Predicting the particulate matter emissions from spray-guided gasoline direct-injection spark ignition engines

An index which links the fuel composition to particulate matter emissions (the PN index) was developed and is here evaluated with model fuels in a single-cylinder optical-access spray-guided direct-injection engine; the model fuels have independent control of the double-bond content and volatility, as used in the index. This index is investigated in three different engines: a single-cylinder research engine, a V8 engine recently available in the market and a current-production supercharged V6 engine. A number of market gasolines were tested in all three engines, and the results follow the trends predicted by the particle number index. Imaging of the in-cylinder sprays shows that the composition of the model fuels affects the mixture homogeneity and their particulate matter emissions; in particular, the lack of a light end in the model fuel composition can lead to misleadingly low particle number emissions owing to improved mixture preparation which is unrepresentative of market fuels. The PN index was inv...