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Büyümekte olan küresel ekonomi, sanayileşme, nüfus artışı, kentleşme ve gelişmiş enerji erişimi ihtiyacı küresel enerji talebini hızla arttırmaktadır. Dünya enerji pazarının geleceği üzerine yürütülen tahminlerde 50 yıllık yakın gelecekte enerji talebinin karşılanmasında fosil yakıtların günümüzde olduğu gibi en yüksek orana sahip kaynak olacağı öngörülmektedir. Ancak fosil yakıtlardan enerji üretimi hava kirliliğinin ve küresel ısınmanın başlıca sebebidir. Fosil yakıtlar kullanılarak enerji üretimi sağlayan makinelerin daha düşük oranlarda salım yapmasının sağlanabilmesi çevreye verilen zararların indirgenebilmesi için oldukça önemlidir. Fosil yakıtlar kullanılarak enerji üretimi yapan dizel motorlar yüksek termal verimi sebebiyle enerji üretiminde sıklıkla tercih edilmektedir. Dizel motorların çalışması sırasında ortaya çıkan hava kirletici maddelerin salım oranlarının azaltılması için uygulanabilecek çeşitli yöntemler bulunmaktadır. Bu yöntemler; motorun çalışma parametreleri üzerinde yapılan değişikliklerle egzoz salımlarının azaltılması, egzoz gazı resirkülasyonu sistemleri kullanılarak egzoz salımlarının azaltılması ve egzoz gazı son işleme sistemleri kullanılarak oluşan hava kirleticilerin atmosfere salınmadan önce ortadan kaldırılması veya çevreye daha az zararlı hale getirilmesi olarak sıralanabilir. Dizel motorlarda silindir içerisine yakıt püskürtme ve emme havası gönderimi stratejilerinde yapılan değişikliklerle egzoz salımlarının kontrolü mümkün olmaktadır. Bu tezde farklı yakıtların kullanımında yakıt püskürtme stratejisinde yapılabilecek değişikliklerden püskürtme basıncı ve püskürtme zamanlamasının değiştirilmesinin egzoz salımları ve motor performansı üzerindeki etkileri araştırılmıştır. Bu amaçla, yakıt olarak motorin, denizcilik motorini ve denizcilik motorini içeriğine yüzde 5 oranda artık denizcilik yakıtı eklenerek hazırlanmış yakıt karışımı kullanılan tek silindirli, 11,4 kw gücünde bir dizel motorda püskürtme basıncının sırasıyla 180, 200 ve 220 bar basınçlarına ve püskürtme zamanlamasının sırasıyla üst ölü noktanın 15, 20 ve 25 derece öncesine alınmasının motor egzoz sıcaklığı, özgül yakıt harcamı ve egzoz gazı içeriğindeki karbondioksit, karbonmonoksit, oksijen, kükürtdioksit ve azot oksitler oranları üzerindeki etkileri deneysel olarak araştırılmıştır. Deney sonuçlarına göre dizel motorlarda yakıt püskürtme stratejisinin kullanılan yakıt tipine, motor yüküne ve çevresel koşullara bağlı olarak belirlenmesiyle çevreye verilen zararın önemli oranda azaltılabileceği sonucuna ulaşılmıştır. Growing global economy, industrialization, population growth, urbanization and improved need for energy access cause rapid increase of global energy demand. Studies on estimation of the future of energy market argues the fact energy production from fossil fuels will still be dominant on global energy market in the next 50 years. However, energy production from fossil fuels is the main cause of air pollution and global warming. Diesel engines that generate energy by using fossil fuels are often preferred for energy production due to high thermal efficiency. There are various methods that can be applied to reduce the emission rates of air pollutants during the operation of diesel engines. These methods include; reduction of exhaust emissions by changes in engine operating parameters, reduction of exhaust emissions using exhaust gas recirculation systems, and removal of air pollutants using exhaust gas aftertreatment systems. In diesel engines it is possible to control the exhaust emissions by changing fuel injection and intake air supply strategies. In this thesis, influence of changes in injection pressures and injection timing on exhaust emissions and motor performance in the use of different fuels have been investigated. For this purpose, tests were conducted on a one cylinder, 11.4 kw diesel engines to investigate effects of different injection pressures (180, 200 and 220 bar) and different injection timings (15, 20 and 25 crank angle degree before top death center) by using diesel oil, marine diesel oil and fuel blend (95 percent marine diesel oil and 5 percent marine residual fuel) as fuel on specific fuel consumption, exhaust temperatures and carbon dioxide, carbon monoxide, oxygen, sulfur dioxide and nitrogen oxides emissions. The results of the test indicate the fact that diesel engines based air pollution can be reduced by using optimum injection strategy determined according to fuel type, engine load and environmental conditions. 164

Homojen dolgulu sıkıştrıma ile ateşlemeli (HCCI) motorların endüstriyel olarak kullanılabilmesi için yüksek yüklerde oluşan vuruntu problemi ve düşük yüklerde oluşan tekleme probleminin giderilmesi gerekmektedir. Bu çalışmada, direkt enjeksiyonlu HCCI bir motorda, hava/yakıt oranının, emme havası giriş sıcaklığının, enjeksiyon zamanlamasının, süperşarj uygulamasının, n-heptan, RON20 ve RON40 yakıtlarının HCCI yanması üzerindeki etkileri deneysel olarak incelenmiştir. HCCI motorunun çalışma aralığını belirleyebilmek için, 800 min-1'den 1800 min-1 motor hızı aralığında, 40 ̊C, 60 ̊C, 80 ̊C ve 100 ̊C emme havası sıcaklıklarında ve üç farklı n-heptan, RON20 ve RON40 yakıtları kullanılarak farklı hava fazlalık katsayılarında deneyler yapılmıştır. Emme havası giriş sıcaklığının artması ile motorun çalışma aralığının genişleyerek daha fakir karışımlarda ve daha yüksek motor hızlarında HCCI yanmasının elde edilebildiği görülmüştür. Fakat emme havası sıcaklığının yükseltilmesinin vuruntu oluşumunu arttırdığı görülmüştür. Enjeksiyon zamanlamasının avansa alınması ile karışımın homojenliğinin artması ile maksimum silindir içi basıncın arttığı ve yanmanın avansa alınarak ısı yayılım oranında iki aşamalı bir HCCI yanmasının gerçekleştiği, basınç artış oranın yükselerek vuruntunun oluştuğu görülmüştür. Emme manifoldu basıncının artması ile hacimsel verimin 160 kPa'da % 82'ye kadar ulaştığı belirlenmiştir. Yüksek emme manifold basıncının HCCI motorunun çalışma aralığının genişlettiği, IMEP ve BMEP değerlerini yükselttiği, yanma verimini iyileştirerek efektif özgül yakıt tüketimini düşürdüğü görülmüştür. Özellikle yüksek emme manifoldu basınçlarında HCCI motoru çok daha fakir karışımlarda çalışabilmiştir. Yakıtlar ile ilgili yapılan deneylerde oktan sayısının artması ile kendi kendine ateşlenmenin zorlaştığı ve yanma başlangıcının gecikmeye alındığı görülmüştür. Oktan sayısının düşmesi ile maksimum silindir basıncının ve maksimum ısı yayılımının ÜÖN'ya yaklaştığı ve maksimum basınç artış oranın arttığı gözlemlenmiştir. Bu çalışmada, en uygun yakıtın RON20 yakıtı olduğu belirlenmiştir. Son olarak da, aşırı fakir karışımlarda tekleme sınırına