柴油烃族组分对柴油机排放的影响

柴油烃族组分可影响柴油的理化特性,从而影响柴油机的燃烧过程,进而对排放产生重要影响.本研究针对烃族组分含量不同的14种柴油,开展了排放特性的试验研究,基于试验结果采用主成分分析法及回归分析法揭示影响柴油机排放性能的关键组分及作用规律,并得到了柴油机排放与关键组分的经验公式,可在一定程度上预测排放特性.分析结果表明,总芳烃是影响柴油机排放的关键组分,当其含量介于5%～17%时,可使NO_x、soot(碳烟)、CO、HC排放均处于较低水平.此外,多环芳烃对柴油机排放有重要影响,其中的苊类、苊烯类对NO_x、碳烟、CO排放的影响作用更为显著,而其他烃族组分与柴油机排放的规律性相对较差.不同工况下,柴油机排放规律有所不同,在低负荷下柴油机排放对总芳烃含量更加敏感.

Effect of diesel hydrocarbon group components on diesel engine emissions

The hydrocarbon group components of diesel oil have an influence on the physical and chemical properties of diesel oil, thus affecting the combustion process of diesel engine and then have an important impact on emissions. In this study, the experiment on emission characteristics was performed using 14 kinds of diesel oil with different hydrocarbon group contents. Based on the results, principal component analysis and regression analysis were used to reveal the key components and relationships of influence on the emission performance of diesel engine. The empirical formulas of diesel engine emissions and key components were obtained, by which the emission characteristics can be predicted to a certain extent based on diesel fuel components. The analytic results show that total aromatics are the key components to affect diesel engine emissions. When the content of total aromatics is between 10% and 17%, the emissions of NO_x, soot, CO and HC are at a low level. In addition, polycyclic aromatic hydrocarbons (PAHs) have an important influence on diesel engine emission, among which alicyclic hydrocarbon and acenaphthylene have more significant effects on NO_x, soot and CO emissions. However, the regularity of other hydrocarbon group components and diesel engine emission is relatively poor. Under different engine load conditions, the emissions of diesel engine behave differently. Diesel engine emission is more sensitive to the total aromatic content under the low load.