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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 Properties and emission indicators of biodiesel fuels obtained from waste oils from the Turkish industry(Elsevier, 2014-03-14) Altun, Şehmus; Lapuerta, MagínThree waste oils from traditional manufacturing industries in Turkey, such as leather fat, obtained as a by-product in the leather industry, waste anchovy fish oil, derived from the fish-processing industry, and waste frying cottonseed oil from food industry, have been evaluated as alternative raw materials for biodiesel production, with potentially low life-cycle greenhouse emissions. Measured properties such as heating value, density, viscosity, flash point, acidity and cold flow properties, showed that the obtained biodiesel fuels fulfilled both the European and American quality standards and could be used to partially replace petroleum diesel in automotive engines. From gas chromatography analysis, detailed fatty acid profile was obtained, which permitted the application of group contribution methods for the estimation of thermodynamic properties (critical parameters, acentric factor) and thermochemical properties (enthalpies of vaporization and formation). This information was useful to calculate some indicators related to the most important diesel engine emissions, such as soot (main component of particulate matter) and nitric oxide emissions. Soot indicators reveal significant reduction potential with respect to fossil diesel fuels, and, among the studied biodiesel fuels, soot emissions would be lowest for the most saturated and shortest carbon-chain length biodiesel fuel. Adiabatic flame temperature, selected as the main nitric oxide emission indicator, shows small differences among the studied biofuels. Both the properties and emission indicators of the biodiesel fuels studied are within the typical ranges of other conventional biodiesel fuels.Öğe Improved combustion of asphaltite coals in a rotating head combustor with various air supply arrangements(ACS Publications, 2014-04-16) Altun, Şehmus; Öner, CengizWhen burned in conventional stokers, coals with high swelling properties such as asphaltites make coke blocks (coking). The plastic layer formed on them prevents air from diffusing into coal; hence, the air provided for swollen coal to burn becomes insufficient. This problem can partially be resolved by shaking the flame bed automatically or by mixing the burning coals manually in order to provide continuous air for the surface of the unburned coal. Therefore, in this study, a coal combustion system with the rotating head was manufactured for burning effectively Turkish coking coals characterized by high sulfur and ash content in agitation conditions with air supply arrangements. This type of coals known as asphaltite, abundantly found in southeastern Anatolia coal basin in Turkey, were burned in the rotating head combustor in order to investigate the effect of operating parameters, such as excess air ratio, coal particle size and feeding speed, air delivery type, addition of flange, bed slope, and rotation speed on the combustion efficiency and temperature distribution on the head. Experimental results showed that both the rotating of combustion chamber and additional air supply, which was blown out with pressure from the air delivery holes, reduced the negative impact of ash on the combustion efficiency, mainly due to the coal getting in touch with air better. It was possible to increase the peak combustion efficiency over 80% by both improving the air supply and agitation of coalbed preventing coking during combustion. As a result, this system could be highly recommended to burn the coals with high swelling properties like asphaltite at a high efficiency.Öğe 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 Investigation of the effect of barium-based additive on smoke and NOx emissions of a diesel engine fueled with conventional and biodiesel fuels(SpringerLink, 2020-06-13) Altun, Şehmus; Arca Batı, ZülalNowadays, increasing energy demand and environmental and air pollution issues have spread the use of alternative fuels such as biodiesel in diesel engines. While the advantages of biodiesel that are comparable to petroleum-based diesel fuels and low unburned HC, carbon monoxide and smoke (soot) emissions make the use of this fuel environmentally signifcant; high NOx emissions are still a problem to be solved. The formation of decreased smoke reducing radiative heat transfer from combustion chamber in biodiesel engines and increase in formation of NOx due to rise in fame temperature are among the reasons reported for high NOx in the literature. In this study, in a diesel engine using biodiesel, soot emissions produced by petroleum diesel fuel were reduced to biodiesel level by using metallic additive (Ba), and NOx emissions were compared. When the amount of Ba in the fuel was increased, there was a signifcant decrease in the smoke emissions, but in this case, NOx emissions decreased slightly, while they were expected to increase. When NOx emissions of diesel and biodiesel were compared for the same or similar smoke emissions, it was seen that high NOx emissions were achieved with biodiesel. As a result, although Ba additive reduced smoke emissions, it was seen that its efect on NOx formation was not very clear.