yaklaşıldığından dolayı COVIMEP'in artarak kabul edilebilirlik seviyesini aştığı tespit edilmiştir. Knocking and misfiring problems of HCCI (Homogeneous Charged Compression Ignition) engines, which occurred at high and low engine loads respectively, should be come over in order to use them for industrial purposes. In this study, the effects of air/fuel ratio, inlet air temperature, injection timing, supercharging, n-heptane, RON20 and RON40 fuels were experimentally investigated in an early direct injection HCCI engine. The experiments were performed between 800-1800 min-1 engine speeds at 40 ̊C, 60 ̊C, 80 ̊C and 100 ̊C inlet air temperatures with n-heptane, RON20, RON40 and different air/fuel ratios in order to determine HCCI operating range. It was observed that the test engine was operated with leaner mixtures at higher inlet air temperatures and higher engine speeds on HCCI combustion resulting in wider HCCI operating range. However, knocking tendency increased with rise of inlet air temperature. It was pointed out that the homogeneity of the charge mixture was improved and maximum in-cylinder pressure increased with the advance of injection timing. Higher pressure rise rate was also seen resulting in knocking with the advance of injection timing. Moreover, the combustion was advanced and two stage heat release rate was observed with the advance of injection timing. It was determined that the volumetric efficiency increased up to 82 % at 160 kPa inlet manifold pressure. It was seen that the increase of inlet manifold pressure caused extension of HCCI operating range, and increased IMEP and BMEP values. Furthermore, effective specific fuel consumption decreased with improving combustion efficiency. Particularly, HCCI engine managed to run with leaner mixtures at higher inlet manifold pressures. Test results showed that auto ignition was deteriorated, and combustion was delayed with the increase of octane number of fuels. The test results also showed that maximum in-cylinder pressure and heat release rate were determined toward the top dead center, and pressure rise rate increased with the decrease octane number of test fuels. In this study, RON20 was described as the most suitable fuel. As a result, it was seen that COVIMEP increased and exceeded the desired value with very lean mixtures due to misfiring problem. 207

Yakıt dolum performansı trafikte faal olarak kullanılan bir taşıtta gerçekleştirilen yakıt dolumunun hem tasarımsal parametreler açısından hem de müşteri memnuniyeti açısından hedeflenen kriterlerin ne kadar karşılandığı olarak açıklanabilir. Yakıt dolum performansında hedef, taşıtın katalog değerinde belirtilmiş olan izin verilen doldurulabilir yakıt miktarından belirli bir tolerans dahilinde dolumun yapılabilmesine ilaveten, müşteriye ya da dolumu gerçekleştirecek operatöre hata modlarını göstermeden ve çevre diğer taşıt sistemlerine olumsuz bir etki bırakmadan gerçekleştirmektir. Özellikle taşıtlarda kullanılan yakıt gibi tutuşması ve alevlenmesi kolay, yangına ya da mal ve can kaybına sebebiyet verebilecek olayların önlenmesi için yakıt ile ilgili her konuda gerektiği gibi yakıt dolumunda da prosesin de yakından incelenmesi gerekir. Bu inceleme ile birlikte hem olası hata modlarının neler olabileceği, bu hata modlarının hangi kök nedenlerden kaynaklanabileceği, ortaya çıkan hata modlarının nasıl önlenebileceğinin yanı sıra yakıt dolum performansına etki eden hem çevresel hem de tasarımsal parametreler ile bu parametrelerin etkileri incelenmiştir.İnceleme toplamda 8 ana bölümden oluşmaktadır. Birinci bölümde yakıt dolumunun nasıl gerçekleştirildiği ve yakıt dolum performansı ile ne anlatılmak istendiği açıklanmıştır. Ayrıca bu bölümde yakıt dolumuna etki eden regülasyonlardan da bahsedilmiştir. İkinci bölümde ise yakıt dolumunda görev alan tüm alt sistemler ve komponentleri tanıtılmıştır. Üçüncü bölümde ise yakıt dolum performansında istenilen seviye ve bu seviyenin karşılanamaması durumunda oluşabilecek hata modları tanıtılmıştır. Dördüncü bölüm dahilinde yakıt dolum performansına etki edebilecek ya da etmesi beklenen parametrelerin ne olduğuna bakılmıştır. Yakıt dolumu için önemli parametrelerden birisi olan ve hem yakıt dolumunu gerçekleştiren kişiden hem de taşıt üreticisi firmaların tasarım departmanlarından bağımsız en büyük parametrelerden birisi olan tabanca türlerinin detayları verilmiştir. Beşinci bölümde yakıt dolum performansı testlerinin gerçekleştirilmesi sırasında kullanılacak ekipmanlar, incelenecek çıktılar, testin nasıl gerçekleştirileceği ve teste girecek olan taşıtlar ile test planları bulunmaktadır. Altıncı bölümde test sonucunda elde edilen verilere göre belirlenen parametrelerin yakıt dolum performansına nasıl etki ettikleri gösterilmiştir. Bu bölümde bölümde ayrıca etkisi olması beklendiği halde etkisi olmayan parametreler de belirlenmiştir. Yedinci bölümde elde edilen bulgular ışığında optimum yakıt dolum performansı için dikkat edilmesi gereken noktalar ve optimum yakıt sistemi tasarımı için tavsiyeler bulunmanktadır. Son bölüm olan sekizinci bölümde ise teste giren taşıtların mukayesesine ek olarak incelemenin taşıt üreticisi firmalar açısından faydası ve bu incelemenin ileride nasıl geliştirilebileceğine dair fikirler paylaşılmıştır. Refueling performance can be stated as how much the demanded acceptance criteria are met according to design and customer satisfaction during a refueling process on an active road vehicle. Target of a successful refueling process is to fill up the fuel tank up to given catalogue value within its tolerances while showing no failure modes to customer or operator and no negative effect to surrounding other vehicle systems. Like the other fuel related processes refueling process must be also examined closely as road vehicle fuel types are flammable or easy to ignite and that can lead to fires causing loss of life and property. With this examination it will be possible to determine possible failure modes, these failure modes' root causes, how these failure modes can be avoided along what are design related and environmental parameters affecting refueling and how they are affecting.This investigation consists 8 main chapters. In the first chapter refueling process and refueling performance are explained in details. Additionally emission regulations are mentioned in this chapter. Fuel sub-systems and fuel components are introduced in second chapter. In third chapter demanded refueling performance is explained and failure modes are defined. Parameters that can or may have an effect on refueling are determined in fourth chapter. One of the main parameters that can have an effect on refueling independent from vehicle manufacturers and customers/operators