Autoignition chemistry in a motored engine: An experimental and kinetic modeling study
- Lawrence Livermore National Lab., CA (United States)
- Politecnico Milano, Milan (Italy). Chemical Engineerng Dept.
- General Motors Research Lab., Warren, MI (United States)
Autoignition of isomers of pentane, hexane, and primary reference fuel mixture of n-heptane and iso-octane has been studied experimentally under motored engine conditions and computationally using a detailed chemical kinetic reaction mechanism. Computed and experimental results are compared and used to help understand the chemical factors leading to engine knock in spark-ignited engines. The kinetic model reproduces observed variations in critical compression ratio with fuel molecular size and structure, provides intermediate product species concentrations in good agreement with observations, and gives insights into the kinetic origins of fuel octane sensitivity. Sequential computed engine cycles were found to lead to stable, non-igniting behavior for conditions below a critical compression ratio; to unstable, oscillating but nonigniting behavior in a transition region; and eventually to ignition as the compression ratio is steadily increased. This transition is related to conditions where a negative temperature coefficient of reaction exists, which has a significant influence on octane number and fuel octane sensitivity.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 224306
- Report Number(s):
- UCRL-JC-123264; CONF-9603137-1; ON: DE96007158
- Resource Relation:
- Conference: Western States section meeting, Tempe, AZ (United States), 11-12 Mar 1996; Other Information: PBD: Feb 1996
- Country of Publication:
- United States
- Language:
- English
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