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Öğe Catalytic reduction of NOx on vanadium exchanged natural zeolite using microwave irradiation(Inderscience Enterprises Ltd, 2012) Emiroğlu, Alaattin Osman; Eldoğan, O.; Teker, Murat; Keskin, Ahmet; Ekmekçi, İsmailZeolite-based catalysts are used commonly to control NOx emissions in selective catalytic reduction applications in lean combustion gasoline engines. In this study, a catalyst was prepared by ion-exchange of vanadium promoted using microwave irradiation, over the clinoptilolite type of natural zeolite to selectively reduce the nitrogen oxides, especially in lean combustion conditions with the HCs in the exhaust gas. According to experimental results, the maximum NOx conversion efficiency reached 28 % at temperature of 287 degrees C and space velocity of 30,000 h(-1).Öğe Catalytic reduction techniques for post-combustion diesel engine exhaust emissions(Sila Science, 2010) Keskin, Ahmet; Emiroğlu, Alaattin OsmanStrict exhaust emission regulations set for limiting the air Pollution caused by motor vehicles have oriented the producers and researchers to investigate new techniques to reduce exhaust emissions. The main pollutants caused by diesel engines are particle matters (PM), nitrogen oxides (NO,), hydrocarbons (HC), and carbon monoxides (CO). Among the preventive actions to keep the emissions caused by motor vehicles at a certain level are enhancing the fuel quality, preventing the pollutant formation in the engine, and developing the post-combustion emission control systems. There are many different technologies used for reducing the amount of pollutants in diesel engine exhausts. In this study, the main post-combustion techniques applied for reducing these pollutants catalytically are being examined.Öğe Deri Endüstrisi Atık Yağlarından Üretilen Biyodizelin Dizel Motor Yanma Performans ve Emisyonlarına Etkisinin İncelenmesi(2022) Inal, Oğulcan Mustafa; Keskin, Ahmet; Emiroğlu, Alaattin Osman; Şen, MehmetBu çalışmada öncelikle deri endüstri atık yağından biyodizel yakıtı üretilmiştir. Daha sonra elde edilen biyodizel, petrol kökenli dizel yakıtı (D100) ile %10 ve %30 oranlarında karıştırılarak sırasıyla elde edilen D90 ve D70 yakıt karışımlarının motor performans, egzoz emisyon ve yanma karakteristikleri analiz edilerek referans motorin yakıtı ile karşılaştırılmıştır. Motor testlerinde, hava soğutmalı, tek silindirli, dört zamanlı ve direk püskürtmeli bir dizel motoru kullanılmıştır. Deneyler motor tam yükte iken farklı motor devirlerinde gerçekleştirilmiştir. Test sonuçları, biyodizel karışımlarının yanma sürelerinin kısa olması sebebiyle maksimum ısı salınımı ile maksimum silindir basıncının motorine kıyasla daha yüksek olduğunu göstermiştir. Biyodizel oranının artmasıyla ısıl verim ve moment değerlerinde azalma gözlenmiştir. Ayrıca, biyodizel karışımları, NOx emisyonlarında önemli bir değişikliğe neden olmazken, is emisyonlarında ise azalmaya neden olmuştur.Öğe The effect of cottonseed oil methyl ester-eurodiesel fuel blends on the combustion, performance and emission characteristics of a direct injection diesel engine(Gazi Universitesi Muhendislik-Mimarlik, 2019) Keskin, AhmetIn this study, the effect of cottonseed oil methyl ester addition in eurodiesel fuel on the combustion, performance, and exhaust emissions of a direct injection single-cylinder diesel engine was investigated. Experiments were carried out at constant engine speed (1500 rpm) at different engine loads.The cottonseed oilmethyl ester blends obtained by mixing 10%, 20%, and 50% of the cottonseed oil methyl ester with eurodiesel fuel (called PYME10, PYME20 and PYME50 respectively) and eurodiesel fuel(PYME0) were usedin the experiments.The obtained fuels were tested in a single-cylinder, four-stroke, air-cooled diesel engine loadable with electric dynamometer, and the results were compared to the reference eurodiesel. The results showed that the ignition delay of the cottonseed oil methyl ester mixtures was longer than the eurodiesel. The maximum cylinder pressure is higher for all engine loads than for the eurodiesel. The heat release rate of cottonseed oil methyl ester mixtures is higher than the eurodiesel. Eurodiesel has the lowest specific fuel consumption and highest thermal efficiency compared to cottonseed oil methyl ester mixtures for all engine loads. PYME10, PYME20 and PYME50 mixtures follow eurodiesel respectively. It has been observed that cottonseed oil methyl ester addition causes a slight increase in NOx emissions while causing a decrease in smoke and CO emissions, HC emissions were observed to low values. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.