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Öğe Exhaust emissions from a spark-ıgnition engine operating on Iso-propanol and unleaded gasoline blends(Technology, 2010) Altun, Şehmus; Öner, Cengiz; Fırat, MüjdatIn this study, the effect of blends of iso-propanol and unleaded gasoline on exhaust emissions of a sparkignition engine were experimentally investigated. Exhaust emission tests were conducted on a four-stroke, four cylinder and direct injection spark-ignition engine. The engine tests were performed at three-fourth throttle opening position at four various speeds in the range of 1000-4000 rpm with 1000 rpm period. The experimental results compared with unleaded gasoline showed that emissions of carbon monoxide (CO) and hydrocarbon (HC) decreased with iso-propanol-unleaded gasoline blends while carbon dioxide (CO2) emission increased.Öğe Effect of a mixture of biodiesel diesel ethanol as fuel on diesel engine emissions(Electronic Journal of Vehicle Technologies, 2011) Altun, Şehmus; Yaşar, Fevzi; Öner, Cengiz; Fırat, MüjdatÖğe Using gasoline-like fuel obtained from waste automobile tires in a spark-ignited engine(Taylor & Francis, 2014-05-01) Altun, Şehmus; Varol, Yasin; Öztop, Hakan Fehmi; Fırat, MüjdatAn experimental study on performance and exhaust emission of a spark-ignited engine fueled by gasoline-like fuel obtained from waste automobile tires using the prolysis process was performed in this study. Gasoline-like fuel has a higher octane number than unleaded gasoline; however, it has higher in viscosity in comparison to unleaded gasoline, which limited the use of gasoline-like fuel in neat form. Therefore, gasoline-like fuel was blended with unleaded gasoline from 0% to 100% with an increment of 10%, volumetrically. Obtained blends were then used in a spark-ignited engine. It was observed that the test engine was normally run up to blended fuel containing gasoline-like fuel of 60%. It is concluded that gasoline-like fuel can be partially substituted for the gasoline fuel up to 60% in blended form in terms of performance parameters and emissions without any engine modification.Öğe Numerical investigation of the effect of spray cone angle on spraydynamics of a DI diesel engine(Gazi Üniversitesi, 2019) Altun, Şehmus; Fırat, Müjdat; Varol, YasinIn this study, the effect of spray cone angle on spray dynamics of DI diesel engine equipped with common-rail fuel injection system is investigated numerically using a multidimensional Computational Fluid Dynamics (CFD) simulation tool, AVL-FIRE code. The in-cylinder spray dynamics such as spray and vapor penetration, droplet diameter, and Turbulence Kinetic Energy (TKE) as well as droplet distribution are investigated for different spray cone angles changed from 120o to 160o . The simulation results indicate that the selected spray cone angle actually changed all spray dynamics. Spray and vapor penetration and droplet diameter are affected with increasing spray cone angle. In-cylinder air motion was later studied for a number of spray cone angles, which identified a slightly changed in-cylinder Turbulence Kinetic Energy (TKE) around the compression top dead center (TDC). Additionally, it was determined that spray cone angles have considerable affects the fuel spray dynamics. Both liquid and vapor penetration are directly linked to the spray cone angleÖğe Effects of isopropanol-butanol-ethanol (IBE) on combustion characteristics of a RCCI engine fueled by biodiesel fuel(Journals & Books, 2021-10) Altun, Şehmus; Okcu, Mutlu; Varol, Yasin; Fırat, MüjdatThe reactivity controlled compression ignition (RCCI) strategy using fuels with different reactivity’s has attracted attention due to its high thermal efficiency as well as very low NOx and PM emissions in comparison to conventional combustion. As previous studies have shown that the type and amount of low reactivity fuel have a significant contribution to the in-cylinder reactivity, thus RCCI combustion, in this study, Iso-Propanol-Butanol-Ethanol (IBE), which has comparable characteristics to n-butanol and ethanol, is employed as low reactivity fuel (LRF) in a RCCI engine fueled by petroleum based EN590 fuel and commercial biodiesel. The IBE mixture was in volumetric ratios of 3:6:1 as in the fermentation process of butanol, that is to say; 30% Iso-Propanol, 60% Butanol and 10% Ethanol. In each experimental condition, keeping the total energy of the fuel supplied to the engine in conventional combustion mode for each cycle as constant, the premixed ratio (Rp) in case RCCI combustion was applied as 0%, 15%, 30%, 45% and 60% (the amount of LRF in energy basis) over this energy amount. The effect of premixed ratio of IBE on combustion characteristics were investigated in a single-cylinder RCCI engine under different loads with using both petroleum diesel and biodiesel as high-reactivity fuels (HRF), respectively. According to experimental results, a higher in-cylinder pressure was measured by using diesel in both conventional and RCCI mode compared to the use of biodiesel. Considering the peak in-cylinder pressure and rate of heat release, the premixed ratio (Rp) of up to 45% was found as optimum for all loads while it was up to 30%Rp for the NOx emissions. In addition, the biodiesel-fueled RCCI engine produced the lowest smoke opacity in all loads and it gradually decreased by up to 97% with the application of the RCCI strategy. Furthermore, the results showed that a simultaneous reduction in NOx and smoke opacity could be obtained under 60% load and up to 30% Rp with a marginal increase in unburned HC emissions.Öğe A numerical study of no and soot formation in an automotive diesel engine fueled with diesel-biodiesel blends(Uluslararası Yakıtlar, Yanma ve Yangın Dergisi, 2016-12-01) Altun, Şehmus; Fırat, Müjdat; Varol, YasinIn this paper, engine simulation results are presented to give information on the effect of diesel-biodiesel blends on combustion and emission characteristics of a multiple injection automotive diesel engine. Numerical Study was performed in Computational Fluid Dynamics (CFD) simulation software AVL-FIRE coupled to AVL-ESE Diesel. An improved version of the ECFM-3Z combustion model has been applied coupled with advanced Zeldovich and Kinetic models for NO and soot formation, respectively. The simulation results were validated against the experimental results by comparing the in-cylinder pressure and heat release rate for diesel-biodiesel blends at 2000 rpm under 100% load, and a maximum variation of 5% deviation on the peak cylinder pressure and 4% for heat release rate was found. Simulation results revealed that with the increase of biodiesel amount in the fuel, CO and soot emissions were reduced while NO increased at the simulated operating conditions. In addition, in-cylinder NO and Soot mass fractions were found to be high at 20 and 10 CA ATDC, respectively.
