Kozeny-Carman's equation is used for the determination of the specific surface area of particles by gas permeametry. We found that using this equation the measured values of particle size under the same experimental conditions vary widely. After conducting many experiments, a scatter in measured values of specific surface area of particles was obtained. However, the obtained scatter of points is thought not to be due solely to experimental error, but they suggests that the value of
K is not a constant but is infact variable. Using glass spheres of known density and specific surface area, we proceeded to calculate the value of
K.
The sorted glass spheres were prepared by the following procedure. Toshiba glass beads (#GB741) were sieved using JIS standard screens (-420+350μm), decantated and nonspherical particles were removed using an inclined rotating circular plate. The mean particle diameter, specific surface area and density of the glass spheres are 362.5μm, 165.5cm
2/cm
3 and 2.50g/cm
3, respectively. The experiments were repeated under the same conditions as follows:
Sectional area of the cylindrical cell A is 32.047cm
2, the coefficient of viscosity of the nitrogen gas at 20°C η is 1.766×10
-5Pa·s, and the weights of the glass spheres are 200, 430, 860 and 1, 290g.
The experimental results obtained are as follows
(1) The values of Kozeny constant
K obtained by the reverse calculation technique vary widely, and the distribution curves of the values of
K are shown as normal distributions.
(2) In the case where the weight of the glass spheres is 200, 430, 860 and 1, 290g, the mean values of the constant
K are found to be 4.478±0.3234, 4.584±0.1844, 4.602±0.1168 and 4.58±0.0883 and the number of repetitions are 210, 90, 90 and 80 times, respectively.
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