Application of a Decoupling Methodology for Development of Skeletal Oxidation Mechanisms for Heavy n-Alkanes from n-Octane to n-Hexadecane

Abstract

A series of skeletal mechanisms was developed based on a decoupling methodology to describe the oxidation of n-alkanes from n-octane to n-hexadecane. In the decoupling methodology, a fuel oxidation mechanism is divided into two parts: one is an extremely simplified model for species with a carbon atom number larger than two to simulate the ignition characteristics of n-alkane; the other is a detailed mechanism for H2/CO/C1 to predict the concentrations of small molecules, laminar flame speed, and extinction strain rate. The new skeletal mechanism includes only 36 species and 128 reactions for each n-alkane from n-octane to n-hexadecane. The mechanism was extensively validated against the experimental data in a shock tube, jet-stirred reactor, flow reactor, counterflow flame, and premixed laminar flame. Good agreements on ignition delay, the concentrations of major species, laminar flame speed, and extinction strain rate between the predictions and measurements were obtained over wide ranges of temperature, pressure, and equivalence ratio, which demonstrates the capability of the decoupling methodology to build skeletal oxidation mechanisms for n-alkanes. Due to the compact size of the new skeletal mechanism, it can be easily integrated into the computational fluid dynamics (CFD) simulation.

Development of a skeletal oxidation mechanism for biodiesel surrogate

“…The decoupling methodology has shown good performance in developing skeletal mechanisms for n-alkanes [22,25] and iso-alkanes [26]. Because of the different molecular structure between alkanes and methyl esters, necessary modifications were conducted for the construction of mechanisms for MD and MD5D by introducing a skeletal sub-mechanism containing the ester group in this study.…”

A Shock Tube Study of <i>n</i>-Undecane/Air Ignition Delays over a Wide Range of Temperatures

“…Till now, other experimental ignition delay data for n-undecane in air are not available. The comparisons of current results with simulations based on LLNL 15 mechanism, mechanism of Mzé-Ahmed et al 17 , mechanism of Chang et al 18 and JetSurF2.0 mechanism 19 are shown in Fig.4 for high temperature condition and in Fig.3 mainly for low temperature condition. As shown in Fig.4(a) and (b), predictions of the JetSurF2.0 mechanism, the LLNL mechanism, and the mechanism of Mzé-Ahmed et al are in closer accord with current experimental data, and in Fig.4(c), the computed ignition delay times from the LLNL mechanism are in good agreement with measured data.…”

“…Mzé-Ahmed et al 17 have studied the oxidation kinetic model of n-undecane and n-dodecane in a Jet-Stirred Reactor. Chang et al 18 have also developed skeletal oxidation mechanisms for heavy n-alkanes from n-octane to nhexadecane. These mechanisms can be applied to high and low temperatures.…”

Application of the Optimized Decoupling Methodology for the Construction of a Skeletal Primary Reference Fuel Mechanism Focusing on Engine-Relevant Conditions

“…A reduced C 2 -C 3 mechanism serves as the transition between the skeletal large-molecule mechanism and the detailed H 2 /CO/C 1 mechanism. With the decoupling methodology, a series of skeletal mechanisms for normal and branched alkanes have been constructed (Liu et al, 2012;Chang et al, 2013b). By comparing with experimental data, it is found that the mechanisms can satisfactorily reproduce the auto-ignition and oxidation behaviors from low to high temperatures in various reactors and practical engines.…”