113 research outputs found
The effect of expanded natural graphite added at different ratios of metal hydride on hydrogen storage amount and reaction kinetics
No full textIn this study, metal hydride pellets were formed to accelerate the hydrogen charge/ discharge processes. The heat transfer in hydrogen storage material was improved by employing Expanded natural graphite (ENG). The ideal grinding time for LaNi5 material was determined to be 5 h. In the study, LaNi5 alloy was mixed with ENG in 1%, 5%, 10%, and 20% proportions by weight. The amount of hydrogen stored in the reactor by each mixture at 10 bar pressure was measured depending on time. Within the scope of experimental studies, the thermal conductivity coefficient of LaNi5 materials containing 20% ENG by weight was increased by 1380%. Thus, hydrogen charge/discharge processes were accelerated. Storage materials were characterized by XRD and SEM. The thermal conductivity coefficients were measured with the Hot Disk Thermal Constants Analyzer device, and the densities were measured with the Helium Pycnometer device. LaNi5 was chosen as the storage material in the study. It was found that 1-5 wt% ENG addition increased the reaction kinetics without significantly reducing the hydrogen storage capacity in storage alloys. However, in alloys with higher ENG concentrations, the hydrogen storage capacity decreased. The reaction kinetics were increased in the range of 135-260%. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Scientific and Technical Research Council of Turkey (TUBITAK) [121M529]; Council of Higher Education (YOK) [100/2000]The authors would like to thank the Scientific and Technical Research Council of Turkey (TUBITAK) for the financial support under contract number 121M529. The first author, Gamze ATALMIS,, would like to thank the Council of Higher Education (YOK) for the 100/2000 Ph.D. Scholarship Program
The effect of copper coated metal hydride at different ratios on the reaction kinetics
No full textIn this study, the process parameters that affect the improvement of hydrogen storage material properties were investigated. In order to accelerate the hydrogen charge/ discharge processes and to obtain the required hydrogen at the desired flow rates in a short time, the thermal conductivity of the storage materials has been improved, and density analyses have been made. The ideal grinding time has been determined for the LaNi5 material. Within the scope of the experimental studies, the thermal conductivity coefficients of LaNi5 coated with copper and LaNi5 ground for 5 h and coated with copper were increased by 500-750%, and the copper plating ratios were optimized. The materials obtained were characterized by XRD, SEM, and their density was measured with the Helium Pyknometer device and their thermal conductivity coefficients with the Hot Disk Thermal Constants Analyzer. In addition, the hydrogen storage of materials with increased thermal conductivity was investigated experimentally in the metal hydride reactor at the determined pressure. In the study, it was seen that the storage material coated with copper increases the heat transfer, reduces the hydrogen charging time in the metal hydride reactor, and increases the stable discharge time. & COPY; 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Scientific and Technical Research Council of Turkey (TUBITAK) [121M529]; Council of Higher Education (YOK)The authors would like to thank the Scientific and Technical Research Council of Turkey (TUBITAK) for the financial support under contract number 121M529. The first author, Gamze ATALMIS, would like to thank the Council of Higher Education (YOK) for the 100/2000 Ph.D. Scholarship Program
Strategic groups in the European airline industry and their competitive position
No full textAuthor Gamze Ilbeyi, BScMasterarbeit Universität Linz 202
Europeanization integration and identity: A social constructivist fusion perspective on Norway
