Analysis of particulate matter composition from a heavy-duty diesel engine

Abstract

In order to control particulate matter (PM) in the exhaust of diesel-powered automobiles, a better understanding of the components of PM is required. In this report, the ECE R49 13-mode engine test cycle was performed on a heavy-duty diesel engine. Unlike the usual ECE R49 13-mode sample method, PM in the exhaust was separately sampled in this research under every test mode. Oxides of nitrogen (NOx) in the exhaust were also measured. Soluble organic fraction (SOF) and insoluble fraction (ISF) of the PM were partitioned with an ultrasonic elution, and then every SOF sample was analysed by combined gas chromatography / mass spectrometry (GC / MS). The results show that the mass flux of PM increases with increasing engine loads, and there is an exponential growth function between the PM mass flux and the engine power under the same engine speed. Concerning the engine's NOx emissions, there is an exponential decay function between the concentration of NOx and engine power. By comparing the results obtained, the effects of load and speed on the contents of ISF and SOF in PM were observed. The percentages of ISF and SOF contents in PM are markedly changed with the load, but are less influenced by the speed at the same percentage of load. The dominant component in SOF is paraffin hydrocarbon and second is polycyclic aromatic hydrocarbon (PAH). The percentage of PAH content in PM is higher at lower loads. In addition, naphthalene and phenanthrene are the main organic components of PAH.