is nozzle type and many nozzle types are introduced in this chapter. In fifth chapter equipment that will be used during refueling performance test, output that will be examined, test procedure and vehicles to be tested along test plans are given. In sixth chapter it is investigated that which parameter affects refueling performance and how it affects. Also parameters that are expected to have an effect on refueling but not are classified. In seventh chapter important points for refueling performance is stated in the light of outcomes of refueling performance tests with advices for an optimum fuel system design. In the last and eighth chapter comparison of test vehicles, benefits of this investigation to vehicle manufacturers and how this investigation can be developed in future stages are given.Refueling process can be considered as a simple fuel flow from fuel dispenser to fuel tank shell of fuel system of the vehicle. In theory this is basically true but a very very short summary of the phenomena. In refueling many physical event takes place and it is a combination of high degree fluid mechanics both related with liquid state and gaseous state. In refueling it is very important to consider both liquid pressure drop and vapor management. Refillable volume, dispensed fuel and nozzle shut-off are determined by system pressure build-up. A good refueling performance is achieving a full fuel tank shell based on catalogue values given by vehicle manufacturers along with no error states or failure modes like, spitback, wellback, premature shut-off, not being able to start refueling, violation of emission regulations that vehicle will be sold, damage or harm to surrounding vehicle systems or inflammation and ignition inside the fuel system.Fuel system's refueling related side is composed of three main subsystems which are fuel filling subsystem, fuel tank subsystem and evaporative emissions subsystem. In fuel filling subsystem there may be up to six component groups that are fuel filler pipe, fuel filler insert, fuel filler neck and head, fuel hoses, clamps and flow regulator parts. Under fuel tank subsystem there may be up to four component groups that are fuel tank shell, in-tank valves, fuel tank straps with fasteners and fuel distribution modules. Under evaporative emission subsystem there may be up to three component groups that are vapor lines, atmospheric line and carbon canister.For a good or optimum refueling performance fuel system designers are aiming to fill the fuel tank shell just around exact allowed fillable level. If fillable level will not be met but will stay in limits a little higher filling volume is appreciated. All other targets given above are almost mandatory and it is strongly recommended to be met. If required refueling performance cannot be met there must be a reason and as a result there should be a failure mode related with the issue. In result of a bad refueling performance the person performing the refueling process may face with spitback which is a slight amount of fuel coming out of fuel system after shut off, wellback which is a state that even the fuel system is filled but nozzle does not shut off, premature shut off where nozzle shuts off but fuel system is not filled until its allowed fillable capacity, not being able to start refueling, violation of emission regulations that vehicle will be sold which is a exceed of limits allowed by regulations or laws that are applicable for mentioned vehicle, damage or harm to surrounding vehicle systems such as damage to body paint or fuel spillage on exhaust system and inflammation and ignition inside the fuel system due to high friction between fuel system and fuel, especially on gasoline fueled vehicles.Parameters that may have an effect on refueling can be classified in six main groups. First group is environmental parameters such as ambient temperature, ambient pressure or transportation conditions. Another group is customer or operator based parameters such as positioning of vehicle in fuel stations that may lead to improper latching or different clock position orientation then 6 o'clock position. Also leaning on nozzle is a parameter for this group. In third group it is possible to combine time based parameters such as metal fatigue, creep or torque loss of fastener that can lead to malfunctions on fuel systems. In fourth group there is the relation with surrounding components such as excessive heat transfer from exhaust system or bad tolerance stack up on body system components that may change the position of fuel system parts. Fifth group is the refueling equipment related parameters such as nozzle types and flow rates. Last group is the design related parameters such as inlet angle, height of inlet point from ground or routing of fuel filler pipe.As having a complete vehicle for testing is expensive and it is way hard to dispense fuel after refueling fixtures are built for refueling performance tests. Having a fixture will also allow having the instrumentation easier compared to having vehicle. Only important point is to build the fixture as matching as with the original position of vehicle. Fixture should be built vehicle's most selling variant for each fuel type. After fixture build test fuels to be determined for refueling tests. Test fuels must be chosen according to markets that vehicles will be sold. This process must be repeated for nozzle types also. After completing instrumentation and choosing the data channels to be tracked test procedure is determined. Every vehicle manufacturer company has their own standards built on their own experience and know-how. After completing the all selection above last action is to determine the vehicle or vehicles for refueling performance test. Key factor in determining the test vehicles is to allow a healthy comparison and a good examination base for all parameters. This leads to vehicles some same and some different properties within each other. In final test plan can be built to see how many refueling will be performed on which vehicle with which fuel type and with which different parameters.Investigation starts after completing all refueling tests. Test results are datamined for determining the parameter or parameters that has no significant or useful effect on refueling performance. Later on effect of fuel flow rate, nozzle type rate, positioning and orientation of nozzle, type of fuel filler insert, all design related parameters, type of fuel used in refueling performance tests, dispensed fuel temperature and ambient temperature are defined. All those parameters have different effects and any major change of these parameters cause or eliminate different failure modes in every vehicle.In the light of all test results and after defining all parameters effects of refueling process it can be proposed how the fuel system and components' design should be for an optimum refueling performance. It may not be possible to find a common fuel system design for all vehicle's all variants but defining refueling performance affecting parameters can give an idea for the design.All three vehicles in this investigation are compared to each other for a final conclusion and understanding. Benefits of this investigation can lead to the refueling performance such as reduction is warranty costs and increase in customer satisfaction which will also result in positive for vehicle manufacturer's economics. 159