No full textThis book analyses how domestic and European structures impact on national actors' identities, interests and foreign policy practices. Employing Norway as the case study area, the author uses this nation as an example to assess Europeanization and identity politics across the European Union (EU).Utilising an original and innovative approach called 'social constructivist fusion perspective', the author addresses Europeanization across several key factors. The author assesses the influence of the EU on 'half-way member countries', and the impact of identity politics and domestic structures, which factors contribute to or hinder Europeanization, and attempts to empirically measure Europeanization at the actor level. It analyses the impact of domestic and European structures on the identities, interests, attitudes and foreign policy practices of the Norwegian policy-makers. Whilst contributing to knowledge and literature on how constructivist approaches can be utilized in empirical studies of political elites, this book goes beyond theory to demonstrate that Europeanization is not only institutional, and provides evidence of the influence of identity politics.Europeanization, Integration and Identity will be or interest to students, scholars and policy-makers in the field of European Union politics, international relations, social constructivism and Scandinavian politics. © 2012 Gamze Tanil
Experimental improvement of the performance of the open cathode-direct methanol fuel cell stack by magnetic field effect
No full textOpen Cathode Direct Methanol Fuel Cell (OC-DMFC) stack performance is achieved at different methanol temperatures (25, 40, 55 and 70 degrees C), methanol concentrations (0.5, 1, 2 and 4 M) and air flow rates (3.5, 4.8 and 6.4 m/s). Each parameter, whose performance was tested separately, was presented by making comparisons within itself. The effect of performance changes on peak power densities under relatively low electromagnetic fields (4.7, 12.4, 28 and 35 mT) was investigated by exposing the 10-cell OC-DMFC stack to a magnetic field with the help of ferritic magnets. Ferritic magnets placed on the OC-DMFC stack anode and cathode surfaces, It is designed to create an electromagnetic field. Thus, the magnetic field affected both surfaces. When the magnetic field was 35 mT, the OC-DMFC reached a power density of 17.5 mW cm(-2). When the DMFC stack is exposed to the magnetic field, its performance is increased by similar to 16%
2D-axisymmetrical modeling and experimental study of hydrogen absorption in copper coated metal hydride
No full textThe 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.Scientific and Technical Research Council of Turkey (TUBITAK) [121M529]; Council of Higher Education (YOK)The authors would like to thank The Scientific and Technical Research Council of Turkey (TUBITAK) for the financial support under contract number 121M529. 100/2000 Ph.D. Scholarship Program governed by Council of Higher Education (YOK) is also acknowledged
THE EXPERIMENTAL STUDIES ON ELECTROLYSER MODE OPERATION OF UNITIZED REGENERATIVE PEM FUEL CELL
No full textBAU; et al.; INOGEN; Republic of Turkey, Ministry of Energy and Natural Resources; TENMARK; Turkish Airlines23rd World Hydrogen Energy Conference: Bridging Continents by H2, WHEC 2022 -- 26 June 2022 through 30 June 2022 -- Istanbul -- 186176A unitized regenerative proton exchange membrane fuel cell (UR-PEMFC) is an electrochemical component that is capable of operating both as electrolyser and fuel cell mode. While UR-PEMFC produces hydrogen and oxygen by decomposing water in the electrolyser mode, it can also produce electricity and heat by using hydrogen as fuel in the fuel cell mode. A reversible system possesses several distinctive advantages for instance, high specific energy, pollution free, and most importantly, the decoupled energy storage capacity with rated power [1]. In this study, the performance of a unitized regenerative fuel cell and stack in electrolyser mode was investigated. The active areas of URFC are 100 cm2, and the stack has three cell, which has a 100 cm2 active area. The clamping pressure is optimized for cell and stack by using pressure film. Thus, the contact resistance was minimized, and optimum contact was achieved. © 2022 Proceedings of WHEC 2022 - 23rd World Hydrogen Energy Conference: Bridging Continents by H2. All rights reserved.International Association for Hydrogen Energy; Ömer Halisdemir Üniversitesi, (MMT 2021/7-LÜTEP
Development of ceramic fiber reinforced glass ceramic sealants for microtubular solid oxide fuel cells
No full textCeramic 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
Karanlık kişilik özelliklerinin kişilerarası bağlamda risk alma, kendini sunma ve öz-farkındalık duyguları ile ilişkisinin incelenmesi
