Soot Characterization of Diesel/Gasoline Blends Injected through a Single Injection System in CI engines

In the past few years’ various studies have shown how the application of a highly premixed dual fuel combustion for CI engines leads a strong reduction for both pollutant emissions and fuel consumption. In particular a drastic soot and NOx reduction were achieved. In spite of the most common strategy for dual fueling has been represented by using two different injection systems, various authors are considering the advantages of using a single injection system to directly inject blends in the chamber. In this scenario, a characterization of the behavior of such dual-fuel blend spray became necessary, both in terms of inert and reactive ambient conditions. In this work, a light extinction imaging (LEI) has been performed in order to obtain two-dimensional soot distribution information within a spray flame of different diesel/gasoline commercial fuel blends. All the measurements were conducted in an optically accessible two-stroke engine equipped with a single-hole injector. According to previous research, operating conditions with three different flame soot amounts were investigated. Commercial gasoline and diesel fuels were employed in four different blending percentages. Thus, this work aims at evaluating and quantifying the soot emission variation according to the different composition of the blend and thermodynamic characteristics of ambient. As expected the soot amount increases with higher ambient gas temperature and lower injection pressure as well as with the Diesel proportion in the blend, and so with the reactivity of the injected fuel.