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Öğe BIODIESEL PRODUCTION FROM ANCHOVY (Engraulis encrasicolus) OIL AND ITS EFFECT ON DIESEL ENGINE PERFORMANCE AND EMISSIONS(Gazi Univ, Fac Engineering Architecture, 2016) Sekmen, Yakup; Sen, SedatThe interest in biodiesel as an alternative fuel increases due to increasing awareness of the depletion of fossil fuel resources, concerns about the environment, recycling of waste products, and restrictions imposed on exhaust emissions. Biodiesel can be produced from vegetable oils, animal fat or waste cooking oil. Main advantages of biodiesel may be summarized as; biodegradable, sulphur-free, non-poisonous, consisting oxygen and high cetane number and lubricity. In this study, in order to identify performance and exhaust emission characteristics of a four-stroke, single cylinder diesel engine were operated with anchovy oil based biodiesel, diesel fuel and their blends (volumetrically 5, 20, 50 and 100%) at full load and various engine revolutions. We have noted that, increasing the proportion of the biodiesel in the mixture with respect to petroleum based diesel fuel, the specific fuel consumption increases 5-12%, while engine torque decrease %2-6. The emission analyses show that the CO, HC and smoke emission decrease while NOx emissions increase.Öğe THE EFFECT OF DIFFERENT COOLING UNIT CONFIGURATIONS AND COOLING TEMPERATURES ON GLASS TEMPERING QUALITY(Begell House Inc, 2016) Akcay, Mehmet; Yazici, Hilmi; Golcu, Mustafa; Sekmen, YakupIn this study, an auto glass tempering process was conducted in different cooling unit configurations and cooling temperatures, and the changes in the sudden cooling time and the number of broken glass particles of the tempered glass plates were examined. Six-millimeter-thick glass plates were heated up to T-h = 680 degrees C and then suddenly cooled at four different cooling temperatures (T-c = 70, 250, 300, and 400 degrees C). In the sudden cooling process, the rate of the distance between nozzle axes to nozzle diameter (S/D) was taken as 4 <= S/D <= 8, the rate of the distance to the glass surface to nozzle diameter (H/D) was taken as 2 <= H/D <= 8, and the Reynolds number was kept constant at Re = 20,000. According to the results revealed in the study, as the S/D and H/D rates increased, the cooling time increased and the number of particles decreased. It was found that the sudden cooling time and the number of particles changed in inverse proportion to the cooling temperature. When the cooling temperature was decreased from 250 degrees C to 70 degrees C for each cooling unit configuration (S/D = 4, 6, and 8), there was a high increase in the cooling time, whereas the increase in the number of particles was quite small.Öğe THE EFFECT OF HEATING AND COOLING TEMPERATURES ON RAPID COOLING TIME AND PARTICLE NUMBER IN AUTO GLASS TEMPERING PROCESS(Gazi Univ, Fac Engineering Architecture, 2014) Akcay, Mehmet; Sekmen, Yakup; Golcu, MustafaIn terms of tempering quality, controlling and applying of heating and rapid cooling processes are very important in the glass tempering process. In this study, auto glass tempering process was implemented in the prototype glass tempering unit which was designed specifically, exchange of cooling time and particle number was investigated according to heating and cooling temperatures. Without going out of standards, it was aimed to determine the tempering conditions which are needed to keep the energy consumption at minimum in glass tempering process. Glasses that were heated to three different average surface temperatures (T-h=620, 650 and 680 degrees C) were rapidly cooled to four different average surface temperatures (T-c=70, 250, 300 and 400 degrees C). The distance between the nozzle and the glass surface is H, the distance between the nozzle axes is S. It was considered 2 <= H/D <= 8, S/D=4 and Reynolds number Re=20000. According to the study; while higher heating temperature of the glass resulted in higher particle number, higher cooling temperature resulted in lower particle number. Although there are quite high differences between the sudden cooling times for cooling temperatures T-c=70, 250 and 300 degrees C, particle numbers are close to each other.