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Öğe 2D-axisymmetrical modeling and experimental study of hydrogen absorption in copper coated metal hydride(Pergamon-Elsevier Science Ltd, 2023) Atalmis, Gamze; Toros, Serkan; Timurkutluk, Bora; Kaplan, YukselThe storage of hydrogen in metal hydride reactors is examined experimentally and numerically in this paper. In this respect, as-received LaNi5 powders are coated with different amounts of copper by using copper sulphate solution to accelerate the hydrogen charging processes. The thermal conductivity of the copper-coated storage material is found to reach up to 8 times of the uncoated powders. A two-dimensional axisymmetric model regarding complex heat and mass transfer occurring during hydrogen charging process in metal hydride reactors is numerically solved at macro level. The developed model is validated by using experimental data related to the amount of hydrogen stored and the reactor temperatures. In accordance with the experimental results, the simulation results show that more homogenous temperature distribution in the reactor can be obtained with the copper coating due to improved thermal properties. Moreover, charging time is also improved by the copper coating. However, since the reactor is loaded with coated/uncoated LaNi5 powders at the same weight of 65 g, the total amount of hydrogen stored decreases with the copper coating due to reduced amount of LaNi5. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe A review on cell/stack designs for high performance solid oxide fuel cells(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Timurkutluk, Bora; Timurkutluk, Cigdem; Mat, Mahmut D.; Kaplan, YukselBesides the general advantages of fuel cells, including clean and quiet operation, solid oxide fuel cells (SOFCs) as being one of the high-temperature fuel cells also provide a relatively high efficiency due to enhanced reaction kinetics at high operating temperatures, The high operation temperature of SOFC also enables internal reforming of most hydrocarbons and can tolerate small quantities of impurities in the fuel. However, a high operation temperature limits the SOFC application areas to stationary applications because of a long start-up period and also is not desirable from the viewpoint of cost reduction and longterm stability especially for the cell materials. Therefore, the lowering the operation temperature of SOFCs is crucial for the cost reduction and the long term operation without degradation as well as the commercialization of the SOFC systems. The reduced operating temperature also helps to reduce the time and to save the energy required for the system start-up enabling SOFCs to have wider application areas including mobile/portable ones. Apart from the low operating temperature, the high performance along with a small volume is another requirement for SOFC to be used in mobile applications. Both can be achieved by fabricating novel SOFCs generating a high power output at low operating temperatures. Therefore, this paper reviews the current status and related research on the development of these high performance-SOFC cell/stack designs. (C) 2015 Elsevier Ltd. All rights reserved.Öğe A review on micro-level modeling of solid oxide fuel cells(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Timurkutluk, Bora; Mat, Mahmut D.Solid oxide fuel cells (SOFCs) are ceramic based electrochemical devices operating at high temperatures and generates electricity and useful heat energy utilizing various fuels at a high efficiency. The main structure of the cell comprises a dense electrolyte coated with two porous anode and cathode electrodes. The electrolyte is responsible for the transfer of oxide ion while the electrochemical reactions take place in the electrodes. The cell performance is limited by the number of reaction zones known as triple/three phase boundaries (TPBs). Therefore, the electrodes play a crucial role in achieving high power as well as long service life. When the requirements that SOFC electrodes should meet are considered, the most successful electrode materials seem to be composite ones, including ionic and electronic conductive phases with pores for the gas transport. However, this combination is not enough alone since the contiguous contact of these three phases within the electrodes is also necessary to obtain electrochemically active reaction zones. The number of these areas can be a useful metric for predicting the cell performance or provide a relationship between the performance and microstructure. The determination of the electrochemical reaction zones at the micro-scale and the microstructural parameters influencing their density are required to link the microstructure to the performance. Therefore, in this paper, micro-modeling studies of SOFC electrodes through advanced microstructural characterization are reviewed. