The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform

M. Choi - One of the best experts on this subject based on the ideXlab platform.

  • DETERMINATION OF NUMBER DENSITY, SIZE AND MORPHOLOGY OF AggregateS IN COFLOW DIFFUSION FLAMES USING LIGHT SCATTERING AND LOCAL SAMPLING
    Journal of Aerosol Science, 2000
    Co-Authors: J. Cho, M. Choi
    Abstract:

    Abstract Number density, size, and morphology of Silica Aggregate particles in coflow diffusion flames have been determined experimentally using a novel method combining light scattering and local sampling techniques. The number density and volume fraction of both Aggregates and spherical particles have been calculated from the scattering cross section measured from 90° light scattering with the combination of determining particle size and morphology from the localized sampling and TEM image analysis. Rayleigh–Debye–Gans and Mie theories have been applied to the calculations for fractal Aggregates and spherical particles, respectively. Of particular interests are the effects of carrier gas flow rates, different carrier gases, and flame temperatures on the growth of Silica particles and the roles of radial heat and H 2 O diffusion have been studied when using N 2 or O 2 as a carrier gas.

  • Measurements of Silica Aggregate Particle Growth Using Light Scattering and Thermophoretic Sampling in a Coflow Diffusion Flame
    Journal of Nanoparticle Research, 1999
    Co-Authors: M. Choi, J. Cho, J. Lee, H.w. Kim
    Abstract:

    The evolution of Silica Aggregate particles in a coflow diffusion flame has been studied experimentally using light scattering and thermophoretic sampling techniques. An attempt has been made to calculate the Aggregate number density and volume fraction using the measurements of scattering cross section from 90° light scattering with combination of measuring the particle size and morphology from the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh–Debye–Gans and Mie theory for fractal Aggregates and spherical particles, respectively. Using this technique, the effects of H_2 flow rates on the evolution of Silica Aggregate particles have been studied in a coflow diffusion flame burner. As the flow rate of H_2 increases, the primary particle diameters of Silica Aggregates have been first decreased, but, further increase of H_2 flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal Aggregates finally become spherical particles. For the cases of high flame temperatures, the particle sizes become larger and the number densities decrease by coagulation as the particles move up within the flame. For cases of low flame temperatures, the primary particle diameters of Aggregates vary a little following the centerline of burner and for the case of the lowest flame temperature in the present experiments, the sizes of primary particles even decrease as particles move upward.

J. Cho - One of the best experts on this subject based on the ideXlab platform.

  • DETERMINATION OF NUMBER DENSITY, SIZE AND MORPHOLOGY OF AggregateS IN COFLOW DIFFUSION FLAMES USING LIGHT SCATTERING AND LOCAL SAMPLING
    Journal of Aerosol Science, 2000
    Co-Authors: J. Cho, M. Choi
    Abstract:

    Abstract Number density, size, and morphology of Silica Aggregate particles in coflow diffusion flames have been determined experimentally using a novel method combining light scattering and local sampling techniques. The number density and volume fraction of both Aggregates and spherical particles have been calculated from the scattering cross section measured from 90° light scattering with the combination of determining particle size and morphology from the localized sampling and TEM image analysis. Rayleigh–Debye–Gans and Mie theories have been applied to the calculations for fractal Aggregates and spherical particles, respectively. Of particular interests are the effects of carrier gas flow rates, different carrier gases, and flame temperatures on the growth of Silica particles and the roles of radial heat and H 2 O diffusion have been studied when using N 2 or O 2 as a carrier gas.

  • Measurements of Silica Aggregate Particle Growth Using Light Scattering and Thermophoretic Sampling in a Coflow Diffusion Flame
    Journal of Nanoparticle Research, 1999
    Co-Authors: M. Choi, J. Cho, J. Lee, H.w. Kim
    Abstract:

    The evolution of Silica Aggregate particles in a coflow diffusion flame has been studied experimentally using light scattering and thermophoretic sampling techniques. An attempt has been made to calculate the Aggregate number density and volume fraction using the measurements of scattering cross section from 90° light scattering with combination of measuring the particle size and morphology from the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh–Debye–Gans and Mie theory for fractal Aggregates and spherical particles, respectively. Using this technique, the effects of H_2 flow rates on the evolution of Silica Aggregate particles have been studied in a coflow diffusion flame burner. As the flow rate of H_2 increases, the primary particle diameters of Silica Aggregates have been first decreased, but, further increase of H_2 flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal Aggregates finally become spherical particles. For the cases of high flame temperatures, the particle sizes become larger and the number densities decrease by coagulation as the particles move up within the flame. For cases of low flame temperatures, the primary particle diameters of Aggregates vary a little following the centerline of burner and for the case of the lowest flame temperature in the present experiments, the sizes of primary particles even decrease as particles move upward.

