Strategies for mechanism reduction for large hydrocarbons: n-heptane

Journal Article · Tue Jul 15 00:00:00 EDT 2008 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2007.11.013· OSTI ID:21044878

Lu, Tianfeng; Law, Chung K ^[1]

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1. Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

A 55-species reduced mechanism for n-heptane oxidation was derived from a 188-species skeletal mechanism, which was previously obtained from a detailed mechanism consisting of 561 species using a directed relation graph (DRG). This reduced mechanism was derived by first obtaining a skeletal mechanism with 78 species using DRG-aided sensitivity analysis. The unimportant reactions were eliminated by using the importance index defined in computational singular perturbation (CSP), with a newly posited restriction to treat each reversible reaction as a single reaction. An isomer lumping approach, also developed in the present study, then groups the isomers with similar thermal and diffusion properties so that the number of species transport equations is reduced. It was found that the intragroup mass fractions of the isomers can be approximated as constants in the present reduced mechanism, leading to a 68-species mechanism with 283 elementary reactions. Finally, 13 global quasi-steady-state species were identified using a CSP-based time-scale analysis, resulting in the 55-species reduced mechanism, with 283 elementary reactions lumped into 51 semiglobal steps. Validation of the reduced mechanism shows good agreement with the detailed mechanism for both ignition and extinction phenomena. The inadequacy of the detailed mechanism in predicting the experimental laminar flame speed is also demonstrated. (author)

• OSTI ID: 21044878
• Journal Information: Combustion and Flame, Vol. 154, Issue 1-2; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HEPTANE
ISOMERS
LAMINAR FLAMES
COMBUSTION
COMBUSTION KINETICS
TRANSPORT THEORY
APPROXIMATIONS
FLAME PROPAGATION
FLAME EXTINCTION
OXIDATION
VALIDATION
IGNITION
VELOCITY
Mechanism reduction
Isomer lumping
Computational singular perturbation
Quasi-steady-state approximation