Influence of ethanol blended and dual fueled with gasoline on soot formation and particulate matter emissions in a small displacement spark ignition engine

The implementation of environmentally friendly internal combustion engines (ICEs) has become an urgent need in recent years due to the strict current legislation. The high pollutant emissions such as particulate matter (PM) exhausted from ICE has driven many researchers to explore the possible advantages of alternative fuels. Ethanol is one of the most suitable alternative fuel for spark-ignition (SI) engines due to its higher heat of evaporation, octane number and larger oxygen content that allow to obtain positive effects on engine performance and particle formation and emissions. The main goal of the experimental research is the study of the effect of the different methods of ethanol fueling on particulate matter by means of the correlation between the in-cylinder soot formation and the exhaust particle emissions. The experimental investigation was carried out in a 4-stroke small displacement optical spark ignition engine operated at 2000 and 4000 rpm under full load conditions. The engine was fueled with gasoline and ethanol pure, blended (E30) and dual fueled (EDF). For both E30 and EDF configurations, 30 vol% of ethanol in gasoline was supplied. An optical technique based on 2D-digital imaging was used. Two-color pyrometry theory was applied to assess the in-cylinder soot formation. Particle emissions were measured at the exhaust by means of a smoke meter. The particle size distribution function (PSDF) was measured in the range from 5.6 to 560 nm with an Engine Exhaust Particle Sizer (EEPS). The research has shown that the effect of ethanol on soot formation and particle emission depends not only on ethanol fuel properties, but also on engine configuration and engine operating conditions.