Autoignition behavior of lean mixtures: Chemical and thermodynamics effects
- Princeton Univ., NJ (United States). Dept. of Mechanical and Aerospace Engineering
- Lawrence Livermore National Lab., CA (United States)
Knock characteristics of natural gas (NG), 89 octane unleaded gasoline, 2,2-dimethyl butane (22DMB), and methyl tert-butyl ether (MTBE) in stoichiometric and lean fuel-air mixtures were studied in a production 4-cylinder automotive engine. The Intake Temperature at the Knock Limit (ITKL) was different for each fuel but always higher in lean mixtures. Gasoline and 22DMB exhibited much greater increases in ITKL than MTBE and NG at lean conditions. Surprisingly, for lean mixtures 22DMB exhibited higher ITKL than MTBE and was almost as high as NG. Comparison with detailed numerical modelling was very favorable. Computations show that both differences in chemistry and end-gas temperature and pressure histories are responsible for these trends. This behavior is interpreted in terms of the Negative Temperature Coefficient behavior of hydrocarbon oxidation. The implication of these results for the specification of optimal fuels for lean-burn engine is discussed.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 10131938
- Report Number(s):
- UCRL-JC--109673; CONF-920707--24; ON: DE92009690
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201
ALTERNATIVE FUELS
AUTOMOTIVE FUELS
BUTANE
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
CHEMICAL REACTION KINETICS
EFFICIENCY
ETHERS
GASOLINE
IGNITION
KNOCK CONTROL
MATHEMATICAL MODELS
NATURAL GAS
SPARK IGNITION ENGINES
SPARK-IGNITION
TEMPERATURE DEPENDENCE
TESTING