Gasoline includes various kinds of chemical species. Thus, the reaction model of gasoline components that includes the low-temperature oxidation and ignition reaction is necessary to investigate the method to control the combustion process of the gasoline engine. In this study, a gasoline combustion reaction model including n-paraffin, iso-paraffin, olefin, naphthene, alcohol, ether, and aromatic compound was developed.
KUCRS (Knowledge-basing Utilities for Complex Reaction Systems) [1] was modified to produce paraffin, olefin, naphthene, alcohol automatically. Also, the toluene reactions of gasoline surrogate model developed by Sakai et al. [2] including toluene, PRF (Primary Reference Fuel), ethanol, and ETBE (Ethyl-tert-butyl-ether) were modified. The universal rule of the reaction mechanisms and rate constants were clarified by using quantum chemical calculation. Then, the heptane, iso-octane, 2,4,4-trimethyl-1-pentene (iso-octene), methylcyclohexane reaction model produced by KUCRS and the toluene, ethanol, and ETBE model were merged to produce gasoline surrogate master model. Chemical species and elementary reactions of the gasoline surrogate master model were reduced by using the Directed Relation Graph (DRG) method to produce 803 chemical species and 3222 reactions.
To validate this reduced gasoline surrogate model, reaction calculation in the combustion chamber of a rapid compression machine (RCM) was performed. PRF, toluene/heptane mixture, and oxygenate (ethanol, ETBE) /heptane mixture were used for fuels. The comparison of experimental and calculation results of hot ignition period for RCM combustion of this study lay on a straight line. Thus, this gasoline surrogate model improved the combustion reaction under RCM combustion condition in which low-temperature oxidation process occurred.