Hekzan ve N-Heptan Yakıt Karışımları ile Çalışan Homojen Dolgulu Sıkıştırma İle Ateşlemeli (HCCI) Bir Motorda Hava Fazlalık Katsayısının Yanma ve Motor Performansı Üzerindeki Etkileri

Homojen dolgulu sıkıştırma ile ateşlemeli motorlar düşük sıcaklık yanma eğilimine ve yüksek termik verime sahip motorlardır. Yanma üzerinde doğrudan kontrolün olmadığı bu motorların çalışma aralığı vuruntu ve tutuşamama problemleri nedeniyle sınırlandırılmaktadır. Bu noktada silindire alınan karışım kompozisyonu ve farklı çalışma parametreleri ile özellikle yüksek yüklerde vuruntu probleminin ortadan kaldırılması amaçlanmaktadır. HCCI yanması motor çalışma parametrelerinden oldukça etkilenmektedir. Bu çalışmada tek silindirli dört zamanlı, buji ile ateşlemeli bir motor homojen dolgulu sıkıştırma ile ateşlemeli motora dönüştürülmüştür. Deney motoru hekzan ve n-heptan yakıt karışımları ile 1400 d/d’da, 1.9 ile 2.74 hava fazlalık katsayısı (HFK) değerleri arasında, tam yükte HCCI yanma modunda çalıştırılmıştır. Hekzan yakıtının silindir basıncı, ısı dağılımı, silindir içi sıcaklık, yanma süresi, yanma başlangıcı, çevrimsel farklılıklar, vuruntu yoğunluğu, indike ortalama efektif basınç (imep), termik verim ve emisyonlar (HC ve CO) üzerindeki etkileri deneysel olarak incelenmiştir. Sabit emme havası giriş sıcaklığında yapılan deneylerde hava fazlalığı arttıkça silindir basıncınıngenişletilebileceği görülmüştür.

Anahtar Kelimeler:

Hava Fazlalık Katsayısı; Hekzan; Homojen Dolgulu Sıkıştırma İle Ateşlemeli Yanma; Motor Performansı

Effects of Air Excess Ratio on Combustion and Engine Performance in a Homogeneous Charge Compression Ignition Engine fuelled with Hexane and N-Heptane Fuel Mixtures

Homogeneous charge compression ignition engines are engines with low temperature combustion tendency and high thermal efficiency. The operating range of these engines, where there is no direct control over combustion, is limited because of knock and misfire problems. At this point, it is aimed to eliminate the knocking problem especially at high loads with the mixture composition taken into the cylinder and different operating parameters. HCCI combustion is highly affected by engine operating parameters. In this study, a single-cylinder four-stroke spark-ignition engine was converted to a homogeneous charge compression ignition engine. The test engine was operated with hexane and n-heptane fuel mixtures at 1400 rpm and between 1.9 and 2.74 air excess ratio in full load HCCI combustion mode. The effects of hexane fuel on cylinder pressure, heat release rate, in-cylinder temperature, combustion duration, start of combustion, cyclic variations, knock density, indicated mean effective pressure (imep), thermal efficiency and emissions (HC and CO) were investigated experimentally. In the experiments carried out at constant intake air inlet temperature, it was observed that the cylinder pressure and heat release rate decreased with increasing air excess ratio. As a result, HCCI combustion was found to be highly affected by air excess ratio and fuel composition. It has also been found that the range of operation can be extended in the knock boundary zone in HCCI combustion.

Keywords:

Air Fuel Ratio; Hexane; Homogeneous Charge Compression Ignition; Engine Performance,

