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Öğe 1-D Modelling Comparative Study to Evaluate Performance and Emissions of a Spark Ignition Engine Fuelled with Gasoline and LNG(E D P Sciences, 2016) Yontar, Ahmet Alper; Dogu, YahyaIn this study, a spark-ignition engine fuelled with gasoline and LNG was modelled in 1-D at wide open throttle by using Ricardo-Wave software. Different engine speeds ranging from 1500rpm to 4500rpm with an increment of 500rpm were studied to evaluate the effects of gasoline and LNG on engine performance and exhaust emissions. It is determined that LNG decreases engine performance and emissions as well, at especially high speeds.Öğe Buji ateşlemeli motorda saf ve karışımlı alternatif yakıtların motor performansına ve emisyonlarına etkilerinin sayısal ve deneysel incelemesi(Kırıkkale Üniversitesi, 2016) Yontar, Ahmet Alper; Doğu, YahyaBu doktora tez çalışmasında buji ateşlemeli bir motorda saf ve karışımlı yakıt kullanımının motor performansı ve egzoz emisyonlarına etkileri sayısal ve deneysel olarak incelenmiştir. Saf yakıt olarak benzin, CNG, LPG ve karışımlı yakıt olarak benzin-CNG ve benzin-LPG kullanılmıştır. İncelemede; deneysel yöntem yanında, 1-boyutlu modelleme ve 3-boyutlu modelleme olmak üzere iki adet sayısal yöntem kullanılmıştır. Çalışmanın deneysel kısmında, ticari bir motorun bağlı olduğu motor test düzeneğinde saf ve karışımlı yakıtlar için motor performans parametreleri ve egzoz emisyonları ölçülmüştür. Bu amaçla, çalışamaz durumda olan laboratuvardaki motor test düzeneği üzerinde birçok işlem gerçekleştirilerek motor test düzeneği çalışır hale getirilmiştir. Test düzeneği, değişik saf yakıtların ve karışımlı yakıtların kullanımı ve testi için uyarlanmıştır ve testler gerçekleştirilmiştir. Motorun benzin, CNG, LPG, benzin-CNG ve benzin-LPG ile kullanım testleri yapılmış, performans ve emisyon ölçümleri tamamlanmıştır. Sayısal çalışmalarda ise deneysel çalışmadaki motor ve test düzeneği Wave programı ile 1-boyutlu olarak modellenmiştir. Ayrıca, Star-CD programı ile motorun silindir-piston sistemi 3-boyutlu modellenerek silindir içi yanma modeli oluşturulmuş ve HAD (Hesaplamalı Akışkanlar Dinamiği) analizleri yapılmıştır. Test, 1-boyutlu model ve 3-boyutlu model sonuçlarının birbiri ile oldukça yakın ve benzerlik içinde olduğu gözlenmiştir. Sonuçlardaki kısmi farklılıkların ise modellemelerdeki idealize kabuller ile testlerdeki kontrol edilemeyen gerçek şartlar arasındaki farklardan kaynaklandığı söylenebilmektedir. Genel sonuç olarak, benzine göre CNG ve LPG kullanımının motor performans parametrelerini düşürdüğü ve egzoz emisyonlarını iyileştirdiği gözlenmiştir. Karışımlı yakıtların ise performans ve egzoz emisyonları açısından değişken sonuçlar verdiği belirlenmiştir. Tüm elde edilen sonuçlar ve gözlemler incelenen tüm yakıtlar için test ve model sonuçları olarak detaylı bir şekilde verilmiş ve yorumlanmıştır.Öğe Effects of equivalence ratio and CNG addition on engine performance and emissions in a dual sequential ignition engine(SAGE PUBLICATIONS LTD, 2020) Yontar, Ahmet Alper; Doğu, YahyaCompared to widening usage of CNG in commercial gasoline engines, insufficient but increasing number of studies have appeared in the open literature during last decades, while engine characteristics need to be quantified in exact numbers for each specific fuel and engine. CNG usage in spark-ignition engine offers many advantages such as high specific power outputs, knock resistance, and low CO(2)emission. Engine performance and emissions are strong functions of equivalence ratio. This study focuses on determination of the effects of equivalence ratio on engine performance and emissions for a unique commercial engine for three fuels of gasoline, CNG, and gasoline-CNG mixture (90%-10%: G9C1). For this aim, the tests and the three-dimensional in-cylinder combustion computational fluid dynamics analyses were employed in quantification of engine characteristics at wide open throttle position. Equivalence ratios were defined between 0.7 and 1.4. The engine's