Ignition and combustion of boron slurry agglomerates

Journal Article · Wed Jan 01 00:00:00 EST 1986 · Combust. Sci. Technol.; (United States)

DOI:https://doi.org/10.1080/00102208608923847· OSTI ID:5657850

Holl, J T; Turns, S R; Solomon, A S.P.; Faeth, G M

The behavior of agglomerates of boron particles, formed during the combustion of boron slurry fuels, was studied in the post-flame region of a flat-flame burner. Agglomerates having initial diameters of 175-800 ..mu..m were supported on a probe and placed in the hot gas environment. Measurements were made of the variation of agglomerate size with time. Quenched agglomerate surface morphology was studied using a scanning electron microscope. Burner operating conditions were varied to give fuel equivalence ratios in the range 0-3-0.7 and gas temperatures in the range 1690-1975 K at atmospheric pressure. Flame environments both with and without water vapor were considered. Observations of surface morphology of partially-reacted slurry agglomerates suggest that the ignition and combustion process consists of the heat-up of a relatively porous agglomerate composed of individual boron particles covered with a solid oxide coating followed by oxide melting to form a liquid coating of low porosity. The oxide layer then gasifies, leaving an open, porous structure of reacting boron particles. Finally, the boron melts and transforms the agglomerate to a droplet. Measurements of ignition times and burning rates were interpreted in this framework for agglomerates formed from three different slurries. Burning rates computed from a diffusion-limited, equilibrium analysis were in reasonable agreement with measurements.

• Research Organization: Dept. of Mechanical Engineering, The Pennsylvania State Univ., University Park, PA 16802
• OSTI ID: 5657850
• Journal Information: Combust. Sci. Technol.; (United States), Vol. 45:3/4
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BORON
COMBUSTION KINETICS
ATMOSPHERIC PRESSURE
BURNERS
FLAME PROPAGATION
FUEL SLURRIES
IGNITION
MELTING
MORPHOLOGY
OPERATION
OXIDES
PARTICLE SIZE
PARTICLES
POROUS MATERIALS
PROBES
QUENCHING
SCANNING ELECTRON MICROSCOPY
TIME MEASUREMENT
VERY HIGH TEMPERATURE
WATER VAPOR
CHALCOGENIDES
CHEMICAL REACTION KINETICS
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTS
FLUIDS
FUELS
GASES
KINETICS
MATERIALS
MICROSCOPY
MIXTURES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REACTION KINETICS
SEMIMETALS
SIZE
SLURRIES
SUSPENSIONS
VAPORS
400800* - Combustion
Pyrolysis
& High-Temperature Chemistry