Kinetic modeling of ion chemistry in diesel engines using a novel reduced ionic chemical mechanism

Abstract

BackgroundModeling ion current in combustion processes based on chemical kinetics mechanisms, results in more accurately calculating of the temperature and pressure of the combustion chamber. The use of ionic mechanisms also estimates the output pollutants of the combustion chamber with higher accuracy. MethodsThe aim of the current study is modelling of ion chemistry during diesel combustion. To achieve this goal, a multi-zone thermodynamic model was used to model the diesel engines performance. The chemistry of the combustion is simulated based on a kinetic mechanism with 327 reactions and 75 species. To reduce this mechanism, the progress rates of the reactions were calculated at the start of combustion, end of combustion, and CAD50 for three different cases, and essential reactions were detected. The reduced mechanism includes 44 species and 92 reactions. At the next step, ions and ion-based reactions were added to the reduced mechanism, and the reduced ionic mechanism was developed with 98 reactions and 49 species Significant FindingsThe results show that CH formation during the combustion process is the source of ion production inside the combustion chamber. The reduced ionic mechanism could accurately predict in-cylinder pressure, heat release rate, the start of combustion, and the location of 50% cumulative heat release. The highest error in prediction of CAD50 is less than 0.1%.