maximum torque speed of 2800 r/min was examined. The tested commercial engine is an intelligent dual sequential ignition engine which has unique features such as diagonally positioned two spark-plugs, dual sequential ignition with variable timing and asymmetrical combustion chamber. This gasoline engine was equipped with an independent CNG port-injection system and a specific engine control unit for CNG. In addition, the engine test system has a concomitant dual fuel delivery system that supplies gas fuel into intake airline while liquid gasoline is injected behind the intake valve. Other than testing the engine, the three-dimensional in-cylinder combustion computational fluid dynamics analyses were performed in Star-CD/es-ice software for the three fuels. The CFD model was built by using renormalization group equations, k-epsilon turbulence model, and G-equation combustion model. Computational fluid dynamics analyses were run for the compression ratio of 10.8:1, equivalence ratio of 1.1, and engine's maximum torque speed of 2800 r/min. Test results show that brake torque for all fuels increases rapidly from the lean blend to the rich blend. The brake-specific fuel consumption for all fuels decreases from phi = 0.7 through the stoichiometric region and then slightly increases up to phi = 1.4. The volumetric efficiencies for three fuels have similar decreasing trend with respect to equivalence ratio. Overall, CNG addition decreases the performance values of torque, brake-specific fuel consumption, volumetric efficiency, brake thermal efficiency, while it decreases emissions of CO2, CO, HC, except NOx. Engine model results show that the maximum in-cylinder pressure is 72 bar at 722 crank angle degree (CAD), 68 bar at 730 CAD, and 60 bar at 735 CAD for gasoline, CNG, and G9C1, respectively. The cumulative heat release for gasoline is 9.09% higher than G9C1, while G9C1 is 15.71% higher than CNG. The CO(2)mass fraction for gasoline is about 22.58% lower than G9C1, while it is 40.32% higher than CNG. The maximum mass fraction value of CO is 0.21, 0.17, and 0.08 for gasoline, CNG, and G9C1, respectively. The CO for G9C1 is overall 60.04% lower than CNG and 67.45% lower than gasoline. At maximum point, HC for G9C1 is 31.43% and 71.43% higher than gasoline and CNG, respectively. CNG has the highest level of NO(x)formation. Maximum NO(x)mass fractions are 0.0098, 0.0070, and 0.0043 for CNG, G9C1, and gasoline, respectively. After the ignition, the flame development is completed at 1.07, 1.18, and 1. 28 ms for gasoline, G9C1, and CNG, respectively. Flame velocities are 28.52, 30.93, and 34.11 m/s for CNG, G9C1, and gasoline, respectively, at 2800 r/min and phi = 1.1. When the time between ignition moment and top dead center moment is considered, the increment rate of flame center temperature is 904.19, 884.10, and 861.77 K/s for CNG, gasoline, and G9C1, respectively. The highest temperature increment rate occurs for CNG.Öğe Experimental and numerical investigation of effects of CNG and gasoline fuels on engine performance and emissions in a dual sequential spark ignition engine(Taylor & Francis Inc, 2018) Yontar, Ahmet Alper; Doğu, YahyaCompared to widening usage of CNG in commercial gasoline engines, insufficient but increasing number of studies have appeared in open literature during last decades while engine characteristics need to be quantified in exact numbers for each specific fuel converted engine. In this study, a dual sequential spark ignition engine (Honda L13A4 i-DSI) is tested separately either with gasoline or CNG at wide open throttle. This specific engine has unique features of dual sequential ignition with variable timing, asymmetrical combustion chamber, and diagonally positioned dual spark-plug. Thus, the engine led some important engine technologies of VTEC and VVT. Tests are performed by varying the engine speed from 1500rpm to 4000rpm with an increment of 500rpm. The engine's maximum torque speed of 2800rpm is also tested. For gasoline and CNG fuels, engine performance (brake