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Anode-supported solid oxide fuel cells with ion conductor infiltration(WILEY-BLACKWELL, 2011) Timurkutluk, Bora; Timurkutluk, Cigdem; Mat, Mahmut D.; Kaplan, YukselNano ion conductor infiltration to anode andcathode side of solid oxide fuel cell (SOFC) significantly improves the performance of an SOFC. The effects of processing parameters such as molar concentration, sintering temperature and holding time are investigated. The performance of fuel cell is evaluated with a test station and an impedance analyzer. The SEM investigation showed that a nano ion conductor phase forms around the main phase in the anode and the cathode. The results showed that nano infiltration enhances significantly the performance of SOFC. The power density is found to increase around two times with infiltration. It is also found that the particle size and the porosity significantly affect the performance of infiltrated SOFC cell. While smaller infiltrated grains enhance the performance lower porosity adversely affects the performance. Copyrightr (C) 2011 John Wiley & Sons, Ltd.Öğe Boosting the performance of bolt-microtubular solid oxide fuel cells through surface pattern tuning(Elsevier Sci Ltd, 2024) Onbilgin, Sezer; Altan, Tolga; Timurkutluk, Cigdem; Timurkutluk, BoraA number of bolt-microtubular anode supports (BMASs) are manufactured by winding the corresponding thin tapes on threaded rods of different thread pitches and depths, followed by co-lamination using isostatic press. Bolt-microtubular cells (BMCs) are also constructed on BMASs to investigate the effects of the created surface patterns on the cell performance and microstructure. The bolt-microtubular cell, whose anode support is patterned by using a threaded rod with 0.8 mm thread pitch and 0.4 mm thread depth, exhibits similar to 92% higher maximum performance than that of the reference cell at 800 degrees C under 0.3 NL/min hydrogen flow and stagnant air. The almost doubled performance is mainly due to the increase in anode-electrolyte and cathode-electrolyte interfacial areas by the surface patterns created. The cell is also subjected to a 200-h life test at 800 degrees C and 0.7 V and demonstrates a stable performance.Öğe Comparison of electrolyte fabrication techniques on the performance of anode supported solid oxide fuel cells(Pergamon-Elsevier Science Ltd, 2020) Onbilgin, Sezer; Timurkutluk, Bora; Timurkutluk, Cigdem; Celik, SelahattinA comparison of three solid oxide electrolyte fabrication processes, namely dip coating, screen printing and tape casting, for planar anode supported solid oxide fuel cells (SOFCs) is presented in this study. The effect of sintering temperature (1325-1400 degrees C) is also examined. The anode and cathode layers of the anode-supported cells, on the other hand, are fabricated by tape casting and screen printing, respectively. The quality of the electrolytes is evaluated via performance measurements, impedance analyses and micro structural investigations of the cells. It is found that the density of the electrolyte increases with the sintering temperatures for all fabrication methods studied. The results also show that with the process and fabrication parameters considered in this study, both dip coating and screen printing do not yield a desired dense electrolyte structure as proven by open circuit potentials measured and SEM photos. The cells with tape cast electrolytes, on the other hand, provide the highest performances regardless of the electrolyte sintering and cell operating temperatures. The best peak performance of 0.924 W/cm2 is obtained from the cell with tape cast electrolyte sintered at 1400 degrees C. SEM investigations and measured open circuit potentials reveal that almost fully dense electrolyte layer can be obtained with a tape cast electrolyte particularly sintered at temperatures higher than 1350 degrees C. Impedance analyses indicate that the main reason behind the significantly higher performances is due to not only increased electrolyte density but a decrease in the interface resistance of the anode functional and electrolyte layer is also responsible. This can be explained by theload applied during the lamination step in the fabrication of the tape cast electrolyte, providing better powder compaction and adhesion. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Design and fabrication of novel anode flow-field for commercial size solid oxide fuel cells(Elsevier, 2017) Canavar, Murat; Timurkutluk, BoraIn this study, nickel based woven meshes are tested as not only anode current collecting meshes but also anode flow fields instead of the conventional gas channels fabricated by machining. For this purpose, short stacks with different anode flow fields are designed and built by using different number of meshes with various wire diameters and widths of opening. A short stack with classical machined flow channels is also constructed. Performance and impedance measurements of the short stacks with commercial size cells of 81 cm(2) active area are performed and compared. The results reveal that it is possible to create solid oxide fuel cell anode flow fields with woven meshes and obtain acceptable power with a proper selection of the mesh number, type and orientation. (C) 2017 Elsevier B.V. All rights reserved.