Öğe The effect of cottonseed oil methyl ester-eurodiesel fuel blends on the combustion, performance and emission characteristics of a direct-injection diesel engine(Gazi Univ, Fac Engineering Architecture, 2019) Keskin, AhmetIn this study, the effect of cottonseed oil methyl ester addition in eurodiesel fuel on the combustion, performance, and exhaust emissions of a direct injection single-cylinder diesel engine was investigated. Experiments were carried out at constant engine speed (1500 rpm) at different engine loads.The cottonseed oilmethyl ester blends obtained by mixing 10%, 20%, and 50% of the cottonseed oil methyl ester with eurodiesel fuel (called PYME10, PYME20 and PYME50 respectively) and eurodiesel fuel(PYME0) were usedin the experiments.The obtained fuels were tested in a single-cylinder, four-stroke, air-cooled diesel engine loadable with electric dynamometer, and the results were compared to the reference eurodiesel. The results showed that the ignition delay of the cottonseed oil methyl ester mixtures was longer than the eurodiesel. The maximum cylinder pressure is higher for all engine loads than for the eurodiesel. The heat release rate of cottonseed oil methyl ester mixtures is higher than the eurodiesel. Eurodiesel has the lowest specific fuel consumption and highest thermal efficiency compared to cottonseed oil methyl ester mixtures for all engine loads. PYME10, PYME20 and PYME50 mixtures follow eurodiesel respectively. It has been observed that cottonseed oil methyl ester addition causes a slight increase in NOx emissions while causing a decrease in smoke and CO emissions, HC emissions were observed to low values.Öğe Effect of ulexite and cashew on the wear and friction characteristics of automotive brake pad(Scibulcom Ltd, 2016) Sugözü, İlker; Mutlu, İbrahim; Keskin, AhmetThe aim of the current research is to investigate as a new automotive friction material using together ulexite and cashew on the brake pad for braking performance. Therefore, newly formulated brake pads have been produced using ulexite and cashew. Tribological properties of the friction materials were obtained using brake test equipment. The variation of friction coefficient, the temperature of friction surface and amount of wear were examined to assess the performance of these samples. In addition, micro-structural characterisations of braking pads were carried out using Scanning Electron Microscopy (SEM). Results showed that the friction materials containing ulexite and cashew have an important effect on friction stability and fade resistance. The strategy proposed in this paper can be considered as alternative friction materials of ulexite, and cashew can be used as friction materials in the brake pads.Öğe The effect of using heat treated ulexite and cashew in automotive friction materials(Carl Hanser Verlag, 2015) Sugözü, İlker; Mutlu, İbrahim; Keskin, AhmetIn this experimental study, the use of heat treated ulexite and cashew as a new material in brake pads was investigated. The change of friction coefficient, the temperature of friction surface and amount of wear were examined to assess the performance of these samples. Additionlly, microstructural characterizations of braking pads were carried out using scanning electron microscopy. The results showed that the heat treated samples containing ulexite and cashew have an important effect on friction stability and fade resistance. It can be concluded that heat treated ulexite and cashew can be used as friction materials in the automotive brake pads.Öğe The effects of porosity in friction performance of brake pad using waste tire dust(Assoc Brasil Polimeros, 2015) Mutlu, İbrahim; Sugözü, İlker; Keskin, AhmetThis research is focused on the effect of porosity on the friction-wear properties of automotive brake pads. Waste Tire Dust (WTD) was used as a new friction material in brake pads. Newly formulated brake pad materials with five different components have been produced by conventional techniques. In the experimental studies, the change of the friction coefficient, the temperature of the friction surface, the specific wear rate, and the hardness, density and porosity were measured. In addition, the micro-structural characterizations of brake pads are determined using Scanning Electron Microscopy (SEM). The mean coefficient of friction, porosity and specific wear are increased due to a WTD rate increases, on the other hand, hardness and density are decreased. As a result, WTD can be considered as an alternative to revalorize this kind of waste products in the brake pads and the amount of porosity of the brake pad affected the friction coefficient and wear behavior of the pad.