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Effects of six different fuels on low temperature premixed compression ignition (PCI) combustion were experimentally investigated in this paper with a light-duty HSDI engine. The PCI combustion concept reduces NOx and smoke emissions simultaneously by low temperature and premixed combustion, respectively. To achieve low temperature and premixed combustion, the ignition delay is prolonged and the injection duration is shortened. Six fuels were chosen to examine the influence of cetane number (CN) and other fuel properties on low temperature PCI combustion. The fuel selection also included a pure Gas- to-Liquid (GTL) fuel and a blend of base diesel and 20% soy based biodiesel (B20). Fuel effects were studied over a matrix of seven part load points in the low temperature combustion mode. The seven part load points were specified by engine speed (RPM) and brake mean effective pressure (BMEP).

Thanks to a high specific torque, associated to a low fuel consumption, the market share of the Diesel engine has not stopped increasing during the last decade. Nevertheless, due to the strong emissions regulations to come, the challenge of the Diesel will be to save its advantage in CO2 and to drastically reduce NOx and particulate emissions, whilst offering the save driving pleasure. Hence new concepts of combustion are in development in order to keep NOx emissions as low as possible at an acceptable cost. The homogeneous combustion, by generating a lower pollutant level directly in the combustion chamber, seems to be a very promising way in this direction. Especially, the NADI™ concept, developed by IFP has already shown a high potential in NOx and particulate simultaneous reduction, but up to now its relative low specific power at full load compared to the next generation of conventional Diesel engines could be a major drawback for a global application.