ÖZETİSOBÜTANOL-DİZEL KARIŞIMLARININ MOTOR PERFORMANSI VE EGZOZ EMİSYONLARINA ETKİSİMotorlu taşıtlarda kullanılan petrol ve petrol türevli yakıtların sınırlı olması, yeni ve yenilenebilir alternatif yakıt arayışları, yakıt tüketimi ve egzoz emisyonlarını azaltma düşüncesi bu çalışmanın temelini oluşturmaktadır. Bu çalışmada, isobutanol-dizel (ISB5, ISB10, ISB15) karışımlarının motor performansı ve egzoz emisyonlarına etkisi deneysel olarak incelenmiştir. Deneyler altı silindirli, turbo şarjlı, direk enjeksiyonlu ve dört zamanlı dizel bir motorda 1400 d/d sabit motor devrinde ve 150, 300, 450 N.m motor yüklerinde gerçekleştirilmiştir.ISB5, ISB10 ve ISB15 yakıt karışımlarından elde edilen sonuçlar, dizel yakıtı ile yapılan deneysel veriler referans alınarak karşılaştırılmıştır. Deneyler sonucunda, isobutanol - dizel karışımlarının özgül yakıt tüketimlerinin dizel yakıta göre arttığı ve genel olarak CO, HC, CO2 ve NOx emisyonlarının azaldığı gözlenmiştir.ABSTRACTTHE EFFECT OF ENGINE PERFORMANCE AND EXHAUST EMISSIONS OF ISOBUTANOL-DIESEL BLENDSThis study is based on the assumption that there is a shortage of petroleum fuels used in internal combustion engines. Besides researches for new and renewable alternative fuels and attempts to reduce fuel consumption and exhaust emission constitute a basis for this study. In this study, the effects isobutanol-diesel (ISB5, ISB10, ISB15) blends on engine’s performance and exhaust emissions were investigated experimentally. In the experiments, a vehicle which has a six-cylinder, turbo changed, direct enjection and four-stroke diesel engine was used. The experiments were performed at the 1400 speed and 150, 300, 450 Nm varied load. The results obtained from ISB5, ISB10, ISB15 were compared with the reference diesel fuel. In the result of experiments, it was seen that the specific fuel consumptions of isobutanol-diesel blends were increased and generally seen that CO, HC, CO2 and NOx emissions decreased compared to diesel fuel.

Geleneksel motor yakıtları, sınırlı doğa kaynaklarına dayanan doğal ham petrolden üretilmektedir. Taşıt motorlarının toplam yakıt tüketimleri ve yakıt fiyatları sürekli olarak artmaktadır. Ayrıca daha temiz ve verimli motor istekleri, alternatif yakıtların veya mevcut yakıtların geliştirilmesinin araştırılmasını gerektirmektedir. Son yıllarda; fümigasyon, Diesel motorlarında en çekici yöntemlerden biri durumuna gelmiştir. Fümigasyon, alternatif yakıtın karbürasyon ve buharlaştırma ile motora gönderildiği veya alternatif yakıtın havanın içerisine püskürtüldüğü bir yöntemdir. Sunulan çalışmada; farklı oranlardaki benzin ve etanol fumigasyonunun, motor performansı ve eksoz gazlan emisyonları üzerindeki etküerinin teorik olarak incelenmesi amaçlanmıştır. Bu amaçla Diesel motoru çevrimi için Termodinamiğin Birinci Kanununa dayanan bir matematiksel model geliştirilmiştir. Söz konusu model, demetin oluşumu, yakıt-hava karışımı, girdap, ısı transferi ve emisyon modelleri gibi alt modellerden oluşan sanki boyutlu çok bölgeli yanma modeli kavramlarını içermektedir. Saf Diesel yakıtı ve farklı fümigasyon oranlarındaki Diesel yakıtı-benzin/etanol karışımlarının yakıt olarak kullanıldığı dört ve altı silindirli turbojarşlı iki farklı Diesel motorunun performans parametreleri ve eksoz gazlan emisyonları teorik olarak hesaplanmıştır. Değişken ekivalans oranlarında benzin fumigasyonu attıkça efektif güç, özgül yakıt tüketimi (ÖYT) ve karbon monoksit (CO) oranı artmaktadır. Öte yandan, efektif verim ve azot oksit (NO) konsantrasyonu azalmaktadır. Sabit ekivalans oranlarında benzin fumigasyonu attıkça efektif güç, efektif verim ve CO oranı artmaktadır. Bununla birlikte, ÖYT ve NO konsantrasyonu azalmaktadır. Değişken ekivalans oranlarında etanol fumigasyonu attıkça efektif güç, efektif verim ve CO oranı artmaktadır. Bunun yanında, ÖYT ve NO konsantrasyonu ise azalmaktadır. Sabit ekivalans oranlarında etanol fumigasyonu attıkça efektif güç, efektif verim ve NO konsantrasyonu genel olarak artmaktadır. Bu durumda, ÖYT önemli ölçüde artmaktadır ve CO oranı genel olarak artma eğilimi göstermektedir. Anahtar Kelimeler: Diesel Motoru Çevrim Modellemesi, Çok Bölgeli Yanma Modeli, Fümigasyon, Alternatif Yakıtlar, Demet Geometrisi, Çift Yakıtlı Motorlar VII Effects of Using Diesel Fuel-Light Fuel Blends on Combustion and Engine Performance in Diesel Engines The conventional engine fuels are derived from crude oil based on limited natural sources. The fuel cost and total fuel consumption of the vehicle engines gradually increase. Furthermore, the demand for cleaner and more efficient engines requires to research the alternative fuels and to improve the fuel quality. In recent years, fumigation has become one of the most attractive methods for Diesel engines. Fumigation is a method by which alternative fuel is introduced into the engine by carbureting and vaporizing or injecting alternative fuel into the intake air stream. In the presented study, theoretical investigation of the effects of different gasoline and ethanol fumigation ratios on the engine performance and the exhaust emissions is aimed. For this purpose, a mathematical Diesel engine cycle model based on the First Law of Thermodynamics has been developed. This model includes a quasi-dimensional multi- zone combustion-modeling concept which consists of several sub-models such as spray formation, air-fuel mixing, swirl, heat transfer and emission models. The engine performance parameters and exhaust emissions for two different turbocharged Diesel engines having four and six cylinders fueled with pure Diesel fuel and Diesel fuel-gasoline/ethanol blends at different fumigation ratios have been predicted. Increasing gasoline fumigation at varied equivalence ratios increases the effective power, specific fuel consumption (SFC), carbon monoxide (CO) ratio while decrease effective efficiency and nitric oxide (NO) concentration. With increasing ratio of gasoline fumigation at constant equivalence ratios effective power, effective efficiency and CO ratio increase, however SFC and NO concentration decrease. Increasing ethanol fumigation at varied equivalence ratios increases the effective power, effective efficiency and CO ratio, however it decreases SFC and NO concentration. Effective efficiency, effective power and NO concentration increase generally by increasing the ethanol fumigation at constant equivalence ratios. In this case, SFC increases significantly and CO ratio exhibits generally increment tendency. KeyWords: Diesel Engine Cycles Modeling, Multi-Zone Combustion Modeling, Fumigation, Alternative Fuels, Spray Geometry, Dual Fueled Engines vni 201

