乙醇-汽油燃料汽油机非常规污染物的排放特性

以90#无铅汽油为基础油，按照体积分数5％、10％、15％和20％的甲基叔丁基醚-汽油混合燃料中的氧含量，配制出相应氧含量的乙醇-汽油混合燃料．利用气相色谱技术，分析研究了电喷汽油机燃用不同掺混比乙醇-汽油混合燃料时的非常规排放特性，以及三效催化器对其的净化效率．研究结果表明，在不改变汽油机任何参数的情况下，随着乙醇掺混比的增大，苯的排放量明显降低，尤其当乙醇体积分数为9．826％时，最大降幅接近50％；同时对甲醛排放也有改善作用，但排气中的乙醛和未燃乙醇浓度却相应增加．三效催化器对苯和甲醛的净化效率较高，其中苯的平均净化效率为87％，催化后排气中未检测出甲醛，而对乙醛和乙醇的净化效率相对较低.

Unregulated Emissions from Gasoline Engine Using Ethanol-Blended Gasoline as Fuels

Referring to the oxygen concentrations in the mixture of gasoline with 5%, 10% ,15% and 20% methyl tertiary butyl ether(MTBE) respectively, ethanol anhydrous(EA) was mixed into 90# unleaded gasoline. Using gas chromatography, the effects of ethanol blended gasoline on unregulated emissions from an electronic fuel in-jection(EFI) gasoline engine without modification and the catalytic conversion efficiencies were investigated. The experimental results indicated that with the increase of ethanol concentration in the blended fuels, the benzene emission was drastically reduced ( the max reduction level is 50 % when the ethanol concentration is 9.826%) , and formaldehyde emission was also reduced. Contrastively, engine-out acetaldehyde and unburned ethanol emissions were increased due to ethanol addition to gasoline. Three-way catalyst was effective to reduce benzene and formaldehyde emissions, while acetaldehyde and ethanol were the most resistant compounds to oxidation. The average catalytic conversion efficiency of benzene exceeded 87%, and there was no formaldehyde detected in the tailpipe after the catalyst operation.