Published in:Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment 389, 173 S. (2017). = RWTH Aachen, Diss., 2017
Language:
English
ISBN:
978-3-95806-263-4
ISSN:
1866-1793
Origination:
Footnote:
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Description:
Fuel cells are energy conversion devices that generate electricity and heat through electrochemical reactions involving hydrogen and oxygen. They are divided into different types according to the electrolytes and the operating temperatures. One promising fuel cell type, which can be used as an on-board power supply in trucks or airplanes, is the high-temperature polymer electrolyte fuel cell (HT-PEFC). In a HTPEFC, phosphoric acid-doped polybenzimidazole is employed in the electrolyte. The typical working temperature of this fuel cell type is between 150 °C and 180 °C. The aim of this thesis is the 3D modeling of HT-PEFC at the cell level, in order to better understand the physical and electrochemical processes within the cell. The open-source software Open FOAM is used as a platform for model development. Four models were implemented to describe different phenomena.• The first model describes electrochemistry with effective parameters related to the geometric surface of the catalyst layer. Mass transfer in the porous gas diffusion layer is represented by a simpleFick’s law approach. • The second model employs a macrohomogeneous approach for the description of electrochemistry, whereby the penetration depth of the electrochemical reaction in the catalyst layer is considered to be a function of the current density. • A mathematical description of water transport from the cathode side to the anode side of the phosphoric acid doped polybenzimidazole membrane, during fuel cell operation, is depicted in thethirdmodel. • The fourth model compares gas transport in the gas diffusion layer, as described by a Stefan-Maxwell approach, with the gas transport according to model 1, above. The mathematical models developed in the present work were validated by comparison of the numericalcalculations with experimental data and analytical solutions. Two different cell geometries were considered: a cell with parallel straight channels, with an active area of 0.2 cm$^{2}$, and a 50 cm$^{2}$ cell, with meandering (serpentine) ...