Fuel pre-vaporization effects on the minimum ignition energy of n-heptane spray/vapor mixtures
The effect of the extent of fuel pre-vaporization on the minimum ignition energies of n-heptane spray/vapor mixtures at atmospheric pressure was investigated by adding vaporized fuel to monodisperse sprays. The droplet diameter in the sprays were 50 ..mu..m. The minimum ignition energy (E/sub min/) was determined as a function of the extent of prevaporization (..cap omega..) and the equivalence ratio (phi). ..cap omega.. was set to approximately 0, 0.5 and 1.0. Phi was varied from 0.5 to 2.0 for the sprays and spray/vapor combinations, and 0.5 to 3.0 for the premixed prevaporized case. Increasing the equivalence ratio from 0.5 to 2.0 enhanced the ignitability of the sprays and spray/vapor mixtures. Equivalence ratios in the range 1.5 < phi < 2.0 were optimum for ignition of premixed prevaporized n-heptane-air mixtures, and ignition became increasingly more difficult as equivalence ratios extended beyond this range. Ignition was enhanced as ..cap omega.. increased from 0 to 1 for stoichiometric and fuel-rich mixtures. For fuel lean mixtures there was an optimum fuel vapor fraction for ignition which was less than 1. This optimum vapor fraction appeared to increase as the equivalence ratio increased. These findings suggest that the optimum extent of prevaporization may be that which produces the most ignitable mixture of fuel vapor and air in the interdroplet spacing.
- OSTI ID:
- 5845382
- Report Number(s):
- CONF-861211-
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
ATMOSPHERIC PRESSURE
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
DISPERSIONS
DROPLETS
EVAPORATION
FLUID FLOW
FLUIDS
FUEL-AIR RATIO
GASES
HEPTANE
HYDROCARBONS
IGNITION
KINETICS
MIXTURES
OPTIMIZATION
ORGANIC COMPOUNDS
PARTICLES
PHASE TRANSFORMATIONS
REACTION KINETICS
SPRAYS
STOICHIOMETRY
TWO-PHASE FLOW
VAPORS