ÖZET Bu çalışma, çağımızda dünyamızın şüphesiz en büyük sorunlarından olan enerji dar boğazı ile ilgilidir. İlk olarak motor yakıtı olarak kullanılabilen alternatif yakıtlardan olan doğal gaz, hidrojen ve LPG'nin elde edilişi, fiziksel ve kimyasal özellikleri ile depolanması, taşınması ve motorlarda kullanımı sonucu oluşacak olan egzoz emisyonlarından bahsedilmiştir. Bu yakıtların araçlarda kullanılmasının avantajlarına ve dezavantajlarına değinilmiştir. Ayrıca günümüzde kullanılmakta olan gaz karbüratörlü LPG sistemlerinden örnekler verilerek incelenmiştir. Çalışmanın esas amacı ise yeni bir yakıt - hava ön karışım modeli geliştirmektir. Bu nedenle Motorlar Laboratuvarında bulunan Renault 12 tipi deney motorunun LPG ile çalışabilmesi için motor kafasında bazı değişiklikler yapılmıştır. Bunun için geliştirilen dahili karışım hazırlama yönteminde, emme supabı hareketiyle kontrol edilen bir mekanizma yardımı ile, gaz halindeki LPG doğrudan yanma odasına gönderilmektedir. Karışım oluşumu emme supabı oturma yüzeyinde gerçekleşmektedir. Emme supabı oturma yüzeyinde çevresel olarak 1 mm çapında 12 adet delik bulunmakta olup bu delikler çevresel bir kanal ile birbirlerine ve motor gövdesinde bulunan LPG giriş hattına bağlıdır. Yakıt gönderme işlemi kam milinin hareketine bağlı olarak supabın yuvasından kalkması ile açılan delikler üzerinden yapılmaktadır. Deney motorunun performansı ve egzoz emisyonları benzin ile çalıştırılarak bir seri deney ile belirlenmiştir. Aynı deneyler LPG kullanılarak tekrarlanmış ve elde edilen sonuçlar birbirleriyle mukayeseli olarak grafikler halinde verilmiştir. xviii SUMMARY ALTERNATIVE ENGINE FUELS AND EXPERIMENTALLY COMPARISION LPG WITH GASEOLINE AS AN AUTOMATIVE FUEL. The rapid depletion of conventional energy sources together with the introduction of strict limitations on emissions of polluting combustions products, has lead to an intensive search for alternative fuels. Natural gas and Hydrogen with clear advantages over fossil based conventional fuels is one of the strong candidates for future applications. For heavy duty engines pure natural gas or nature! gas /diesel dual fuel is the best short term solution for meeting the present emission targets. Adaptation of diesel engines to nature! gas operation can be achieved by two different approaches. Dedicated nature! gas engines operating with premixed homogenous charge under Otto cycle, can either use lean or stochiometric mixture. Stochiometric mixture operations are preferred for additional 3- way catalytic converter aplications at the exhaust system to reduce emissions, where as lean operation is more economical. Another method for the utilization of nature! gas in present heavy duty diese! engines is the use of pilot injection of diese! fuel to ignite premixed naturel gas- air mixture. This applications is widely used for the conversion of diese! engines that are already in use. With all these applications reduction of PM emissions is achieved white keeping the CO, HC and NOx emissions at low levels. Hydrogen being the cleanest fuel for internal combustion engines, will be the long term solution for automative emissions. Use of gaseous hydrogen reduces power output of the engine to a certain degree, but produces excellent results in terms of exhaust of emissions as the fuel used does not possess any carbon molecular. This elimanates the production of CO, HC, C02 and PM. In the second part of this study LPG is told as an engine fuel. Liquid Petroleum Gases (LPG) is a hydrocarbon that is mainly made up of a propane and butane mixture. These hydrocarbons are present in nature only in petrol and obtained during the refinement of crude oil or its derivatives. With today' s refinement technology only 3 to 4 % of cruide oil can be obtained as LPG. Therefore, LPG has been never considered as an overall alternative to gasoline. Thus, LPG conversion of passenger cars is limited to 3 to 4 percent of passenger car park in time world. Table 1 lists the physical and chemical characteristics of butane and propane. In the fifties LPG was introduced in Italy, Netherlands and some other European countries as an automative fuel. The growth of the industry was based on beneficial running cost since for a customer real benefit comes after a certain break even mileage per year. The break - even mileage is determined mainly by the following :. initial investment c fuel prices (LPG - gasoline). exces road tax Today Italy and Netherlands are two leading countries in Europe in LPG automative applications and the conversion market. Because of the governmental policies LPG was attractive to use in automobiles xixTable 1. Physical and chemical properties. Burning velocity (cmfe)inair 32 32 In Turkey, because there was no governmental policy in favor of LPG as an automative fuel and the lack of LPG automotive know how until today, there has not been a serious enterprise on this subject. Besides, for time being LPG or CNG conversion of any any type of car and truck etc. is still illegal. The related Turkish law has been rearranged recently and will be applicable by the end of this year.