Deliverables Statistical correlation of fuel properties with particle emissions A statistical analysis on the emission results from a common-rail vehicle was conducted using fuel properties as sample classification parameters. The statistical analysis is applied on integrated gaseous and particulate emissions collected over transient tests. Two statistical tools are applied: - Analysis of Variance to distinguish, which fuel properties lead to statistically significant emission differentiation. - Principal Component Analysis to identify whether any observed effect on pollutants are due to the physical or chemical character of the fuel, by grouping different properties. Results show that NOx seems to be more dependant on the chemical fuel character while PM is more dependant on physical properties. One may insist that this is also consistent with the diesel combustion process because PM strongly depends on injection characteristics, which are affected by physical properties of the fuels while NOx rather depends on peak temperatures inside the cylinder, which have limited direct dependence on fuel physical properties. Sensitivity of modern common rail diesel engines Modern Common Rail Diesel engines, employing pilot and main injection strategy, confirm their little sensitivity in terms of combustion evolution to fuel quality and confirm their tendency to produce low level of unburned emissions. The unburned emissions upstream the catalyst seems mainly ascribed to the presence of a pilot injection, but due to the presence of oxidant catalyst, differences among fuels are smooted. Nevertheless some trend can be noticed: The reduction of surface tension slightly reduces smoke emissions, while it produces increases of HC and CO. Fuel density variation showed a little effect on smoke emission. In particular, the reduction of density produces a decrease on smoke and an increase on unburned emissions (HC, CO). Viscosity has more or less the same effect of density on all the emissions. In particular decreasing viscosity decreases smoke emissions and HC and CO increases. The oxygen content of fuels has a positive effect on soot emission reduction while Nox emission slightly rises. No differences were found varying the kind of oxygenated fuel (bio-derived or synthetic). DI engine performance and emissions Effect of Fuel Density Increase on DI Engine Performance and Emissions: - Small increase of Cylinder Pressure. - Slight increase of Injection Pressure. - Small decrease of Ignition Delay. - Increase of Soot emissions. - No serious effect on NO emissions. - No serious effect on CO emissions. - Small decrease of HC emissions. Effect of Surface Tension Increase on DI Engine Performance and Emissions: - No serious effect on Cylinder Pressure. - No effect on Injection Pressure. - No serious effect on Ignition Delay. - No significant effect on Soot. - No considerable effect on NO emissions. - No serious effect on CO emissions. - Small decrease of HC emissions. Effect of Fuel O2 Content Increase on DI Engine Performance and Emissions: - Reduction of Cylinder Pressure. - No effect on Injection Pressure. - Small decrease of Ignition Delay. - Decrease of Soot emissions. - Slight increase of NO emissions. - Small decrease of CO emissions. - Slight decrease of HC emissions. Effect of Fuel Viscosity Increase on DI Engine Performance and Emissions - Small increase of Cylinder Pressure. - Increase of Injection Pressure. - Small decrease of Ignition Delay. - Increase of Soot emissions. - No significant effect on NO emissions. - No serious effect on CO emissions. - Small decrease of HC emissions. Effect of Fuel Compressibility Increase on DI Engine Performance and Emissions: - No serious effect on Cylinder Pressure. - Decrease of Injection Pressure. - No serious effect on Ignition Delay. - Small increase of Soot emissions. - Slight decrease on NO emissions. - No serious effect on CO emissions. - Small decrease of HC emissions. Test fuel formulation, blending, analysis and delivery The results of the NeDeNef project will give data of the effects of a possible threshold effect of aromatics as well as the difference in the aromatic types. The 9 % oxygen content of the diesel test fuels is substantially higher than is to be expected for use in commercially available fuel blends. This will therefore give interesting additional information to the data already existing of oxygen containing diesel fuels. All the information will be used as a basic database in the research and development of new reformulated traffic fuels. The reformulation of the traffic fuels is targeted on a long time schedule and the information from this project will be used in future projects. Correlation between the soot emission indexes A correlation between the soot emission indexes was carried out from smoke meter by MIRA correlation and that measured by mini tunnel samples. The correlation include both Particulate and IOF values. The correlation is quite good. Emissions behaviour of a four cylinder common rail engine burning oxygenated fuels In the modern common rail engines the oxygen addition is effective in reducing soot. However the soot reduction is sensible only to the oxygen percent and effective only with a fuel oxygen content above 3%. NOx emission is not influenced significantly by fuel quality. HC and CO emissions are reduced when oxygen content increase. No significant differences can be observed on engine indicated data among the base fuel and the 3 oxygenated fuels. However, the pilot injection activation reduces drastically the ignition delay time, hiding the cetane number influence. Effect of fuel properties on vehicle particle emissions The effect of different fuel properties (incl. density, surface tension, viscosity and compressibility) on the emissions of a passenger car were studied. Also, three different oxygenated fuels were examined. The vehicle was equipped with a Euro 3 common-rail diesel engine and was driven over a variety of driving conditions, including the certification NEDC test and real world cycles which simulated driving under realistic everyday conditions. Aim was to identify the effect of fuel under actual vehicle operation. Emissions studied included all conventional pollutants (CO, NOx, THC and PM), measured according to the legislation over transient testing. Moreover a detailed characterization of exhaust emissions was conducted using specialized equipment and a dedicated protocol. The particle properties examined included particle number concentration, mean particle size, active surface and distinction to solid / semi-volatile particles. All measurements were conducted in real-time using raw exhaust sampling and sample conditioning under constant dilution ratio, temperature and residence time. This enabled to reveal the actual effect of fuel on particle characteristics, without interference from sampling parameter variation. The results were collected in a database format, which enables the evaluation of the effect of different fuel parameters on gaseous and particulate emissions. The current study showed that a current diesel passenger car, equipped with an advanced common rail injection engine, seems to be rather insensitive to physical fuel properties and chemical character. Effects of fuel properties and chemical composition are found in the +/-10% range with no tuning of the engine for any of the fuels used. Oxygen content can however significantly reduce PM with no effect on CO2 and a moderate increase of NOx and fuel consumption. The decrease of PM mass emissions was consistent with a shift of the accumulation mode size distribution to smaller sizes as oxygen content increases in the fuel. This size shift can give important messages for the effect of fuel oxygen on the soot suppression mechanisms. It was also observed that NOx emissions are more dependant on fuel chemical character than physical properties. Emission levels increased as paraffinic content increased and napthenic content decreased. Finally, fuels studied seem to generally follow a PM � NOx trade-off pattern that makes concurrent fulfilment of more strict NOx and PM emission standards impossible with tuning of the fuel properties only. Particle characteristics -database Data base on characteristics of diesel vehicle particulate emissions from different fuels and different fuel injection systems, measured with different physical methods. Application of 2D two colour measurements 2D two colour measurements can be considered a reliable technique to investigate on soot loading behaviour, providing further information on in-cylinder shooting tendency of diesel fuels. The peculiarity of the method is to measure simultaneously flame temperature, local soot concentration as well as total soot loading in the whole piston bowl. This permitted to discriminate that a sensible fuel oxygenation change the way in which the soot is distributed improving the oxidation process. The analysis of flame temperature shows that only for fuel with higher oxygen content higher flame temperature can be discriminated. The comparison between the bio-derived (RME) oxy fuel and the synthetic one have shown no important differences. Results varying the fuel quality confirm that, also in the modern CR diesel engine, the presence of oxygen in the fuel reduces the in-cylinder soot loading. Searching for OpenAIRE data... There was an error trying to search data from OpenAIRE No results available
