Ultrafine Particles from a Heavy Duty Diesel Engine Running on Rapeseed Oil Methyl Ester 2009-01-2691

Rapeseed oil methyl ester, two common fuels and one artificial blend were investigated their effects on particulate emissions. A heavy-duty diesel engine equipped with a diesel oxidation catalyst (DOC) was used for this test. Properties such as composition of particulate matter, as well as particle size and number distributions were measured using an electronic low pressure impactor (ELPI) and a scanning mobility particle sizer (SMPS) besides the regulated emissions: carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO_x), and particulate matter (PM). Furthermore investigations were carried out regarding the influence of dilution temperature on particle number distribution measured via SMPS. Studies were carried out with and without a DOC. Additionally the mutagenic potency of the particulate and gaseous emissions was determined using the Ames test.

RME led to lower regulated emissions than common diesel fuel with exception of NO_x. With DOC a further decrease in emissions was obtained. On the other hand also a light increase of NO_x emissions was observed when the DOC was used. Regarding the non-regulated emissions RME showed the lowest values compared with the other fuels. In measurements via SMPS higher emissions of particles in the nuclei mode were observed for RME compared to the other three fuels. In course of investigations regarding the composition of particulate matter from raw exhaust gas (PM_reg) as well as investigations of the influence of dilution temperature it could be demonstrated that these nuclei particles mainly result from emission of unburned fuel.

The mutagenicity of all PM extracts was very low compared to prior studies. A further slight decrease of the mutagenic potential was obtained when using a DOC.