No full textGültekin, Gamze (Dogus Author) -- 26.06.2018 tarihine kadar kullanımı yazar tarafından kısıtlanmıştır.Bu çalışmanın amacı Karanlık Kişilik Özelliklerinin kişilerarası bağlamda keşfedilmesi ve kişilerarası risk kavramı altında bulunan, etik risk alma, sosyal risk alma, statü odaklı risk alma değişkenleriyle ilişkisinin incelenmesidir. Buna ek olarak, Karanlık Kişilik Özelliklerinin kendini sunma ve öz farkındalık duyguları olarak adlandırılan benlik kavramları ile ilişkisi incelenmektedir. 171 kadın 175 erkek olmak üzere toplam 346 katılımcıdan oluşmaktadır. Çalışmada kullanılan materyaller, demografik bilgi formu, Statü odaklı risk alma ölçeği, Alan odaklı risk alma ölçeği, Revize edilmiş Kendini Sunma Ölçeği, ve Uygunluk Endişesi Ölçeği'dir. Çalışmada kullanılan analizler doğrulayıcı faktör analizi, korelasyon analizi ve çoklu lineer regresyon analizidir. Çalışmada bulunan temel sonuçlara göre her Karanlık Kişilik Özelliği statü-amaçlı risk alma ile pozitif yönde ilişki gösterirken sosyal risk alma ile negatif ilişki göstermektedir; fakat sadece Makyavelizm ve psikopati etik risk alma ile pozitif ilişki göstermektedir. Kendini sunma davranışı hem açgözlü hem de koruyucu stillerle narsisizm ve Makyavelizm ile pozitif yönde ilişki gösterirken psikopati sadece koruyucu stil ile pozitif ilişki göstermiştir. Öz farkındalık duygularıyla olan ilişkiye bakıldığında ise, sadece narsisizm utanç ile negatif ilişki gösterirken, tüm karanlık kişilik özellikleri suçlulukla negatif yönde ilişki göstermiştir. Kibirli gururla olan ilişkide hem Makyavelizm hem psikopati pozitif yönde ilişki gösterirken, gerçekçi gururda ise sadece psikopati negatif yönlü ilişki göstermiştir. Bulgular ilgili literatür çerçevesinde tartışılmıştır.The aim of this study is to examine Dark Triad personality traits in interpersonal context by examining their relationship with ethical risk taking, social risk taking and status-driven risk taking which are conceptualized as interpersonal risk taking. Moreover, Dark Triad's relationship with self-concepts is examined, namely self-presentation styles and self-conscious emotions. 346 participants, 171 men and 175 women participated in this study. The questionnaire used in the present study included demographic questions, Short Dark Triad Scale, Status-driven Risk Taking Scale, Domain-specific Risk Taking Scale, Revised Self-Monitoring Scale and Concern for Appropriateness Scale. Confirmatory Factor Analysis, Correlation Analysis and Multiple Linear Regression Analysis were conducted. The main results found in the study were that each Dark Triad trait was positively correlated with Status-driven risk taking and social risk taking, however only psychopathy and Machiavellianism showed positive relationship with ethical risk taking. For the self-presentation, narcissism and Machiavellianism were positively related with both acquisitive and protective styles; psychopathy was only related with protective self-presentation style. For the self-conscious emotions, only narcissism was negatively related with shame; all facets of dark triad were negatively related with guilt. For the hubristic pride, both Machiavellianism and psychopathy were related positively; for the authentic pride only psychopathy showed negative relationship. Results are discussed in the light of literature
Fabrication of glass ceramic sealants with ceramic fiber filler for solid oxide fuel cells
No full textIn this study, ceramic fibers are used as a filler material for glass ceramic sealant in solid oxide fuel cells to improve the thermal cycle behavior. Beside the bare glass ceramic sealant for comparison, multilayered sealants with different ceramic fiber contents are fabricated to investigate the effect of ceramic fiber quantity also. The mechanical performances of the samples are measured via tensile tests by placing them between two metallic interconnector plates after the glass formation process as well as after 1, 5 and 10 thermal cycles. The results show that the mechanical strength in general tends to decrease with increasing the ceramic filler content, which can be attributed to poor adhesion due to reduced glass ceramic composition. On the other hand, thermal cycle behavior of the samples with ceramic fibers is found to be improved at some extend. This may be due to the behavior of ceramic filler network and relatively slow crystallization with increasing the amount of the filler as proven by microstructural observations. Especially for the sample including 4 ceramic fiber interlayers each having 0.030 g ceramic fibers, the mechanical strength shows an increasing trend with the number of thermal cycles
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