Abstract
This paper presents both a general discussion of the phenomenon of particulate formation and emission in direct injection engines, and a wide range of results on the subject. Emissions tests were conducted on a pool of Euro 5 vehicles in BOSMAL’s exhaust emissions laboratory, in accordance with the EU emissions test procedure (NEDC). Specifically, a portion of the diluted exhaust gas was passed through foil-backed TX40 filters (one per phase) to quantify PM and an additional portion of the diluted exhaust gas was passed through a condensation particle counter to quantify solid particles in the exhaust gas. This study employed the legislative method for all test vehicles, including the port injected vehicles, for which a particulate sampling test methodology is not specified. Beyond the scope of legislative tests, experiments were also performed at low ambient temperatures. Furthermore, a particle size classification unit was also employed to produce particle size profiles. The results presented here indicate that under standard laboratory conditions mass-based emissions are low, while number-based emissions are high. Low ambient temperature increases emissions considerably, with different magnitudes of deterioration for particle mass and number. Generally, the size distribution profiles indicated the presence of large numbers of small particles, including non-negligible quantities of diameter <23 nm.
KEYWORDS – particulate matter (PM); direct injection spark ignition engine (DISI); nanoparticles.