Investigation of n-dodecane pyrolysis at various pressures and the development of a comprehensive combustion model

Abstract

n-Dodecane combustion was investigated experimentally and numerically in present study. Pyrolysis experiments of n-dodecane at pressures of 0.0066, 0.039, 0.197 and 1 atm, temperatures from 750 to 1430 K were studied in a flow reactor. Mole fractions of n-dodecane, argon and pyrolysis products (including active radicals) were evaluated. A kinetic model of n-dodecane was developed by validating both present and literature reported experiments. The rate of production analysis reveals H-abstraction and CC bond fission reactions are main consumption pathways of n-dodecane. The β-CC scission reactions of alkyls contribute to the formation of alkenes, which are mainly consumed via the allylic CC fission reactions. As a soot precursor, benzene is largely produced from the recombination of C3 species. Moreover, effects of carbon chain length on flow reactor pyrolysis were investigated for n-decane, n-dodecane and n-tetradecane. The decay of n-tetradecane is the fastest, followed by n-dodecane and n-decane, indicating that the pyrolysis reactivity of n-alkanes increases as the carbon chain length increases from C10 to C14n-alkanes. Ignition delay times and laminar burning velocities (LBVs) of n-alkanes under similar conditions were also compared, the result shows that effects of the carbon chain length on ignition delay times and LBVs are slight.