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Öğe Thermodynamic and economic analyses of a spark-ignition engine operating with bioethanol-gasoline blends(Taylor & Francis Inc, 2023) Doğan, Battal; Yılbaşı, Zeki; Yaman, Hayri; Yeşilyurt, Murat KadirThe problems associated with the use of fossil energy sources, as well as the constant rise in energy demand, have increased the importance of biofuels. In this study, the use of gasoline/bioethanol dual fuel blend as an alternative fuel in an SI engine was investigated by experiments and thermodynamic analysis. In experimental studies, performance and emission tests were performed at three different bioethanol ratios (10%-30%) at five different engine speeds (1200-1600 rpm). Thermodynamic and economic analyses were accomplished considering fuel consumption, torque, temperatures of cooling water and exhaust gases, and emissions obtained from these tests. Besides that, the sustainability index value of the fuel blends was taken into account. The augmentation of bioethanol fraction in the mixtures leads to a decline in thermal and exergy efficiencies. When the speed is 1600 rpm, the thermal and exergetic efficiencies of B0 fuel are 2.66% and 3.73% higher than those of B30 fuel, respectively. When the bioethanol concentration in the blends increased, the destroyed exergy increased. The exergy lost for G100, B10, B20, and B30 fuel blends were calculated as 6.822, 6.985, 6.908, and 7.017 respectively when the speed was adjusted to be 1200 rpm. The exergetic efficiency values for G100 and B30 at 1200 rpm were observed to be 36.82% and 35.39%, respectively. Based on the exergoeconomic analysis, the rise in the concentration of bioethanol in the blends increases the fuel cost rate, and accordingly, the unit cost of engine power exergy increases. The unit cost of engine power exergy in B30 fuel is approximately 50% higher than that of G100 fuel. The exergoeconomic factor was found to be 2.52 for G100, 1.893 for B10, 1.511 for B20, and 1.217 for B30 at the speed of 1200 rpm. The minimum sustainability index in all engine speeds in bioethanol fuel blends was calculated as 1.548.Öğe The investigation of environmental behaviors by energy and exergy analyses using gasoline/ethanol fuel blends(Springer, 2023) Doğan, Battal; Erol, Derviş; Üstün, SüleymanThis study aims to evaluate the use of ethanol/gasoline fuel blends in a single-cylinder spark-ignition engine with energy, exergy, exergoeconomic and exergoenvironmental analysis. Test fuels (G100, E10, E20, E30, E40, E50, and E100) prepared by adding ethanol obtained from agricultural products to gasoline at different ratios were utilized in experimental studies. Thermodynamic analyses were carried out using the performance and emission data obtained from the engine tests. Thermal efficiency and exergy efficiencies were computed with energy and exergy analyses. The highest efficiencies were acquired at 2500 rpm for all fuels. The exergy efficiency of G100, E20 and E40 fuels at this engine speed is 17.13%, 15.81% and 14.62%, respectively. Furthermore, cost of engine shaft work in exergoeconomic analysis and environmental cost of shaft work in exergoenvironmental analysis were found in study. When an engine speed was 2500 rpm in E50 fuel, the cost of shaft work was 74.21 $ MJ(-1), and the environmental cost of shaft work was 59.07 $ GJ(-1). Moreover, exergoeconomic factor and exergoenvironmental factor values of fuel blends were computed. It was revealed that increased ethanol ratio in fuel blends increased economic and environmental costs. In terms of economy and environment, it can be considered appropriate that the ethanol ratio in fuel blends is between 30 and 40%. If ethanol is used higher than these rates, costs increase and fuels become uneconomical.Öğe The investigation of energy and exergy analyses in compression ignition engines using diesel/biodiesel fuel blends-a review(Springer, 2023) Doğan, Battal; Erol, DervişBiodiesel is used as an alternative fuel or fuel additive in diesel engines. In the literature, engine performance, exhaust emission, and thermodynamic analyses have been conducted using biodiesel, diesel-biodiesel, diesel-biodiesel-alcohol, and diesel-biodiesel-nanoparticle fuel blends as alternative fuels in diesel engines. The present research examined and discussed only studies related to energy and exergy analyses. Using energy efficiency, exergy efficiency, and destroyed exergy values, a distinct perspective has been given to using biodiesel as an alternative fuel. While a certain decrease occurs in engine power with biodiesel, an improvement is observed in engine emissions. Hence, the exergy efficiency of biodiesel fuel blends is lower than pure diesel fuel. Some studies in the literature have reported exergy destruction due to the use of biodiesel to be 5-15% higher than pure diesel fuel.The exergy efficiency of some biodiesel types is very low compared to diesel fuel. When nanoparticles such as Al2O3 and TiO2 are added to diesel-biodiesel fuel blends, exergy destruction in the engine decreases and, thus, the useful work increases. Whereas nanoparticles ensure a 2-5% power increase in diesel-biodiesel blends, they cause exergy destruction to decrease at the same rate. This study reviewed in detail the effects of using biodiesel fuels in diesel engines on energy and exergy performance and aimed to contribute to researchers working in this field.