The finite nature and instability of fossil fuel supply has led to an increasing and enduring investigation demand of alternative and regenerative fuels. The Institute for Combustion Engines at the RWTH Aachen University carried out an investigation program to explore the potential of tailor made fuels to reduce engine-out emissions while maintaining engine efficiency and an acceptable noise level.
To enable optimum engine performance a range of different hydrocarbons having different fuel properties like cetane number, boiling temperature and different molecular compositions have been investigated. Paraffines and naphthenes were selected in order to better understand the effects of molecular composition and chain length on emissions and performance of an engine that was already optimized for advanced combustion performance.
The diesel single-cylinder research engine used in this study will be used to meet Euro 6 emissions limits and beyond. The test conditions were optimized by means of a Design of Experiment (DOE) approach at four part-load conditions and full-load, which represents a wide range of engine operation including NEDC load points.
Tailor-made fuels have an enormous potential to reduce engine-out emissions when an ideal fuel composition is determined. In this paper, it is shown that fuels with a reduced cetane number and a simple molecular composition without ring structures have a positive impact on engine-out emissions.