Hava Fazlalık Katsayısı ve Oktan Sayısı Değişiminin HCCI Yanma Karakteristiklerine ve Motor Performansına Etkileri

Year 2019, Volume: 22 Issue: 3, 607 - 618, 01.09.2019

Alper Calam , Yakup İçingür

https://doi.org/10.2339/politeknik.444377

Cited By: 5

Abstract

Homojen dolgulu sıkıştırma ile ateşlemeli
(HCCI) motorlar yüksek termik verimleri ve düşük egzoz emisyonları nedeniyle
mevcut içten yanmalı motorlara alternatif bir yanma modelidir. Bu çalışmada, port tipi
enjeksiyonlu, tek silindirli bir HCCI motorda hava fazlalık katsayısının ve
oktan sayısının HCCI yanması üzerine etkileri deneysel olarak incelenmiştir.
Deneyler tam yük şartlarında, 60 ^oC emme havası giriş sıcaklığında
ve 800 min^-1 motor hızında yapılmıştır. Ayrıca deneyler farklı hava
fazlalık katsayılarında yapılmıştır. Oktan sayısının artırılması ile maksimum
silindir içi basıncın oluşum noktası daha geç krank açılarında gerçekleşmiştir.
Oktan sayısının artırılması yanma süresinin uzamasına neden olmuştur. Hava/
yakıt oranının artması basınç artış oranını azaltmıştır. Hava/yakıt oranının
azaltılması silindir içerisine sürülen enerji miktarını artırmıştır. Böylece en
yüksek silindir içi basınçlar bu şartlar altında elde edilmiştir. En yüksek
indike termik verim RON60 yakıtı kullanımında, hava yakıt oranının 2,14 olduğu
şartlarda % 40,6 olarak tespit edilmiştir. Hava yakıt oranının azaltılması
yanmanın erken gerçekleşmesini sağlamıştır. Bu nedenle net iş azalmıştır.
Böylece indike termik verim de azalmıştır.

Keywords

Hava yakıt oranı, HCCI, yanma, RON20, RON60, egzoz emisyonları

The Effects of Air Fuel Ratio and Octane Number on HCCI Combustion and Engine Performance Characteristics

Abstract

Homogeneous compression ignition (HCCI) engines are an alternative
combustion model to existing internal combustion engines due to their high
thermal efficiency and low exhaust emissions. In this study, the effects of air
fuel ratio and octane number on combustion and engine performance
characteristics were investigated with port type injection single cylinder HCCI
engine. Experiments were carried out at full load conditions, intake
temperature of 60 ^oC and 800 rpm engine speed. Also, experiments
were carried out with different air excess coefficients. The maximum
in-cylinder pressure occured at a later crank angle by increasing the number of
octane. Increasing the octane number has caused the increase of the combustion
duration. The increase of air fuel ratio decreases the pressure rise rate.
Decreases of air fuel ratio has increased the amount of injected energy to the
cylinder. So that, the highest in-cylinder pressures are obtained under these
conditions. The highest indictical thermal efficiency 40.6 %, provided that the
air fuel ratio was 2.14 with using RON60 fuel. Decreases of air fuel ratio
caused the combustion advance. For this reason net work decreased. Thereby,
indicated thermal efficiency decreased.

Keywords

Air fuel ratio, HCCI, combustion, RON20, RON60, exhaust emissions

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