Particulate Emissions of Gasoline Vehicles and Influence of the Sampling Procedure

In this paper, we present the results of an experimental study on particulate emissions of gasoline vehicles. The objective of the project was to investigate the particulate emissions on the basis of number and total mass and to gain experience in the influence of the sampling method on the results. The measurements were carried out with three passenger cars at a chassis dynamometer. Two vehicles with premixed combustion and one direct injection engine were tested at constant loads and driving cycles. For the aerosol sampling we used a standard CVS system, an ejector and a rotating disk unit. The samples were analyzed by SMPS and ELPI. Samples for gravimetric analysis were taken downstream of the CVS tunnel and from a mini tunnel.

The results show that all three vehicles produce significantly less particulate in number and mass than a common diesel vehicle. Increased particle emissions were observed for the direct injection vehicle during the driving cycles and for the premixed engines for rich air-fuel equivalence ratios. It was found that the sampling method has a rather high influence on the results of the total number and the number size distribution. The result of the comparison between ELPI and SMPS depends strongly on the particle density, which is in general not known.