Reaktif kontrollü sıkıştırma ile ateşlemeli (RCCI) bir motorda doğalgaz yakıtının yanma ve performans üzerindeki etkilerinin incelenmesi
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Tarih
2024
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Hitit Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Son zamanlarda yapılan birçok çalışma, Reaktivite Kontrollü Sıkıştırma Ateşleme (RCCI) motorların diğer içten yanmalı motorlara kıyasla daha iyi termal verimlilik, ultra düşük nitrojen oksit (NOx) ve is emisyonlarına sahip düşük sıcaklıkta bir yanma stratejisi olduğunu göstermektedir. Bu motorda kullanılacak yakıt türleri ise hem çevreci hem de yüksek verim sağlayacak ekonomik yakıt çifti olmalıdır. Konvansiyonel fosil yakıt türü olan petrol rezervlerinin gün geçtikçe azalması ve kanunlar ile belirlenen egzoz emisyon değerlerinin katı bir şekilde azaltılması, içten yanmalı motorlarda alternatif yakıt arayışlarına sebep olmaktadır. Doğal gaz yakıtı diğer fosil yakıtlar ile kıyaslandığında emisyon değerleri daha düşük, rezerv miktarı ise oldukça yüksektir. Fakat oktan sayısının yüksek olması konvansiyonel içten yanmalı motorlarda yanma verimi azaltacağı için bir takım sorunlara sebep olmaktadır. RCCI yanma stratejisi ile çalışan bir motorda hem yüksek reaktiviteye hem de düşük reaktiviteye sahip iki yakıt kullanıldığı için bu sorun ortadan kalkmaktadır. Çift yakıt teknolojisi ile yanma başlangıcı ve yanma sürecinin kontrolü kolaylaşmaktadır. Emme portundan düşük reaktiviteye sahip yakıt ile hava karıştırılarak silindir içerisine alınmakta, sıkıştırılan yakıt ve hava karışımı üzerine enjektörden yüksek reaktiviteye sahip yakıtı püskürtülerek yanma gerçekleşmektedir. Bu çalışma, Reed Hanson ve ark. tarafından literatüre kazandırılmış olan Fuel Effects on Reactivity Controlled Compression Ignition (RCCI) Combustion at Low Load isimli deneysel çalışma ile valide edilmiştir. Bu çalışmaya göre 4 zamanlı tek silindirli 2.44 L hacminde, Caterpillar 3401E SCOTE motorunun RCCI yanma modunda modellemesi yapılmıştır. Düşük reaktiviteli yakıt olarak Metan, yüksek reaktiviteli yakıt olarak ise Heptan tercih edilmiştir. Converge CFD programı kullanılarak farklı lambda değerlerinde giriş havası basınç artışının, motor hızındaki artışın ve port/enjeksiyon yakıt oranındaki değişikliğin yanma üzerindeki etkilerini incelenmiştir. Sabit 800 rpm motor hızında giriş basıncının artması ile paralel olarak lambda değerinin azalması yanma olayına olumlu katkılar sağlamakta iken tam tersi durumda yanma kötüleşmekte ve verim azalmaktadır. Sabit 1.5 bar giriş hava basıncında motor hızının 2200 rpm değerine kadar arttığı durumlarda lambda değerinin azalması motor verimini artırmakta, 2200 rpm üzrinde ise bütün lambda değerlerinde verimin azaldığı görülmektedir. Sabit 1.5 bar giriş hava basıncında ve 800 rpm motor hızında ise enjektör yakıt oranının artırılması bütün lambda değerlerinde verimin arttığını göstermektedir.