Öğe Design and fabrication of novel interconnectors for solid oxide fuel cells via rubber pad forming(Wiley, 2020) Timurkutluk, Bora; Onbilgin, SezerRubber pad forming is studied numerically and experimentally to fabricate interconnectors for solid oxide fuel cells (SOFCs) from thin Crofer sheets instead of classical thick ones with machined flow channels. In the theoretical program, the effects of the rib angle, rib width and channel depth on the formability are numerically investigated and optimized as 120 degrees, 0.5 mm and 0.5 mm, respectively. In addition, flow simulations are performed to analyze the flow uniformity in the flow-field for the final geometry and homogenous reactant distributions are observed. In the experimental program, the interconnector with numerically optimized geometry is successfully manufactured by rubber pad forming, trimming, piercing and spot welding processes. This interconnector is used to build a two-cell stack. A similar stack is also constructed with a conventional interconnector for comparison. The performances of these stacks are measured at different operating temperatures. According to the simulation and experimental results, rubber pad forming is found to be a highly effective manufacturing route to fabricate SOFC interconnectors from thin Crofer sheets, providing higher specific and volumetric power density values for SOFC stacks compared to those of conventional stacks with interconnectors having machined flow channels.Öğe Design and fabrication of stair-step-type electrolyte structure for solid oxide fuel cells(WILEY-BLACKWELL, 2013) Palaci, Yuksel; Timurkutluk, BoraThe design and the fabrication of novel stair-step electrolyte based on yttria stabilized zirconia are presented. The novel electrolyte has gradually reduced oxide ion transport paths achieved by the stair-step design. The mechanical and electrochemical performance of the novel electrolyte are investigated and compared to those of standard electrolyte support. Three-point bending tests indicate that the fracture displacement and force measured for the novel electrolyte are 11% and 32% less than those of the standard electrolyte support, respectively. However, the cell based on the novel electrolyte exhibits40% higher electrochemical performance than the standard electrolyte supported cell at an operation temperature of 700 degrees C. Impedance analyses revealed that the enhanced cell performance is mainly due to the decrease in the ohmic resistance of the cell achieved by the novel electrolyte design. In addition, the electrode resistances are found to be decreased due to the increased electrochemical reaction zones since the contact area between the novel electrolyte and both electrodes are increased by the novel electrolyte design. Moreover, the cell with novel electrolyte produced 0.47 Wcm2 peak power at 750 degrees C while the standard electrolyte supported cell shows almost the same power output at around 800 degrees C. Thus, novel designed electrolyte also offers some amount of reduction in the operation temperature of solid oxide fuel cells. Copyright (c) 2012 John Wiley & Sons, Ltd.Öğe Design and optimization of functionally graded anode electrode with integrated functional layer for microtubular solid oxide fuel cells(Elsevier Sci Ltd, 2024) Timurkutluk, Cigdem; Altan, Tolga; Onbilgin, Sezer; Timurkutluk, BoraThis study investigates the influence of porosity-graded anode microstructures on the performance of microtubular solid oxide fuel cells (SOFCs). Fabricated using tape casting coupled with isostatic pressing, the anode microtubes consist of three layers with varying porosities. The porosity of each layer is regulated by the quantity of pore former added to the corresponding tape casting slurry. Homogeneous microtubular anode supports having different porosities are also fabricated similarly for comparison purposes. Microtubular cells are manufactured on both types of anodes by dip coating other cell layers, and test and characterization studies are carried out. Experimental results reveal that increasing the pore former content in the anode tape casting slurry leads to reduced triple phase boundary (TPB) density, primarily due to increased porosity and pore size, resulting in higher charge transfer resistance and decreased cell performance, despite an associated decrease in the gas transport resistance. However, optimization of the anode microstructure demonstrates that porosity gradients can enhance gas transport and overall cell performance. Additionally, the study explores the impact of anode thickness and the presence of transition layers on cell performance and structural integrity.