Öğe Effect of the degree of unsaturation of biodiesel fuels on the exhaust emissions of a diesel power generator(Elsevier, 2013-09-25) Altun, ŞehmusIn this work, three biodiesel fuels with iodine numbers ranging from 59 to 185 were tested in a direct-injection diesel engine powered generator set at constant speed of 1500 rpm under variable load conditions to investigate the effect of the degree of unsaturation of biodiesel fuels, which are quantified by the iodine number, on the performance and exhaust emissions of a diesel engine. The increase in unsaturation involved a decrease in cetane number, and therefore, allowed for the maximization of the effect of the cetane number, while other properties, such as oxygen content, heating value, and viscosity, varied within a small range. Experimental results showed that biodiesel fuels resulted in lower emissions of nitrogen oxides, carbon monoxide, and smoke opacity, with some increase in emissions of unburned hydrocarbons. With their low energy content, neat biodiesel fuels resulted in an increase in fuel consumption compared to the conventional diesel fuel (ultra-low sulphur diesel). The degree of unsaturation of biodiesel fuels had effects on engine emissions via its effect on the cetane number and adiabatic flame temperature while engine performance was not significantly affected by the type of biodiesel fuel or its degree of unsaturation. The biodiesel having lowest iodine number had highest cetane number, and lowest density and adiabatic flame temperature, which was good to reduce NOx emissions, as it agreed with experimental results. Additionally, more unsaturated biodiesel fuels showed higher NOx emissions, smoke opacity, and lower HC emissions. It can be said that cetane number and adiabatic flame temperature are responsible for such results.Öğe Flue gas emissions from the burning of asphaltite and lignite in a rotating head combustor with secondary air delivery(ACS Publications, 2014) Altun, Şehmus; Öner, CengizIn this work, a rotating head combustor, which has been designed for burning the coking coals effectively, was deployed to burn a range of coals available in Turkey under agitation conditions with secondary air delivery. The coals were lignite (Tunçbilek, Turkey) and asphaltite with high swelling property known as coking coal (Şırnak, Turkey). The performance was investigated by determining the temperature distribution on the head, combustion efficiency, and the amount of unburned substances (such as C) in the ash, and flue gas emissions of O2, CO, CO2, SO2, and NOx were measured during the experiments. The effect of operating conditions such as excess air ratio (EAR) and coal feeding rate was also investigated. The temperature distribution on the head was found to be high in the case of using the secondary air delivery and combustion efficiency was above 80% at the EAR of 1.3 and coal feeding rate of 9 kg/h when asphaltite was used as the fuel in the rotating head combustor. The comparison between asphaltite and lignite could lead to the conclusion that asphaltite provides slightly higher efficiency than lignite, and the difference is very small at the EAR of 1.3. When flue gas emissions are compared, it is seen that CO and SO2 emissions from asphaltite combustion are higher while CO2 and NOx emissions are lower than those derived from lignite combustion. For the combustion of both fuels, secondary air sent to the bed surface had a noticeable influence on combustion and emission characteristics via its effect on the combustion of volatility products and released gases from the bed surface. However, it should be more for lignite combustion in order to get better performance.Öğe Developing correlations by extreme learning machine for calculating higher heating values of waste frying oils from their physical properties(Springer Nature, 2017-11-01) Altun, Şehmus; Ertuğrul, Ömer FarukIn this study, a novel approach was proposed based on extreme learning machine (ELM) for developing correlations in order to calculate higher heating values (HHVs, kj/kg) of waste frying oils from their physical properties such as density (ρ, kg/m 3 ) and kinematic viscosity (v, mm 2 /s) values. These values can easily be determined by using laboratory equipment. For developing the correlations, an experimental dataset from the literature covering 35 samples was collected to be employed in the training and validation steps. The obtained optimum parameters of artificial neural network in the training stage by ELM were employed to develop new correlations. The HHVs calculated by using density-based correlation (HHV = 50823.183 − 12.34095ρ) showed the mean absolute and relative errors of 145.8048 kJ/kg and 0.3695 %, respectively. In the case of the viscosity-based correlation (HHV = 40172.85 − 17.93615v), they were found as 129.04 kJ/kg and 0.327 %, respectively. Additionally, new correlations were performed better than those available in the literature and those obtained by other machine learning methods; therefore, it is highly suggested that the proposed approach can be used for developing new correlations.Öğe Gaseous emission comparison of a compression-ignition engine fueled with different biodiesels(Islamic Azad University of Research and Technology, 2012-12-14) Altun, Şehmus; Öner, CengizIn this study, it was performed a comparison of the performance and emissions of two methyl ester fuels: one obtained from animal fat and the other from crude canola oil, in a compression-ignition engine against diesel fuel. The experimental results compared with diesel fuel showed that significant reductions could be obtained by biodiesel derived from animal fat in carbon monoxide and oxides of nitrogen emissions. Carbon dioxide emissions showed a trend of decreasing with the biodiesel fuels. An increase in brake specific fuel consumption was observed for different biodiesel fuels when compared with diesel fuel. It was concluded that animal tallow methyl ester performed better than canola oil methyl ester, whereas slightly higher brake torque is observed with canola oil methyl ester.