Many recent studies show that Reactivity Controlled Compression Ignition (RCCI) engines are a low-temperature combustion strategy with better thermal efficiency, ultra-low nitrogen oxide (NOx) and soot emissions compared to other internal combustion engines. The type of fuel to be used in this engine must be both environmentally friendly and economical fuel that will provide high efficiency. The decreasing amount of oil reserves, which is a type of conventional fossil fuel, and the strict reduction of exhaust emission values determined by law, lead to the search for alternative fuels in internal combustion engines. Compared to other fossil fuels, natural gas fuel has lower emission values and a higher reserve amount. However, a high octane number causes some problems in conventional internal combustion engines as it reduces combustion efficiency. This problem is eliminated because two fuels with both high reactivity and low reactivity are used in an engine operating with the RCCI combustion strategy. With dual fuel technology, the start of combustion and control of the combustion process becomes easier. Low reactivity fuel and air are mixed through the intake port and taken into the cylinder, and combustion occurs by spraying high reactivity fuel from the injector onto the compressed fuel and air mixture. This study was carried out by Reed Hanson et al. It was validated by the experimental study titled Fuel Effects on Reactivity Controlled Compression Ignition (RCCI) Combustion at Low Load, which was introduced to the literature by. According to this study, the 4-stroke single cylinder, 2.44 L volume, Caterpillar 3401E SCOTE engine was modeled in RCCI combustion mode. Methane was preferred as the low-reactivity fuel, and Heptane was preferred as the high-reactivity fuel. Using the Converge CFD program, the effects of inlet air pressure increase, engine speed increase and change in port/injection fuel ratio on combustion at Lambda values were examined. While the decrease in the Lambda value in parallel with the increase in inlet pressure at a constant 800 rpm engine speed makes positive contributions to the combustion event, in the opposite case, combustion worsens and efficiency decreases. In cases where the engine speed increases up to 2200 rpm at a constant 1.5 bar inlet air pressure, decreasing the Lambdavalue increases the engine efficiency, and it is observed that the efficiency decreases at all Lambda values above 2200 rpm. At a constant 1.5 bar inlet air pressure and 800 rpm engine speed, increasing the injector fuel ratio shows that efficiency increases at all Lambda values.
Many recent studies show that Reactivity Controlled Compression Ignition (RCCI) engines are a low-temperature combustion strategy with better thermal efficiency, ultra-low nitrogen oxide (NOx) and soot emissions compared to other internal combustion engines. The type of fuel to be used in this engine must be both environmentally friendly and economical fuel that will provide high efficiency. The decreasing amount of oil reserves, which is a type of conventional fossil fuel, and the strict reduction of exhaust emission values determined by law, lead to the search for alternative fuels in internal combustion engines. Compared to other fossil fuels, natural gas fuel has lower emission values and a higher reserve amount. However, a high octane number causes some problems in conventional internal combustion engines as it reduces combustion efficiency. This problem is eliminated because two fuels with both high reactivity and low reactivity are used in an engine operating with the RCCI combustion strategy. With dual fuel technology, the start of combustion and control of the combustion process becomes easier. Low reactivity fuel and air are mixed through the intake port and taken into the cylinder, and combustion occurs by spraying high reactivity fuel from the injector onto the compressed fuel and air mixture. This study was carried out by Reed Hanson et al. It was validated by the experimental study titled Fuel Effects on Reactivity Controlled Compression Ignition (RCCI) Combustion at Low Load, which was introduced to the literature by. According to this study, the 4-stroke single cylinder, 2.44 L volume, Caterpillar 3401E SCOTE engine was modeled in RCCI combustion mode. Methane was preferred as the low-reactivity fuel, and Heptane was preferred as the high-reactivity fuel. Using the Converge CFD program, the effects of inlet air pressure increase, engine speed increase and change in port/injection fuel ratio on combustion at Lambda values were examined. While the decrease in the Lambda value in parallel with the increase in inlet pressure at a constant 800 rpm engine speed makes positive contributions to the combustion event, in the opposite case, combustion worsens and efficiency decreases. In cases where the engine speed increases up to 2200 rpm at a constant 1.5 bar inlet air pressure, decreasing the Lambdavalue increases the engine efficiency, and it is observed that the efficiency decreases at all Lambda values above 2200 rpm. At a constant 1.5 bar inlet air pressure and 800 rpm engine speed, increasing the injector fuel ratio shows that efficiency increases at all Lambda values.
Açıklama
Hitit Üniversitesi, Lisansüstü Eğitim Enstitüsü