Öğe Determination of optimum ejector operating pressures for anodic recirculation in SOFC systems(Pergamon-Elsevier Science Ltd, 2017) Genc, Omer; Toros, Serkan; Timurkutluk, BoraIn this study, a numerical analysis of an ejector for micro combined heat and power system based on 18 kW Solid Oxide Fuel Cell (SOFC) using methane as fuel is presented. An ejector design, which reflects the real system conditions in the view of the flow characteristics, is provided and the ejector performance is numerically investigated for various methane pressure to exhaust pressure ratios and methane inlet temperatures. The results show that the fuel inlet temperature and the pressure ratio of the methane to exhaust significantly affect the steam to carbon ratio (STCR) and entrainment ratio. The higher pressure ratio and methane temperature allow a high entrainment ratio and STCR, but as pressure ratio and methane temperature increase, STCR and entrainment ratio remain unchanged after a specific value. 1140 different scenarios related with the inlet and outlet pressures of the ejector and methane temperature are created to determine the optimum operating conditions. The simulations show that the optimum methane inlet pressure is 7 bar and exhaust pressure is 1.159 bar for the ejector geometry of the interest. The entrainment ratio and STCR are determined as 2.05 and 0.92, respectively at this optimum scenario. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Development of anodes for direct oxidation of methane fuel in solid oxide fuel cells(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Akdeniz, Yelda; Timurkutluk, Bora; Timurkutluk, CigdemIn addition to pure hydrogen, solid oxide fuel cells (SOFCs) can utilize hydrocarbons as a fuel. However, conventional Ni-based anodes exhibit an excellent catalytic activity towards the hydrocarbon cracking reaction and thus the carbon deposition occurs in the anode. The deposited carbons quickly deactivate the anode irreversibly by covering the active surface of the anode catalyst. As a result, a significant degradation in the cell performance can be seen. In this study, the anode structure is modified by the addition of copper (Cu) and ceria (CeO2) to increase the coking resistance of the cell under direct methane fuel. In this respect, the anodes are infiltrated by different amounts of Cu and CeO2 nitrates via the wet impregnation technique to investigate the effects of Cu and CeO2 loadings on the carbon tolerance of the cell. The effects of the anode porosity and composition are also considered in the study. The carbon resistance thus the service life of the cell with Cu/CeO2/Ni/YSZ anodes is found to be significantly higher than that of conventional Ni-based anodes under direct dry methane fuel. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Development of ceramic fiber reinforced glass ceramic sealants for microtubular solid oxide fuel cells(Elsevier Sci Ltd, 2022) Timurkutluk, Cigdem; Toruntay, Furkan; Onbilgin, Sezer; Atalmis, Gamze; Timurkutluk, BoraCeramic fibers in various forms with different fiber sizes are tested to improve the sealing performance of glass ceramic seals for micmtubular solid oxide fuel cell applications. In this regard, several sealing pastes are prepared by mixing each ceramic fibers type with glass ceramics at 1.25 wt %. Five layered micmtubular anode supported cells are also fabricated by extrusion and dip coating methods to evaluate the sealing performance of the composite sealants. The pastes are applied between the cells and gas manifolds made of Crofer22 APU. The electrochemical and sealing performances at an operating temperature of 800 degrees C under hydrogen are investigated after the glass forming process. Microstructures of the sealants are also examined by a scanning electron microscope. Experimental investigations reveal that the cells sealed by the pastes with ceramic bulk fiber and ceramic fiber rope gasket show acceptable open circuit potentials close to the theoretical one. These cells can be also pressurized up to around 150 kPa back pressure in the sealing performance tests. On the other hand, the pastes without any filler, with ceramic rope and with ceramic blanket exhibit poor sealing performance due to gas leakage originated from flowing of the main glass ceramic matrix from the joints. Therefore, ceramic bulk fiber and ceramic fiber rope gasket are found to behave as a stopper and can be used to prevent glass ceramics from flowing for microtubular solid oxide fuel cells or similar applications.