Abstract
Research and/or Engineering Questions/Objective
The new emission standard EURO 6c will become mandatory starting September 2017. Downsizing in conjunction with charging and direct injection of the fuel as the development path chosen in recent years implies challenges. In particular, the limitation of the number of emitted particles will challenge the gasoline combustion process. Fuels have a significant impact on the emissions of particulates. Since in future emission testing is also performed under real conditions on the road (RDE), thus all in field available fuels will be certification relevant. Therefore, the knowledge of the influence of various fuels on particulate formation and also the EMS calibration is of high importance for the development process. In particular the difference from gas station fuels and certification fuel, which is defined by legislation, is particularly important. In addition, there is the need to be able to assess the effect of fuels from various markets in terms of particulate emissions. For this purpose, in this paper the influence of individual fuel components on particulate emissions will be evaluated, and critical components identified.
Methodology
The investigations are performed on the basis of steady state measurements on an engine test bench. Test carrier is a supercharged direct injection engine with a central mounted injector. For the measurements, a, at GM standardized, test for evaluating the particle emission level is used. This covers the speed and load profile of a typical customer driving profile and is representative for expected vehicle test results. The test includes measurements at warm and cold engine. The impact of the fuel on the pollution of the injector and thus indirectly on the particulate emissions will also be considered. The evaluation of the impact of single fuel components is based on a gas chromatography analysis whereat the fuel components are classified in terms of carbon groups.
Results
The results show a significant impact of fuels on particulate emissions. The range from the worst to the best fuel has a factor of 3. Negative effects on particulate emissions have of low-volatility fuel components. In particular aromatics having a high carbon number have to be mentioned.
Limitation of this study
The tests are restricted to steady state engine test bench results.
Conclusions
The results of the study, presented in this paper, give the developer a tool in his hand to estimate the influence of different or new fuels on particulate emissions based on existing tests.
Key Words : Fuel, Fuel components, Particle emissions, Direct injection