正丁醇/乙醇-汽油HCCI发动机的低温燃烧与排放特性

Combustion and Emission Characteristics of a HCCI Engine Fuelled with n-Butanol/Ethanol-Gasoline Blends

在一台单缸4冲程发动机上利用负气门重叠角方法,在转速为1 500,r/min、气门相位与升程不变的情况下,研究了不同掺醇比例下正丁醇-汽油与乙醇-汽油均质充量压缩着火(HCCI)发动机的燃烧与非常规排放特性.结果表明,随着掺醇比例的增加,HCCI发动机的着火时刻提前,燃烧持续期缩短,而且使用正丁醇-汽油时HCCI发动机的着火时刻更早,燃烧持续期更短,但平均指示有效压力(IMEP)呈下降趋势,而且使用正丁醇-汽油时HCCI发动机的IMEP与指示热效率更低.汽油中掺醇均会导致HCCI发动机的甲烷、甲醛、乙醛和乙烯排放增加,但芳香烃排放显著降低,而且在相同掺醇比例下,使用正丁醇-汽油时的甲烷和乙醛排放要低于使用乙醇-汽油时的值,而甲醛、乙烯和芳香烃排放则高于使用乙醇-汽油时的值.此外,在汽油中掺混乙醇,会减少HCCI发动机的丙烯排放,但是在汽油中掺混正丁醇,则会增加HCCI发动机的丙烯排放.

The combustion and emission characteristics of a homogeneous charge compression ignition（HCCI） engine fuelled with n-butanol/ethanol-gasoline blends were investigated on a single cylinder four stroke engine with the negative valve overlap at fixed intake/exhaust valve timing and lift at 1,500,r/min. Results show that with the increase of n-butanol/ethanol volume content in the blends,autoignition timing advances and combustion duration shortens,the autoignition timing for n-butanol-gasoline blend is earlier and combustion duration is shorter compared to that for ethanol-gasoline blend at the same alcohol volume content. However,indicated mean effective pressure（IMEP）decreases with alcohol volume content in the blend while IMEP and indicated thermal efficiency are lower for n-butanol-gasoline blend at the same alcohol content relative to those of ethanol-gasoline blend. The addition of alcohol to gasoline increases methane,formaldehyde,acetaldehyde,ethylene emissions and dramatically decreases aromatic emissions. Compared to ethanol-gasoline blend,methane and acetaldehyde emissions are lower while formaldehyde,ethylene and aromatic emissions are higher for the n-butanol-gasoline blend at the same alcohol content. In addition,the ethanol-gasoline blend induces a reduction in propylene emissions,but for the n-butanol-gasoline blend,an increase is observed.