torque, brake power, brake specific fuel consumption, brake mean effective pressure), emissions (O-2, CO2, CO, HC, NOx, and lambda), and the exhaust gas temperature are evaluated. In addition, numerical engine analyses are performed by constructing a 1-D model for the entire test rig and the engine by using Ricardo-Wave software. In the 1-D engine model, same test parameters are analyzed, and same test outputs are calculated. Thus, the test and the 1-D engine model are employed to quantify the effects of gasoline and CNG fuels on the engine performance and emissions for a unique engine. In general, all test and model results show similar and close trends. Results for the tested commercial engine show that CNG operation decreases the brake torque (12.7%), the brake power (12.4%), the brake mean effective pressure (12.8%), the brake specific fuel consumption (16.5%), the CO2 emission (12.1%), the CO emission (89.7%). The HC emission for CNG is much lower than gasoline. The O-2 emission for CNG is approximately 55.4% higher than gasoline. The NOx emission for CNG at high speeds is higher than gasoline. The variation percentages are the averages of the considered speed range from 1500rpm to 4000rpm.Öğe Experimental investigation of effects of single and mixed alternative fuels (gasoline, CNG, LPG, acetone, naphthalene, and boron derivatives) on a commercial i-DSI engine(TAYLOR & FRANCIS INC, 2020) Dogu, Yahya; Yontar, Ahmet Alper; Kantaroglu, EmrahA commercial i-DSI (Intelligent-Dual Sequential Ignition) engine is tested to investigate performance and emissions for single fuels and alternative fuels mixed into gasoline. The novelty of the study is the first time testing of the unconventional mixture of boron derivatives and quantification and comparison of real engine characteristics for 11 different fuels for the same commercial engine. Tested single fuels are gasoline (G100), CNG (CNG100), and LPG (LPG100). While the engine runs with gasoline, gaseous fuels are injected into the intake line at a mass rate of 10% CNG (CNG10) and 5% LPG (LPG5). The engine is also tested by adding 25-50% acetone (A25-A50) and 50% naphthalene (N50) into gasoline. Tests are also performed by mixing boron derivatives of borax-pentahydrate (BP), anhydrous-borax (AB), and boric-acid (BA) into gasoline. Tested fuels worsen engine performance compared to gasoline, except for brake specific fuel consumption (BSFC). There is a positive change in emissions for tested fuels compared to gasoline, except that NOx increases 4-5 times for CNG and LPG. One of the important findings is that, for boron-gasoline mixtures, the torque reduces by 4.0% for BP, 4.4% for AB, and 4.4% for BA. The volumetric efficiency decreases by 6.3% for BP, 7.3% for AB, and 8.5% for BA. The BSFC decreases 5.8% for BP, increases 0.4% for AB and decreases 15.2% for BA. Boron derivatives dissolved in gasoline diversely affect combustion and give some advantage in particular for BA and BP in terms of BSFC. In addition, boron-gasoline reduces the formation of HC and NOx.Öğe Flame Radius Effects on a Sequential Ignition Engine Characteristics(2018) Yontar, Ahmet Alper; Doğu, YahyaThe effects of the flame radius and flame propagation have been investigated at a sequential ignition engine with numerically. A single cylinder of the sequential ignition engine was modeled in STAR-CD/es-ice software for the gasoline usage taking into account all components related to the combustion chamber. The effect of flame on engine characteristics is the function of flame radius and flame thickness. In the numerical analysis, compression ratio is 10.8:1, air-fuel ratio is 1.2, ignition advance at 30-25 CAD, engine speed is 3000 rpm and the flame thickness is 0.0001 m were kept constant. The analysis, k-? RNG turbulence model, Angelberger wall interaction and G-equation combustion model were used and optimum flame radius value was determined. Three different analysis were carried out to determine the effect of the flame radius and the flame radius was changed to 0.0005 m, 0.0010 m and 0.0020 m, respectively. As a result of the study, images of flame formation and propagation were obtained for the time period up to the top dead center at the time of sequential ignition. The effects of flame radius on CO2 formation and NOx formation were evaluated. The net work area was obtained from the highest engine power and pressure-volume graph when the flame radius was 0.0010 m for the specified operating conditions.