Nanoparticles characterization at spark ignition engine exhaust

The aim of the paper is the characterization in terms of chemical and physical nature of particles at exhaust of spark ignition (SI) engine. Measurements were carried out at exhaust of 16v - 1.2-liter Port Fuel Injection Spark Ignition engine downstream a catalyst. The emission of nanoparticles was investigated by optical techniques and conventional methods. In particular laser-induced incandescence (LII) and broadband multi-wavelength, extinction-scattering spectroscopy (BUVESS) were used. LII allowed the detection and sizing of primary particles of carbonaceous nature. BUVESS measured particle size distribution by numerical procedure that took advantage by data at several wavelengths. The optical results were compared with those obtained by conventional methods like opacimeter for mass concentration and Electrical Low Pressure Impactor (ELPI) for sizing. Different engine operating conditions were selected in order to evaluate their influence on the particle nature and size distribution.