clearly defined. This leads to inhomogeneities in the pore-scale model that the volume-averaged model is not able to capture despite the overall flux through the GDL is similar in both cases.