Simultaneous particulate matter and nitrogen oxide emission reduction through enhanced charge homogenization in diesel engines

Abstract

In the presented study, low temperature combustion was established with a direct injection of diesel fuel being a representative of high reactivity fuels and tire py-rolysis oil being a representative of low reactivity fuels. Tire pyrolysis oil was tested as a potential waste derived fuel for low temperature combustion, as it fea-tures diesel-like physical properties and lower cetane number compared to diesel fuel. The goal of this study was determination of suitable injection strategies and exhaust gas re-circulation rates to explore potentials of both fuels in reducing emissions in low temperature combustion modes. It was demonstrated that rela-tively small changes in the engine control strategy possess the potential to signif-icantly improve NOx/particulate matter trade-off with minor effect on engine effi-ciency. In addition, low temperature combustion was for the first time successful-ly demonstrated with tire pyrolysis oil fuel, however, it was shown that lower re-activity of the fuel is by itself not sufficient to improve NOx /soot trade-off com-pared to the diesel fuel as entire spectra of fuel properties play an important role in improving NOx /soot trade-off. This study thus establishes relations between different engine control strategies, intake manifold pressure and exhaust gas re -circulation rate on engine thermodynamic parameters and engine-out emissions while utilizing innovative waste derived fuel that have not yet been analysed in similar combustion concepts.