Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
10 results
Search Results
Master Thesis Design and Techno-Economic Analysis of a Smart Solar Greenhouse(01. Izmir Institute of Technology, 2022) İçöz, Didem; Ebil, Özgenç; Dindaroğlu, BurakThe aim of this study is to examine the combination of agriculture and energy, which are two indispensable concepts for the existence of humanity, more efficiently. Energy, which is an indispensable part of human life, is at the top of the issues discussed in the world agenda today as it was in the past. Energy continues to be an indispensable factor in the economic and social development of countries, and therefore in increasing social welfare. With the developments in the agricultural sector, the energy need of the sector is increasing and energy diversity is important. In parallel with the world population, the demand for foodstuffs is increasing day by day. In order to meet this increasing food demand, greenhouse cultivation, where high efficiency is obtained from the unit area, is gaining more and more importance all over the world. Providing optimum conditions according to the location and seasonal characteristics of the location is essential for greenhouse efficiency. The need to heat greenhouses to provide these conditions constitutes a substantial energy cost. However, it is a known fact that fossil fuels, which are one of the energy sources, cause global climate changes, as they are an important source of CO2, known as a greenhouse gas. In this context, approaches to the use of renewable energy sources in agricultural activities are of great importance for the development of the sector. This study was prepared to examine the use and techno-economic analysis of photovoltaic panels for the energy needs of greenhouses. The solar greenhouse, where optimum conditions are provided with the automation system, will generate income from electricity sales as well as agricultural income in the months when it produces more electricity than its self-consumption.Master Thesis Grid-Connected Photovoltaic Systems for Fuel Stations: a Complete Techno-Economic Analysis(01. Izmir Institute of Technology, 2022) Kılınç, Mehmet Emin; Ebil, Özgenç; Dindaroğlu, BurakThe purpose of this study, beyond being an engineering practice, is an attempt to overcome a bottleneck that has not been overcome so far with scientific methods and to use the power of science for the benefit of the environment, the public, fuel distribution companies, petrol stations and almost every part of the society. Due to rapid changes in in terms of technology, efficiency, environmental sensitivity, consumer preferences, cost structure and legal base, this study is investigating and making suggestions for oil station companies regarding on-grid photovoltaic applications. Successful management of the process depends on effective calculation including, system requirements considering local solar radiation and financials from many aspects. Considering that, many fuel station owners cannot effectively approach the technical, bureaucratic, and financial aspects of photovoltaic applications and that academic studies that will guide the interested parties in a package form are not sufficient, the importance of this study will be more clearly demonstrated. Information obtained through the literature review, applying the engineering economics models and also with a widespread field study including petrol stations, solar material supply and installation companies, health and safety company and bank. It has been tried to set a user’s manual for concerned parties both in, academia, oil & solar sector and financial system in Turkey.Master Thesis Sintering and Densification Behavior of Gdc Infiltrated Porous Gdc Electrolyte(01. Izmir Institute of Technology, 2021) Tekin, Sinem; Akkurt, Sedat; Ebil, ÖzgençIt is desired that the electrolytes used in solid oxide fuel cells have a dense structure. Ceria-based electrolytes require temperatures of 1400-1500oC to densify. High densification temperatures make this material less in demand despite its good ionic conductivity. In this study, it was aimed to sinter and densify porous GDC scaffolds made of GDC (Gd0.10Ce0.90O1.95) material at low temperatures using infiltration technique. A porous GDC scaffold is first produced by sintering the GDC pellet around 1000oC to obtain an intermediate product ready to be infiltrated by a GDC-bearing solution. Multiple infiltration and drying cycles were intended to fill the pores by GDC nanoparticles which are expected to densify at lower temperatures. Two different groups (infiltrated and non-infiltrated) were formed and their densification behaviors with temperature and infiltration repetition cycles were investigated using a vertical dilatometer. The porous GDC scaffold was infiltrated with a polymeric solution prepared from Ce(NO3)3.6H2O and Gd(NO3)3.6H2O. The prepared samples were sintered at 1400oC. As a result of the experiments, it was observed that the densification decreased with the increase in temperature and infiltration cycles. This is thought to be because the porous scaffold could not be completely dried during the infiltration cycles. This led to the formation of a dense outer layer of GDC and porous inner layer. This dense layer inhibited shrinkage of the pellet during dilatometric analysis. Further studies need to be conducted to fully evaporate the solvent during drying of the infiltrated pellets.Master Thesis Effects of Grid Design on Lead-Acid Battery Performance(Izmir Institute of Technology, 2017) İşler, Tuğçe; Ebil, Özgenç; Top, AybenIn today’s world, approximately 88 percent of the total energy demand is supplied by fossil fuels; however, it has become clear that; other energy sources are needed due to limited fossil fuels. The demand for energy can most effectively be filled by renewable energy sources as installed energy storage capacity is growing rapidly. If renewable energy sources advance enough to fulfill the high demand, earth-friendly, clean and sustainable energy will help to protect the environment, thus ensuring a healthier life for future generations. Energy storage systems are essential in this endeavor, and in order to become more prevalent, storage systems for renewable energy