Abstract: 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 Tetradecane 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.

Key words: Aromatic hydrocarbon, Diesel engine, Gas chromatography-mass spectrometry, Paraffin hydrocarbon, Particulate matter, Soluble organic fraction