H.w. Kim - One of the best experts on this subject based on the ideXlab platform.

  • Measurements of Silica Aggregate Particle Growth Using Light Scattering and Thermophoretic Sampling in a Coflow Diffusion Flame
    Journal of Nanoparticle Research, 1999
    Co-Authors: M. Choi, J. Cho, J. Lee, H.w. Kim
    Abstract:

    The evolution of Silica Aggregate particles in a coflow diffusion flame has been studied experimentally using light scattering and thermophoretic sampling techniques. An attempt has been made to calculate the Aggregate number density and volume fraction using the measurements of scattering cross section from 90° light scattering with combination of measuring the particle size and morphology from the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh–Debye–Gans and Mie theory for fractal Aggregates and spherical particles, respectively. Using this technique, the effects of H_2 flow rates on the evolution of Silica Aggregate particles have been studied in a coflow diffusion flame burner. As the flow rate of H_2 increases, the primary particle diameters of Silica Aggregates have been first decreased, but, further increase of H_2 flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal Aggregates finally become spherical particles. For the cases of high flame temperatures, the particle sizes become larger and the number densities decrease by coagulation as the particles move up within the flame. For cases of low flame temperatures, the primary particle diameters of Aggregates vary a little following the centerline of burner and for the case of the lowest flame temperature in the present experiments, the sizes of primary particles even decrease as particles move upward.

J. Lee - One of the best experts on this subject based on the ideXlab platform.

  • Measurements of Silica Aggregate Particle Growth Using Light Scattering and Thermophoretic Sampling in a Coflow Diffusion Flame
    Journal of Nanoparticle Research, 1999
    Co-Authors: M. Choi, J. Cho, J. Lee, H.w. Kim
    Abstract:

    The evolution of Silica Aggregate particles in a coflow diffusion flame has been studied experimentally using light scattering and thermophoretic sampling techniques. An attempt has been made to calculate the Aggregate number density and volume fraction using the measurements of scattering cross section from 90° light scattering with combination of measuring the particle size and morphology from the localized sampling and a TEM image analysis. Aggregate or particle number densities and volume fractions were calculated using Rayleigh–Debye–Gans and Mie theory for fractal Aggregates and spherical particles, respectively. Using this technique, the effects of H_2 flow rates on the evolution of Silica Aggregate particles have been studied in a coflow diffusion flame burner. As the flow rate of H_2 increases, the primary particle diameters of Silica Aggregates have been first decreased, but, further increase of H_2 flow rate causes the diameter of primary particles to increase and for sufficiently larger flow rates, the fractal Aggregates finally become spherical particles. For the cases of high flame temperatures, the particle sizes become larger and the number densities decrease by coagulation as the particles move up within the flame. For cases of low flame temperatures, the primary particle diameters of Aggregates vary a little following the centerline of burner and for the case of the lowest flame temperature in the present experiments, the sizes of primary particles even decrease as particles move upward.

David Boldridge - One of the best experts on this subject based on the ideXlab platform.

  • Morphological Characterization of Fumed Silica Aggregates
    Aerosol Science and Technology, 2010
    Co-Authors: David Boldridge
    Abstract:

    Transmission electron microscopy has been used to evaluate the primary particle size distributions and Aggregate structure of a fumed Silica sample. The primary particle size distribution within an individual Aggregate is narrow, with a geometric standard deviation of ∼ 1.2. The distributions of maximum diameters, projected areas, and average primary particle diameters were all skewed, and all were better described by a log-normal distribution than a normal distribution. The data confirmed the fractal description of the fumed Silica Aggregate structure, with a mass fractal dimension of 1.86. The fractal prefactor or lacunarity was evaluated from the Aggregate volume and the maximum particle dimension, and found to have a value of 0.83 for this sample.