Computer aided detailed mechanism generation for large hydrocarbons: n-decane

Martin Hilbig, Lars Seidel, Xiaoxiao Wang, Fabian Mauss, Thomas Zeuch

Abstract

Common engine fuels consist of a mixture of hundreds of hydrocarbons which differ in chain length and structure. For engine simulations real fuels are modeled by surrogate fuels. The most known surrogate fuel for gasoline is a mixture of n-heptane and iso-octane, and for diesel a mixture of n-decane and α-methylnaphthalene. For predicting pollutant formation more comprehensive fuel models are needed. Automatic mechanism generators can be applied to limit the amount of work in developing mechanisms for complex surrogate fuel blends.
Our group developed in the past detailed kinetic mechanisms for n-heptane and iso-octane. For this we followed the mechanism generation rules provided by Curran et al., with rate constants optimized such that the base chemistry from Hoyermann et al. [5] can be applied. We kept the reaction mechanism compact by applying the generation rules for low temperature oxidation to the fuel molecules only, and by introducing a linear lumping algorithm. In this work we demonstrate that rate coefficients, resulting from the mechanism optimization for n-heptane, can be used to generate a reaction mechanism for higher hydrocarbons i.e. n-decane. The thermodynamic data for the larger species are derived by Benson rules based on the thermodynamic data for n-heptane. The final mechanism is validated by shock tube and jet stirred reactor experiments. The mechanism is analyzed by reaction flow and sensitivity analyses. Ignition delay times and species concentration profiles agree well with the experimental data. Our prior work was limited to the prediction of ignition delay times. Recently detailed mechanisms for n-decane have been generated by Ranzi et al, Battin Leclerc et al. and Curran et al.