Abstract
Environmental and human health concerns over emissions from internal combustion engines continue to bring about increasingly stringent emissions standards and drive research into the use of non-conventional, cleaner-burning fuels. For compression-ignition (diesel) engines, oxygenated fuels have been shown to dramatically reduce particulate matter (PM) while also improving or maintaining acceptable levels of other regulated emissions (NO,, HC and CO). The mechanisms through which oxygenates reduce PM, however, are not fully understood. In addition to changes in combustion chemistry, the influence of thermophysical properties on fuel injection and fuel-air mixing can play a significant role. To gain further insight into the effect of oxygenates on diesel engine PM emissions, Accelerator Mass Spectrometry (AMS) was used to investigate the relative contribution to soot (the carbonaceous component of PM) from the ethanol and diesel fractions of blended fuels.