Öğe Development of high performance and low-cost solid oxide fuel cell stacks: Numerical optimization of flow channel geometry(Wiley, 2021) Timurkutluk, Bora; Ucar, EmreSolid oxide fuel cell (SOFC) stacks with small volume and weight are essential to obtain higher specific and volumetric power densities as an alternative to conventional SOFC stacks with interconnectors having machined flow channels. This can be achieved by employing thin sheet interconnectors with flow channels formed by stamping methods rather than conventional machining of thick bulk materials. Besides the determination of process parameters providing defect free manufacturing of the desired channel design, the channel geometry is also significant for the cell performance. This study, therefore, focuses on the performance based parametric optimization of those flow channels in SOFCs by numerical simulations. In this respect, the effects of rib width, channel depth and rib angle on the cell performance are numerically investigated after the model validation with experimental results. The optimum rib width, channel depth and rib angle are determined to be 0.5 mm, 0.5 mm and 90 degrees, respectively, within the parameter ranges considered in this study. In addition, the rib width is turned out to be the most effective parameter on the cell performance, while the cell performance almost remains unchanged for different channel depths.Öğe Development of high-performance anode supported solid oxide fuel cell(WILEY-BLACKWELL, 2012) Timurkutluk, Bora; Timurkutluk, Cigdem; Mat, Mahmut D.; Kaplan, YukselA high performance five-layered anode supported solid oxide fuel cell (SOFC) is developed by low-cost tape casting, co-sintering, and screen printing techniques. The cell is composed of NiO/scandium stabilized zirconia (ScSZ) anode support, NiO/ScSZ anode functional layer (AFL), ScSZ electrolyte, lanthanum strontium ferrite (LSF)/ScSZ cathode functional layer, and LSF cathode current collecting layer. The effects of fabrication parameters on the cell performance are investigated and optimized, including co-sintering temperature, thickness of the anode support, and AFL. The effects of GDC ion conducting phase impregnated into both electrodes also are investigated. The microstructure of the cell is observed using a scanning electron microscope, and the cell performances at various operation temperatures are evaluated by a fuel cell test station. The final cell produces 1.34 W.cm(-2) maximum power density at an operation temperature of 700 degrees C. The high performance is attributed to optimized cell structure as well as increase in the oxide ion conductivity and three-phase boundaries of both anode and cathode layers by nano ion conductor infiltration. Copyright (c) 2011 John Wiley & Sons, Ltd.Öğe Development Of Redox Tolerant Solid Oxide Fuel Cells(Niğde Üniversitesi, 2013) Timurkutluk, Bora; Mat, Mahmut D.Anode supported solid oxide fuel cells (SOFCs) having various properties are developed and the effects of fabrication parameters on the cell performance and redox behavior of the cell are investigated experimentally and theoretically. In the experimental program, an yttria stabilized zirconia based anode supported membrane electrode group (MEG) is developed with the tape casting, co-sintering and screen printing methodology. For comparison, various anode supported cells with different electrolyte thickness and anode support porosities are also fabricated. An experimental setup is devised for the performance measurement of the cells before and after redox cycling. The effects of anode fabrication parameters on the cell performances and the redox stability of the cells are investigated. The mechanical performance of the cell before and after redox cycling is also measured via three point bending tests. Experimental results reveal that the porosity of the anode support and the thickness of the electrolyte should be carefully decided by considering not only the cell performances but also the redox stability. In theoretical study a mathematical model is developed to represent the fluid flow, the heat transfer, the species transport and the electrochemical reaction in solid oxide fuel cells. In addition, a redox model representing the mechanical damage in the v electrochemical reaction zones due to redox cycling is developed by defining a damage function as a function of strains and a damage coefficient. The differential equations are solved numerically with a commercial code which employs a finite element based approach. The effects of anode porosity and the electrolyte thickness on the cell performance and redox stability of the cells are numerically investigated. The experimental and numerical results are compared to validate the mathematical model. The mathematical model is found to agree reasonable with experimental data.