Öğe The investigation of effects on the engine performance characteristics of different channel geometries in the displacer cylinder for a beta-type Stirling engine with the slider-crank drive mechanism(Sage Publications Ltd, 2023) Yaman, Hayri; Doğan, Battal; Erol, Derviş; Yeşilyurt, Murat KadirThis study was focused to develop a power generation system that could use renewable energy resources more efficiently. In accordance with this purpose, the design, manufacturing, and testing of a Stirling engine with a beta-type slider-crank drive mechanism were carried out. Helium, nitrogen, and air were utilized as working fluids, and experimental studies were performed at various charge pressures. Moreover, the effects of three different channel geometries in the displacer cylinder on the performance were researched. The maximum power was obtained as 160.5 W in a 120-slot channel displacer cylinder in the helium working fluid at a charge pressure of 4 bar and 400 rpm engine speed. The highest torque was found to be 7.92 Nm in a 66-slot channel displacer cylinder in the helium working fluid at the aforementioned charge pressure and 100 rpm engine speed. The lowest engine power output among the maximum engine powers was obtained to be 48.3 W when air was used as a working fluid at a pressure of 4 bar and an engine speed of 200 rpm, using a smooth displacer cylinder. Use of channels in the displacer cylinder and the increased number of channels had positive effects on engine performance. It was determined that the maximum engine power output obtained in the experimental studies was 46.0% and 49.86% higher in the 66-slot channel, and 120-slot channel cylinders, respectively, compared to the smooth displacer cylinder. It has been observed that when the number of channels on the displacer cylinder was increased by approximately 81.8%, an increase of approximately 2.62% was obtained in the engine power output. This situation revealed that optimization of the number of channels is important.Öğe The influence of n-pentanol blending with gasoline on performance, combustion, and emission behaviors of an SI engine(Elsevier - Division Reed Elsevier India Pvt Ltd, 2021) Yaman, Hayri; Yeşilyurt, Murat KadirThis experimental research deals with the characteristic work on the performance, combustion, and exhaust pollutants for unleaded gasoline mixed with n-pentanol in the proportion of 5%, 10%, 15%, and 20% (by vol.) of the total quantity. The trials were performed on a 1-cylinder, 4-stroke, water-cooled, port-fuel injection (PFI) spark-ignition (SI) engine loading an AC active dynamometer so as to scrutinize the aforementioned behaviors of n-pentanol. The test fuels (unleaded gasoline, Pt5, Pt10, Pt15, and Pt20) were experimented with at various loads ranging from 1 kW to 5 kW with intervals of 1 kW under 1600 rpm fixed speed. The findings coming from the tests exhibited that the infusion of n-pentanol to gasoline has caused to reducing the HC, CO, CO2, and NO emissions in contrast to the baseline gasoline however, O-2 levels were observed to be higher. At all of the engine loads, n-pentanol blends exhibited an improvement in BTE when compared with gasoline by reason of the inherent oxygen concentration of used alcohol. As hoped, the peak in-cylinder pressure and apparent heat release rate (HRR) values for the tested fuel blends were found to be higher than that of UG test fuel. It is to be noticed that the higher-order alcohol namely n-pentanol may be used as a partial replacement for gasoline fuel in the SI engine applications according to the experimental outcomes. (C) 2021 Karabuk University. Publishing services by Elsevier B.V.