Measurement of the Number and Size Distribution of Particles Emitted from a Gasoline Direct Injection Vehicle 1999-01-3530

The number and size distribution of particles emitted from a gasoline direct injection vehicle have been measured over the current European drive cycle and a range of steady state conditions. Measurements were made using the Scanning and Differential Mobility Particle Sizers (SMPS/DMPS) and an Ultrafine Particle Monitor (UPM). During the steady state testing, the number distribution of particles between 7nm-320nm was monitored using the SMPS and the integrated total particle count compared to the UPM measurement. Excellent agreement was seen between the two techniques, except at high speed (120km/h) where the UPM measured a greater number of particles than the SMPS indicating an increase in particles outside the range scanned by the SMPS. During the drive cycles, specific size ranges of particles were monitored using the SMPS/DMPS and the total particle count measured using the UPM. Comparisons between the techniques are also made for Diesel and gasoline vehicles.

Results showed that the number emissions from the GDI vehicle are much higher than those historically seen from a gasoline vehicle and are more in line with Diesel particle emissions, both with respect to number and size. The effect of air fuel ratio from the different operating strategies of the GDI on the particle emission is examined; particle production is shown to occur more predominantly during the lean operating conditions.

The effect of fuel quality was assessed using two fuels representative of European 1996 and expected 2000 gasoline specification. The latter was shown to reduce the number of particles when assessed against the individual sizes measured (as measured by SMPS), but no significant difference was seen between the fuels when assessed by the UPM.