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Environmental Engineering Research 1998;3(2): 79-86.
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Optical Characterization of the Nonspherical Aerosol Particles
Generated by Combustion
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Hyuksang Chang,†, Hankwon Chang, Hoyeun Hong, and Yangsoo Won |
Hyuksang Chang, Hankwon Chang, Hoyeun Hong and Yangsoo Won Environmental Aerosol Engineering Laboratory Department of Environmental Engineering, Yeungnam University, Kyungsan City 712-749, Korea |
Corresponding Author:
Hyuksang Chang, , |
Received: February 18, 1998; Accepted: May 19, 1998. |
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ABSTRACT |
For the characterization of the nonspherical particles formed in the combustion process, an optical system which is based on the classical light scattering theory was used. For the simulation of light scattering measurements, the fumed silica agglomerate formed by the oxidation of SiCk near the premixed flame front was used for testing materials. Using the light scattering measurements technique, the average particle size and particle size distribution were determined based on the spherical assumption on the particle geometry. By the addition of small amount of POCl3 vapor in the gas mixing, the morphology of the silica aerosol agglomerate was transformed. Using the multiangular light scattering measurement techniques, the morphological characteristics of aerosol was determined. Using the determined morphological parameters, the corrections on the particle sizes were done. For the determination of aerosol parameters in the evolution process, the scattered light signal data were fitted into the inversion algorithm in which the theoretically calculated values and experimental values were coupled to reduce the particle size distribution parameters. For the theoretical calculation of the light scattering from an spherical single particle, Mie scattering theory was used. And the scattering signals from the agglomerate were fitted into the Rayleigh-Debye scattering theory to reduce the mophological paramaters. Application of two different scattering theories were used to make up the deviations caused by the changes of morphological characteristics in the aerosol along the measuring position in the flame downstream zone. In the light scattering measurement on the single component aerosol of silica in flame, the deviation is quite noticeable but the deviation becomes narrower with increasing the amount of phosphoric anhydride as it lowers the fusion temperature of silica particulate. The particle size distribution were determined by the inversion of light signals measured from the fixed three different angles with the assumption of spherical geometry of each particle, and the continuous different angular scattering spectrum which were measured simultaneously were used for morphological correction of the agglomerate. |
Keywords:
Multiangular Light Scattering | Morphology | Nonspherical Aerosol | Particle Size Distribution | Fumed Silica | Flame | Inversion |
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