An Investigation On Chemical Kinetic Model Of Gasoline Surrogate Mixture

In recent years, homogeneous charge compression ignition(HCCI) draws a worldwide attention due to its high thermal efficiency and low emissions. The chemical kinetics of the fuels plays a key role in HCCI engines, which is different from the traditional gasoline and diesel engines. Gasoline is a complex mixture of hundreds of hydrocarbons and it is necessary to select some representative components in gasoline to simulate the numerical combustion. In the study, a quaternary gasoline surrogate mixture including of toluene, isooctane, n-heptane and diisobutylene, are investigated.Firstly, dissobutylene was selected to represent the olefin class in the gasoline surrogate mixture and the combustion characteristic of dissobutylene was carried out under the condition of HCCI engine combustion. At the same time, the chemical kinetics study was conducted and the important reactions, species and reaction paths were obtained through the path analysis and sensitivity analysis. Dissobutylene is mainly consumed through H-abstraction reactions by OH radical and direct decomposition reaction. Dissobutylene firstly reacts with OH in the H-abstraction reactions path and form three isomers, namely, JC8H15-A, JC8H15-B, and JC8H15-D. DMPD13,DMPD13-E,DMPD13 O,DMPD13HO and DMPD13 CO are also the important intermediate products in the H-abstraction reactions path. The another main consumption of dissobutylene is direct decomposition reaction and two important C4 products were formed by the decomposition reaction(JC8H16=IC4H7+TC4H9), namely, TC4H9 and IC4H7. Then these C4 products transform the C1-C3 generation through a few reactions.Dissobutylene is added into gasoline surrogate mixture and combined with n-heptane, iso-octane, toluene to form quaternary gasoline surrogate mixture, namely TRF/DIB. A new reduced chemical kinetic model of TRF/DIB is developed, which includes 103 species and 199 reactions. The results agree well with the experiment results through validations of the ignition delay times which are performed under the pressure of 1.5~2MPa and 4.5~6MPa for ternary mixture TRF and the pressure of 10, 20, 30 bar for TRF/DIB. At the same time, good agreements had been achieved between the simulation and the experiment in an HCCI engine. Base on above the comparison, the reduced TRF/DIB model has reliable performance for HCCI combustion simulations.