Öğe The investigation of an energetic and exergetic performance characteristics of a beta-type Stirling engine with a rhombic drive mechanism(Springer Heidelberg, 2021) Erol, Derviş; Doğan, Battal; Çalışkan, SinanIn this study, effects of using helium, nitrogen, air, carbon dioxide and argon gases as working fluid in a beta-type Stirling engine with rhombic drive mechanism and swept volume of 365 cm(3) on the engine performance characteristics for two different stainless steel and titanium displacer pistons at charge pressures of 1-5 bar were examined. The performance characteristics of manufactured Stirling engine were investigated at 1000 K (+/- 10 K) hot end and 300 K (+/- 5 K) cold end temperatures using a specifically designed electrical heater. Energy and exergy analyses were carried out using temperature, pressure, speed and torque values measured in performance tests. As a result of the exergy analysis, helium gas performed the best in the stainless steel displacer piston at a charge pressure of 4 bar and an engine speed of 550 rpm. Under the said conditions, 0.3726 W/K entropy generation and 195.53 W destroyed exergy were calculated in thermodynamic analysis in the helium working fluid. Furthermore, under the same conditions, helium gas achieved the highest efficiency values of 48.04% for thermal efficiency, 56.54% for exergy efficiency and 69.2% for Carnot efficiency. The lowest exergetic performance was revealed in titanium displacer piston when argon was used as working fluid.Öğe The industrial-grade hemp (Cannabis sativa L.) seed oil biodiesel application in a diesel engine: combustion, harmful pollutants, and performance characteristics(Edp Sciences S A, 2022) Yılbaşı, Zeki; Yeşilyurt, Murat Kadir; Yaman, Hayri; Arslan, MevlütThe core focus of the present investigation is regarding biodiesel production from industrial hemp seed oil applying single-stage homogenous catalyzed transesterification process obtaining high yield of methyl ester. The engine tests were carried out on a single-cylinder, four-stroke, water-cooled, unmodified diesel engine operating with hemp seed oil methyl ester as well as its blends with conventional diesel fuel. The experimental findings of the test fuels were compared with those from diesel. The results pointed out that the performance and combustion behaviors of biodiesel fuels are just about in line with those of diesel fuel propensity. The specific fuel consumption for 5% biodiesel blend (0.291 kg/kW h), 10% biodiesel blend (0.305 kg/kW h), and 20% biodiesel blend (0.312 kg/kW h) blends at full load was closer to diesel (0.275 kg/kW h). In the meantime, the thermal efficiency for biodiesel was found to be at the range of 15.98-24.97% and it was slightly lower than that of diesel (18.10-29.85%) at the working loads. On the other hand, the harmful pollutant characteristics of carbon monoxide, hydrocarbon, and smoke opacity for biodiesel and its blends were observed to be lower in comparison with diesel during the trials. However, the oxides of nitrogen emissions for biodiesel were monitored to be as 6.85-15.40 g/kW h which was remarkably higher than that of diesel (4.71-8.63 g/kW h). Besides that, the combustion behaviors of biodiesel and its blends with diesel showed much the same followed those of diesel. Namely, the duration of ignition delay of biodiesel-diesel blends was shorter than that of diesel fuel because of the higher cetane number specification of the methyl ester. The highest gas pressures inside the cylinder as well as the rates of the heat release of biodiesel including test fuels are lower in contrast to the diesel due to the shorter ignition delay. It could be concluded that the utilization of biodiesel produced from industrial hemp seed oil in the diesel engine up to 20% (by vol.) will decrease the consumption of diesel and environmental pollution, especially in developing countries.Öğe The examination of performance characteristics of a beta-type Stirling engine with a rhombic mechanism: The influence of various working fluids and displacer piston materials(Wiley, 2021) Erol, Derviş; Çalışkan, SinanIn this study, to develop a power generation system that can use renewable energy resources more efficiently, a beta-type Stirling engine with rhombic mechanism was designed and manufactured. Kinematic and thermodynamic analyses of a beta-type Stirling engine were performed numerically in the Fortran program. Volume and pressure changes depending on crankshaft angle of Stirling engine were made using the isothermal analysis. The effects of the basic parameters related to engine performance, such as working fluid mass, charge pressure, heater, and coolant temperatures, on the net work amount were investigated. Five different gases, including helium, air, nitrogen, carbon dioxide, and argon, were used as a working fluid in experimental studies. The effects of all these gases on engine performance characteristics were examined at charge pressures of 1 to 5 bar for two different displacer pistons made of stainless steel and titanium material. The performance characteristics of Stirling engine manufactured were tested using a specially designed electrical heater, at 727 degrees C hot end and 27 degrees C cold end