Development of soot formation sub-model for Scania DC-9 diesel engine in the steady-state condition

Abstract

The purpose of the present study is to provide a sub-model for the formation and oxidation of soot based on chemical kinetics for the DC-9 Scania diesel engine. The present model is a phenomenological soot model, consisting of nine main stages in the formation of soot including acetylene formation, precursors formation, particle inception, coagulation, surface growth, oxygen, and hydroxyl surface oxidation and oxidation of acetylene and precursors. Acetylene is considered as the main ingredient in the formation of soot, and together with the carbon precursors, the two middle species of the soot mechanism control the soot formation process. Also, in this sub-model, the hydroxyl surface oxidation step has been added. The present sub-model has advantages over two-stage models and is capable of predicting mass growth of soot, precursors, particle diameter and its number. The following inputs of the soot sub-model, including pressure, temperature, volume and unburned fuel content, are derived from a zero-dimensional combustion model developed in this study. Also, an equilibrium sub-model has been used to calculate the concentration of some of the participating species in the soot sub-model. A comparison of the theoretical results with relevant experimental results shows that the present sub-model has been able to predict the pure amount of produced soot accurately. The average particle diameter is about 40 nm, which is very small in the range of particulate matter. The sub-model also predicts that the number of particles to be 1019 particles per unit volume.