Nanoparticle Emissions of DI Gasoline Cars with/without GPF

In the present paper some results of investigations of nanoparticles from five DI gasoline cars are represented. The measurements were performed at vehicle tailpipe and in CVS-tunnel. Moreover, five variants of “vehicle – GPF” were investigated. These results originate from the project GasOMeP (Gasoline Organic & Metal Particulates), which focused on metal-nanoparticles (including sub 20nm) from gasoline cars with different engine technologies. The PN-emission level of the investigated GDI cars in WLTC without GPF is in the same range of magnitude very near to the actual limit value of 6.0 x 10 #/km. With the GPF’s with better filtration quality, it is possible to lower the emissions below the future limit value of 6.0 x 10 #/km. There is no visible nuclei mode and the ultrafine particle concentrations below 10mm are insignificant. Some of the vehicles show at constant speed operation a periodical fluctuation of the NP-emissions, as an effect of the electronic control. Introduction The nanoparticles (NP) * count concentrations are limited in EU for Diesel passenger cars since 2013 and for gasoline cars with direct injection (GDI) since 2014. The limit for GDI was temporary extended to 6 x 10 #/km (regulation No. 459/2012/EU). Nuclei of metals as well as organics are suspected to significantly contribute especially to the ultrafine particle size fractions, and thus to the particle number concentration. The invisible nanoparticles (NP) from combustion processes penetrate easily into the human body through the respiratory and olfactory pathways and carry numerous harmful health effects potentials. The nanoaerosol in vehicle exhaust is known to be a complex mixture of different volatile and non-volatile species often showing a bimodal particle size distribution with a nucleation mode smaller than 20 nm and a larger accumulation mode that mainly contains aggregates of primary particles. * Abbreviations see at the end of this paper The larger accumulation mode is usually composed of more graphitic soot particles with an elemental carbon (EC) structure, whereas the particles in the nucleation mode are reported to be mainly volatile organics, especially when sulphur is absent from fuel and lubrication oil, [1-4]. However, recent studies detected also low-volatility particle fractions in the ultrafine size range when sampling was carried out according to PMP protocol at 300 °C, [5-7]. These particles are suspected to be nucleated metal oxides originating from metal additives in lubrication oil or fuels [8-11]. The formation of this particulate fraction was especially observed when the soot content was low as in idle condition of diesel vehicles. These particles mainly appear in the ultrafine size rage <23 nm. While the mass contribution of these ultrafine particles in vehicle emissions is very low, their contribution to the number concentration is significant. Moreover, these ultrafine particles may contribute to the surface composition of the aerosol and have therefore a significant impact on health effects associated with pollution. Knowledge about the emission level, chemistry and formation mechanisms of these particles is an important objective in order to assess their toxic potential, and to propose effective measures to reduce these emissions. Studies for gasoline fuelled internal combustion engines pointed out that also this vehicle class can emit remarkable amounts of particles, [6, 12, 13]. Especially gasoline direct injection technology (GDI) shows particle number (PN) emissions significantly higher than modern diesel cars equipped with best available DPF technology. Since the trend for gasoline vehicles with GDI technology is increasing, a significant rise in emission is predicted in the near future. The nanoparticles emissions are produced especially at cold start and warm-up conditions and at a dynamic engine operation, [14]. The lube oil contributes to this emission in the sense of number concentrations in nuclei mode and composition, [8, 9, 10]. Jan Czerwinski, Pierre Comte University of Applied Sciences, Biel-Bienne, AFHB * Switzerland Norbert Heeb EMPA, Switzerland Andreas Mayer TTM, Switzerland Volker Hensel VERT, Germany s o u r c e : h t t p s : / / d o i . o r g / 1 0 . 2 4 4 5 1 / a r b o r . 7 5 2 5 | d o w n l o a d e d : 1 6 . 1 0 . 2 0 2 0