SEYFİ POLAT, AHMET UYUMAZ, DUYGU İPCİ, H. Serdar YÜCESU, HAMİT SOLMAZ, EMRE YILMAZ

Doğalgaz Yakıtlı HCCI Bir Motorda Hidrojen İlavesinin Yanma Karakteristikleri Üzerindeki Etkilerinin Nümerik Olarak İncelenmesi

Homojen dolgulu sıkıştırma ile ateşlemeli motorlar konvansiyonel içten yanmalı motorlarla karşılaştırıldığında yüksek termik verim, NOx ve is emisyonlarındaki eş zamanlı azalma avantajlarından dolayı yeni bir araştırma alanı olmuştur. HCCI motorlarda kendi kendine tutuşma zamanlaması üzerinde direkt kontrol olmadığından çalışma ve yük aralığı sınırlı kalmaktadır. Yanma işlemini etkileyen en önemli parametrelerden bazıları karışımın kompozisyonu ve yakıtın kimyasal özellikleridir. Bu çalışmada sıkıştırma oranı 10:1 olan doğal emişli, tek silindirli, dört zamanlı, dört supaplı, doğal gaz ile çalışan bir HCCI motorunda hidrojen ilavesinin yanma işlemi üzerindeki etkileri açık kaynak kodlu KIVA-4 yazılımı ile nümerik olarak incelenmiştir. Bu amaçla doğalgaz yakıtının içerisine %0, %10, %20, %30,%40, oranlarında hidrojen ilave edilerek beş farklı yakıt karışımı hazırlanmıştır. Bununla birlikte yanma analizi üç farklı hava fazlalık katsayısı değerinde (λ=1.5, λ=2, λ=2.5) gerçekleştirilmiştir. Sonuçta, hidrojen ilavesinin kendi kendine tutuşma zamanlaması, toplam yanma süresi, ısı dağılımı, silindir içi basınç ve silindir içi sıcaklık üzerindeki etkileri araştırılmıştır.

A Numerical Investigation of the Effects of Hydrogen Addition on Combustion Characteristics in a HCCI Engine Fueled With Natural Gas

Homogenous Charge Compression Ignition (HCCI) engines have become a new field of research because of high thermal efficiency compared to the internal combustion engines and reduction of NOx and particular matter emissions simultaneously. Operating and load range were limited as there is no direct control on the controlling auto-ignition timing and combustion process in the HCCI engines. Some of the most important parameters affecting the combustion process are the mixture composition and chemical properties of the fuel. In this study, the effects of hydrogen addition on combustion process were investigated numerically using open coded software KIVA-4 in a single cylinder, four-stroke, four-valve, naturally aspirated and compression ratio of 10:1 HCCI engine fuelled with natural gas. For this purpose, five different fuel mixtures were prepared by addition hydrogen into the natural gas at different rates 0% - 10% - 20% - 30% and 40%. In addition, combustion analysis was performed with three excessive air coefficient (λ=1.5, λ=2, λ=2.5). As a result, the effects of hydrogen addition were investigated on the self-ignition timing point, total combustion duration, heat release rate, in-cylinder pressure, cylinder temperature.

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