Investigation on the Octane Sensitivity of Gasoline Fuel

Abstract

The potential improvement of SI combustion has been investigated for the alkane fuels with distinguished autoignition properties, that is, the negative octane sensitivities. From the reported RON and MON of pure hydrocarbons, the alkane compounds with negative octane sensitivity were selected and then numerical simulations have been performed by generating the oxidation mechanisms by KUCRS auto-generation tool. As a common features of the negative octane-sensitivity fuels, the prominent NTC (negative temperature coefficient) behaviors were observed. The relationship between the NTC or octane sensitivity and chemical structures of alkanes were discussed. As a general trend, the alkyl substitution decreases the octane sensitivity especially when the substitution was made at third (or larger) position from the edge of the main chain. The replacement of substituent from methyl group to ethyl group significantly decreases the octane sensitivity. The investigation on the pressure and equivalence ration dependences were shown. The autoignition trends have been investigated by varying the compression ratio.