(1995). Most of the present LPG cars and light trucks on the road are based on production gasoline engines. Various retrofit systems for LPG use are offered from different producers. The necessity for a large range of adaptibilitiy to various engine types leaves limited spaces for indivual optimization. Lack of equipment in some service stations is another reason for limited performance of many LPG vehicles on the road. Only the careful selection of a suitable LPG equipment and its best adaptation to the engine makes the full utilization of all advantages of this excellent engine fuel possible. Still better results can be obtained if the engine vehicle cocept is optimized to the LPG fuel as well. A lean bum engine promises low emissions at good performance, where the economy of the vehicle i.e. the operation cost depend on the local fuel prices in the different countries. There are some essential differences between normal gasoline and LPG, which consist of a propan-butane mixture fed into the engine as a gas, thus facilatating optimal mixture preparation and an even mix with the intake air. In contrast to normal liquid fuels, LPG is the totally vaporized during the intake cycle and thus takes up a grater volume ; moreover, the latent heat of vaporazition does not affect the tiermodynamic processes in the engine because its equalized in the cooling water heated vaporizer before entering the gas mixer. Since the composition of the LPG varies greatly from one region to another it can be expected that the characteristics will vary accordingly. In Europe, for example, the propane- butane ratio in different countries fluctuates between 96 % and 20 % propane content, which accounts for the differences in the characteristics. Similiar differences can be observed in other countries depending on the availability of the components and climatic conditions ; propane gives much higher pressures at given temperatures. The usual variation of the propane-butane ratio on the market means otherwise a difference of approximately 9 % in calorific value and stoichiometric air-fuel ratio and up to 17 octane numbers.(Tab!e 2). XXTable 2. Variîion of engine relevant LPG properties by different composition. PROPANE N-BUTANE 96 % Density 15% KG/L Vol. Calorific Value MJfL Stoichiometric Air Fuel Ratio (Volumetric) Octane Numbers RON yoN Advantages and disadvantages in the application of LPG are classified as the below. Advantages: High octane numbers Potential for better fuel distribution Effective combustion Lean burning possible Low emissions Low strain on lubricants Less deposits in combustion chamber High durability of exhaust system. Disadvantages : High weight of fuel tank Space requinment of fuel tank Reduced power output No additives possible Deposits in intake systems and evaparator/ pressure regulator. If we look at emission levels we find that the air - fuel ratio related CO concentration is independent of the fuel. However, NO* and HC emissions show significant diferences compared with the traditional gasoline engine. The NOx values are significantly higher for LPG than for gasoline, whereas the HC values are lower. Furthermore, under normal driving conditions, the gas driven engine allows leaner mixtures at acceptable driveability. Hence the limit for the lean mixture operation can be extended and consequently lower NOx emissions can be achieved. During the trials for the engines under consedaretion here the acceptable limit for lean operation with gasoline was at 10 to 15 % lean mixture, whereas with gas the values can be stretched to over 35 % lean, without the driving characteristics suffering in any way. Nowadays, if gas is required as a fuel, it is usual to modify production vehicles with gasoline engines after they have left the factory, in which case the vehicle can be run on either gasoline or gas, as desired. Production vehicles, however, already have certain features for example the principal design and installation situation, the air filter, mixture formation, the intake pipe and the spark timing. The gas system must be adapted so as to conform to this given situation which sometimes means restrictions. Various manufacturers of LPG retrofit equipments have range of systems on the market to meet the different requirements. In every system there is abasic similarity in the operation of the xxivaporizer - pressure regulator, which is heated by the cooing water; also the quantity of gas flowing through is usually determined with respect to the pressure in front of the throttle valve of the intake system. There are various principles governing the mixing of the gas and air. In most cases a gas mixer is inserted in the air filter or in front of the carburettor. Such a mixer must fullfill certain requirements :. It must produce an equlized mixture so that there is uniform distribution of the air - fuel ratio in all cylinders.. The vacuum signal necesary for the regulation of the gas flow must be faithfully passed on to the vaporizer - pressure regulator by the mixer.. The mixer should not interfere with any future operation using normal gasoline. This sometimes would seem to be a problem, particularly during high load operation, float chambers and also the vacuum - controlled enrichment at full load are both more or less affected by the mixer. Other constructions place the gas supply behind the throttle valve and thus avoid some of the problems metioned above : however, they require a more complex regulating system to control the gas flow, like, for instance, an additional linkage controlled throttle valve for the gas. Since the assembly kits commercially available must cater for awide variety of vehicles, they must also be adjustable in the necesarry range. The performance of the vehicle after adaptation depends on the exact match between the gas system and the engine ; this in turn will depend onnthe quality of the service station doing the fitting and its facalities for carrying out the measurements involved in the job. Factory - modified LPG vehicles are offered on the automotive market only in some countries. For instance in Japan some companies produce special LPG modified vehicles with their own gas mixture and metering systems. In many Japanese cities nearly all taxis use LPG. To achieve the best possible result an LPG system should be favorably monovalent, that is, designed and optimized to use only LPG as a fuel. This obviates any problems associated with having to match the system to various fuels. As far as the combustion chamber, the compression ratio, the spark timing and the mixture preparation are concerned, the system is designed such that the advantages of LPG can be utilized to the full. This also the case for the gas mixing system which can be constructed without regard to possible restrictions imposed by dual gasoline - LPG operation. The traffic increase influences more and more negatively the environment and the energetic consumption. The transport field is particularly responsible for emissions of carbon and nitrogen monoxide, unburnt hydrocarbons, lead, carbon bioxide, sulphurous anhydride, coal particles (diesel) etc... in the environment. Combustion is inevitably polluting. Emissions coming from it are linked to the chemical and physical properties of fuel, to the composition of the fuel - comburent mixture but also to the combustion process and tothe environment characteristics. When comparing petrol, unleaded fuel, diesel and LPG emissions, we can note that all these fuels produce carbon and nitrogen monoxide as well as unburnt hydrocarbons while lead is only produced by petrol. Moreover, LPG does not produce sulfurous anhydride and aromatics. All products coming from combustion negatively