Yazar "Mat, Abdullah" seçeneğine göre listele

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    Effects of ceramic based pastes on electrochemical performance of solid oxide fuel cells
    (ELSEVIER SCI LTD, 2014) Mat, Abdullah; Timurkutluk, Bora; Timurkutluk, Cigdem; Kaplan, Yuksel
    Various commercially available anode and cathode materials are investigated as the anode and cathode contact paste, respectively, for solid oxide fuel cells. In order to obtain a printable paste, chosen materials are mixed with an organic vehicle and a thinner as well as a pore former. The effect of the contact materials on the cell performance is evaluated experimentally via cell performance measurements by installing a short stack. The pastes are brush painted on the corresponding interconnector and current collecting mesh. A short stack without any contact paste is also tested for comparison as a base case. The impedance and microstructural analyses are also performed through an impedance analyzer and a scanning electron microscope, respectively. The effects of solid loading for two anode and two cathode contact paste materials which provide the best two performances during the electrochemical performance tests are also studied. After optimizing the solid loading in the anode and cathode contact paste according to the performance results, the best contact materials for each side are decided. The final short stack is then installed by using the best combination of contact pastes and then tested. The final cell shows 0.39 W cm(-2) and 0.90 W cm(-2) peak power densities at 700 degrees C and 800 degrees C, respectively, whereas the base cell provides only 0.26 W cm(-2) peak power density at 800 degrees C. The improvement in the cell performance is considered to be due to the enhanced contact and better current collecting by employing contact pastes. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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    Investigation of micro-tube solid oxide fuel cell fabrication using extrusion method
    (PERGAMON-ELSEVIER SCIENCE LTD, 2016) Mat, Abdullah; Canavar, Murat; Timurkutluk, Bora; Kaplan, Yuksel
    Extrusion is one of the most effective and inexpensive methods used in the production of ceramic tubes for tubular or micro-tubular solid oxide fuel cell (SOFC) applications. In this method, the parameters such as the viscosity of the ceramic slurry, the extrusion speed and the die temperature need to be optimized for a high performance. In this study, anode supported micro-tubular solid oxide fuel cells are successfully fabricated via a specially designed vertical-type piston extruder machine. The die design enables the production of micro-tubular SOFCs with outer diameters from 3 to 4.5 mm. The die temperature is determined to be the most important process parameter and the suitable die temperature is ranging 40-70 degrees C depending on the slurry content. The electrolyte layer is coated on the anode support tube by vacuum assist dip coating technique and co-sintering is applied with a home-made porous sintering apparatus to avoid dimensional anomalies. The effects of the parameters such as the composition of the electrolyte solution, the vacuum pressure and the immersion time on the electrolyte thickness are investigated. It is found that the electrolyte thickness decreases when the immersion time and vacuum pressure are reduced. Moreover, the thickness of the electrolyte is found to be depended on the content of the electrolyte solution. The effect of the pre-sintering temperature on the electrolyte quality is also investigated. The sintering temperatures of 1000 degrees C and 1100 degrees C provide a similar and desired electrolyte microstructure. A peak power density of 140 mW cm(-2) is obtained at 700 degrees C from the final cell. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Investigation of temperature distribution and performance of SOFC short stack with/without machined gas channels
    (PERGAMON-ELSEVIER SCIENCE LTD, 2016) Canavar, Murat; Mat, Abdullah; Celik, Selahattin; Timurkutluk, Bora; Kaplan, Yuksel
    Solid oxide fuel cells (SOFCs) generate clean energy via electrochemical reactions at high operating temperatures. The distribution of the electrochemical reactions in the cell depends on the flow field design of the interconnectors. The non-uniform distribution of the reactions due to the flow field design may cause the development of thermal stresses which may lead to micro or macro cracks in the cell and thus a significant performance loss even a cell failure. In this study, the effects of operating current densities and fuel flow rates on the temperature profile within the cell and the cell performance are experimentally investigated for two different flow-field designs with Crofer 22 APU interconnectors, i.e. Design I and Design II. Design I, which mimics the conventional interconnector structure, has machined gas channels and porous nickel mesh at the anode side for the distribution of hydrogen and the collection of the current generated in the cell while at the anode side of Design II, only wire woven nickel mesh is employed. The experimental results indicate that Design II provides much more uniform temperature distributions under 20-40 A current loads and 1-2 NL/min H-2 flow rates when compared to those of Design I. Furthermore, Design II exhibits a higher peak power density than Design I at an operation temperature of 800 degrees C. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Katı oksit yakıt pilleri için iletken pasta geliştirilmesi
    (Niğde Üniversitesi / Fen Bilimleri Enstitüsü, 2011) Mat, Abdullah; Kaplan, Yüksel
    Yüksek verimle çalışan Katı Oksit Yakıt Pillerinden iyi bir performans elde edebilmek için akım toplayıcılar ile yakıt pili anot ve katot tabakaları arasında düzgün bir kontak sağlanmalıdır. Bu amaçla kontak pastaları kullanılmaktadır. Kontak pastalarının; yakıt pili anot ve katot tabakalarıyla uyumlu olması, yüksek çalışma sıcaklığından dolayı korozyona dayanıklı olması, uzun süreli çalışmalara uygun olması gibi özellikleri sağlaması gerekmektedir. Bu çalışmada beklenen özellikler doğrultusunda anot ve katot tarafları için kontak pastaları geliştirilmiştir. Anot için geliştirilen pastalar ticari Ni pasta; katot için geliştirilen pastalar ticari LSM pasta ile karşılaştırılmıştır. Deney sonuçlarına göre geliştirilen kontak pastalar içinde anot tarafında ticari pasta yerine, geliştirilen NiO-Q pasta; katot tarafında da ticari pasta yerine, geliştirilen LSM 20P kontak pastaların daha yüksek sonuçlar verdiği görülmüştür.