Yazar "Mat, Mahmut Dursun" seçeneğine göre listele

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    A novel two-layered glass-ceramic sealant design for solid oxide fuel cells
    (John Wiley and Sons Ltd, 2017) Bakal, Ahmet; Mat, Mahmut Dursun
    A thermo-mechanical stress develops on the sealant of an solid oxide fuel cell (SOFC) stack because of thermal expansion coefficient (TEC) differences among ceramic electrolyte, metallic interconnector, and glass-ceramic sealant. The stress initiates cracks and usually results in a sealing failure. This study offers a thermo-mechanically stable two-layered sealant to decrease thermo-mechanical stresses among the SOFC components. The novel sealant involves two layers in which TEC of the first layer is close to that of the interconnector, while TEC of the second layer is similar to that of the electrolyte. SiO2, CaO, Al2O3, and Na2O glass-ceramics are selected as a sealant material, and five cases are prepared by changing the amount of Al2O3 to obtain the appropriate properties close to both the interconnector and the electrolyte, separately. Tensile strength, wetting angles, shrinkages, and electrical resistances are measured to determine the sealant properties. To see effect of the reaction on the microstructure, scanning electron microscopy (SEM) tests are conducted for the samples exposed both in air and in crofer 22 APU. Long-term sealing performance of the novel sealant is compared with the traditional designs. While the two-layered sealant keeps 35 kPa pressure for 500 h after 100 thermal cycles, test pressure with traditional design reduces to 31–32 kPa after 50 h. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
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    A novel two-part interconnector for solid oxide fuel cells
    (John Wiley and Sons Ltd, 2014) Bakal, Ahmet; Aydın, Fatma; Mat, Mahmut Dursun; İbrahimoğlu, Beycan; Pamuk, İbrahim
    A 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. © 2014 John Wiley & Sons, Ltd.
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    Numerical investigation of amounts of heat, power and temperature distribution in IT-SOFC
    (Electrochemical Society Inc., 2013) Bakal, Ahmet; Kaya, Murat; Mat, Mahmut Dursun
    In this study, thermodynamic and heat transfer concepts were combined to understanding correlation of heat, power and temperature gradient on the cell. All of heat sources and amounts has been determined for electrolyte supported SOFC having 81 cm2 active area and thus temperature gradient due to each heat source can computed and total temperature distribution clearly has been shown. For this, electrochemical, ohmic, activation and concentration polarization heat sources have been computed by using the boundary conditions taken from the experimental data such as current-voltage-power and mol fraction. Then 80% of the heat generated at 0.7 V and 700°C was removed by the heat transfer and then the maximum temperature difference is found less than 6 °C. Also, it was found that the electrical and the heat generations are 25.41 and 23.03 W, respectively. © The Electrochemical Society.