Particle diameter mass fraction

Min particle diameter Max particle diameter Mean particle diameter Mass fraction % Mass fraction in sieve fractionj mean diameter Cumulative mass fraction... 

The particle mass retained by each sieve is determined by weighing after drying when necessary, and each fraction is designated by the sieve size it passed and the size on which it was retained. The sieve diameter of a particle is therefore defined as the size of the sieve aperture through which the particle in question just passes through. Mass fractions of the particles are then presented in tabular or graphical form. 

The silt fraction is particles 0.20-0.002 mm in diameter. This fraction or separate is produced by the same physical breakdown as described earlier for the formation of sand. Silt is more finely divided silica, but the surfaces are basically the same as those of sand (i.e., silicon and oxygen), and oxygen lone pairs of electrons and hydroxyl groups control its chemistry. Because the particles are smaller, they have more surface area per unit mass. This results in the availability of a greater number of bonds for chemical reactions [1],... 

B. Mass fraction (or weight percent) retained (oversize) vs. average particle diameter... 

B-AP pyrolants made with CTPB are cured with epoxy resin as in the case of conventional AP-CTPB composite propellants. The mixture ratio of large-sized AP particles (200 pm in diameter) and small-sized particles (20 pm in diameter) is 0.30/ 0.70. The mass fraction of boron is variously 0.010, 0.050, 0.075, or 0.150, and the diameter of the boron particles, d, is either 0.5 pm, 2.7 pm, or 9 pm. 

The mass fraction of nickel powder incorporated into the NP pyrolant was 0.01 and the diameter of the nickel particles was 0.1 pm. The NP pyrolants with and without nickel particles were pressed into pellet-shaped grains 1 mm in diameter and 1 mm in length. The BK pyrolant was pressed into pellet-shaped grains 3 mm in diameter and 3 mm in length. 

Fig. 15.8 shows a typical set of burning rate versus pressure plots for GAP pyrolants composed of GAP copolymer with and without burning-rate modifiers. The burning rate decreases as the mass fraction of the burning-rate modifier, denoted by (G), is increased. Graphite particles of diameter 0.03 pm are used as the burn-... 

Fractionating power makes it possible to establish the relative increment in particle diameter or mass that can be separated with unit resolution. It can be demonstrated (by substituting Equations 12.14, 12.20, and 12.21b or c into Equation 12.22a or b, respectively) that F (or F ) can also by expressed by... 

FIGURE 9.60 Excess water in particles with diameters 0.1 ju.ni near the Grand Canyon in 1992 as a function of organic mass fraction (adapted from Saxena et at., 1995). 

Gillani, Leaitch, and co-workers (1995) carried out a detailed study of the fraction of accumulation mode particles (diameters from 0.17 to 2.07 /Am) that led to cloud droplet formation in continental stratiform clouds near Syracuse, New York. When the air mass was relatively clean, essentially all of the particles were activated to form cloud droplets in the cloud interior and the number concentration of cloud droplets increased linearly with the particle concentration. However, when the air mass was more polluted, the fraction of particles that were activated in the cloud interior was significantly smaller than one. This is illustrated by Fig. 14.40, which shows the variation of this fraction (F) as a function of the total particle concentration, Nun. In the most polluted air masses (as measured by large values of Nun), the fraction of particles activated was 0.28 + 0.08, whereas in the least polluted, it was as high as 0.96 + 0.05. The reason for this is likely that in the more polluted air masses, the higher number of particles provided a larger sink for water vapor, decreasing the extent of supersaturation. 

The complete description of a two-component population in the lognormal form requires the determination of five parameters. Where x is used to denote the logarithm of the particle diameter in microns, standard deviation of the variable x, the fraction of the total mass in one of the two populations and subscript 1 to denote the glass component, 2 the crystalline, we have ... 

Example 1.1 One of the applications of using Stokes s law to determine the particle size is the Sedigraph particle analyzer. Table El.l shows the relationship between the cumulative weight percentage of particles and the corresponding particle terminal velocities for a powder sample. The densities of the particle and the dispersing liquid are 2,200 and 745 kg/m3, respectively. The liquid viscosity is 1.156 x 10-3 kg/m s. Find out the relationship of the mass fraction distribution to the equivalent dynamic diameter. 

As an example, for mass fraction

volume fraction ap is about 10-4. The average spacing between particles becomes about 17 particle diameters. Thus, for this example we can consider the direct interactions among particles to be insignificant. 

Table 9 shows the results of the sieve analysis obtained for a sample of a FCC1 powder. The values reported in the first two columns of the table are the standard diameters of the sieve apertures. From these the mean diameter dp is obtained for each two adjacent sieve sizes and the values are reported in the third column. From the mass fraction of powder in each sieve (values in the fourth column) the weight percentage is obtained and reported in the fifth column. Thus, the sum of the mass fraction over the mean diameter allows the calculation of the volume-surface mean particle diameter of the distribution using Equation (1) ... 

Mean particle diameter at 16% 84% of cumulative mass fraction... 

Here G(a) is the intensity scattered by the particles with diameters between a and art-da, kfi is Boltzmann s constant, T the temperature, k the scattering vector (dependent on scattering angle and wavelength), t the correlation time and n the viscosity. To find the mass fraction distribution, F(a), we use... 

The simplest kind of a fixed catalyst bed is a random packing of catalyst particles in a tube. Different particle shapes are in use like spheres, cylinders, rings, flat disc pellets or crushed material of a certain sieve fraction. Mean particle diameters range from 2 to 10 mm, the minimum diameter is limited primarily by pressure drop considerations, the maximum diameter by the specific outer surface area for mass and heat transfer. 

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