Mean diameter number

Mean diameter Number Mean length cross-section Total blood of total... 

Ferefs diameter (Fig. 20-5) is the perpendicular projection, in a fixed direction, of the tangents to the extremities of the particle profile. Martin s diameter is a hne, parallel to a fixed direction, which divides the particle profile into two equal areas. Since the magnitude of these statistical diameters varies with particle orientation, these diameters have meaning only when a sufficient number of measurements are averaged. 

Particle Diameter (pm) Mean Flow Rate (L min 1) Group13 Number of Samples Mean SE... 

Before carrying out particle sizing on a sample, the microscope s ocular scale must be calibrated. This is normally done with a stage micrometer, which has a linear graduated scale. The micrometer is aligned with the eyepiece ocular to determine the length per ocular scale division. The ocular can then be used to read the diameters of particles on a slide. When sufficient particles are sized, the length-number mean can be calculated ... 

Treatment Mean number of individuals per plot Mean diameter (cm) Mean weight (9) Total yield per plot (tons/acre)... 

The geometric number mean diameter, D%N, is related to the arithmetic mean of In (diameter) ... 

Number average, or mean d or d Z,n,d, L,n, Diameter Number in class... 

C — hydrocydooc pressure-drop constant Cm m inlet oil-m-water concentration Cot dean-water outlet oil-m-waler concentration d - hydrocydooe major diameter d mean oil droplet diameter - efficiency Nfe - Reynolds number pm inlet pressure p0y, outlet pressure... 

Choice of which average diameter to use in a given situation depends on how the diameter was measured or how it is to be used. For the case where aerosol mass is measured and the fractions collected are associated with specific particle diameters, the resulting average value is the mass median diameter. In studying chemical reaction rates, the volume-surface mean diameter may be more important than just the arithmetic mean or geometric number mean. 

Analysis The characteristic length (which is the hydraulic diameter), the mean velocity, and the Reynolds number in this case are... 

Figure 12.2 Effects of low- and high-shear swirl distribution on arithmetic mean diameter, number density, and volume flux for (a) nonburning and (6) burning cases for equal combustion airflow distribution between inner and outer annulus of the burner 1 — 50°/30° and 2 — 65 /30°. The upper panels correspond to X = 30 mm, and the lower panels correspond to X = 5 mm.

The arithmetic mean diameter (or number mean) is calculate... 

Number mean diameter, Dp Dp jj fo Dpti iDp) dDp Average diameter of the population... 

Our previous discussion indicates that there may be significant differences between the mass and the number mean aerosol scavenging efficiency. The scavenging coefficient A dp) given by (20.53) applies both to mass and number of aerosols of diameter dp. However, A , refers exclusively to mass. The mean number scavenging efficiency A is defined by... 

The volume mean diameter is higher than the number mean and surface mean diameters and equals 2.29 mm. 

TABLE 9.6 Definitions of Number Mean Diameters (Allen 1990)... 

Hewitt [34] derived formulas for Mass Mean Diameter (MMD) and Number Mean Diameter (NMD) for air-assist nozzles. He claims that SMD is primarily a function of liquid density and air velocity. The effects of nozzle geometry are neglected from his study, as his study was aimed more at rotary nozzles (as explained later in Rotary Nozzles section). 

The slip flow near the boundary surface can be analyzed based on the type of fluids, i.e., gas and Newtonian and non-Newtonian liquids. The sUp flow in gases has been derived based on Maxwell s kinetic theory. In gases, the concept of mean free path is well defined. Slip flow is observed when characteristic flow length scale is of the order of the mean free path of the gas molecules. An estimate of the mean free path of ideal gas is /m 1/(Vlna p) where p is the gas density (here taken as the number of molecules per unit volume) and a is the molecular diameter. The mean free path / , depends strongly on pressure and temperature due to density variation. Knudsen number is defined as the ratio of the mean free path to the characteristic length scale... 

Usually, for systems not very near an instability, the range of influence of the central particle on the surrounding molecules does not exceed a distance, R, which is on the order of a few molecular diameters. This means that gy f) = 1 for r > R and that correlations between the central molecule and the surrounding ones are active only at r Denoting as the volume around the central molecule i where correlations are effective, and with the volume of one mole of mixture, the total number... 

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