sources must supply electricity without interruption as much as possible. As an electrochemical storage, a battery with a high level of performance, high energy density and life cycle could offer a viable solution for electricity storage provided that battery cost should be economically viable. This thesis aims to improve the geometry of the grid used in lead acid batteries in order to obtain a more uniform current and potential distribution, and minimize the potential drop for improved battery performance. A 3D mathematical model was developed using finite element method to evaluate the behavior of the grid under various conditions. Five different porous grid geometries were simulated under different loads and optimum grid geometry was identified. The 3D mathematical model of the lead-acid battery based on finite element method was simulated under certain conditions in order to evaluate the effect of grid geometry on battery performance.Master Thesis 3d-Printed Multiprobe Analysis System for Solar Fuel Research; Design, Fabrication and Testing(Izmir Institute of Technology, 2016) Harmanlı, İpek; Karabudak, Engin; Ebil, ÖzgençMethods of generating electricity with unlimited, clean and cheap energy from solar energy are tried to be investigated and developed in practical and theoretical academic fields. Especially, photocatalytic water splitting (PWS) systems have been identified as the main method in this study as well as in many studies due to the advantages provided by production of solar fuels from water. In this research, a study was carried out on the alternatives of the both used experimental set-up and used photocatalytic material for PWS systems. A study has been carried out on both the used experimental setup and the used photocatalytic material alternatives in PWS systems. As an alternative experimental setup that allows small volume analysis for PWS by Unisense gas microsensors, a mini photoreactor was designed using 3-D drawing and printing techniques and its usability was tested for PWS applications. Moreover, some characterization results for the electronic band structure and the band gap of the lead (II) trioxovanadate (V) chloride [PbVO3Cl] crystal, which was discovered by Eanes and co-workers in 2007 at IZTECH, was introduced in this study by not only theoretical (DFT approximations; LDA, GGA and HSE06) but also experimental (XRD, Diffuse Reflectance Method- Tauc Plot, Raman Spectroscopy, Four Probe) methods. Also, its estimated theoretical price and its potential for future application in tandem solar fuel device as a photoanode in combination with Si photocathode was calculated and discussed. The results showed that the designed mini photoreactor system is an open to development apparatus that is suitable for PWS, besides, PbVO3Cl has an "indirect transition" band structure and a band energy of ~ 2.2 eV. Although it did not give an effective result in PWS applications done by the designed mini photoreactor, it can be said that it is a semiconductor which is worth studying and developing in detail for other researches in this field due to the compatibility of its band energy amount and optical properties for PWS.Master Thesis Fabrication of Polymeric Nano-Coatings Via Chemical Vapor Deposition(Izmir Institute of Technology, 2016) Kırköse, Sema; Ebil, ÖzgençThin film coatings are used to provide protection to the substrate of interest against physical and chemical elements. Coating can also be applied to modify the surface properties of the substrate. One of the most important aspects of coating processes is controlling the thickness of coating material over the substrate. As a subset of a family of chemical vapor deposition methods, iCVD relies on vapor-to-surface reactions to form solid ultrathin polymer films. Unlike other CVD methods, iCVD is unique in that a polymerization reaction is induced by a thermally or chemically activated initiator molecule, much like in liquid-based thermal polymerization except without the use of a liquid solvent medium. The aim of the study is to fabricate polymeric protective nano-coatings via iCVD on flat surfaces at low or ambient temperatures. A variety of polymers, including homopolymers of glycidyl methacrylate (GMA), cyclo hexyl methacrylate (CHMA) and 1H, 1H, 2H, 2H,-Perfluorodecyl acrylate (PFDA) and P(GMA-PFDA) copolymers were fabricated via iCVD. The surface roughness and contact angle values were measured. Smooth hydrophobic surfaces having high contact angle (approximately 130˚) were obtained with PPFDA and PGMA-co-PPFDA thin films. Chemical compositions of the homo and co-polymer films were also evaluated confirming the retention of functional groups during polymerization, thus opening possibility of using iCVD produced films in various sensor applications.Master Thesis Modelling and Simulation of Zinc Based Batteries(Izmir Institute of Technology, 2016) Toptop, Evren; Ebil, Özgenç; Yüksel Özşen, AslıEnergy is the determining factor of productivity and quality of living. Electric energy is the most used energy form and lack of reserve for it hinders widespread use of renewable energy technologies. Advancements in renewable energy technologies, electric vehicles and consumer electronics are highly dependent on developments of new battery technologies. High energy density, long service life, using benign and abundant materials are few of the key requirements for next generation batteries. A model, a mathematical description of the system, is an effective tool to predict the behavior of batteries under specific conditions, thus reducing cost and time for the development. A mathematical model using finite element method was designed to simulate the discharge behavior of an experimental nickel-zinc battery that includes composite zinc and commercial nickel electrodes. The model employs thermodynamic and kinetic expressions for porous electrodes considering the concentration dependency of battery characteristics. The effects of initial zinc and nickel concentrations, anodic transfer coefficients of zinc and nickel electrode reactions on the electrochemical performance of the battery have been simulated. The discharge voltage, electrode porosities, and species concentrations in electrodes as a function of model parameters