High Pressure Oxidation of Liquid Fuels from Low to High Temperature. 2. Mixtures of n-Heptane and iso-Octane

Abstract

The oxidation of mixtures of n-heptane and iso-octane in a high-pressure jet-stirred reactor has been investigated experimentally in a wide range of conditions covering the low and high temperature oxidation regimes (550-1150K, 10 atm, ø=1). The cool flame and negative temperature coefficient regimes were observed below 750K, Above 750 K, the normal high temperature oxidation of both fuels was observed. Reactants, intermediates and final products have been measured providing a useful picture of n-heptane-iso-octane mixtures oxidation. Cyclic ethers resulting from the low-temperature oxidation chemistry of n-heptane and iso-octane were identified. The evolution of their concentration as a function of RON have been measured. These results are interpreted in terms of reaction mechanism. Tentative correlations between RON and CO, CO₂ and C₂H₄ in the cool flame region and for the high temperature oxidation (normal combustion) are presented.

Key Words:

• Subject Index: Combustion
• oxidation
• engine-knock
• hydrocarbon
• kinetics
• GC-MS

compound Index:

• n-heptane
• iso-octane
• 2,2,4-trimethylpentane