Öğe Experimental investigation of the effects of turkey rendering fat biodiesel on combustion, performance and exhaust emissions of a diesel engine(Elsevier Sci Ltd, 2018) Emiroğlu, Alaattin Osman; Keskin, Ahmet; Şen, MehmetIn this study, turkey rendering fat biodiesel (TRFB) was produced by two-step reactions (esterification and transesterification). Fatty acid ester content and yield in methyl ester were found 96.7% and 88.5% respectively. TRFB was blended with diesel fuel (DF) at 10%, 20%, and 50% (v/v) proportion to obtain fuel blends named TRFB10, TRFB20 and TRFB50, respectively. The effects of TRFB blends on the combustion, performance and exhaust emissions of a direct injection single cylinder diesel engine were systematically investigated under different engine loads, at the constant engine speed of 2000 rpm. The results show that the maximum cylinder pressure (CPmax) and maximum heat release rate (HRRmax) values of the TRFB blends were higher than those of DF for all engine loads because of the low cetane number of the TRFB and the rapid burning of the fuel accumulated in the combustion chamber during the long ignition delay. It was observed that the DF has a higher exhaust gas temperature than the biodiesel blends at high loads because of the longer combustion duration of the DF. The brake thermal efficiency (BTE) values of the TRFB blends were found to be lower than those of DF at all loads. Since the heating value of the biodiesel is lower than that of DF, it was observed that the brake specific fuel consumption (BSFC) values of TRFB blends are higher compared to those of DF. In addition, TRFB10, TRFB20 and TRFB50 blends reduce smoke opacity approximately 20%, 25% and, 40%, respectively, and cause a slight increase in nitrogen oxide (NOx) emissions.Öğe Experimental studies on biodiesel production from leather industry waste fat and its effect on diesel engine characteristics(Elsevier Sci Ltd, 2020) Keskin, Ahmet; Şen, Mehmet; Emiroğlu, Alaattin OsmanIn this study, biodiesel was produced from the leather industry waste fat (LWFB), which is harmful to the environment and paid for its disposal. The methyl ester yield of the produced biodiesel was found to be 86.8%. LWFB was mixed with petroleum diesel fuel at 10% and 30% ratios and was named LWFB10 and LWFB30, respectively. The impacts of LWFB blends on a single cylinder four stroke cycle direct injection diesel engine operating characteristics were analyzed under different engine loads and speeds. The results showed that the LWFB blends began to be injected earlier than petroleum-based diesel fuel. The ignition delay was almost the same for all test fuels since the cetane number of LWFB is the same as the reference diesel fuel. The combustion duration of LWFB blends were shorter at all engine loads and speeds than diesel fuel. The peak values of cylinder pressure and heat release rate of LWFB blends were almost the same as the diesel fuel. It was noticed that the brake specific fuel consumption values of LWFB blends were higher than the reference diesel fuel at all engine loads and speeds and brake thermal efficiency was inversely proportional to brake specific fuel consumption as expected. It was also found that LWFB blends reduced smoke emissions but did not cause a significant change in NOx emissions.Öğe Friction and wear behaviour of ulexite and cashew in automotive brake pads(Inst Za Kovinske Materiale I In Tehnologie, 2015) Sugözü, İlker; Mutlu, Ibrahim; Keskin, AhmetIn the experimental studies, ulexite and cashew were investigated as new materials in brake pads. A newly formulated brake-pad material with five different ingredients was produced using ulexite. Tribological properties of the friction materials were obtained using the brake-test equipment. The friction and wear characteristics of the samples in contact with a disk made of cast iron were studied. The change in the friction coefficient, the temperature of the friction surface and the amount of the wear were examined to assess the performance of these samples. In addition, microstructural characterizations of the braking pads were carried out using scanning electron microscopy (SEM). The results showed that the friction materials containing ulexite and cashew have an important effect on the friction stability and fade resistance. The strategy proposed in this paper can be considered for the alternative friction materials where ulexite and cashew can be used as friction materials in the brake pads.