Sub-23 nm particle emissions: nature and measure 2020-01-0396
Air quality is one of the greatest challenges of today because of the many sources of pollutant emissions. In the urban area the internal combustion engines play a dominant role on pollution despite the innovative technologies. Great efforts have been paid to reduce NOx and PM as their serious toxicological impact on human health and the environment. Nowadays, the regulation regards only the particles larger than 23 nm, but the attention is shifting towards the sub-23 nm particles because of their large presence at the exhaust of the modern engines and their negative impact on human health. The main challenge of the regulation of these particles is the definition of a proper procedure for their measure. The nature of the sub-23 nm particles is not well understood and their measure is strongly affected by the sampling conditions.
The aim of this paper is to provide information on the nature of the sub-23 nm particles in order to define the most suitable procedure for their measure. The analysis was performed on a 4-cylinder GDI engine fueled with gasoline and ethanol. The tests were carried out at steady and transient conditions, WLTC. Particle emissions were characterized in terms of mass concentration, by means of a Smokemeter, and of number and size. The sampling was performed by a PMP compliant system, which permits to change the main sampling parameters. Particular attention was focused on the interval of 10-23 nm, to better characterize the effect of the sampling parameters on these particles, with the aim of determining a proper procedure for the measurement. A commercial Engine Exhaust Particle Sizer (EEPS), working in the size range 5.6-560 nm. Moreover, to better define the nature of the sub-23 nm particles the instruments developed within the European Project Sureal23 were used as well.
Silvana Di Iorio, Francesco Catapano, Paolo Sementa, Bianca Maria Vaglieco, Giovanna Nicol, Mauro Francesco Sgroi