temperature, depending on engine speed. In all experimental studies, maximum power output was acquired to be 215.48 W, at 4 bar and 550 rpm when a stainless steel displacer piston and helium gas as a working fluid were used, and maximum torque value was acquired to be 7.54 Nm, at 5 bar and 150 rpm. The lowest engine power output among maximum engine powers was acquired to be 34.66 W when argon gas was used as a working fluid at 3 bar and 300 rpm, using a displacer piston made of titanium material. Maximum power output acquired in the experimental studies using a stainless steel displacer piston and helium; it was determined that it is 72.12%, 73.69%, 241.49%, and 288.81% higher than the engine power acquired by nitrogen, air, carbon dioxide, and argon gases, respectively.Öğe The experimental investigation of performance behaviors of a beta-type Stirling engine with bell-crank motion mechanism(Sage Publications Ltd, 2024) Erol, DervişThe current study aims to develop a novel power generation system that is capable of working with a Stirling engine. Within this context, a beta-type Stirling engine design has been created with a bell-crank motion mechanism and a 365 cm3 swept volume. The engine has been manufactured, and then a detailed assessment has been conducted to determine the impact of the motion mechanism on engine performance characteristics. The designed and manufactured engine has been tested using a range of working fluids, such as air, argon, carbon dioxide, helium, and nitrogen gases. The performance tests of this engine have been carried out at 1000 K (+/- 10) heater and 300 K (+/- 5) coolant temperatures. Based on the outcomes of the experimental studies, the highest engine power and torque values have been obtained at a charge pressure of 4 bar using helium gas, with 143.5 W at 267 rpm and 7.75 Nm at 100 rpm, respectively. Moreover, the maximum engine power values obtained from other tests with nitrogen, air, carbon dioxide and argon gases have been compared with helium gas. Helium gas has been found to outperform nitrogen, air, carbon dioxide, and argon gases in tests by 67.3%, 73.9%, 197.1%, and 200.2%, respectively. Finally, the highest thermal efficiency value has been obtained with helium gas as 48.7% at a charge pressure of 4 bar.Öğe The effects of different channel geometries in the displacer cylinder, working fluids, and engine speed on the energy and exergy performance characteristics of a β-type Stirling engine with a slider-crank drive mechanism(Sage Publications Ltd, 2023) Doğan, Battal; Erol, Derviş; Yeşilyurt, Murat Kadir; Yaman, HayriStirling engines are power generation systems working with the external heating principle and converting heat energy into mechanical energy. In this study, thermodynamic analyses were performed using the data of performance tests in which helium, nitrogen, and air were utilized as working fluids in a beta-type Stirling engine with a swept volume of 365 cm(3) and a slider-crank drive mechanism. Moreover, the impact of different channel geometries in the displacer cylinder on engine power was revealed. In the study, three displacer cylinders, smooth, 66-slot channel, and 120-slot channel displacer cylinders, were used. Performance tests were conducted at five charge pressures varying between 1 and 5 bar, with the hot end temperature of 1000 +/- 10K and the cold end temperature of 300 +/- 5K. The heat transferred to the hot zone, thermal losses and efficiency were calculated in the energy analysis. The highest thermal efficiency was 45.50% when a 120-slot channel displacer cylinder was used with helium as the working fluid. Thermal efficiency values were 32.87% and 32.60% for nitrogen and air, respectively, under the same conditions. Entropy generation, exergy destruction, and exergy efficiency were calculated in the exergy analysis. The lowest exergy destruction was obtained using a 120-slot channel displacer cylinder with helium as the working fluid. Furthermore, the impact of engine speed on exergy efficiency was determined.Öğe The effect of Cr and Nb addition on the structural, morphological, and magnetic properties of the mechanically alloyed high entropy FeCoNi alloys(Springer Heidelberg, 2022) Yakın, Alican; Şimşek, Telem; Avar, Barış; Chattopadhyay, Arun K.; Özcan, Şadan; Şimşek, TuncayIn this study, four different equimolar compositions of FeCoNi, FeCoNiNb, FeCoNiCr, and FeCoNiNbCr were synthesized by the mechanical alloying method. The effects of Cr and Nb addition on the structural, morphological, and magnetic properties of FeCoNi alloy were investigated in detail. The structural aspects of the samples were analyzed by X-ray diffractometer and scanning electron microscope equipped with an energy dispersive X-ray spectrometer. High and low-temperature magnetic