A single-cylinder DI diesel engine experiment was conducted in order to investigate the effects of cetane number and fuel properties on diesel emissions, especially particulate matter (PM) emission and poly-nuclear aromatic hydrocarbons (PAHs) emissions. Normal paraffin fuel and iso-paraffin fuel were used to prepare the base fuel. By adding a cetane number improver, aromatic compounds and heavy fraction to base fuel, various test fuels were prepared to investigate the effects of cetane number, aromatic compounds, heavy fractions on emissions independently. PAHs in soluble organic fraction (SOF) were measured using HPLC/UV method. As a result, increase of cetane number and aromatic compounds of fuel caused larger soot emission. Addition of heavy fraction to fuel produced higher soluble organic fraction (SOF) in PM. It is considered that PAHs were produced mainly from PAHs from unburned fuel. The experimental result using commercialized gas oil support this investigation. Also, aromatic compounds could have little effect on the in-cylinder formation of PAHs. This result suggests that pathway to produce PAHs is different from that to produce soot. Results of unburned hydrocarbon (THC) emission, carbon mono-oxide (CO) emission and oxides of nitrogen (NOx) emission corresponded to previous studies.
Exhaust emission, Diesel fuel, Cetane number improver, Particulate matter, Poly-nuclear aromatic hydrocarbon