Attachment coefficient calculation

Theoretical calculations of unattached fractions of radon progeny require prediction of an attachment coefficient. Average attachment coefficients for aerosols of various count median diameters, CMD, and geometric standard deviations, ag, are calculated using four different theories. These theories are ... 

The two fundamental theories for calculating the attachment coefficient, 3, are the diffusion theory for large particles and the kinetic theory for small particles. The diffusion theory predicts an attachment coefficient proportional to the diameter of the aerosol particle whereas the kinetic theory predicts an attachment coefficient proportional to the aerosol surface area. The theory... 

From Figure 1 it can be seen that Fuchs theory and equation (5) predict similar attachment coefficients. Equation (5) is therefore used in calculating average attachment coefficients. 

The average attachment coefficient 3 can be calculated for the diffusion and the kinetic theory from the equation ... 

The kinetic-diffusion approximation predicts an attachment coefficient similar to the hybrid theory for all CMDs and for both Og m 2 and 3 (Figs. 3 and 4). The advantage of this theory is that the average attachment coefficient can be calculated from an analytical solution numerical techniques are not required. 

Figure 5 shows the variation of the hybrid theory with CMD for various Og. It is obvious that assuming an aerosol to be mono-disperse when it is in fact polydisperse leads to an underestimation of the attachment coefficient, leading in turn to large errors in calculation of theoretical unattached fraction. 

Calculation of the attachment coefficient is required for theoretical prediction of the unattached fraction of radon progeny. The hybrid theory, which is a form of Fuchs theory with certain justifiable assumptions, can be used to describe attachment to aerosols under all conditions of Og and CMD. 

The calculated parameters X, qf, cp and ri are presented in Tables lb, lib and III. In addition the attachment equivalent diameter 3 was determined from the attachment coefficient 6 = X/Z by means of the attachment theory (Porstendorfer et al., 1979). 

Since physical parameters were held constant in these experiments, the theoretical single collector efficiency, r/(p, c)theor, is constant at 0.00256. The experimental attachment efficiency, a(p, c)exp, however, varies from 0.014 to 0.94, depending on the chemical composition of the solution. In the presence of a high concentration of Ca2+, the attachment coefficient approaches 1. This means that, in the absence of a repulsive chemical interaction, the mass-transport rale as calculated with Eq. 4 successfully describes the performance of these laboratory columns. At low ionic strength (pNa = 3.0), the sticking coefficient is reduced to a value of 0.014 by repulsive chemical interactions (presumably primarily electrostatic) between the suspended latex particles and the stationary glass collectors. Only 1.4% of the contacts produced by mass transport lead to attachment and deposition of the latex particles from the suspension. 

P are the attachment coefficients of the point defects by the planar SI AC of radius r , calculated in accordance with Duparc et al. (2002) from Equation 2.5 ... 

The fluid model is a description of the RF discharge in terms of averaged quantities [268, 269]. Balance equations for particle, momentum, and/or energy density are solved consistently with the Poisson equation for the electric field. Fluxes described by drift and diffusion terms may replace the momentum balance. In most cases, for the electrons both the particle density and the energy are incorporated, whereas for the ions only the densities are calculated. If the balance equation for the averaged electron energy is incorporated, the electron transport coefficients and the ionization, attachment, and excitation rates can be handled as functions of the electron temperature instead of the local electric field. 

The disadvantage of the fluid model is that no kinetic information is obtained. Also, transport (diffusion, mobility) and rate coefficients (ionization, attachment) are needed, which can only be obtained from experiments or from kinetic calculations in simpler settings (e.g. Townsend discharges). Experimental data on... 

The tank in Problem 66 is 6 in. in diameter and contains water at a depth of 3 ft. On the side of the tank near the bottom is a 1.5 in. ID outlet to which is attached a ball valve, which has a loss coefficient of 1.2. When the valve is opened, the water flows out in a horizontal stream. Calculate ... 

UV-VIS-NIR diffuse reflectance (DR) spectra were measured using a Perkin-Elmer UV-VIS-NIR spectrometer Lambda 19 equipped with a diffuse reflectance attachment with an integrating sphere coated by BaS04. Spectra of sample in 5 mm thick silica cell were recorded in a differential mode with the parent zeolite treated at the same conditions as a reference. For details see Ref. [5], The absorption intensity was calculated from the Schuster-Kubelka-Munk equation F(R ,) = (l-R< )2/2Roo, where R is the diffuse reflectance from a semi-infinite layer and F(R00) is proportional to the absorption coefficient. 

Carbon atoms are classified depending on their hybridization and whether their neighbors are carbon atoms or heteroatoms. Halogen atoms are classified by the hybridization and oxidation state of the C atom to which they are attached. O, S, Se, N, and P are classified in different ways. The model uses 120 different atom-type descriptions and has been developed with a training set of 893 compounds. Observed versus calculated log Kow showed a correlation coefficient of 0.926 and a standard deviation of 0.496. This method has been implemented in the Toolkit. Applications are shown in Figures 13.4.5 and 13.4.6 for the same compounds used to illustrate the Broto et al. method (Figs. 13.4.2 and 13.4.3). 

A circumferential fin of rectangular profile is constructed of I percent carbon steel and attached to a circular tube maintained at I50°C. The diameter of the fin is 5 cm, and the length is also 5 cm with a thickness of 2 mm. The surrounding air is maintained at 20°C and the convection heat-transfer coefficient may be taken as 100 W/m2 °C. Calculate the heat lost from the fin. 

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