properties were evaluated by a vibrating sample magnetometer. It was noticed that the addition of Nb caused amorphization, while Cr promoted crystallization in the alloys. The crystallite sizes were calculated as 9.7, 3.1, 8.3, and 4.4 nm for the FeCoNi, FeCoNiNb, FeCoNiCr, and FeCoNiCrNb alloys, respectively, after 20 h of milling. The SEM images of the as-milled alloys revealed irregular and layered structures for FeCoNi and FeCoNiCr alloys of mean particle sizes around 140 and 120 mu m. In contrast, the addition of Nb in these alloys, viz. FeCoNiNb and FeCoNiNbCr alloys, formed mostly spherical with irregular morphologies of particle sizes ranging between 55 and 80 mu m. It was noticed that the low solubility of Cr caused precipitation at the grain boundaries of the alloy particles, and it contributed to the formation of hard structures of irregular and layered morphologies. The observed increase in the lattice parameters and lattice strain in the solid solution phases of all-alloy systems studied was mainly due to the lattice distortion and intense plastic deformations. The maximum saturation magnetization obtained from the room temperature hysteresis loops was 150.4 emu/g for the FeCoNi alloy after 10 h of milling. The additions of non-magnetic Cr, Nb, and both into FeCoNi, caused a significant decrease in the saturation magnetization. The coercivity of the as-milled alloys was also found to decrease with the reduction in the nano-crystallite sizes, which elucidated that the crystallite sizes of the alloys were smaller than the magnetic exchange length. The high-temperature magnetization curves revealed that all alloys studied had Curie temperature higher than 700 K.Öğe The assessment of fusel oil in a compression-ignition engine in the perspective of the waste to energy concept: investigation of the performance, emissions, and combustion characteristics(Taylor & Francis Ltd, 2022) Erol, Derviş; Yaman, Hayri; Doğan, Battal; Yeşilyurt, Murat KadirFusel oil can be obtained from all agricultural products containing sugar, as well as from starchy products such as corn and potatoes, and from cellulosic products such as sulfite liquor, which is a wood and paper mill residue. Fusel oil is produced as a waste product during the production of bioethyl alcohol or biomethyl alcohol from sugar beet pulp remaining during sugar production in Turkey. In this study, alternative fuel blends prepared by infusing 5, 10, 15, and 20% of fusel oil to diesel (DF) by volume were tested in a single-cylinder, diesel engine at 1500 rpm and different loads, and thus, engine performance, pollutant emissions, and combustion characteristics were determined and compared with reference diesel. As a result, since fusel oil has lower calorific values than diesel, alcohol fuel blends caused a decrease in brake thermal efficiency (BTE) and an increase in brake specific fuel consumption (BSFC). It was observed that carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx), and smoke emissions decreased significantly with addition of FUSEL oil to diesel while carbon dioxide (CO2) and oxygen (O-2) emissions, which are an indicator of complete combustion, increased. This occurred since oxygen molecules in chemical structure of fusel oil improved emissions. Concerning combustion characteristics, it was observed that addition of fusel oil to baseline diesel generally increased in figures of in-cylinder pressure and net heat release rate. Moreover, it was determined that alcohol fuel blends generally increased ignition delay time compared to diesel due to their low cetane numbers. When all experimental results are evaluated, it can be said that fusel oil additive significantly reduces exhaust emissions without considerably affecting combustion and performance characteristics.Öğe Synthesis of biocompatible Ti-6Al-4V composite reinforced with ZrO2 and bioceramic produced by powder metallurgy: Morphological, structural, and biocompatibility analysis(Wiley, 2024) Pul, Muharrem; Erdem, Ümit; Bozer, Büşra Moran; Şimşek, Tuncay; Yılmazel, Rüstem; Erten, Mustafa YasinIn this experimental study, the initial phase involved preparing composite structures with various mix ratios using the Ti-6Al-4V alloy, widely used in clinical applications, in conjunction with ZrO2 and hydroxyapatite (HA) synthesized via the precipitation method, employing powder metallurgy techniques. Subsequently, the microstructures of the resultant hybrid composite materials were imaged, and x-ray diffraction (XRD) phase analyses were conducted. In the final phase of the experimental work, tests were performed to determine the biocompatibility properties of the hybrid composites. For this purpose, cytotoxicity and genotoxicity assays were carried out. The tests and examinations revealed