and time have been evaluated. It is observed that the model results are consistent with the experiment results considering that the battery operation is limited with zinc concentration. Initial zinc concentration is the major determining factor on discharge duration. Nickel oxyhydroxide concentration affects voltage magnitude. Transfer coefficients have only limited effects on discharge voltage and concentrations.Master Thesis An Investigation of Electrochemical Stability of Zinc Electrodes for Battery Applications(Izmir Institute of Technology, 2014) Payer, Gizem; Ebil, Özgenç; Çiftçioğlu, MuhsinEnergy is the most important and inevitable requirement for humankind. The increasing energy demand has been connected with technological advances and the population growth. One of the most serious problems of the world is to provide sustainable energy. New alternative energy sources and renewable energy technologies have become notable research subjects due to wide availability of renewable energy sources in the world. However, most renewable energy sources do not provide uninterrupted energy to consumers. An economic, efficient and reliable energy storage technology is desperately needed. Therefore, academic research has focused on improving the capacity of electrochemical energy storage technologies. The main goal of this study is the preparation and characterization of zinc electrodes for battery applications using different zinc oxide powders with various morphologies and additives. Zinc oxide powders were synthesized with chemical precipitation method under different conditions (precursors, temperatures and aging times) in order to investigate their effects on ZnO morphology and on the performance of nickel-zinc battery. It was found out that the initial morphology of ZnO powder was not crucial for the electrochemical performance. Nickel-Zinc batteries with zinc electrodes prepared from commercial ZnO powder had discharge capacities around 247 mAhg-1 and showed slightly better performance compared to nickel-zinc batteries with zinc electrodes prepared from ZnO powders synthesized via chemical precipitation method. It was also determined that zinc electrode morphology was greatly affected by battery additives (PVA and PEG) and charging current density. The effects of some selected electrode additives (Ca(OH)2, PbO and PEG) on battery performance were also investigated. Zinc electrode with all additives showed improved electrochemical properties, such as higher discharge capacity (322 mAhg-1) and utilization ratio (48.86 %.)Master Thesis Selective Loading of Organofilic Ag Nanoparticles in Ps-Pmma Blends(Izmir Institute of Technology, 2014) Tüzüner, Şeyda; Demir, Mustafa Muammer; Ebil, ÖzgençThe association of nanoparticles with polymer blends offers significant features beyond the advantages of polymer composites prepared by single homopolymer. Since the blends undergo phase separation due to incompatibility of the constituent polymers into various internal structures, the particles can be segregated into one of the phases. Different location of the particles allows to develop novel microstructures; and thus, control over physical properties. In this study, Ag nanoparticles were prepared by reduction of AgNO3 via NaBH4. The particles were capped by cetyl ammonium bromide (CTAB) and were mixed with equimass blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) in tetrahydrofurane (THF). The solid content of blend solution was fixed at 2.5% w/v. The concentration of the particles with respect to polymer blend was at 0.7 wt %. The composite film was cast on glass slide. Surface feature of the composite films was examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The surface of blend film without particles shows spherical pits with a size of 4.5 μm and rich in terms of PMMA. When particle size was small (diameter is around 20 nm), they preferentially located at the interface of the domains. The large particles with a diameter of 90 nm were found to locate in PMMA phase. Upon annealing of the composite film at 165 ˚C for 3 days, the particles move to the PS domains independent of the particle size and merely PS loaded composite is achieved.Master Thesis Preparation and Characterization of Polymer-Zeolite Composite Membranes(01. Izmir Institute of Technology, 1999) Ebil, Özgenç; Çiftçioğlu, MuhsinThis thesis is on the investigation of polymer-zeolite composite membranes for gas separation and the effects of a number of parameters such as solvent and zeolite type, zeolite content, polymer/solvent ratio and preparation temperature on the microstructure of the final membrane. Although there is an increasing interest in polymeric composite membranes, most of the previous work concentrated on the synthesis and performance measurements of new membrane materials rather than the effects of different methods and parameters on processmg.In this study polymer-zeolite composite membranes were prepared by a phase inversion technique. Polysulfone, natural zeolite and synthetic zeolite 13X were used as polymer and second phases respectively. Dichloromethane and dimethylformamide were used as solvents. Four experimental sets of membranes containing the same polymer but different solvents and zeolites with increasing zeolite loadings were prepared and characterized by thermo gravimetric analysis, infrared spectroscopy, optical microscopy and scanning electron microscopy.It has been found that the types of the solvent and zeolite directly affect the final microstructure of the membranes. Solvent removal rate and distribution of zeolite particles are important and have strong effects on the mechanical performance of the membranes.Membranes prepared by using synthetic zeolite 13X and dichloromethane were determined to be the best zeolite distributions in the microstructure by optical microscopy and thermogravimetric analysis. Uniform and mechanically strong membranes with 20-60 % synthetic zeolite contents were prepared. Mechanically weak and relatively nonuniform membranes were prepared by using natural zeolite clinoptilolite. The incorporation of an ultrasonic treatment of the zeolite dispersion most likely contributed in the successful deagglomeration of the second phase in the polymer matrix.