Abstract
Nanoparticle emissions from various engines and vehicles were investigated with the differential mobility spectrometer (DMS) and the partial flow dilution system (PPFDII) which had been developed for the behaviour study on nanoparticles in the atmosphere.
A gasoline passenger vehicle (MPI), a diesel passenger vehicle equipped oxidation catalyst, light duty diesel trucks, heavy duty diesel engines, a heavy duty diesel truck with an urea- SCR system and a medium duty diesel engine with a DPNR system were selected. Measured size distribution data was converted to a data in a second and the average size distribution through the transient test cycle was calculated. Gasoline vehicle dose not form nuclei mode particle under the usual transient test cycle. Light duty diesel trucks which comply with the 1998 exhaust regulation, emits nuclei mode particles under the deceleration period and idling.
These nuclei mode particle were able to reduce by an oxidation catalyst certified as diesel particulate matter reduction systems by eight prefectures and municipalities in Japan. The diesel passenger vehicle equipped with an oxidation catalyst, nuclei mode particles did not form under the transient mode.
Under the unusual condition which causes high exhaust temperature, nuclei mode particles form with high sulphur fuels (300 ppmS). Under the low dilution ratio such as 40, these nuclei mode particles were also formed with 28 ppm sulphur fuel which was used in Japanese market until 2004. If dilution ratio was increased over 80, nuclei mode particle was not formed. Current sulphur content in diesel fuel is below 10 ppm, no nuclei mode particles were not formed with this unusual condition.
The heavy duty diesel truck equipped with the urea-SCR system, which meets 2005 exhaust regulation, nuclei mode particles hardly formed and accumulation mode particles were also reduced. The heavy duty diesel truck equipped with the DPF, both mode particles was reduced.
Keywords:Diesel, Gasoline, Nano-particles, Nuclei mode, Size distribution