Dilution effects on ultrafine particle emissions from Euro 5 and Euro 6 diesel and gasoline vehicles

Abstract

Dilution and temperature used during sampling of vehicle exhaust can modify particle number concentration and size distribution. Two experiments were performed on a chassis dynamometer to assess exhaust dilution and temperature on particle number and particle size distribution for Euro 5 and Euro 6 vehicles. In the first experiment, the effects of dilution (ratio from 8 to 4000) and temperature (ranging from 50 °C to 150 °C) on particle quantification were investigated directly from tailpipe for a diesel and a gasoline Euro 5 vehicles. In the second experiment, particle emissions from Euro 6 diesel and gasoline vehicles directly sampled from the tailpipe were compared to the constant volume sampling (CVS) measurements under similar sampling conditions. Low primary dilutions (3-5) induced an increase in particle number concentration by a factor of 2 compared to high primary dilutions (12-20). Low dilution temperatures (50 °C) induced 1.4-3 times higher particle number concentration than high dilution temperatures (150 °C). For the Euro 6 gasoline vehicle with direct injection, constant volume sampling (CVS) particle number concentrations were higher than after the tailpipe by a factor of 6, 80 and 22 for Artemis urban, road and motorway, respectively. For the same vehicle, particle size distribution measured after the tailpipe was centred on 10 nm, and particles were smaller than the ones measured after CVS that was centred between 50 nm and 70 nm. The high particle concentration (≈10 6 #/cm 3) and the growth of diameter, measured in the CVS, highlighted aerosol transformations, such as nucleation, condensation and coagulation occurring in the sampling system and this might have biased the particle measurements.

Physico-Chemical Characterization of Fine and Ultrafine Particles Emitted during Diesel Particulate Filter Active Regeneration of Euro5 Diesel Vehicles

“…The FPS dilution system allows us to sample at the tailpipe using constant temperature and dilution ratios. It can, therefore, provide a better assessment of the volatile fraction of PM with respect to the CVS, where PM emission are measured using variable dilution ratios and temperatures …”

Particle emissions measurements on CNG vehicles focusing on Sub-23nm

“…Those earlier results were obtained in the laboratory over steady state operation or outdated driving cycles (NEDC) (Schreiber et al 2007), utilizing constant volume sampling (CVS) to collect particles (Schreiber et al 2007;Magara-Gomez et al 2014;Giechaskiel, L€ ahde, et al 2019) in most of the cases. CVS is prone to small particle formation artifacts or can lead to a measurement bias of the PSD (Louis et al 2017;Giechaskiel 2019a;Giechaskiel 2019b). As a result, high particle losses from tailpipe to CVS (Giechaskiel, L€ ahde, et al 2019).…”

Evolution under dark conditions of particles from old and modern diesel vehicles in a new environmental chamber characterized with fresh exhaust emissions

“…Moreover, few of these studies were conducted in the last decade, resulting in a lack of knowledge on modern vehicles, motorizations and aftertreatment technologies. Some studies focusing on particle physical evolution use a constant volume sampler (CVS) (Louis et al, 2017), but they are limited by the short residence time.…”