Developing a high-fidelity reduced chemical kinetic mechanism for liquefied petroleum gas (LPG)

The current study aimed at developing an optimal and highly accurate reduced chemical kinetic mechanism for the Liquid Petroleum Gas (LPG). A three-stage reduction process including pre-processing, the main body reduction, and post-processing was utilized. In the main body reduction, a five-step reduction schematic was applied to the detailed mechanism including 980 species and 4972 reactions released by LLNL utilizing the Direct Relation Graph Error Propagation (DRGEP) method coupled with the isomer lumping and sensitivity analysis. Four different reduced mechanisms including 88, 73, 67, and 44 species were developed and compared with the experimental data. The laminar flame speed/equivalence ratio, ignition delay/temperature curves of the LPG combustion as well as 3D combustion parameters including in-cylinder pressure, mean temperature, heat release rate, and fuel consumption rate for an LPG-fueled opposed-piston engine were considered. It was seen that the 73 species mechanism results for the ignition delay/temperature and laminar flame speed/equivalence ratio matched with the experimental data with discrepancies of 3% and 5%, respectively. The 88 species and 73 species mechanisms showed good agreement in 3D modeling for all the considered parameters in comparison with the detailed mechanism with error values less than 2%. However, the 67 and 44 mechanisms results were not in accordance with the experimental data. Consequently, the developed 73-species mechanism was considered the optimal mechanism for LPG fuel.