Öğe The effects of ethanol-unleaded gasoline blends on engine performance and exhaust emissions in a spark-ignition engine(Pergamon-Elsevier Science Ltd, 2009) Koc, Mustafa; Sekmen, Yakup; Topgul, Tolga; Yucesu, Hueseyin SerdarAlcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline-ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NOx) and hydrocarbon (HC) emissions. It was also found that ethanol-gasoline blends allow increasing compression ratio (CR) without knock occurrence. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Effects of Soybean Oil Methyl Ester on Diesel Engine Performance and Exhaust Emissions(Gazi Univ, 2008) Sekmen, Yakup; Aktas, AbdurrazzakBiodiesel is an alternative fuel for diesel engine that can be produced by chemically reacting a vegetable oils, waste cooking oils, and animal fats with an alcohol to form alkyl esters. It is an oxygenated, sulfur-free, non-toxic, biodegradable, and renewable fuel with a higher cetan number and lubricity and can be used as pure or blends without any significant modification in diesel engines. In this study, the effects of using soybean oil methyl ester as a fuel in a direct injected diesel engine on the performance and exhaust emissions were investigated experimentally. Experimental study was performed using diesel fuel no. 2 and soybean oil methyl ester at full load and engine speeds ranging from 1200 to 2400 rpm. The results showed that the biodiesel produced lower effective power and higher specific fuel consumption than diesel fuel due to lower heating value of soybean oil methyl ester. In addition, CO, HC, NOx and smoke emissions from biodiesel were lower than that of diesel fuel no.2.Öğe EXPERIMENTAL INVESTIGATION OF COOLING WITH MULTIPLE AIR JETS ON AUTO GLASS TEMPERING(Gazi Univ, Fac Engineering Architecture, 2012) Golcu, Mustafa; Yazici, Hilmi; Akcay, Mehmet; Koseoglu, Mehmet Fevzi; Sekmen, YakupImpinging air jets due to their high heat and mass transfer capacity are widely used for heating, cooling and drying applications in nowadays industry. This study aims to investigate auto glass tempering project. Heat transfer characteristics of heated glass plates during their cooling with mutually placed circular air jets have been experimentally investigated. 4 mm thick glass samples were used in the experiments. Cooling process has been performed with 16 mutually placed nozzles of 8 mm in diameter and 80 mm in length in staggered arrangement. Nozzles were made of seamless aluminum pipes. Experiments have been conducted for dimensionless jet to plate distances (H/D) between 1 and 10, and S/D ratios which represents dimensionless distance between nozzle axis, for 2 <= S/D <= 10. Reynolds number has been fixed at 30000 for all experiments. According to the results the highest average Nusselt number (Nu(m)) has been achieved for S/D=2 and H/D=4 with a value 123.3 and the lowest average Nusselt number was obtained for S/D= 10 and H/D= 10 with a value 58.6.Öğe Hamsi (engraulis encrasicolus) yağindan biyodizel üretimi ve dizel motor performans ve emisyonlarina etkisi(2016) Sekmen, Yakup; Şen, SedatPetrol kaynaklarının sınırlı olması, çevre ile ilgili endişeler, atık ürünlerin değerlendirilmesi ve kirletici emisyonlara getirilen sınırlamalar alternatif yakıt olan biyodizele olan ilgiyi artırmaktadır. Biyodizel, bitkisel, hayvansal ve atık yağlardan üretilebilen; oksijen içerikli, sülfür içermeyen, zehirleyici olmayan, bozunabilir, yüksek setan sayılı ve yağlayıcılık özelliği daha iyi yenilenebilir alternatif bir dizel yakıtıdır. Bu çalışmada, hamsi yağından üretilmiş biyodizel ve dizel yakıtı ile karışımlarının (hacimsel olarak %5, 20, 50 ve 100), dört zamanlı, tek silindirli bir dizel motorda performans ve egzoz emisyonlarına etkileri tam yük ve değişik devirlerde test edilmiştir. Deneyler sonucunda, karışımdaki biyodizel oranı arttıkça dizel yakıta göre özgül yakıt tüketiminde %5-12 artış, motor momentinde ise %2-6 azalma belirlenmiştir. Emisyon testleri sonucunda, CO, HC ve is emisyonlarında azalma, NOx emisyonlarında artış belirlenmiştir.