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- Title
- Numerical Simulation of Electrolyte-Supported Planar Button Solid Oxide Fuel Cell.
- Creator
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Aman, Amjad, Orlovskaya, Nina, Xu, Yunjun, Das, Tuhin, University of Central Florida
- Abstract / Description
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Solid Oxide Fuel Cells are fuel cells that operate at high temperatures usually in the range of 600oC to 1000oC and employ solid ceramics as the electrolyte. In Solid Oxide Fuel Cells oxygen ions (O2-) are the ionic charge carriers. Solid Oxide Fuel Cells are known for their higher electrical efficiency of about 50-60% [1] compared to other types of fuel cells and are considered very suitable in stationary power generation applications. It is very important to study the effects of different...
Show moreSolid Oxide Fuel Cells are fuel cells that operate at high temperatures usually in the range of 600oC to 1000oC and employ solid ceramics as the electrolyte. In Solid Oxide Fuel Cells oxygen ions (O2-) are the ionic charge carriers. Solid Oxide Fuel Cells are known for their higher electrical efficiency of about 50-60% [1] compared to other types of fuel cells and are considered very suitable in stationary power generation applications. It is very important to study the effects of different parameters on the performance of Solid Oxide Fuel Cells and for this purpose the experimental or numerical simulation method can be adopted as the research method of choice. Numerical simulation involves constructing a mathematical model of the Solid Oxide Fuel Cell and use of specifically designed software programs that allows the user to manipulate the model to evaluate the system performance under various configurations and in real time. A model is only usable when it is validated with experimental results. Once it is validated, numerical simulation can give accurate, consistent and efficient results. Modeling allows testing and development of new materials, fuels, geometries, operating conditions without disrupting the existing system configuration. In addition, it is possible to measure internal variables which are experimentally difficult or impossible to measure and study the effects of different operating parameters on power generated, efficiency, current density, maximum temperatures reached, stresses caused by temperature gradients and effects of thermal expansion for electrolytes, electrodes and interconnects.Since Solid Oxide Fuel Cell simulation involves a large number of parameters and complicated equations, mostly Partial Differential Equations, the situation calls for a sophisticated simulation technique and hence a Finite Element Method (FEM) multiphysics approach will be employed. This can provide three-dimensional localized information inside the fuel cell. For this thesis, COMSOL Multiphysics(&)#174; version 4.2a will be used for simulation purposes because it has a Batteries (&) Fuel Cells module, the ability to incorporate custom Partial Differential Equations and the ability to integrate with and utilize the capabilities of other tools like MATLAB(&)#174;, Pro/Engineer(&)#174;, SolidWorks(&)#174;. Fuel Cells can be modeled at the system or stack or cell or the electrode level. This thesis will study Solid Oxide Fuel Cell modeling at the cell level. Once the model can be validated against experimental data for the cell level, then modeling at higher levels can be accomplished in the future. Here the research focus is on Solid Oxide Fuel Cells that use hydrogen as the fuel. The study focuses on solid oxide fuel cells that use 3-layered, 4-layered and 6-layered electrolytes using pure YSZ or pure SCSZ or a combination of layers of YSZ and SCSZ. A major part of this research will be to compare SOFC performance of the different configurations of these electrolytes. The cathode and anode material used are (La0.6Sr0.4)0.95-0.99Co0.2Fe0.8O3 and Ni-YSZ respectively.
Show less - Date Issued
- 2012
- Identifier
- CFE0004349, ucf:49431
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004349
- Title
- A multi-scale approach to study Solid Oxide Fuel Cells: from Mechanical Properties and Crystal Structure of the Cell's Materials to the Development of an Interactive and Interconnected Educational Tool.
- Creator
-
Aman, Amjad, Orlovskaya, Nina, Xu, Yunjun, Das, Tuhin, University of Central Florida
- Abstract / Description
-
Solid Oxide Fuel Cells are energy conversion devices that convert chemical energy of a fuel directly into electrical energy. They are known for being fuel-flexible, have minimal harmful emissions, ideal for combined heat and power applications, highly energy-efficient when combined with gas or steam turbines. The current challenges facing the widespread adoption these fuel cells include cost reduction, long-term testing of fully integrated systems, improving the fuel cell stack and system...
Show moreSolid Oxide Fuel Cells are energy conversion devices that convert chemical energy of a fuel directly into electrical energy. They are known for being fuel-flexible, have minimal harmful emissions, ideal for combined heat and power applications, highly energy-efficient when combined with gas or steam turbines. The current challenges facing the widespread adoption these fuel cells include cost reduction, long-term testing of fully integrated systems, improving the fuel cell stack and system performance, and studies related to reliability, robustness and durability. The goal of this dissertation is to further the understanding of the mechanical properties and crystal structure of materials used in the cathode and electrolyte of solid oxide fuel cells, as well as to report on the development of a supplementary educational tool that could be used in course related to fuel cells. The first part of the dissertation relates to the study of LaCoO3 based perovskites that are used as cathode material in solid oxide fuel cells and in other energy-related applications. In-situ neutron diffraction of LaCoO3 perovskite during uniaxial compression was carried out to study crystal structure evolution and texture development. In this study, LaCoO3 was subjected to two cycles of uniaxial loading and unloading with the maximum stress value being 700-900 MPa. The in-situ neutron diffraction revealed the dynamic crystallographic changes occurring which is responsible for the non-linear ferroelastic deformation and the appearance of hysteresis in LaCoO3. At the end of the first cycle, irreversible strain was observed even after the load was removed, which is caused by non-recoverable domain reorientation and texture development. At the end of the second cycle, however, no irreversible strain was observed as domain reorientation seemed fully recovered. Elastic constants were calculated and Young's modulus was estimated for LaCoO3 single crystals oriented along different crystallographic directions. The high temperature mechanical behavior study of LaCoO3 based perovskites is also of prime importance as solid oxide fuel cells operate at high temperatures. Incidentally, it was observed that as opposed to the behavior of most materials, LaCoO3 exhibits stiffening between 700 oC to 900 oC, with the Young's modulus going from a value of ~76 GPa at room temperature to ~120 GPa at 900 oC. In-situ neutron diffraction, XRD and Raman spectroscopy were used to study structural changes occurring in the material as it was heated. The results from these experiments will be discussed.The next portion of the dissertation will focus on electrolytes. Numerical simulation was carried out in order to predict the non-linear load-stress relationship and estimation of biaxial flexure strength in layered electrolytes, during ring-on-ring mechanical testing.Finally, the development of an interactive and inter-connected educational software is presented that could serve as a supplementary tool to teach fuel cell related topics.
Show less - Date Issued
- 2016
- Identifier
- CFE0006436, ucf:51467
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006436