that structures compatible both morphologically and elementally were obtained with no phase transformations that could disrupt the structure. The incorporation of ZrO2 into the Ti-6Al-4V alloy was observed to enhance cell viability values. The value of 98.25 +/- 0.42 obtained by adding 20% ZrO2 gave the highest cell viability result. The addition of HA into the hybrid structures further increased the cell viability values by approximately 10%. All viability values for both HA-added and HA-free groups were obtained above the 70% viability level defined in the standard. According to the genotoxicity test results, the highest cytokinesis-block proliferation index values were obtained as 1.666 and 0.620 in structures containing 20% ZrO2 and 10% ZrO2 + 10% HA, respectively. Remarkably, all fabricated composite and hybrid composite materials surpassed established biocompatibility standards and exhibited nontoxic and nongenotoxic properties. This comprehensive study contributes vital insights for future biomechanical and other in vitro and in vivo experiments, as it meticulously addresses fundamental characterization parameters crucial for medical device development.Öğe Synthesis and characterization of amorphous-nanocrystalline Fe70Cr10Nb10B10 powders by mechanical alloying(Springer Heidelberg, 2022) Avar, Barış; Chattopadhyay, Arun K.; Şimşek, Tuncay; Şimşek, Telem; Özcan, Şadan; Kalkan, BoraIn this study, structural, morphological, thermal and magnetic properties of amorphous-nanocrystalline Fe70Cr10Nb10B10 (at.%) alloy are discussed. The formation and evaluation of amorphous-nanocrystalline structures of the alloy were followed by XRD, SEM-EDX, TEM, DTA, and VSM techniques. After 50 h of milling Cr, Nb, and B were completely dissolved into the Fe lattice forming 82% of the amorphous phase of the alloy. A gradual dissolution of the alloying elements also increased the lattice parameters concurrently. The lattice parameters reached a maximum value of 2.908 angstrom after 20 h of milling and then leveled off to a value of 2.891 angstrom at the end of 50 h of milling. Based on the XRD data, crystallite size and lattice strain of the alloy were calculated as 3.2 nm and 3.34% respectively. TEM analyses revealed that the alloy particulates comprised needle-shaped nanoparticles of an average size of 21 nm. The room temperature magnetic hysteresis loops showed that the increased duration of milling decreased the saturation magnetization from 91 to 24 emu/g. This was mainly due to the upsurge on the amorphous phase content in the alloy as the milling progressed. The increase in amorphous phase content and the subsequent reduction of the saturation magnetization were due to the inter-diffusion of the non-ferromagnetic Cr and B atoms into the Fe lattice. Thermal studies revealed that around 350 degrees C the amorphous phase of the alloy began crystallizing. The magnetic saturation of the heat-treated alloy also increased with the growth in the crystalline phases. The 50 h milled sample annealed at 700 degrees C was found to have the highest magnetic anisotropy as observed from the temperature-dependent zero-field cooled and field cooled magnetization measurements. The high-pressure X-ray diffraction measurements revealed that the amorphous state of the alloy remained stable up to 11.3 MPa. It also revealed the structural similarities of the Fe70Cr10Nb10B10 alloy with those of the Fe70M10B20 (M = Nb and Cr) types. For all practical purposes, the microstructural stability under high compressive pressure represents the consolidation properties of the nanostructured magnetic materials since both pressure and temperature-induced phase transformations are the primary controlling factors for the specific magnetization properties of the alloy.Öğe Structural stability of mechanically alloyed amorphous (FeCoNi)70Ti10B20 under high-temperature and high-pressure(Elsevier Science Sa, 2021) Avar, Barış; Şimşek, Tuncay; Özcan, Şadan; Chattopadhyay, Arun K.; Kalkan, BoraNanostructured (FeCoNi)(70)Ti10B20 (at%) alloy was synthesized by mechanical alloying from elemental powder mixture of Fe, Co, Ni, Ti and B using ball milling. The effect of ball milling time on the evolution of structure and morphology was investigated by X-ray diffraction, scanning and transmission electron microscopy and differential thermal analysis. It was observed that the formation of solid solution of (FeCoNi)(70)Ti10B20 started from the very onset of the milling process. Crystallite size and lattice strains seemed to be leveled off after 20 h of milling with no further major changes. The milling process for longer periods introduced severe plastic deformations causing formation of amorphous phase of (FeCoNi)(70)Ti10B20. The amorphous alloy composition was confirmed by energy