Öğe Mathematical modeling of a si engine cycle with actual air-fuel cycle analyses(2007) Sekmen, Perihan; Sekmen, YakupThe performance of an engine whose basic design parameters are known can be predicted with the assistance of simulation programs into the less time, cost and near value of actual. However, inadequate areas of the current model can guide future research because the effects of design variables on engine performance can be determined before. In this study, thermodynamic cycle and performance analyses were simulated for various engine speeds (1800, 2400 ve 3600 1/min) and various excess air coefficients (EAC) (0.95-1.05) to crank shaft angle (CA) with 1 degree increment at full load and 8:1 constant compression ratio (CR) of a SI engine with four stroke, single cylinder and natural aspirated. Brake mean effective pressure, power, thermal efficiency, specific fuel consumption (sfc), etc engine performance parameters were calculated; the values of peak cylinder pressures and temperatures and positions of them were determined by the present program. Variations of these parameters with crank angle, engine speed and excess air coefficient were presented graphically. The calculated results show good agreement with literature. Simulation program is usable to set for varies load, compression ratios, and engine sizes.Öğe Oto cam temperleme deney düzeneğinin kurulumu ve ısıtma-soğutma sürelerinin tayini için örnek bir uygulama(2011) Yazıcı, Hilmi; Akçay, Mehmet; Gölcü, Mustafa; Köseoğlu, Mehmet Fevzi; Sekmen, YakupOto cam temperleme işleminde, kalite ve üretim hızını etkileyen en önemli parametrelerden biri ısıtma diğeri ise ani soğutma işlemidir. Temperleme işleminde soğutma için harcanan enerji, ısıtma için harcanan enerjiden fazladır. Camın temper kalitesini etkileyen çok sayıda faktör olmakla birlikte genel olarak; camın fırında kalış süresi, ani soğutma süresi, H/D, S/D ve Re sayısı şeklinde sıralanabilir. Bu çalışmada, oto cam temperleme deney düzeneği kurularak ölçüm ve kontrol sistemleri hakkında bilgi verilmiştir. Ayrıca, farklı H/D oranlarında ani soğutma işleminde zamana bağlı olarak cam yüzey sıcaklığının değişimi elde edilmiştir. Deneylerde 5x5 cm ebatlarında, 4 mm kalınlığında cam kullanılmıştır. Ani soğutma işleminde kullanılan nozul çapı 8 mm olup, Re=30000 sabit tutulmuştur. Yapılan deneyler sonucunda, H/D=2 oranındaki soğutma süresinin H/D=10 oranındaki soğutma süresinden % 29,4 daha kısa olduğu görülmüştür.Öğe Oto cam temperleme işleminde isitma ve soğutma sicakliklarinin ani soğutma süresine ve parçacik sayisina etkisi(2014) Akçay, Mehmet; Sekmen, Yakup; Gölcü, MustafaCam temperleme işleminde, ısıtma ve ani soğutma aşamalarının hassas bir şekilde kontrol edilmesi ve uygulanması, temper kalitesi açısından oldukça önemlidir. Bu çalışmada; özel olarak tasarlanmış prototip cam temperleme ünitesinde oto cam temperleme işlemi gerçekleştirilmiş, ısıtma ve soğutma sıcaklıklarına göre ani soğutma süresi ve parçacık sayısındaki değişim incelenmiştir. Standartların dışına çıkılmadan, cam temperleme sürecindeki enerji tüketimini minimum seviyede tutulabilmek için uygulanması gereken temperleme şartlarının belirlenmesi amaçlanmıştır. Üç farklı ortalama yüzey sıcaklığına (Th=620, 650 ve 680°C) kadar ısıtılan camlar, daha sonra dört farklı ortalama yüzey sıcaklığına (Tc=70, 250, 300 ve 400°C) düşünceye kadar ani olarak soğutulmuştur. Nozul ile cam yüzeyi arasındaki mesafe H, nozul eksenleri arasındaki mesafe S olmak üzere; 2?H/D?8, S/D=4 ve Reynolds sayısı Re=20000 alınmıştır. Yapılan çalışmaya göre; camın ısıtma sıcaklığının yüksek olması, parçacık sayısının da yüksek olmasına neden olurken, soğutma sıcaklığının yüksek olması ise parçacık sayısının düşük olmasına neden olmuştur. Soğutma sıcaklıkları Tc=70, 250 ve 300°C için ani soğutma süreleri arasında oldukça yüksek bir fark olmasına rağmen, parçacık sayıları arasındaki farkın düşük olduğu görülmüştür.Öğe Soya yağı metil esterinin dizel motor performans ve egzoz emisyonlarına etkileri(2008) Sekmen, Yakup; Aktaş, AbdurrazzakBiyodizel, bitkisel yağlar, atık kızartma yağları ve hayvansal yağların alkil esterler oluşturmak üzere bir alkol ile reaksiyona sokulması ile üretilebilen; oksijen içerikli, sülfür içermeyen, zehirleyici olmayan, bozunabilir, yüksek setan sayılı ve yağlayıcılık özellikli yenilenebilir alternatif bir dizel yakıtıdır ve dizel motorlarda önemli herhangi bir değişiklik yapılmadan saf veya karışım halinde kullanılabilmektedir. Bu çalışmada, direkt enjeksiyonlu bir dizel motorda yakıt olarak soya yağı metil esteri kullanılmasının performans ve egzoz emisyonlarına etkileri deneysel olarak araştırılmıştır. Deneysel çalışma 1200-2400 d/dak hız aralığında ve tam yükte dizel yakıt no.2 ve soya yağı metil esteri kullanılarak yapılmıştır. Biyodizelin ısıl değeri dizel yakıtınkinden düşük olduğundan motor gücünde azalma, özgül yakıt tüketiminde artış belirlenmiştir. Ayrıca, biyodizel ile çalışmada, CO, HC, NOx ve duman emisyonlarında azalma belirlenmiştir.