Öğe Influence of acetone addition into gasoline for i-DSI engine(Springer India, 2022) Kantaroglu, Emrah; Yontar, Ahmet Alper; Dogu, YahyaDespite the notable properties of acetone due to its volatility and oxygen content as a fuel additive, very few studies have been limited to small size special purpose engines. A comparative testing and 3D in-cylinder combustion CFD studies are presented for acetone-gasoline blend in an i-DSI commercial car engine as the first time. The blends contain mass ratio of acetone by 0-2-5-10-20% (G100-A2-A5-A10-A20). In testing, torque reduced 0.33% (A2), 0.66% (A5), 0.84% (A10), and 1.45% (A20) compared to gasoline. The BSFC decreased by 0.27% (A2), 0.55% (A5), 0.79% (A10), and increased 0.26% (A20). Volumetric efficiency decreased by 3.2-6.4-5.1-11.5% for A2-A5-A10-A20. The CO emission for blends is less than gasoline by 1.5% (A2), 4.0% (A5), 15.2% (A10), and 33.6% (A20). The CO2 decreased 0.8% (A2), and increased 1.3% (A5), 4.6% (A10), and 11.4% (A20). The HC reduced by 7.0% (A2), 10.1% (A5), 23.8% (A10), and 34.4% (A20). The NOx formation increased by 3.6% (A2), 4.4% (A5), 27.6% (A10), and 87.8% (A20). Acetone addition decreased torque and slightly increased BSFC. CO and HC decreased while CO2 and NOx increased with increasing acetone ratio. Acetone indeed improves the combustion while its final effect on engine performance is not found to be favorable.Öğe Investigation of the effects of gasoline and CNG fuels on a dual sequential ignition engine at low and high load conditions(Elsevier Sci Ltd, 2018) Yontar, Ahmet Alper; Dogu, YahyaIn this study, a dual sequential spark ignition engine is separately tested either with gasoline or CNG at low and high loads. In addition, numerical engine analyses are performed by constructing a 1-D engine model in Ricardo-Wave software. Engine performance parameters in catalogue are generally given at full load conditions. However, during engine lifetime, vehicle engines rarely run at full load (wide open throttle) while engines work especially at the partial throttle openings. Engine characteristics (engine performance and exhaust emissions) are strong functions of throttle opening level. For this reason, determining engine characteristics at partial throttle openings at which engine mostly runs provides valuable information. In this study, partial throttle openings of 25% and 75% defined as low and high load conditions are examined for gasoline and CNG, as well. For this aim, the Honda L13A4 i-DSI (intelligent dual sequential ignition) engine was tested and engine characteristics were measured. This engine has unique features of dual sequential ignition with variable timing, asymmetrical combustion chamber, and diagonally positioned spark-plugs. Tests and numerical analyses were performed at specified low and high load conditions for gasoline and CNG by varying the engine speed from 1500 rpm to 4000 rpm with an increment of 500 rpm without excepting 2800 rpm. Engine characteristics were determined for the investigated parameters. Tests and 1-D model results are fairly matching each other. The average deviation between them is about 5.4%. Results show that the maximum torque for gasoline at 2800 rpm and 100% throttle opening reduced 12.6% and 26.3% for throttle openings of 75% and 25%, respectively. Compared to gasoline, CNG reduced the torque 15.6% and 19.6% for throttle openings of 75% and 25%, respectively. In general, CNG usage decreases all engine performance parameters (torque, power, volumetric efficiency, specific fuel consumption) and emissions (CO2, HC), except NOx formation.
