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Please use this identifier to cite or link to this item: http://hdl.handle.net/1974/1576

Title: NUMERICAL AND EXPERIMENTAL CHARACTERISATION OF CONVECTIVE TRANSPORT IN SOLID OXIDE FUEL CELLS
Authors: Resch, Emmanuel

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Keywords: solid oxide fuel cell, sofc, convection, permeability, model, cfd, klinkenberg, knudsen, electrode
pressure effects
Issue Date: 2008
Series/Report no.: Canadian theses
Abstract: In this work, numerical and experimental methods are used to characterise the effects of convective transport in an anode-supported tubular solid oxide fuel cell (SOFC). To that end, a computational fluid dynamics (CFD) model is developed to compare a full transport model to one that assumes convection is negligible. Between these two approaches, the variations of mass, temperature, and electrochemical performance are compared. Preliminary findings show that convection serves to reduce the penetration of hydrogen into the anode, and becomes more important as the thickness of the anode increases. The importance of the permeability of SOFC electrodes on the characterization of convection is also investigated. Experiments performed on Ni-YSZ anodes reveal that permeability is a function of the cell operating conditions, and increases with increasing Knudsen number. An empirical Klinkenberg relation is validated and proposed to more accurately represent the permeability of electrodes in a CFD model. This is a departure from an assumption of constant permeability that is often seen in the literature. It is found that a varying permeability has significant effects on pressure variation in the cell, although according to the electrochemical model developed in this work, variation in permeability is only found to have minor effects on the predicted performance. Furthermore, it is revealed that an electrochemical model which makes the simplifying assumption of constant overpotential is in error when predicting current and temperature variation. In this work, this is found to predict an unrealistic spatial variation of the current. It is suggested that this approach be abandoned for the solution of a transport equation for potential which couples the anodic and cathodic currents. This will lead to a more realistic prediction of temperature and performance.
Description: Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-11-04 13:54:35.743
URI: http://hdl.handle.net/1974/1576
Appears in Collections:Mechanical and Materials Engineering Graduate Theses
Queen's Theses & Dissertations

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