Impact of Fuel Properties and Aftertreatment Systems on Particulate Number Emissions from Euro 6 Gasoline Direct Injection Engines

This study examines the influence of gasoline fuel properties on particulate number (PN) emissions from two Euro 6 gasoline direct injection (GDI) vehicles with contrasting aftertreatment systems. One vehicle with a gasoline particulate filter (GPF) and one without GPF were selected. Eight EN 228-compliant E10 gasolines were tested on these vehicles on a chassis dynamometer.

The results demonstrate the significant impact of GPFs on particulate number emissions of particles above 10 nm (PN₁₀). The vehicle equipped with GPFs showed a dramatic reduction in PN₁₀ emissions, exceeding an order of magnitude decrease compared to the vehicle without one. However, the presence of a GPF complicates the evaluation of fuel effects on PN₁₀ emissions, significantly reducing the variability observed between different fuels and essentially blurring these effects on PN₁₀ emissions.

Individual PN₁₀ emission nonlinear models were developed for both vehicles, demonstrating a good correlation between predicted and measured PN₁₀ emissions. For the non-GPF vehicle, the R-square value was 0.995, while for the GPF vehicle, the R-square was lower at 0.923. This finding suggests that it is possible to develop vehicle-specific PN indices based on fuel parameters. However, attempts to apply the model developed for one vehicle to the other failed, demonstrating that a universal PN index based solely on fuel parameters is unlikely to be feasible across a range of vehicle technologies affecting much more profoundly PN₁₀ emissions than the fuel. The diversity of engines and aftertreatment systems available in the market significantly challenges the development of such a universal index.