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[1] Zhao, H., (2007). HCCI and CAI Engines for the Automotive Industry, London, England: Woodhead Publishing Limited, 5-15.
[2] Heywood, J.B., (1988), Internal Combustion Engines Fundamentals, New York, USA: McGraw-Hill, 3-20.
[3] Eng J. A., Characterization of Pressure Wave Oscillation in HCCI Combustion, SAE Technical Paper, 2002-01-2859, (2002).
[4] Stone, R., (1999), Introduction to Internal Combustion Engines, Macmillan Press Ltd, ISBN 0-333-74013- 0, Tesseraux, I.; Toxicoll, Lett., 149, 295-300.
[5] He, B-Q., Yuan, J., Liu M-B, Zhao H., Combustion and emission characteristics of a n-butanol HCCI engine, Fuel, 115: 758–64, (2014).
[6] Benajes, J., Molina, S., García, A., Belarte, E., Vanvolsem, M., An investigation on RCCI combustion in a heavy duty diesel engine using incylinder blending of diesel and gasoline fuels, Applied Thermal Engineering, 63, 66-76, (2014).
[7] Kokjohn, SL, Hanson, RM, Splitter, DA, RD., Experiments and modeling of dual-fuel HCCI and PCCI combustion using in-cylinder fuel blending, SAE Technical Paper, 2009-01-2647, (2009).
[8] Can O., Cinar C., Sahin F., Effects of Premixed Gasoline Charge on HCCI-DI Engine Combustion and Exhaust Emissions, Journal of the Faculty of Engineering and Architecture of Gazi University, 24, 2, 229-236, (2009).
[9] Tsurushima, T., A new skeletal PRF kinetic model for HCCI combustion, Proceedings of the Combustion Institute, 32: 2835-2841, (2009).
[10] Splitter D., Reitz R., Hanson R., High efficiency, low emissions RCCI combustion by use of a fuel additive, SAE International, 2010-01-2167, (2010).
[11] Polat, S, An experimental study on combustion, engine performance and exhaust emissions in a HCCI engine fuelled with diethyl ether–ethanol fuel blends. Fuel Processing Technology, 143: 140-150, (2016).
[12] Dempsey. A., Walker, N., Gingrich, E., Reitz, RD., Comparison of Low Temperature Combustion Strategies For Advanced Compression Ignition Engines With a Focus on Controllability. Combustion Science Technology, 86, 2, 210-41, (2014).
[13] Solmaz, H., Combustion, Performance and Emission Characteristics of Fusel Oil in a Spark Ignition Engine. Fuel Processing Technology, 133, 20-28, (2015).
[14] Splitter, D., Wissink, M., DelVescovo, D., Reitz, R., RCCI Engine Operation Towards 60% Thermal Efficiency. SAE International, 2013-01-0279, (2013).
[15] Hanson, R., Reitz, R., Transient RCCI Operation in a Light-Duty Multi-Cylinder Engine. SAE Technical Paper, 2013-24-0050, (2013).
[16] Reitz, R.D., Duraisamy, G., Review of High Efficiency and Clean Reactivity Controlled Compression ignition (RCCI) Combustion in Internal Combustion Engines. Progress in Energy and Combustion Science, in-press. 1-60, (2014).
[17] Uyumaz, A. An experimental investigation into combustion and performance characteristics of an HCCI gasoline engine fueled with n-heptane, isopropanol and n-butanol fuel blends at different inlet air temperatures. Energy Conversion and Management, 98, 199-207, (2015).
[18] Çınar, C., Uyumaz, A., Solmaz, H., Şahin, F., Polat, S., Yılmaz, E., Effects of intake air temperature on combustion, performance and emission characteristics of a HCCI engine fueled with the blends of 20% n-heptane and 80% isooctane fuels, Fuel Processing Technology, 130, 275–281, (2015).
[19] Çınar, C., Uyumaz, A., Solmaz, H., Topgül, T., Effects of valve lift on the combustion and emissions of a HCCI gasoline engine, Energy Conversion and Management, 94, 159–168, (2015).
[20] Çınar, C., Uyumaz, A., Polat, S., Yılmaz, E., Can, Ö., Solmaz, H., Combustion and performance characteristics of an HCCI engine utilizing trapped residual gas via reduced valve lift, Applied Thermal Engineering, 100, 586–594, (2016).
[21] Uyumaz, A., Solmaz, H., Boz, F., Yilmaz, E., Polat, S., Reaktif Kontrollü Sıkıştırma İle Ateşlemeli (RCCI) Bir Motorda Lamdanın Yanma Karakteristiklerine Etkileri, Afyon Kocatepe Üniversitesi Fen ve Mühendislik Bilimleri Dergisi, 17, 1146-1156, (2017).
[22] Polat, S., Yücesu, H.S., Kannan, K., Uyumaz, A., Solmaz, H., Shahbakhti, M., Experimental Comparison of Different Injection Timings in an HCCI Engine Fueled with N-Heptane, International Journal of Automotive Science and Technology, 1, 1, 1-6 (2017).
[23] Uyumaz, A., Solmaz, H., Emme Havası Giriş Sıcaklığı ve Ön Karışımlı Yakıt Oranının RCCI Yanma Karakteristiklerine ve Motor Performansına Etkileri, Politeknik Dergisi, 20 (3) : 689-698, (2017).
[24] Uyumaz, A., Çınar, C., (2015). Understanding the Effects of Residual Gas Trapping on Combustion Characteristics, Engine Performance and Operating Range in a HCCI Engine, Proceedings of 48th The IIER International Conference, 21-27, Barcelona Spain.