Öğe Development of titanium bipolar plates fabricated by additive manufacturing for PEM fuel cells in electric vehicles(Pergamon-Elsevier Science Ltd, 2022) Celik, Selahattin; Timurkutluk, Bora; Aydin, Ugur; Yagiz, MikailBipolar plates (BPs) are one of the main parts of proton exchange membrane (PEM) fuel cell stacks, which constitute a significant percentage of a PEM fuel cell system in terms of cost, weight, and structural strength. Although frequently used graphite BPs have low density, high conductivity, and high corrosion resistance, machining the desired flow channels on these plates is challenging. On the other hand, BPs made of various materials rather than graphite can be also fabricated by additive manufacturing methods. These methods can be considered as a reasonable alternative to conventional machining for the fabrication of graphite BPs in PEM fuel cells regarding material cost, fabrication of flow channels, and some post-processes in which the large-scale manufacturing of graphite BPs is more complex. This study offers a comparison of formed stainless-steel, additive manufactured titanium and machined composite graphite plates having the same flow-field geometry as a bipolar plate. In addition, titanium BPs are coated with gold and their performances are compared. Among the cells tested, the highest peak power of 639 mWcm-2 is measured from the cell with 450 nm gold coated titanium BP, whereas those of the cell with con-ventional graphite and stainless-steel BP are only around 322 mWcm-2 and 173 mWcm-2, respectively. Moreover, a new titanium bipolar plate design providing high specific power density is also presented. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Düşük çalışma sıcaklığına sahip seramik yakıt pili için çok fonksiyonlu nanokompozit malzeme geliştirilmesi(2018) Fettah, Sevgi; Timurkutluk, Bora; Doğan, Almila Bahar; Pamuk, İbrahim; Kutkan, Halit; Kaynar, Arife Derya Deniz; Aydın, UğurKatı Oksit Yakıt Pilleri (KOYP), gelecek vaat eden yakıt pili teknolojisi olarak dikkat çekmektedir. Diğer yakıt pili teknolojileri ile karşılaştırıldığında, KOYP?nin ürünleşmesi ve ticarileşmesi, yüksek çalışma sıcaklığı (800-1000 ?C) nedeniyle özgün malzeme isteği ve onunla ilişkili maliyetler nedeni ile henüz tam başarıya ulaşamamıştır. Bu nedenle Düşük Çalışma Sıcaklığına Sahip Seramik Yakıt Pilleri (DÇSSYP) dünyada artan ilgi ve çaba ile karşılanmaktadır. Ceria temelli kompozit malzemeler daha düşük sıcaklıklarda çalışabilen ve iyi güç yoğunluklarına erişen KOYP elektrolitleri olarak gelecek vaat etmektedir. Proje, çalışma sıcaklığının düşürülmesi amacıyla Ceria bazlı membranların geliştirilmesi bu sayede maliyet azaltılmasına amacıyla ortaya çıkmıştır. Onaylanan Bütçe: Bu proje, ülkeler arası kaynakların verimli kullanılarak ve güçlü bilimsel bağlantılar oluşturarak Avrupa Birliği ve Hindistan?ın akademik ve endüstri sektörlerinin yüksek seviyedeki araştırma tecrübelerini birleştirerek bilimsel temelde düşük sıcaklık seramik yakıt pili malzeme optimizasyonu, performans iyileştirmesi ve dayanıklılığı konularında dünya çapında araştırmayı amaçlamaktadır. Proje 1001 programı çerçevesinde, AB 7. Çerçeve Programı kapsamında Uluslararası İşbirliği Etkinlikleri alanında Hindistan?a yönelik devam eden ve bölgedeki işbirliklerini arttırmayı hedefleyen New INDIGO ERA-Net (Initiative for the Development and Integration of Indian and European Research) projesi kapsamında ?Yeni Enerji Malzemeleri ve Akıllı Enerji Şebekeleri? alanında, Hindistan DST (Hindistan Bilim ve Teknoloji Bakanlığı, Bilim ve Teknoloji Dairesi) ile ortak araştırma projeleri çağrısı kapsamında desteklenmiştir.Öğe Effect of expanded natural graphite addition and copper coating on reaction kinetics and hydrogen storage characteristics of metal hydride reactors(Pergamon-Elsevier Science Ltd, 2024) Atalmis, Gamze; Toros, Serkan; Timurkutluk, Bora; Kaplan, YukselExperimental and numerical studies are carried out to determine the effects of copper coating and/or ENG (expanded natural graphite) addition on the hydrogen storage performance of ground LaNi5. The amounts of copper coating and/or ENG addition are also investigated. The results reveal that the thermal conductivity of ground LaNi5 can be improved by up to similar to 6 and similar to 12 times with copper coating and ENG addition, respectively. This results in enhanced hydrogen absorption kinetics thereby significantly reduced hydrogen charging times, compared to those determined for LaNi5 without any addition. On the other hand, the amount of hydrogen stored shows a decreasing trend with increasing copper coating and ENG addition since the weight of storage material loaded to the reactor is kept the same. Nevertheless, the optimum copper and ENG contents are determined regarding the amount of stored hydrogen and the corresponding charging time. Similar H/M values are obtained with the optimized powders with additives compared to that of ground LaNi5. Based on these results, various new samples are also prepared by mixing the decided copper coated LaNi5 and ENG added LaNi5 powders and examined to optimize the composition of these blended powders.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.
