Particle Emissions from SI-Engines During Steady State and Transient Operating Conditions

Particle emissions from four spark ignition engines were measured during steady state and transient chassis dynamometer tests. Transient Unified Drive Cycle tests were conducted at 0 °C and room temperature. Particle number, size distribution, active surface area, and photoelectric activity were determined. The results generally show low emission values for steady state operation of the warm engine. High particle concentrations are emitted in the first phase of the high-speed steady state testing. Once the engine is warmed up high emissions mainly occur during transient operation phases. The formation of nucleation mode particles is favored by the low concentration of carbonaceous soot, which offers volatile material little surface area for condensation.