Öğe Impact of pentanol addition and injection timing on the characteristics of a single-cylinder diesel engine(Amer Chemical Soc, 2019) Şen, Mehmet; Emiroğlu, Alaattin Osman; Keskin, AhmetIn this study, first, the effects of addition of 10% (Pen10), 20% (Pen20), and 30% (Pen30) pentanol on the performance, combustion, and emissions of a diesel engine were investigated. Then, the effect of injection timing for Pen30 fuel was investigated by changing the original injection timing of 20 to 22 and 24 degrees BTDC (before top dead center). The engine tests were performed under different loads at 2400 rpm. The results indicated that, with the advancing of the diesel injection timing and increasing the pentanol ratio in the fuel blends, the ignition delay increased and the start of combustion delayed. The maximum heat release rate and cylinder pressure values of pentanol blends were found to be higher than those of diesel fuel. Both the maximum cylinder pressure and the maximum heat release rate increased with the advancing of the diesel injection timing to 22 and 24 degrees BTDC. Brake-specific fuel consumption value of Pen30 was higher than that of diesel fuel at the original injection timing, and it decreased as the injection timing was advanced to 22 and 24 BTDC as compared to that of the original injection timing. NOx emission decreased with the increasing pentanol fraction. Also, NOx emissions increased significantly at 24 BTDC injection timing but decreased slightly at 22 degrees BTDC injection timing. Smoke emissions of the pentanol blends are lower than those of the diesel fuel under all operating conditions as well as decreased with the advancing injection timing.Öğe Investigation of using natural zeolite in brake pad(2011) Keskin, AhmetBrake pads in automobiles are made of composite materials composed of more than ten different ingredients. The choice of the friction material has an important impact on a vehicle's braking performance. Drivers expect the brake system to stop the automobile under all possible conditions. In the present study, natural zeolite was used as a new material in brake pad. Zeolite has a silica ingredient which gives the pad materials a ceramic like behavior. Zeolite is ground to obtain the dust. Different amount of zeolite is used in the mix of other regular ingredients in brake pad. Newly formulated brake pad material with seven different ingredients has been tested under Friction Assessment and Screening Test (FAST). In this experimental study, the change of friction coefficient, the temperature of friction surface and the amount of wear were measured. In addition, micro-structural characterizations of braking pads were carried out using scanning electron microscopy (SEM).Öğe Pamuk Yağı Biyodizeli-Eurodizel Karışımlarının Tam Yükte Yanma, Performans ve Emisyonlara Etkisinin Deneysel Olarak İncelenmesi(2017) Keskin, AhmetBu çalışmada, pamuk yağı biyodizelinin değişik oranlarda eurodizel yakıtına ilavesinin yanma, motor performansı ve emisyonlar üzerindeki etkisi incelenmiştir. Deneyler tam yükte ve 1500 dev/dak ile 3000 dev/dak arasında 500 dev/dak aralıklarla gerçekleştirilmiştir. Deneylerde eurodizel yakıtına (CB0), % 10, %20 ve %50 pamuk yağı biyodizeli eklenerek (sırasıyla CB10, CB20 ve CB50 olarak isimlendirilen) elde edilen yakıt karışımları kullanılmıştır. Elde edilen bu yakıt karışımları elektrik dinamometresi ile yüklenebilen tek silindirli, dört zamanlı, hava soğutmalı, direk püskürtmeli bir dizel motorunda test edilmiş ve sonuçlar referans eurodizel yakıtı ile karşılaştırılmıştır. Sonuçlar, referans eurodizel yakıtına pamuk yağı biyodizeli ilavesinin tüm devirler için motor gücü ve torkunda çok az düşüşe neden olduğunu göstermektedir. Özgül yakıt tüketiminde ise küçük bir artış gözlenmiştir. Tam yükte tüm devirler için pamuk yağı biyodizeli ilavesiyle birlikte CO, HC ve is emisyonlarının azaldığı, NOxemisyonlarının ise arttığı gözlenmiştir. Pamuk yağı biyodizeli karışımlarının tutuşma gecikmesi, pamuk yağı biyodizelinin düşük setan sayısı nedeniyle eurodizelden daha uzun olduğu gözlenmiştir. Ateşleme gecikmesi daha uzun olduğundan, ısı salınım hızı çok hızlı bir şekilde artmış ve yanma süresi kısalmıştır. Yakıtların maksimum yanma basınçları önemli bir değişiklik göstermemiştir.