HCCI experiments with toluene reference fuels modeled by a semidetailed chemical kinetic model

Journal Article · Mon Dec 15 00:00:00 EST 2008 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2008.05.010· OSTI ID:21125489

Andrae, J C.G. ^[1]; Brinck, T ^[2]; Kalghatgi, G T ^[3]

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1. Department of Chemical Engineering and Technology, Royal Institute of Technology (KTH), SE-100 44 Stockholm (Sweden)
2. Department of Physical Chemistry, Royal Institute of Technology (KTH), SE-100 44 Stockholm (Sweden)
3. Shell Global Solutions (UK), P.O. Box 1, Chester CH1 3SH (United Kingdom)

A semidetailed mechanism (137 species and 633 reactions) and new experiments in a homogeneous charge compression ignition (HCCI) engine on the autoignition of toluene reference fuels are presented. Skeletal mechanisms for isooctane and n-heptane were added to a detailed toluene submechanism. The model shows generally good agreement with ignition delay times measured in a shock tube and a rapid compression machine and is sensitive to changes in temperature, pressure, and mixture strength. The addition of reactions involving the formation and destruction of benzylperoxide radical was crucial to modeling toluene shock tube data. Laminar burning velocities for benzene and toluene were well predicted by the model after some revision of the high-temperature chemistry. Moreover, laminar burning velocities of a real gasoline at 353 and 500 K could be predicted by the model using a toluene reference fuel as a surrogate. The model also captures the experimentally observed differences in combustion phasing of toluene/n-heptane mixtures, compared to a primary reference fuel of the same research octane number, in HCCI engines as the intake pressure and temperature are changed. For high intake pressures and low intake temperatures, a sensitivity analysis at the moment of maximum heat release rate shows that the consumption of phenoxy radicals is rate-limiting when a toluene/n-heptane fuel is used, which makes this fuel more resistant to autoignition than the primary reference fuel. Typical CPU times encountered in zero-dimensional calculations were on the order of seconds and minutes in laminar flame speed calculations. Cross reactions between benzylperoxy radicals and n-heptane improved the model predictions of shock tube experiments for {phi}=1.0 and temperatures lower than 800 K for an n-heptane/toluene fuel mixture, but cross reactions had no influence on HCCI simulations. (author)

• OSTI ID: 21125489
• Journal Information: Combustion and Flame, Vol. 155, Issue 4; 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
33 ADVANCED PROPULSION SYSTEMS
TOLUENE
GASOLINE
HEPTANE
AUTOIGNITION
PHENOXY RADICALS
VELOCITY
TIME DELAY
TEMPERATURE RANGE 0400-1000 K
BENZENE
COMBUSTION
LAMINAR FLAMES
COMPRESSION
DIESEL ENGINES
SIMULATION
PRESSURE DEPENDENCE
SENSITIVITY ANALYSIS
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE DEPENDENCE