Characterizing Sooting Tendencies of Complex Technical Fuel Samples using YSI

Abstract

Soot formation remains a critical focus in combustion science due to its adverse effects on human health and climate. The yield sooting index (YSI) is an established standardized metric for comparing the sooting tendencies of single fuel components or fuel mixtures. The index as a useful tool has been widely applied to neat compounds but is barely reported for complex technical fuels. In this study, laser-induced incandescence (LII) as measurement tool was used to quantify soot formation in a co-flow methane flame doped with various hydrocarbon fuels and fuel mixtures. A controlled evaporator mixer (CEM) enabled precise sample injection, and relative soot quantities were determined from peak incandescence signals. Using a standardized calculation approach for the sooting index, YSI values for mixtures were derived by referencing two index compounds with known YSIs. A set of well-characterized hydrocarbons was used to span a sooting range (YSI 60–336), allowing the generation of a reference scale. This scale of sooting tendencies formed the basis for evaluating the sooting behavior of complex fuels, providing a flexible framework for classifying fuel mixtures based on their molecular composition.