Öğe Production of biodiesel from broiler chicken rendering fat and ınvestigation of its effects on combustion, performance, and emissions of a diesel engine(Amer Chemical Soc, 2018) Şen, Mehmet; Emiroğlu, Alaattin Osman; Keskin, AhmetThis study is interested in two-step biodiesel production meeting compatibility requirements in the biodiesel fuel standards by use of broiler chicken rendering fat extracted from a slaughterhouse as feedstock. Broiler rendering fat biodiesel (BRFB) was mixed with petroleum-based diesel fuel (DF) at the ratios of 10%, 20%, and 50%, respectively, so that the fuel blends named BRFB10, BRFB20, and BRFB50 were obtained successfully. The effects of BRFB blends on the performance, exhaust emissions, and combustion behaviors of single cylinder diesel engine with a direct injection were systematically investigated at different engine speeds in the case of full engine load. The values of CPmax and HRRmax of BRFB blends were observed to be higher as compared to those of DF. This is attributed to both the low cetane number of BRFB and rapid combustion of accumulated fuel in the combustion chamber throughout the long ID. The torque values of BRFB blends were observed to be higher as compared to those of DF. Moreover, the NOx emissions were obtained to enhance slightly whereas the quantities of smoke opacity, CO, HC, and CO2 emissions were noted to decrease by using the BRFB blends. The engine performance and emission test results showed that the ideal fuel mixture ratio is achieved with the BRFB20 blend.Öğe Two-step methyl ester production and characterization from the broiler rendering fat: the optimization of the first step(Pergamon-Elsevier Science Ltd, 2018) Keskin, AhmetIn this study, broiler rendering fat obtained from a slaughterhouse was used to produce methyl ester. The acid value of the broiler rendering fat was 5.2 mg KOH g(-1). Therefore, it was needed to perform two-step treatment to broiler rendering fat. For this purpose, sulfuric acid was used as a catalyst and methanol was used as alcohol for the first treatment reactions. The variables affecting the free fatty acid level including the ratio of alcohol, catalyst amount, and reaction time were investigated to determine the best strategy for the first step process. After reducing the free fatty acid level of the broiler rendering fat to less than 1%, the transesterification reaction was completed with the alkaline catalyst. Potassium hydroxide was used as catalyst and methanol was used as alcohol for transesterification reaction. The measured fuel properties of the broiler rendering fat methyl ester (BRFME) were compared to EN 14214:2012 + A1:2014 and ASTM D6751-15 biodiesel standards. The BRFME meet ASTM D6751-15 biodiesel standard. Also, the BRFME meets EN 14214:2012 + A1:2014 biodiesel standard except for oxidation stability. According to the results, the oxidation stability property of the BRFME should be improved and should be investigated in detail. (C) 2018 Elsevier Ltd. All rights reserved.Öğe The use of clinoptilolite as a catalyst in the gasoline engines(Sila Science, 2012) Keskin, Ahmet; Ekmekçi, İsmail; Kolip, AhmetPractical aplication of lean burn gasoline engines on cars has been increasing in recent years. The lean burn gasoline engine is operated under high air/fuel ratio to improve fuel economy. However reduction of emissions from the exhaust under oxygen rich condition is very difficult to achieve. For this purpose, the studies on zeolite catalysts are increasing. In this study, natural zeolite of clinoptilolite type was prepared for use as a catalyst in gasoline engines. 9245 ppm (about 0.93%) copper were deposited on zeolite by various chemical treatments. Ion-exchanged zeolite catalyst was tested at an SI engine. Maximum carbonmonoxide conversion efficiency achieved was 39.5% at 2300 rpm. Maximum hydrocarbon conversion efficiency achieved was 31.5% at 1500 rpm.Öğe Wear behavior of rice straw powder in automotive brake pads(WALTER DE GRUYTER GMBH, 2021) Mutlu, İbrahim; Keskin, AhmetThis paper investigates the use of rice straw powder in a brake pad as a substitute for asbestos which is a carcinogenic with detrimental effects on health. Rice straw powder was used as a novel material in a brake pad. Rice straw powder has a silica content which gives the pad a c eramic-like action. Rice straws were ground after drying in order to produce the powder. Five laboratory varieties were produced, altering the rice straw powder ingredients from 5, 10, 15, 20 and 25 wt.-%, respectively added to other abrasive materials, binder, friction modifiers, solid lubricant, and filler material utilizing conventional techniques. In this study, the friction surface temperature, the wear amount, and the change of the friction coefficient were determined. Additionally, the microstructure specifications of the brake pads were determined using scanning electron microscopy. Experimental results showed that a 15 wt.-% fraction of rice straw powder yielded better wear and thermo-mechanical features as compared with other combinations. The microstructure shows a uniform distribution of the rice straw powder in the matrix. Hence, rice straw powder can be a possible candidate friction material for producing non-asbestos new brake pad without any detrimental impact.
