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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 (NOx), 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 NOx.

The more stringent regulations for diesel engine emissions lead to the requirement that both fuels and engines must be developed jointly. In the future, so-called designer fuels will help to achieve the stringent limits. In our research, conventional diesel fuel, biodiesel, Swedish low sulfur diesel fuel MK1 and a specially designed diesel fuel were compared using a DaimlerChrysler diesel engine, running the modes of the ECE 49 test cycle. The results for regulated and non-regulated gaseous emissions, particulate matter size distributions as well as mutagenic effects of particle extracts are reported.

Ecological aspects, the finiteness of fossil resources and the effort to maintain the agricultural structures motivate the use of renewable materials. Since the seventies, the German Federal Agricultural Research Centre (FAL) has been dealing with the technical use of rape seed oil as alternative fuel. It was easy to demonstrate that pure rape seed oil is not suitable for long-term use in conventional diesel engines, because of the severe engine troubles that occurred. Nevertheless, the use of rape seed oil is possible if either the engine concept or the fuel is changed. Via a different combustion concept or the transesterification of the rape seed oil - mostly to rape seed oil methylester (RME) - rape seed oil can successfully be used as fuel. RME resembles diesel fuel (DF) in its physical properties. Since 1982, an agricultural tractor with unmodified engine has been running in a long term experiment at the FAL. No problems caused by this fuel have occurred.