Particulate Emissions. Particulate emissions are shown in figure 10.15-16. The emissions are separated into SOF (Soluble Organic Fraction) and SOLID, which is the rest of the total particulate matter. In this way the SOLID fraction covers all the insoluble material, i.e. solid carbon, water and other inorganic compounds. From the figures it is clear that the FTP test gives higher particulate emissions than the EU test. It is also evident that the SOF emissions are larger with biodiesel than with other fuels. This is clearly seen in Figure 10.17, where the SOF contribution in percent of the total particulate matter is shown. At the same time biodiesel results in a generally lower emission level due to very low SOLID emission. From the figure it is also seen that during more transient driving (FTP) the biodegradable lubricant gives a higher emission of SOF, whereas the more steady-state EU driving pattern result in a lower SOF emission with the biodegradable lubricant. This latter tendency was, as earlier mentioned, confirmed by the lower lubricant consumption from the biodegradable lubricant during steady state driving, measured by the S-tracer method. This means that there probably, as expected, is a connection between lubricant consumption and lubricant contribution to SOF emissions, again indicating that the lubricant, as many other investigations have pointed out [3,4], is an important contributor to particulate emissions. In order to investigate this further the GC analysis of the SOF could give some more information. GC pictures of the SOF are shown in the figures 10.18-19. For comparison the GC pictures of the three fuels and the two lubricants are shown in Figure 10.20. The horizontal axes in the figures are the retention times and the vertical axes gives the detector response to the compounds found in the sample. The detector is an FID (Flame Ionization Detector), which gives a signal proportional to the mass of carbon in the individual compounds. If we look at the fuels first in Figure 10.20, we see that LSD and Ref.D consists of two groups of hydrocarbons that are relatively light, i.e. low carbon numbers. We also notice that LSD hydrocarbons are a little lighter than Ref.D. hydrocarbons. BioD., on the other hand, consists of two major “humps”, or groups of hydrocarbons, that both consists of higher carbon number compounds compared to the other fuels.
Particulate Emissions. For the evaluation of the particulates, the total sample masses (MSAM,i) or volumes (VSAM,i) through the filters shall be recorded for each mode.
Particulate Emissions. Total particulate emissions (PM) are shown in Figure 10.5. The emissions of SOF (Soluble Organic Fraction of particulate matter) are shown in Figure 10.6, and the contributions of SOF to PM in percent are shown in Figure 10.7. From the PM measurements it is seen that the fresh biolube gave much higher emissions than the used biolube. This is most likely because some components in the lubricant are emitted from the lubricant and burned, or rather partly burned right after the addition of fresh lubricant. After some time these components are no longer present in the lubricant, and the emission level stabilizes. The reason for this behavior is probably that the lubricant is designed for diesel engines rather than gasoline/ethanol engines. If we look away from the results with fresh biolube we notice, that PM emissions with ethanol generally are lower, compared to gasoline. We also notice, that the reference lubricant application results in lower PM emissions, although emissions in all cases are very low (the EURO IV limit is 25 mg/km!). The difference could be a result of differences in load, due to differences in engine friction, caused by the lubricant. This seems to be supported by the fact that PM emissions are lower with biolube in the case of "Petrol EU", an exception that was noticed also for the fuel consumption/CO2 emission measurements. The SOF samples were further investigated for fuel and lubricant contributions. In all cases no fuel was found. Furthermore all hydrocarbons in the SOF were found in the range of lubricant hydrocarbons, indicating that all the SOF is made up by lubricant or lubricant combustion products. The relative amounts of lubricant/lubricant combustion products are listed in Figure 10.8. From this figure we notice that the lubricant contribution to SOF emissions with fresh biolube is much higher compared to used biolube. This supports the earlier suspicion about an excess emission of lubricant right after lubricant exchange with the biolube. PM (mg/km) 6 2 0 Biolube Used biolube Ref.lube Petrol FTP Petrol EU Ethanol FTP Ethanol EU Figure 10.5. PM emissions from the FFV’s. SOF (mg/km) 0,5 0 Biolube Used biolube Ref.lube Petrol FTP Petrol EU Ethanol FTP Ethanol EU Figure 10.6. SOF emissions from the FFV’s. SOF (% of PM) 100 60 40 20 0 Biolube Used biolube Ref.lube Petrol FTP Petrol EU Ethanol FTP Ethanol EU
