Yazar "Ibrahimoglu, Beycan" seçeneğine göre listele
Listeleniyor 1 - 4 / 4
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe A novel two-part interconnector for solid oxide fuel cells(WILEY-BLACKWELL, 2014) Bakal, Ahmet; Aydin, Fatma; Mat, Mahmut D.; Ibrahimoglu, Beycan; Pamuk, IbrahimA two-part interconnector is developed for solid oxide fuel cell stacks to reduce cost and to improve sealing. The novel interconnector involves a metallic core for current collection and gas distribution and a ceramic support to house the metallic core and to separate two short stacks. The new interconnector reduces usage of expensive metallic alloys and substantially reduce mismatch between stack components due to higher expansion coefficient of metals. The new interconnectors also improve sealing with glass-ceramics eliminating chromium evaporation which is a major reason for sealing failure in fully metallic interconnectors. A proof of concept short stack is manufactured and tested in this study. A comparable performance with a convectional interconnector is obtained with new interconnector, while substantially improving the sealing quality. Copyright (c) 2014 John Wiley & Sons, Ltd.Öğe Effect of Nano Ion Conductor Infiltration on the Performance of Anode Supported Solid Oxide Fuel Cells(ELECTROCHEMICAL SOC INC, 2009) Timurkutluk, Cigdem; Timurkutluk, Bora; Mat, Mahmut D.; Kaplan, Yuksel; Ibrahimoglu, Beycan; Pamuk, Ibrahim; Singhal, SC; Yokokawa, HA high performance anode supported solid oxide fuel cell (SOFC) is developed by low-cost tape casting, co-sintering and nano-ion conductor infiltration techniques. A mixture of gadolinium and cerium nitrate solution is infiltrated into both anode and cathode layers and fired at a temperature that gadolinium nitrate and cerium nitrate undergoes a solid state reaction and forms nano ion conductor phase in both electrodes. The effect of molar concentrations and firing temperature of nano ion conductor phase on the cell performance are investigated. The measurements show that nano-sized ion conductor infiltration significantly improves the cell performance. The cell provides 1.718 Wcm(-2) maximum power density at an operation temperature of 750 degrees C. The high performance is attributed to increase in the oxide ion conductivity and three phase boundaries of both anode and cathode layers by nano ion-conductor infiltration.Öğe Micro level two dimensional stress and thermal analysis anode/electrolyte interface of a solid oxide fuel cell(PERGAMON-ELSEVIER SCIENCE LTD, 2015) Celik, Selahattin; Ibrahimoglu, Beycan; Mat, Mahmut D.; Kaplan, Yuksel; Veziroglu, T. NejatThe 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.Öğe Three dimensional stress analysis of solid oxide fuel cell anode micro structure(PERGAMON-ELSEVIER SCIENCE LTD, 2014) 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.
