The aim of this study was to investigate the changes in mass and number based heavy duty diesel engine particle emissions with respect to various test conditions, engine technologies and fuel specifications. Comparative particle size data and regulated particulate matter are presented from three heavy duty engines and three fuels.
This paper describes results from the DETR/CONCAWE/SMMT Particle Research Programme. Three heavy duty diesel (HDD) engines representing Euro I, II and III technologies were tested with a range of fuels. These fuels included UK ultra low sulphur diesel (UK-ULSD), EN590 (EU2000) specification and Swedish Class I fuels.
Continuing research suggests that when changes in regulated particulate mass emissions are compared to both individual mode and total cycle mass and number weighted particle size distributions there is often no significant correlation. In an attempt to provide further data in this area the following measurement methodology was adopted.
Two Scanning Mobility Particle Sizer (SMPS) instruments measuring number weighted particle size distribution were employed in order to cover a measurement range from ∼7nm to ∼710nm. The different configurations used with these two instruments operating over separate size ranges resulted in differences in the results obtained in the overlap region. Because of the perceived importance of the smallest particle range, the instrument measuring the lowest range (7-320 nm) was selected for data comparison. Conclusions may not be supported by a similar SMPS system working under an alternative configuration. Within this paper conclusions are therefore based upon data from that system only.
Particle mass measurements were undertaken via the regulated method and with a Micro Orifice Uniform Deposit Impactor (MOUDI) covering a size range from <56nm to 10μm measuring the mass weighted size distribution. In addition to the particle size distribution, particulate matter and other regulated emissions were measured as mass emissions. Chemical composition of selected particulate samples was undertaken.
The paper concludes that in these tests, at the accumulation mode between 50 and 320 nm, engine effects were greater than fuel effects, with particle numbers in general reducing with advanced engine technology when tested over regulated cycles. Nanoparticles however, seemed to be more sensitive to fuels. These particles were clearly more variable and sensitive to sampling conditions than the accumulation mode particles. Nanoparticles were observed to be more sensitive to fuels. More research in this area is required. As expected, the Swedish Class 1 fuel tended to achieve lower regulated cycle emissions in all three engines tested than the other fuels.
None of the engine technologies or fuel specifications tested reduced particulate mass, nanoparticles (in the SMPS size range 7nm to ∼50nm) and accumulation mode particles (50nm to 320nm) concurrently at all test conditions.