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Öğe Biodiesel production from inedible animal tallow and an experimental investigation of its use as alternative fuel in a direct injection diesel engine(Elsevier, 2009-02-15) Altun, Şehmus; Öner, CengizIn this study, a substitute fuel for diesel engines was produced from inedible animal tallow and its usability was investigated as pure biodiesel and its blends with petroleum diesel fuel in a diesel engine. Tallow methyl ester as biodiesel fuel was prepared by base-catalyzed transesterification of the fat with methanol in the presence of NaOH as catalyst. Fuel properties of methyl ester, diesel fuel and blends of them (5%, 20% and 50% by volume) were determined. Viscosity and density of fatty acid methyl ester have been found to meet ASTM D6751 and EN 14214 specifications. Viscosity and density of tallow methyl esters are found to be very close to that of diesel. The calorific value of biodiesel is found to be slightly lower than that of diesel. An experimental study was carried out in order to investigate of its usability as alternative fuel of tallow methyl ester in a direct injection diesel engine. It was observed that the addition of biodiesel to the diesel fuel decreases the effective efficiency of engine and increases the specific fuel consumption. This is due to the lower heating value of biodiesel compared to diesel fuel. However, the effective engine power was comparable by biodiesel compared with diesel fuel. Emissions of carbon monoxide (CO), oxides of nitrogen (NOx), sulphur dioxide (SO2) and smoke opacity were reduced around 15%, 38.5%, 72.7% and 56.8%, respectively, in case of tallow methyl esters (B100) compared to diesel fuel. Besides, the lowest CO, NOx emissions and the highest exhaust temperature were obtained for B20 among all other fuels. The reductions in exhaust emissions made tallow methyl esters and its blends, especially B20 a suitable alternative fuel for diesel and thus could help in controlling air pollution. Based on this study, animal tallow methyl esters and its blends with petroleum diesel fuel can be used a substitute for diesel in direct injection diesel engines without any engine modification.Öğe The comparison of engine performance and exhaust emission characteristics of sesame oil-diesel fuel mixture with diesel fuel in a direct injection diesel engine(Elsevier, 2008-01-09) Altun, Şehmus; Bulut, Hüsamettin; Öner, CengizThe use of vegetable oils as a fuel in diesel engines causes some problems due to their high viscosity compared with conventional diesel fuel. Various techniques and methods are used to solve the problems resulting from high viscosity. One of these techniques is fuel blending. In this study, a blend of 50% sesame oil and 50% diesel fuel was used as an alternative fuel in a direct injection diesel engine. Engine performance and exhaust emissions were investigated and compared with the ordinary diesel fuel in a diesel engine. The experimental results show that the engine power and torque of the mixture of sesame oil-diesel fuel are close to the values obtained from diesel fuel and the amounts of exhaust emissions are lower than those of diesel fuel. Hence, it is seen that blend of sesame oil and diesel fuel can be used as an alternative fuel successfully in a diesel engine without any modification and also it is an environmental friendly fuel in terms of emission parameters.Öğe Combustion, performance and emissions of a diesel power generator fueled with biodiesel-kerosene and biodiesel-kerosene-diesel blends(Elsevier, 2017-02-05) Bayındır, Hasan; Işık, Mehmet Zerrakki; Argunhan, Zeki; Yücel, Halit Lütfi; Aydın, HüseyinHigh percentages of biodiesel blends or neat biodiesel cannot be used in diesel engines due to high density and viscosity, and poor atomization properties that lead to some engine operational problems. Biodiesel was produced from canola oil by transesterification process. Test fuels were prepared by blending 80% of the biodiesel with 20% of kerosene (B80&K20) and 80% of the biodiesel with 10% of kerosene and 10% diesel fuel (B80&K10&D10). Fuels were used in a 4 cylinders diesel engine that was loaded with a generator. Combustion, performance and emission characteristics of the blend fuels and D2 in the diesel engine for certain loads of 3.6, 7.2 and 10.8 kW output power and 1500 rpm constant engine speed were experimented and deeply analyzed. It was found that kerosene contained blends had quite similar combustion characteristics with those of D2. Mass fuel consumption and Bscf were slightly increased for blend fuels. HC emissions slightly increased while NOx emissions considerably reduced for blends. It was resulted that high percentages of biodiesel can be a potential substitute for diesel fuel provided that it is used as blending fuel with certain amounts of kerosene.