Abstract
In present experimental work, comparative study between supercritical (SC) spray combustion and normal diesel impinging spray combustion is done at direct injection diesel engine-type operating conditions inside cylindrical constant volume combustion chamber. Ranges of hot surface temperature (623–723 K), cylinder air pressure (20–40 bar) and 200 bar fuel injection pressure are chosen. Commercial diesel fuel is used for normal spray combustion study. Dieseline blend having 50% diesel and 50% gasoline by volume is used for producing homogeneous SC sprays. Quantitative study is done between normal diesel spray combustion (non-supercritical) and homogeneous SC spray combustion in terms of soot formation characteristics. Photo transducer (sensor) is employed to indicate whole combustion process on digital four channel scopemeter. Soot formation is estimated as time integrated natural luminosity with the help of scopemeter’s image. Soot formation is characterized through time integrated natural luminosity values. In case of normal diesel impinging spray combustion, soot formation is found to reduce with increase in hot surface temperature and cylinder air pressure. Soot formation decreases with increase in hot surface temperature and cylinder air pressure in SC fuel spray combustion. Soot formation in SC fuel spray combustion is found to be substantially smaller as compared to soot formation in normal diesel spray combustion (percentage reduction is more than 80% at all operating conditions). SC spray combustion system is observed to be a clean combustion for future automotive engines.
