As the demand for green energy and fuel cells grows, more attention is drawn towards Solid Oxide Fuel Cells (SOFCs). Random and complex structure of composite electrodes and underlying electrochemical process has not been completely unveiled yet and further study is required to acquire more understanding. Modeling in this regard plays an important role as it pinpoints key parameters in optimum design of the cell without resorting to costly and uncertain experiments which might even lead to misinterpretations due to random nature of experimental data. The aim of this work is to develop a new rigorous model to study the structure performance relationship of (SOFC) composite electrodes. The work has been conducted in two phases, a two-dimensional continuous approach and three-dimensional discrete model.
A new two-dimensional, geometrical model which captures the inhomogeneous nature of the location of electrochemical reactions based on random packing of electronic and ionic conducting particles has been developed. The results show that the concentration of oxygen inside the cathode in the two-dimensional model is not only a function of the electrode depth but also changes along the width of the electrode. Furthermore the effect of composition of the electrode on the length of three phase boundary (TPB) and total polarization resistance has been demonstrated. A parametric study of the effect of the conductivity of ionic conductor and diffusion coefficient on the performance of the electrode has been given.
To make a more realistic analysis, a three-dimensional reconstruction of (SOFC) composite electrodes was developed to evaluate the performance and further investigate the effect of microstructure on the performance of electrodes. To enhance connectivity between particles and increase the length of TPB, sintering process is mimicked by enlarging particles to certain degree. Geometrical characteristics such as length of TBP and active contact area as well as porosity can easily be calculated using the current model. Electrochemical process is simulated using resistor-network model and complete Butler-Volmer equation is used to deal with charge-transfer process on TBP. The model shows that TPBs are not uniformly distributed across the electrode and location of TPBs as well as amount of electrochemical reaction is not homogeneous. Effects of particle size, electrode thickness, particle size ratio, electron and ion conductor conductivities and rate of electrochemical reaction on overall electrochemical performance of electrode are investigated. / Chemical Engineering
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/1339 |
| Date | 11 1900 |
| Creators | Abbaspour Gharamaleki, Ali |
| Contributors | Luo, Jingli (Chemical and Materials Engineering), Chuang, Karl (Chemical and Materials Engineering), Nandakumar, Krishnaswamy(Chemical and Materials Engineering), Kumar, Amit (Mechanical Engineering), Karan, Kunal (Chemical Engineering) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Detected Language | English |
| Type | Thesis |
| Format | 2728613 bytes, application/pdf |
| Relation | Abbaspour A., Jingli Luo, K. Nandakumar , Three dimensional random resistor network model for solid oxide fuel cell composite electrodes, J. Electrochimica Acta 55(2010), 3944, Abbaspour A., Jingli Luo, K. Nandakumar , Karl T. Chuang, Modeling of SOFC electrodes based on random packing of particles, 8th World Congress of Chemical Engineering, Montreal, Quebec, Canada, August 23-27, 2009, Abbaspour A., X. Wen, Nandakumar K., Luo J., Chuang K. T. Geometrical modeling of microstructure of solid oxide fuel cell composite electrodes. Journal of Power Sources 185 (2008) 961, Abbaspour A., X. Wen, K. Nandakumar, K. T. Chuang and Jingli Luo, Relating Performance to Microstructure of SOFC Composite Electrodes, a Three-Dimensional Modeling Approach, 58th Canadian Chemical Engineering Conference, Edmonton, Alberta, Canada, October 28-31, Abbaspour A., Nandakumar K., Luo J., Chuang K. T. A novel approach to study the structure versus performance relationship of SOFC electrodes. Journal of Power Sources (2006) 2, 965-970, Abbaspour A., K. Nandakumar, K. T. Chuang, J. Luo, A New Approach to Study the Structure vs Performance Relationship of SOFC Electrodes, 7th European SOFC forum, Lucerne, Switzerland, July 3-7, 2006 |
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