Experimental study on in-flame soot formation and soot emission characteristics of gasoline/hydrogenated catalytic biodiesel blends

Abstract

Gasoline compression ignition engine is one of the most promising low-temperature combustion strategies using gasoline as fuel due to its high thermal efficiency and low emission characteristics. While the ignition difficulty under low loads and knocking combustion under high loads limit its practical applications. To solve these problems low reactive gasoline fuel blending with high reactive hydrogenated catalytic biodiesel was proposed. However, soot characteristics of large hydrocarbons are not yet known. In order to understand the relationship between the in-flame soot formation and soot emission for these blending fuels and to find an optimum ratio for GCI engines. Fundamental study on in-flame soot formation in a constant volume combustion chamber is studied using a diffused background-illumination extinction method. The results show that the in-flame soot mass and soot combustion duration was found to be reduced with increasing the ratio of gasoline. Lower ratios of hydrogenated catalytic biodiesel blends are tested in a gasoline compression ignition engine and the experimental results reveal that the increase of hydrogenated catalytic biodiesel ratio increased the total number of soot particle emission. The total number of particle emission showed a positive relationship with soot formation. But there is a weak relationship between the particle size distribution and in-flame soot formation under the same working loads. The results also demonstrated that the particle diameter was mainly depending on working conditions rather than soot formation. The blend ratio of hydrogenated catalytic biodiesel and the injection strategies were mainly contributed to the concentration of particle size.