وب سایت خالد آذری - مقالات


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نوع مقاله : (W.O.S) ISI دارای رتبه
عنوان مقاله : The effect of cell shape on the warpage in solid oxide fuel cells
نویسندگان : Khaled Azari , Younes Alizadeh Vaghasloo , Jamshid Aghazadeh Mohandesi, Amir Hosein Ghobadzadeh
محل چاپ یا ارائه : Journal of Power Sources
سال انتشار : 2015
چکیده مقاله : Planar solid oxide fuel cells (SOFCs) are one of energy conversion systems with high efficiency and low environmental damage. During the fabrication of the cells, the mismatch between the thermo-elastic material properties of the components causes the warpage of cells. The warpage can reduce the performance of the cells. In this study, the planar anode supported half cells are made by tape casting and co-sintering and the effect of the cell shape on the warpage of cells has been investigated under identical conditions. Half cells with three common shapes (circle, square and rectangle) are made and the warpage of all samples is analyzed. The results demonstrate that under these fabrication conditions, rectangular cells are flatter than the square cells and square cells are flatter than the circular cells. All specimens, in spite of the difference in shape, show a semi-cylindrical curvature. This work also provides more accurate criteria for the comparison of cell warpage. For this purpose, statistical based criteria are proposed to analyze the warpage behavior
نوع مقاله : (W.O.S) ISI دارای رتبه
عنوان مقاله : Size dependence of warpage in solid oxide fuel cell
نویسندگان : Khaled Azari , Jamshid Aghazadeh Mohandesi , Younes Alizadeh Vaghasloo
محل چاپ یا ارائه : Journal of Power Sources
سال انتشار : 2016
چکیده مقاله : Planar anode-supported solid oxide fuel cells (SOFCs) typically show curvature behavior. The cell is warped due to the mismatch in the properties of the cell layers during fabrication process. Scaling up anode supported cells for industrial and commercial applications increases the warpage due to geometrical consideration. In this work, the curvature radius and maximum deflection of small cells are compared to large cells to gain a better insight into the warpage behavior in the scaling up process. The obtained results show that the curvature radius significantly increases by increasing cell size, whereas with respect to geometrical consideration, scaling up should result in no radius change. Also, the interaction between cell size and applied load (during sintering) has been investigated. The curvature radius generally increases with increasing total load density and cell size. The influence of total load density decreases for the large cells and the influence of cell size decreases with increasing total load density. Furthermore, an expression is proposed for the estimation of the curvature radius in the scaling up process by taking into account the effect of size and applied load and interaction between them
نوع مقاله : (W.O.S) ISI دارای رتبه
عنوان مقاله : Comparison between using longitudinal and shear waves in ultrasonic stress measurement to investigate the effect of post-weld heat-treatment on welding residual stresses
نویسندگان : Yashar Javadi , Khaled Azari ,Seyed Mahmoud Ghalehbandi ,M. J. Roy
محل چاپ یا ارائه : Research in Nondestructive Evaluation
سال انتشار : 2017
چکیده مقاله : DOI: 10.1080/09349847.2015.1123786 Abstract Fusion welding is a joining process widely used in the industry however, undesired residual stresses are produced once the welding process is completed. Post-weld heat-treatment (PWHT) is extensively employed in order to relieve the welding residual stresses. In this study, effect of PWHT time and temperature on the residual stresses of a ferritic stainless steel is investigated. Residual stress distributions in eight welded specimens were measured by using an ultrasonic method. Ultrasonic stress measurement is a non-destructive method based on acoustoelasticity law, which correlates mechanical stresses with velocity of an ultrasonic wave propagating within the subject material. The ultrasonic wave employed could be longitudinal or shear wave produced by the longitudinal (normal) or transverse (shear) transducers, respectively. Ultrasonic stress measurements based on longitudinal waves use longitudinal critically refracted (LCR) waves in this direction, while shear wave methods use an ultrasonic birefringence phenomenon. The results show that the effect of PWHT can be successfully inferred by both longitudinal and shear wave methods, but the former is found to be more sensitive to stress variation. Furthermore, the distribution of sub-surface residual stresses is found to be more distinguishable when the LCR method is employed
نوع مقاله : علمی پژوهشی ISC
عنوان مقاله : Residual Stress Measurement In Stainless Steel To Carbon Steel Butt Weld Using Nondestructive Ultrasonic Method
نویسندگان : Khaled Azari , Mehdi Ahmadi , Yoness Alizadeh
محل چاپ یا ارائه : Journal of manufacturing and production
سال انتشار : 2012
چکیده مقاله : This study investigated the measurement of residual stress in a stainless steel to carbon steel butt weld using nondestructive birefringence ultrasonic method,which is one of the most-known ultrasonic methods for stress measurement. By using this method, qualitative distribution of residual stresses surrounding weld line in both plates acceptably was described. In quantitative analysis, reported values for residual stresses surrounding weld line are inaccurate, because they are comparative and obtained with no considering acoustoelastic constant changes caused by microstructure changes near weld line. Development of this method by considering its good portability and cost efficiency can have a high capability in residual stress measurement
نوع مقاله : علمی پژوهشی ISC
عنوان مقاله : Experimental investigation of a solid oxide fuel cell stack using direct reforming natural gas
نویسندگان : Torabi, M. Golmohammad, H. Abdoli, H. Mohebi, K. Azari, A. S. Mehranjani, S. Bozorgmehri
محل چاپ یا ارائه : Iranian Journal of Hydrogen & Fuel Cell 4(2017) 301-306
سال انتشار : 2018
چکیده مقاله : In this study, a solid oxide fuel cell (SOFC) stack has been successfully fabricated and tested by using direct natural gas. The main objective of this research was to achieve optimal long-term performance of the SOFC stack without carbon deposition by using low-cost natural gas as a fuel. The stack con guration was improved by a new interconnect design and made of cost-effective raw materials. In this respect, the stack showed maximum power of 31 W while 33 A current was applied at a  ow rate of 1000 ccm for H2 (as fuel) and oxygen. Then, humidi ed natural gas was employed as an internal reforming technique, which showed degradation of 1.4% after 24 h. Maximum obtained power was 32 W under 33 A current at a  ow rate of 1000 ccm. After 48 h of operation, 34 W of power was achieved at the current of 38 A. Therefore, the power was increased from 32 to 34 W after 48 h of operation in upper current. Finally, a suitable SOFC stack made of cost effective materials and using direct natural gas under appropriate conditions was fabricated and developed in this research.