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Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395

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Subject: search.filters.subject.Solid Oxide Fuel Cell

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 30
    Citation - Scopus: 31
    Three Dimensional Stress Analysis of Solid Oxide Fuel Cell Anode Micro Structure
    (Pergamon-Elsevier Science Ltd, 2014-11) Celik, Selahattin; Ibrahimoglu, Beycan; Toros, Serkan; Mat, Mahmut D.
    One of the most common problems in solid oxide fuel cells (SOFCs) is the delamination and thus the degradation of electrode/electrolyte interface which occurs in the consequences of the stresses generated within the different layers of the cell. Nowadays, the modeling of this problem under certain conditions is one of the main issues for the researchers. The structural and thermo-physical properties of the cell materials (i.e. porosity, density, Young's modulus etc.) are usually assumed to be homogenous in the mathematical modeling of solid oxide fuel cells at macro-scale. However, during the real operation, the stresses created in the multiphase porous layers might be very different than those at macro-scale. Therefore, micro-level modeling is required for an accurate estimation of the real stresses and the performance of SOFCs. This study presents a microstructural characterization and a finite element analysis of the delamination and the degradation of porous solid oxide fuel cell anode and electrode/electrolyte interface under various operating temperatures, compressing forces and material compositions by using the synthetically generated microstructures. A multi physics computational package (COMSOL) is employed to calculate the Von Misses stresses in the anode microstructures. The maximum thermal stress in the electrode/electrolyte interface and three phase boundaries is found to exceed the yield strength at 900 degrees C while 800 degrees C is estimated as a critical temperature for the delamination and micro cracks due to thermal stress generated. The thermal stress decreases in the grain boundaries with increasing content of one of the phases (either Ni or YSZ) and the porosity of the electrode. A clamping load higher than 5 kg cm(-2) is also found to exceed the shear stress limit. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
  • Article
    Thermal Stresses in SOFC Stacks: The Role of Mismatch Among Thermal Conductivity of Adjacent Components
    (Tubitak Scientific & Technological Research Council Turkey, 2021-06-30) Aydin, Ozgur; Matsumoto, Go; Shiratori, Yusuke
    Generating power from renewable biogas in solid oxide fuel cells (SOFCs) is an environment-friendly, efficient, and promising energy conversion process. Biogas can be used in SOFCs via a reforming process for which dry reforming is more suitable as the reforming agent exists in the biogas mixture. Biogas can be directly reformed to H-2 -rich fuel stream in the anode chamber of a SOFC by the heat released during power generation. Exploiting the heat and water produced in the SOFC for internal reforming of biogas makes the energy conversion process very efficient; however, various challenges are reported. Thus, indirect internal reforming is opted for which a separate reforming domain is required. In an indirect internal reformer operating at usual conditions, dry reforming rate is quite high in the inlet and it decreases steeply toward the fuel outlet. Great temperature gradients develop over the reformer, since the dry reforming reaction is strongly endothermic. The abruptly varying rate of the reforming reaction affects the temperature fields in the adjacent components of SOFC and hence intolerable thermal stresses emerge on the SOFC components. In our preceding study, we graded the reforming domain, homogenized the temperature profile over the reforming domain, and executed performance and durability experiments. However, most of the experiments failed due to fracturing SOFC components hinting at existence of thermal stresses. In that study, we focused on minimizing the temperature gradients within the reforming domain; namely, we neglected the other processes. To eliminate the thermal stresses, we modeled the entire module of SOFC equipped with a reformer featuring a graded reforming domain. We found that the mismatch between the thermal conductivities of the adjacent module components is the major reason for the thermal stresses. When the mismatch is eliminated, thermal stresses disappear even if the reforming domain is not graded.
  • Conference Object
    Parameter Analysis of a Biomass Based SOFC-Engine Polygeneration System for Cooling, Heating and Power Production
    (Scanditale AB, 2020) Zhu, Pengfei; Guo, Leilei; Yao, Jing; Ren, Jianwei; Kapci, Mehmet Fazil; Bal, Burak; Zhang, Z. X.
    In order to meet the demand of clean and efficient energy conversion technology, a novel combined cooling, heating and power (CCHP) system fueled by biomass is proposed. This system is consists of biomass gasification unit, solid oxide fuel cell, IC engine unit and absorption refrigeration chiller. Thermodynamic model of the CCHP system are developed and then parameter analysis is adopted to optimize the performance of this system. The effect of air equivalent ratio (ER), steam biomass ratio (S/B) and the fuel utilization factor of SOFC (μ) on the performance of the entire system are studied. The results show that increase of S/B and μ will prompt the electrical efficiency, while the increase of ER has a negative effect on electrical efficiency. The exergy analysis shows that the exergy destruction of biomass gasification process and engine is larger, which is 454.5 kW and 207.2 kW respectively. On the contrary, exergy destruction of SOFC and absorption refrigeration chiller are 15.9 kW and 52.8 kW, respectively. © 2024 Elsevier B.V., All rights reserved.
  • Article
    Citation - WoS: 22
    Citation - Scopus: 26
    Micro Level Two Dimensional Stress and Thermal Analysis Anode/Electrolyte Interface of a Solid Oxide Fuel Cell
    (Pergamon-Elsevier Science Ltd, 2015-06) Celik, Selahattin; Ibrahimoglu, Beycan; Mat, Mahmut D.; Kaplan, Yuksel; Veziroglu, T. Nejat
    The delamination and degradation of solid oxide fuel cells (SOFCs) electrode/electrolyte interface is estimated by calculating the stresses generated within the different layers of the cell. The stresses developed in a SOFC are usually assumed to be homogenous through a cross section in the mathematical models at macroscopic scales. However, during the operating of these composite materials the real stresses on the multiphase porous layers might be very different than those at macro-scale. Therefore micro-level modeling is needed for an accurate estimation of the real stresses and the performance of SOFC. This study combines the microstructural characterization of a porous solid oxide fuel cell anode/electrolyte with two dimensional mechanical and electrochemical analyses to investigate the stress and the overpotential. The microstructure is determined by using focused ion beam (FIB) tomography and the resulting microstructures are used to generate a solid mesh of two dimensional triangular elements. COMSOL Multiphysics package is employed to calculate the principal stress and Maxwell Stefan Diffusion. The stress field is calculated from room temperature to operating temperature while the overpotential is calculated at operating temperature. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.