Prakash, A., Aradi, A., Imoehl, W., and Armitage, P., "Impact of Injector Design and Fuel Composition on Particulate Number Generation," SAE Technical Paper 2017-01-2395, 2017.
The impact of fuel composition (ethanol and aromatic content) and injector design on particulate number generation was studied in a 1.0L displacement direct injection spark ignition engine. Two types of engine tests that mimic real-life vehicle operation were carried out using a matrix of eight fuels and two injectors. It was found that the DISI injector design had the biggest impact on the extent of particulate number generation. An injector prototype designed to meet Euro 6c specifications for PN (6*1011 particles/km) resulted in much lower PN values compared to those obtained using a production injector currently available in the market. The impact of fuel composition on PN was apparent only during engine operation with the production injector. Overall, qualitative trends were observed but no statistically significant differences were observed for the impact of ethanol (E10 fuel match-blended for aromatics and octane quality) and aromatic content (19-28%) variation. In the case of the prototype injector, any potential fuel compositional impact on PN was overwhelmed by the extremely low PN values owed to the injector design changes specifically due to higher injector tip temperatures and nozzle hole design.