柴油机排气微粒可溶有机组分的色谱质谱分析

采用超声洗脱法对柴油机排气微粒中可溶有机组分SOF和不可溶组分IOF进行了分离,利用色谱—质谱联用技术对其中SOF的成分进行了分析。结果表明,怠速及中低负荷工况下SOF的排放量较低,随着负荷上升其排放量逐渐增加,在最大扭矩和标定转速工况下达到最高。SOF中最大的组分为烷烃,其次是芳香烃;烷烃中大部分为正烷烃,芳香烃以萘族和菲族等多环芳香烃为主。芳香烃的排放量随着负荷的上升而增加。SOF烷烃碳原子数分布的研究表明,低负荷工况下,燃油中易燃的正十四烷～正十七烷的绝大部分被烧掉,SOF中有些成分不是直接来自燃油,而是来自润滑油或燃油聚合反应的中间产物;高负荷工况下,供油量较多导致一部分正十四烷～正十七烷来不及燃烧就排出机外,SOF中还有些成分则是燃油高温裂解的产物。SOF芳香烃碳原子数分布的研究表明,高负荷工况下高碳原子数的芳香烃大都被烧掉,怠速及低负荷工况下SOF芳香烃化合物的种类相对较多。

ANALYSIS OF SOLUBLE ORGANIC FRACTION IN PARTICULATE MATTER FROM A DIESEL ENGINE BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Soluble organic fraction (SOF) and insoluble organic fraction (IOF) in particulate matter (PM) emission from diesel engine are separated by supersonic elution. The SOF in PM is analyzed by combined gas chromatography/mass spectrometry. Experiments are carried out in a six-cylinder, turbo-charged and intercooled, direct injection diesel engine. A typical 13-mode operating conditions test cycle is performed on the diesel engines. PM emissions from the diesel engine at the thirteen operating conditions are collected. The analysis results show the SOF emission is lower at lower loads, and rises with increasing loads. The dominant component in the SOF is the paraffin hydrocarbon, secondly, is the aromatic hydrocarbon. The majority of paraffin hydrocarbon is the linear paraffin hydrocarbon. The greater parts of aromatic hydrocarbon are the naphthalene and phenanthrene. The aromatic hydrocarbons emission rises with increasing loads. Research results of C atomicity in paraffin hydrocarbons show the linear paraffin hydrocarbons (from Tet-radecane to Heptadecane) are almost burned up at lower loads, and some components of the SOF are not directly from fuel, but from lubricant oil or middle polymerization products of fuel. More fuel supply leads to more paraffin hydrocarbons emission at higher loads, and some components of the SOF are from fuel decomposing at high temperature. Research results of C atomicity in aromatic hydrocarbons show most of aromatic hydrocarbons have higher C atomicity are burned up at higher loads, and more compounds of aromatic hydrocarbons are seen at lower loads.