influence upon the air quality. However, it is more important to know the toxicity grade of each element and define the real injuriousness (table 3) than considering quantity in absolute values. xxiiTable 3. Compounds and toxicity parameters after combustion. From the above table, we can see that the more toxic products of combustion, such as sulfurous anhydride and lead, are not present in LPG. Moreover, LPG unburnt hydrocarbons are less toxic than the other fuelsones because LPG has neither additives nor aromatics. It has to be underlined that LPG pollutes little because :. combustion is done during the gases phase. As LPG is a gas, it suits better this process and assures a more homogeneous mixture without any coal particles.. High thermodynamics characteristics ease and better consumption. there are no additives such as lead, sulphur and aromatics. In the last part of this study I compared LPG with gasoline. LPG is tested in a four cylinder Renault 12 engine. LPG has been introduced directly into the combustion chamber through the passages connected to the gallery placed under the inlet valves seats. Direct and intermittent induction of LPG into cylinders prevented the pre - ignition and back fire problems.The main purpose was to investigate the performance characteristics of a Renault 12 engine operating with LPG / gasoline, in terms of power output and exhaust emissions. The results showed that PM, CO, NOx and HC emissions can be reduced with a little loss in power output of the engine. Moreover the results showed that LPG is more economical than gasoline and also the use of LPG resulted in a loss maximum power output of the engine but it is proved that LPG can give approximately same power output values with lean mixtures as gasoline. 83

ÖZET Günümüzde, artan nüfus ve endüstriyel gelişmelerle birlikte, e nerji gereksinimi sürekli, hızlı bir artış gösterirken; kömür, petrol, doğal gaz gibi rezervleri sınırlı fosil kaynaklı enerjiler yanında, yeni-yenilenebilir enerji kaynakları da büyük önem kazanmaktadır. Ye ni enerji kaynakları arasında biokütle en büyük potansiyele sahiptir. Biokütle kaynaklarının enerji amaçlı en önemli değerlendirilme alanla rından biri alkollerin alternatif motor yakıtı olarak kullanımıdır. Bu çalışmada da, günümüz benzin motorlarında tasarım değişikliği ge rektirmeyecek şekilde, benzine katılabilecek maksimum alkol miktarı olarak önerilen %2Ö (hacimsel) oram gözönüne alınarak, hazırlanan me tanollü ve etanol lü benzinlerin alternatif motor yakıtı olarak değer lendirilebilirlıği incelenmiştir. Deneysel çalışmaların, ilk bölümün de, isopropanol., n-propanol, isobutanol, n-butanol, isoamilalkol, n-amilalkol ve füze! yağı kullanılarak, alkol-benzin karışımlarında faz ayrışma sorunu çözümlenmiş, karışımların faz ayrışma olayı geniş olarak incelenmiştir. î kinci bölümde ise füze! yağı katkılı alkollü benzinlerin ASÎM yöntemlerine göre yakıt özellikleri belirlenerek, el de edilen sonuçların benzin özellikleri ile uyum gösterdiği saptanmış tır. Çalışmanın son bölümünde ise Renault 12 test motorunda yapılan çalışmalar ile alkollü benzinlerin motor karakteristikleri ve egzoz gazı emisyonları belirlenmiştir. EVALUATION OF ALCOHOL-GASOLINE BLENDS AS ENGINE FUEL ALTERNATIVE SUMMARY Energy is one of the most important milestones of human life. Supply-demond irregularities, consecutive oil crisis followed by fluctuations and rise in oil prices led countries to search for new energy sources. As a result, besides the conventional fossil fuels like coal, petroleum, natural gas evaluation of alternative energy sources like the sun, wind, geothermal, hydro! ic, hydrogen and bio- mass were taken into consideration in order to meet the increasing energy demand. Biomass sources have an important place in new and renewable energy sources. World potential of the new and renewable energy sources are given in Table 1 as TOE (tons oil equivalent). Although the new energy sources are used in a limited manner today, these sources seem to gain importance within the world's energy supply in future. One of the ways of evaluating the biomass sources in the field of energy is converting them to alcohols by biotechnological methods which than can be used as engine fuel. Gasolines that contain alcohol up to 20 vol % can safely be used in today's Otto engines without any need for a design change. Table 1- World Production Potential of the New and Renewable Energy Sources, Million TOE/Year ¦ The positive results due to the evaluation of alcohol -gasoline blends as engine fuel alternatives can be summarized as follows: Alcohol -gasoline blends are the first step proposed in the evaluation of new and renewable energy sources in Otto engines, so using them as engine fuels will mean an improvement in the introduction of the new energy sources and evaluation possibilities of biomass potential will thus increase. Addition of alcohol to gasoline will decrease the overall gasoline consumption. This is an important point for Turkey as 90% of the oil consumed in the country is provided through imports. According to the 1988 figures gasoline makes up 2 174 082 tons of the civil petroleum products consumption which is 20 147 354 tons. It can easily be observed that the gasoline consumption is foreign dependant and the import expenses are quite a heavy burden to the country 's vieconomy. Besides a reduced gasoline consumption is important for the petrochemical industry whose raw material is dependant on crude petroleum. Due to the addition of alcohols which have high octane numbers to gasoline and their continious use as alternative engine fuel will cease the environmental pollution caused by lead and even tually positive decrease will also be observed in the other exhaust emissions. In adapting the alcohol-gasoline blends into everyday use in Turkey benefits for the country's economy must be evaluated while scientific research strengthening the idea must also be put forward. Alcohol -gasoline blends are in fact a three component system of gasoline-alcohol and water due to the hygroscopic character of the alcohols. The most important problem in using such blends as engine fuel is their seperation possibility into two liquid phases due to several factors. When such a two phased system is tried to be used in an engine several serious problems occur. Therefore, in the evaluation of alcohol -gasoline blends as engine fuel the first step should be solving the phase seperation problem hence obtaining a homogenous mixture. Therefore in this work the phase seperation problem in gasolines blended with methanol or ethanol was solved by adding special additiv es to the blends and due to the positive results obtained from the fuel property and engine tests the stable blend fuels were proposed as a fuel alternative for today's Otto Engines. Mixtures used in the research were prepared by adding Merck grade pure methanol and distilled (b.p. 78.15DC) ethanol containing 4.4 weight % water to the four unleaded gasoline samples of different composition provided from TÖPRAŞ tzmit Refinery. The alcohol ratio in the mixtures is 5, 10, 15, and 20 % by volume. Research work was realized in three steps: 1. Solving the phase seperation problem of the alcohol-gasoline blends. 