dispersive X-ray spectroscopy analysis that showed an excellent homogeneity of the alloying elements. The phase stability of the mechanically alloyed amorphous sample was further verified by employing high-temperature and high-pressure studies. The alloy samples heat-treated at 700 degrees C revealed crystallization of the amorphous phase. However, synchrotron-based high-pressure ambient temperature X-ray diffraction studies confirmed that the amorphous phase of the alloy remained stable up to the pressure of 30 GPa. The 50 h milled sample after being annealed at 350 degrees C showed improvement in the soft magnetic properties of the alloy, which was due to the probable elimination of the residual stress in the amorphous phase of the alloy powders. (C) 2020 Elsevier B.V. All rights reserved.Öğe Solid-State Synthesis and Characterization of the Stable Nanostructured Ni21Ti2B6 Phase(Wiley-V C H Verlag Gmbh, 2021) Şimşek, Tuncay; Avar, Barış; Özcan, Şadan; Chattopadhyay, Arun K.; Kalkan, BoraHerein, nanostructured ternary Ni-Ti-B alloy synthesized by mechanical alloying from the elemental Ni, Ti, and B powders by high energy ball milling is described. The synthesized alloy of nominal composition of Ni70Ti10B20 results in the formation of a unique stable phase of Ni21Ti2B6, which happens to be stoichiometrically very close to Ni70Ti10B20 in the cubic symmetry. The synthesized alloy samples also show amorphization together with the formation of nanocrystalline phases of Ni21Ti2B6 at both early and later stages of the alloying process. Thermal analysis carried out on Ni70Ti10B20 induces crystallinity and reveals the formation of crystalline Ni-Ti-B ternary alloy, Ni21Ti2B6, above 523 K, confirming the stability of the ternary crystalline phase of the alloy. The magnetic saturation of the alloy is measured as 0.95 emu g(-1) for the starting amorphous phase that increases to 9.05 emu g(-1) for the crystalline phase upon annealing. Correspondingly, the coercivity value for the annealed sample is reduced to 70 Oe from 194 Oe for the amorphous phase. This is the first time that an evidence of the stable crystalline Ni-Ti-B ternary alloy is reported.Öğe Simultaneous optimization of multiple engine parameters of a 1-heptanol / gasoline fuel blends operated a port-fuel injection spark- ignition engine using response surface methodology approach(Pergamon-Elsevier Science Ltd, 2022) Yaman, Hayri; Yeşilyurt, Murat Kadir; Uslu, SametDue to increasing air pollution and decreasing fuel reserves, the search for environmentally friendly fuels continues and a lot of time and money are spent in the experiments for these searches. Therefore, it is very important to be able to determine the optimal parameter levels for a fuel's use in the engine through several experiments. For this purpose, in this study, the design of experiments (DoE)-based response surface methodology (RSM) was used to determine the optimum compression ratio (CR), engine load, and 1-heptanol percentage in a spark ignition (SI) engine to obtain the best performance such as brake thermal efficiency (BTHE), brake specific fuel consumption (BSFC) and emission values such as carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC) and nitrogen oxide (NOx). The data required for the RSM model were obtained from the experiments performed at three different 1-heptanol percentages (0, 10%, and 20%), three different CRs (6.0:1, 8.0:1, and 10.0:1), and three different engine loads (4, 8, and 12 kg). Optimum operating parameters to achieve the best performance and emission values were determined as 8% 1-heptanol, 10.0:1 CR, and 6 kg engine load. The BTHE, BSFC, CO, CO2, HC, and NOx, were found to be 26.03%, 0.32 kg/kWh, 0.56%, 15.07%, 182.54 ppm, and 676.16 ppm according to optimum working parameters, respectively. In addition, according to the validation study, the error rates between the optimum results and the experimental results were acceptable between 0.74% and 8.96%. Experimental results reveal that 10% 1-heptanol addition improved BTHE and BSFC by an average of 5% and 2.5%, respectively, but did not affect NOx, much. With the addition of 20% 1-heptanol, the CO emission was improved by an average of 8.5%. In terms of HC and CO2, the effect of 1-heptanol was negative. By increasing the compression ratio to 10, BTHE, BSFC, CO, and HC were positively affected, while CO2 and NOx emissions were negatively affected. It is thought that this study will be a reference study since it provides optimum operating parameters of the engine when 1-heptanol will be used as an alternative fuel in the gasoline engine. (C) 2020 The Author(s).