Impact of ethanol fuel and blend on sub-23 nm particles and their measure

Great attention has been paid to particle emissions in the last years because of the negative effects on human health. The introduction of ethanol as fuel has had a positive impact on particle emissions in term of mass and number, but the mean diameter of the particles has been reduced. The particle size deeply influences the effect on human health as it influences the penetration capacity up to the pulmonary alveoli. This led to the introduction of a number- based limitation. Anyway, despite smaller the size of particles larger the negative impact on human being, the current regulation cut-off diameter is 23 nm. This study explores the influence of ethanol on sub-23 nm particles emissions and the impact of sampling condition on their measure. The investigation was performed on a small displacement PFI/DI SI engines fueled with gasoline, ethanol and blend of ethanol and gasoline. Particle size distribution and number concentration were measured on-line with an EEPS and CPC. The sampling was performed by a PMP compliant system that allows to change the main sampling parameters.