Development of a Skeletal Mechanism of a Four-Component Diesel Surrogate Fuel Using the Decoupling Method.

Abstract

Alkylcyclohexanes with a long alkyl chain account for more than 30% of diesel fuel but seldom used in the oxidation mechanism of diesel surrogate fuel due to the lack of a reduced skeletal mechanism. Hence, a four-component diesel surrogate fuel was developed with n-butylcyclohexane (NBCH) as the representative of alkylcyclohexanes with a long alkyl chain in real diesel. The surrogate fuel can reproduce the physicochemical characteristics of real diesel, especially the distillation range. The reduced mechanism of NBCH was developed, and the skeletal mechanism of the surrogate fuel was formulated including 80 species and 251 reactions based on the decoupling method. The mechanism was validated under a wide range of conditions with the experimental results of ignition delay time (IDT), laminar flame speed, and species concentrations of both pure components and diesel. The accuracy of the mechanism on the spray and ignition performance was further validated against the experimental data obtained in a constant volume combustion chamber system. The calculated results showed a satisfactory agreement, in which the maximum error of flame lift-off length is 7.82 mm and that of IDTs is 0.16 ms. It was proven that the mechanism is suitable to reproduce the physicochemical properties of diesel and further predict the diesel spray and ignition performance.