Öğe Temperature dependent electrical transport in Al/Poly(4-vinyl phenol)/ p -GaAs metal-oxide-semiconductor by sol-gel spin coating method(Hindawi, 2016-03-10) Özden, Şadan; Tozlu, Cem; Pakma, OsmanDeposition of poly(4-vinyl phenol) insulator layer is carried out by applying the spin coating technique onto p-type GaAs substrate so as to create Al/poly(4-vinyl phenol)/p-GaAs metal-oxide-semiconductor (MOS) structure. Temperature was set to 80-320 K while the current-voltage (I-V) characteristics of the structure were examined in the study. Ideality factor (n) and barrier height (φ b) values found in the experiment ranged from 3.13 and 0.616 eV (320 K) to 11.56 and 0.147 eV (80 K). Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.Öğe Determination of fatigue life of the unidirectional GFRP/Al hybrid composite laminates(Elsevier, 2019-06) Deniz, Mehmet Emin; Aydın, FıratThis paper investigates the effects of loading rate and fiber orientation on the fatigue behavior of the unidirectional glass-fiber reinforced-plastic/aluminum (GFRP/Al) hybrid laminated (GLARE-2) plates. Fatigue tests were performed at three kinds of stress ratios (R = 0.3, 0.1, and −0.1) on specimens with different fiber orientations, θ = 0° 15° 30° 45° 60° 75° and 90° in the GFRP layers. All the fatigue results to be presented in this article were obtained in repeated tension-tension and tension-compression at stress ratios of 0.3, 0.1, and −0.1, and the results were compared with each other. It has been shown that the specimens have the highest fatigue life in the fiber orientation direction at R = 0.3 loading rate. Also, it has been shown that the fatigue life of the specimens decreases as the loading rate decreases.Öğe Wet chemical methods for producing mixing crystalline phase ZrO 2 thin film(Elsevier, 2016-07) Pakma, Osman; Özdemir, Cengiz; Kariper, İshak Afşin; Özaydın, Cihat; Güllü, ÖmerThe aim of the study is to develop a more economical and easier method for obtaining ZrO 2 thin films at lower temperature, unlike the ones mentioned in the literature. For this purpose, wet chemical synthesis methods have been tested and XRD, UV-VIS and SEM analysis of ZrO 2 thin films have been performed. At the end of the analysis, we identified the best method and it has been found that the features of the films produced with this method were better than the films produced by using different reagents, as well as the films reported in the literature. Especially it has been observed that the transmittance of the film produced with this method were higher and better than the films in the literature and the others. In addition, refractive index of the film produced with this method was observed to be lower. Moreover, by using the same method Al/ZrO 2 /p-Si structure has been obtained and it has been compared with Al/p-Si reference structure in terms of electrical parameters.Öğe Synthesis, characterization and application of a novel multifunctional stationary phase for hydrophilic interaction/reversed phase mixed-mode chromatography(Talanta, 2017-11-1) Aral, Tarık; Aral, Hayriye; Çelik, Kadir Serdar; Altındağ, RamazanA novel multifunctional stationary phase based on silica gel was synthesised starting from L- isoleucine and 4-phenylbutylamine and evaluated as a hydrophilic interaction/reversed-phase mixed-mode stationary phase for high-performance liquid chromatography (HPLC). The prepared stationary phase was characterized by elemental analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM), Brunauer, Emmett and Teller (BET) and solid-state 13C nuclear magnetic resonance (NMR). The mechanisms involved in the chromatographic separation are multi-interaction, including hydrophobic, π-π, hydrogen-bonding, dipole-dipole and ion-dipole interactions. Based on these interactions, successful separation could be achieved among several aromatic compounds having different polarities under both hydrophilic interaction liquid chromatography (HILIC) and reversed phase (RP) condition. Nucleotides/nucleosides were separated in the HILIC mode. The effects of different separation conditions, such as pH value, mobile-phase content, column temperature, buffer concentration and flow rate, on the separation of nucleotides/nucleosides in HILIC mode were investigated. The seven nucleotides/nucleosides were separated within 22 min, while six of them were separated within 10 min by isocratic elution. To determine the influence of the new multifunctional stationary phase under the RP condition, a number of moderately and weakly polar and nonpolar compounds, such as 10 substituted anilines and eight substituted phenols were separated successfully under the RP condition within 14 and 15 min, respectively. Additionally, nine mixtures of polar/nonpolar test compounds were simultaneously separated within 19 min, while seven of them were separated within 12 min, under HILIC/RP mixed-mode conditions. Chromatographic parameters, such as the retention factor and peak asymmetry factor, were calculated for all of the analytes, while the theoretical plate number was calculated for analytes separated by isocratic elution. Compared to traditional C18 and commercial HILIC columns, the new stationary phase exhibited both HILIC and RPLC performance, and the scope of analyte separation was thus enlarged.