Öğe Optimization of Parameters Affecting the Performance and Emissions of a Spark Ignition Engine Fueled with n-Pentanol/Gasoline Blends Using Taguchi Method(Springer Heidelberg, 2021) Uslu, Samet; Yaman, Hayri; Yeşilyurt, Murat KadirAs operating factors play an important role in engine emissions and performance, it is important to explore the simultaneous impact of various operating factors on engine performance and emission responses. Taguchi method was used in order to determine the suitability of using n-pentanol in spark ignition engine and to determine the optimum operating conditions with fewer experiments instead of many experiments. Engine load, n-pentanol percentage and ignition advance were selected as engine operating variables. Three different levels were determined for each of the selected engine variables and an experimental design was created using the Taguchi method. Taguchi method proposed L-27 (3 (boolean AND) 3) orthogonal array experimental design for three different variables with three different levels. According to the graphs of signal-to-noise ratio obtained with Taguchi design, simultaneous optimum results of all responses were generally determined as high n-pentanol percentage, average ignition advance and average load. According to results, Taguchi design method is an effective method with the aim of defining the impact rates of engine operating parameters and to optimize engine operating variables for best engine performance and emissions.Öğe Nanocrystalline NiTiB reinforced aluminum matrix composites: Synthesis, structural, mechanical and corrosion properties(Sage Publications Ltd, 2024) Pul, Muharrem; Dağ, İlker Emin; Şimşek, Tuncay; Avar, Barış; Chattopadhyay, Arun K.In this study, aluminum composites were developed using a powder metallurgy route by incorporating varying amounts of nanocrystalline NiTiB into the Al2024 alloy. The effects of nanocrystalline NiTiB on the structural, morphological, corrosion, and mechanical properties of the aluminum composites were thoroughly investigated. The results showed that the base alloy and composites with 2% and 4% NiTiB exhibited the highest relative density. The composite with 4% NiTiB achieved the maximum hardness of 87.4 HV. Additionally, the inclusion of nanocrystalline NiTiB significantly improved the compressive strength, corrosion resistance, and wear resistance of the composites. Specifically, the compressive strength increased by approximately 2% with 2% NiTiB and by around 13% with 12% NiTiB. Corrosion resistance was highest in the composite with 4% NiTiB, as confirmed by electrochemical impedance spectroscopy. In the wear-loss study, the wear loss of the composites was found to be reduced by 244% and 457% for those reinforced with 2% and 12% NiTiB, respectively. These findings underscore the potential of nanocrystalline NiTiB to enhance the performance of Al2024 composites in applications demanding superior corrosion resistance, mechanical strength, and wear resistance.Öğe Modeling of a port fuel injection spark-ignition engine with different compression ratios using methanol blends with the response surface methodology(Sage Publications Ltd, 2023) Yeşilyurt, Murat Kadir; Uslu, Samet; Yaman, HayriIn this study, the response surface methodology was applied to verify the optimum compression ratio, methanol percentage, and engine load in order to obtain the best levels of engine response that will occur when using methanol (0, 10, and 20% by vol.) in a spark-ignition engine under different compression ratio (6.0:1, 8.0:1, and 10.0:1) and engine load (8, 10, and 12 kg) conditions. A response surface methodology aided by analysis of variance was created using the three-factor and three-level central composite full design with the results of the experiment. With the created model, optimum methanol percentage, compression ratio, and engine load levels corresponding to the finest brake thermal efficiency, brake-specific fuel consumption, carbon monoxide, carbon dioxide, hydrocarbon, and nitrogen oxide emission levels were determined. According to the optimization results, the optimum methanol percentage, compression ratio, and engine load were found to be 10.5%, 6.0:1, and 12 kg, respectively. Hydrocarbon, nitrogen oxide, carbon monoxide, carbon dioxide, brake thermal efficiency , and brake-specific fuel consumption corresponding to optimum operating conditions were determined as 63.568 ppm, 840.643 ppm, 0.365%, 14.059%, 28.199%, and 0.286 kg/kWh, respectively. To test the reliability of the response surface methodology results, experiments with optimal methanol, compression ratio, and engine load were carried out and compared with the response surface methodology findings. As a result, it can be said that the response surface methodology is a successful application for the optimization of a spark-ignition engine using methanol as an alternative fuel with different engine parameters.