2. Determining the fuel properties of alcohol -gasoline blends 3. Engine tests, engine characteristics and exhaust emmission values of alcohol-gasoline blends. The phase seperation problem of gasoline-alcohol, blends is solved by using isopropanol, n-propanol, isobutanol, n-butanol, isoamyl- alcohol, n-amylalcohol and fusel oil fraction as additives. The fraction of molasses fusel oil which contains 0.1 vol % water and which boils above 120°C was used in the experiments. According to the results of the GLC analysis fermentation amyl alcohol s make up 86.5 % by weight of this fraction. viiAccording to the results obtained, the additives mentioned can effectively solve the phase seperation problem and they all have approximately the same effect on the phase seperation temperature of the alcohol-gasoline blends. The chemical composition of the gasoline used, environmental temperature, alcohol content and water tolerance of the blend, using ethanol or methanol as the alcohol component all are factors that influence the phase seperation in alcohol-gasoline blends. Fusel oil which is one of the additives used in the experiments is a by-product of ethanol production. Using fusel oil and its already defined fraction as an additive is a new way of evaluating the by product and it is proposed for the first time in this research work. The essential results concerning the change in phase seperation tem peratures of fusel oil added alcohol -gasoline blends are as follows: 1. An increase in the amount of the fusel oil fraction within the alcohol -gasoline blends of known alcohol and water content increases the water tolerance values and decreases the phase seperation tempera tures. 2. The chemical composition of the gasoline used is very important for the alcohol-gasoline blends. An increase in the aromatic charac ter of the gasoline increases the phase seperation temperatures of the blends. 3. In a gasoline-alcohol-water and fusel oil fraction system environmental temperature is vitally important for the stability of the blend. An increase in temperature means an increase in the water tolerance of the blend while the amount of additive needed for a stable blend decreases. 4. Using ethanol or methanol in alcohol gasoline blends causes some differences in the phase seperation temperatures. This fact is due to their solubility differences in the hydrocarbons; for instance solu bility of ethanol is independant of the type of the hydrocarbon. There fore, same phase seperation temperatures were observed for alcohol -gaso line blends prepared with gasolines rich in aromatics and saturates. On the contrary, solubility of methanol in aromatic hydrocarbons is higher compared to other hydrocarbons; therefore, in methanol -gasoline blends prepared with gasoline rich in saturates different phase sepe ration temperature change is observed than the ethanol-gasoline blends. Ethanol --gasoline blends are more water tolerable than methanol- gasoline blends. Therefore, ethanol-gasoline blends prepared with the same gasoline and containing same amounts of water, alcohol and fusel oil fraction had lower phase seperation temperatures than methanol - gasoline blends. In the second part of the research ASTM fuel properties of the viiifuel oil fraction added stable blends were compared with those proper ties of their component gasolines and a general accordance between the results was observed. The fuel property tests and their ASTM numbers are as follows: 1- Density (ASTM D 1298) 2- Distillation Test (ASTM D 86) 3- Reid vapor pressure Test (ASTM D 323) 4- Octane number Research method (ASTM D 2699) Motor method (ASTM D 2700) 5- Corrosion Test This test was applied in two different ways: a) Copper corrosion test (ASTM D 130) b) Test proposed for gasohol (gasoline containing 10 vol % pure ethanol) by The American Society for Testing and Materials. This test was both applied to alcohol-gasoline blends and to the same blends containing 10 vol % water. The materials test ed according to ASTM D 665 were aluminium, zinc, magnesium, lead, zinc coated steel and PVC. Engine tests were realized in a Renault 12 (1200 cc.) laboratory test engine at 21°C, 80% humidity, 101.3 kPa. CO and hydrocarbon emissions were continiously measured with a Hamilton Analyzer throug- out the test period. Nitrogen oxides were determined accordinq to VDI 2456 method. Important results obtained from the engine and ex haust emission, tests using the blend fuels, component gasolines and commercial gasoline can be summarized as follows: 1. Results of the engine tests and engine characteristic values determined through these tests using alcohol blends and plain gaso line all are in accordance within themselves. In alcohol-gasoline blends an increase in specific fuel consumption and thermal effici ency was observed when compared with gasoline itself while power and moment values decreased. It must be noted that these tests could only be carried out under some predetermined conditions. £ngi ne characteristic values under different conditions such as different spark advances, compression ratios and throttle opening positions must be determined and engine performance maps for alcohol -gasoline blends must be constituted. 2. Using alcohol-gasoline blends as engine fuel has positive effects from the exhaust emissions' point of view. In the experi ments carried out at 1/3 and 2/3 throttle opening positions a rapid decrease in CO emission values was observed while nitrogen oxides emitted were approximately at the same level with those in the case of gasoline. On the other hand, in the 1/3 position hydrocarbon emissions were higher compared to gasoline while in the 2/2 position they were approximately the same or lower than the values obtained for gasoline. With a more detailed investigation on engine charact eristics as mentioned above i% will also be possible to comment on the general tendancy of the exhaust emissions. The blends used in the experiments were all prepared with unleaded gasoline, therefore ixthe deformation of the seat material during long term engine tests using b3end fuels must be thoroughly investigated and the most con venient seat material must be selected accordingly. 117