Öğe A novel version of k nearest neighbor: Dependent nearest neighbor(Elsevier, 2017-06) Ertuğrul, Ömer Faruk; Tağluk, Mehmet Emink nearest neighbor (kNN) is one of the basic processes behind various machine learning methods In kNN, the relation of a query to a neighboring sample is basically measured by a similarity metric, such as Euclidean distance. This process starts with mapping the training dataset onto a one-dimensional distance space based on the calculated similarities, and then labeling the query in accordance with the most dominant or mean of the labels of the k nearest neighbors, in classification or regression issues, respectively. The number of nearest neighbors (k) is chosen according to the desired limit of success. Nonetheless, two distinct samples may have equal distances to query but, with different angles in the feature space. The similarity of the query to these two samples needs to be weighted in accordance with the angle going between the query and each of the samples to differentiate between the two distances in reference to angular information. This opinion can be analyzed in the context of dependency and can be utilized to increase the precision of classifier. With this point of view, instead of kNN, the query is labeled according to its nearest dependent neighbors that are determined by a joint function, which is built on the similarity and the dependency. This method, therefore, may be called dependent NN (d-NN). To demonstrate d-NN, it is applied to synthetic datasets, which have different statistical distributions, and 4 benchmark datasets, which are Pima Indian, Hepatitis, approximate Sinc and CASP datasets. Results showed the superiority of d-NN in terms of accuracy and computation cost as compared to other employed popular machine learning methods.Öğe Analysis of ethanol RCCI application with safflower biodiesel blends in a high load diesel power generator(Elsevier, 2016-11-15) Işık, Mehmet Zerrakki; Aydın, HüseyinThe effects of RCCI in a diesel power generator by using safflower oil biodiesel-diesel blends were experimentally investigated. Ethanol was premixed as PFI by rates of 30% and 50% of total mass fuel consumption of the engine. Tests were conducted at constant engine speed of 1500 rpm and fixed load 10.8 kW engine power. The purpose of blending biodiesel with diesel is to increase the fuel reactivity of primary fuel in order to easily initiate the combustion. Therefore, test fuels were prepared by blending 10% of the biodiesel with 90% of diesel, 20% of the biodiesel with 80% of diesel and 50% of the biodiesel with 50% of diesel. The most important combustion, performance and emission indicators of the engine under various conditions have been deeply investigated and results have been presented. The ethanol RCCI operation increased peak pressure values especially with using of B50 as high reactivity fuel while combustion was retarded for both RCCI modes. Overall, many indicators of the combustion was improved. Performance parameters were developed. Especially, bsfc was considerably increased. NOx, emissions were considerably decreased while CO and HC emissions were a bit increased.Öğe Analysis of combustion, performance and emission characteristics of a diesel engine using low sulfur tire fuel(Elsevier, 2015-03-01) Aydın, Hüseyin; İlkılıç, CumaliAn alternative fuel for diesel engines was produced from waste vehicle tires by the method of pyrolysis. In order to reduce sulfur content of produced the liquid fuels, during the reaction Ca(OH) 2 was used. Then, H 2 SO 4 were used after the reaction and the sulfur content of the product was reduced by 83.75%. The properties of diesel fuel, low sulfur tire fuel and fuel mixtures of low sulfur tire fuel and diesel fuel were found. Then the prepared fuel blends and diesel fuel were tested in a diesel engine. Performance, combustion and emission parameters of the engine when using each fuel were obtained and comparisons were made with D2 fuel. Power, torque and mean effective pressure, mass fuel consumption, effective efficiency and bscf values presented. Results justify that the performance of the engine slightly lowers by using blends of LSTF. Cylinder pressure and heat release rate values of the test fuels usage were quite similar with those of D2. CO, HC, and smoke emissions were slightly higher while NOx emissions were lower for LSTF blends. All of these results indicate that desulfurized tire fuels with low percentages can be used as alternative fuel in diesel engine.
