Diffusion volumes

TABLE 5-16 Atomic Diffusion Volumes for Use in Estimating Oab by the Method of Fuller/ Schettler/ and Giddings... 

Atomic and Structural Diffusion-Volume Increments, ) (cmVmol)... 

Matthews-Akgerman The free-volume approach of Hildebrand was shown to be valid for binary, dilute liquid paraffin mixtures (as well as self-diffusion), consisting of solutes from Cg to Cig and solvents of Cg and C o- The term they referred to as the diffusion volume was simply correlated with the critical volume, as = 0.308 V. We can infer from Table 5-15 that this is approximately related to the volume at the melting point as = 0.945 V, . Their correlation was vahd for diffusion of linear alkanes at temperatures up to 300°C and pressures up to 3.45 MPa. Matthews et al. and Erkey and Akger-man completea similar studies of diffusion of alkanes, restricted to /1-hexadecane and /i-octane, respectively, as the solvents. 

A method, proposed more recently by FULLER, SCHETTLER and GlDDlNGSf8 . is claimed to give an improved correlation. In this approach the values of the diffusion volume have been modified to give a better correspondence with experimental values, and have then been adjusted arbitrarily to make the coefficient in the equation equal to unity. The method does contain some anomalies, however, particularly in relation to the values of V for nitrogen, oxygen and air. Details of this method are given in Volume 6. 

Table 10.4. Atomic and structural diffusion volume increments (mVkmol)1 ...

E , J2vi = the summation of the special diffusion volume coefficients for components a b a and b, given in Table 8.5. 

Table 8.5. Special atomic diffusion volumes (Fuller el al., 1966)...

Vi Special diffusion volume coefficient for component i (Table 8.5) L3... 

In Tables 1.12 and 1.13, the diffusion volumes of some molecules and the volume increments of atoms are given (Perry and Green, 1984, 1999). 

Fuller binary diffusion coefficients [9] r. 0.143.10 6r1 75 uij —, 1/2, 1/3. 1/3, pMij (Vj +Vj ) Oxygen Fuller diffusion volume Nitrogen Fuller diffusion volume Hydrogen Fuller diffusion volume Water Fuller diffusion volume 16.3 18.5 6.12 13.1... 

Property of a cell or a material that can be pervaded by a liquid such as by osmosis or diffusion. Volume 1(14). 

The structure of a metallized layer is determined by the surface topography of the web substrate and by interaction of the involved condensation processes (shadowing, surface diffusion, volume diffusion, and desorption), which cause growth in the form of more or less densely packed pillars or conglomerates (Fig. 8.8) [8], Depending on which of the four condensation mechanisms is predominant, the structure will be more or less dense (Zones I—III). The activation energy for the surface and volume diffusion of metals is proportional to their respective melting... 

To obtain the total entropy production in the tower, Equation 11 must be integrated over the total diffusion volume... 

Equation (2.2) is the only equation needed when using the box method and this is sometimes cited as an advantage. It brings one close to the microscopic system, as we shall see, and has - in theory - great flexibility in cases where the diffusion volume has an awkward geometry. In practice, however, most geometries encountered will be - or can be simplified to - one of but a few... 

P = system pressure, pounds per square inch absolute Yj Vi = sum of atomic diffusion volumes shown in Table 1.22... 

Determine the diffusion volumes for benzene and air. Obtain the diffusion volumes for carbon, hydrogen, and an aromatic ring from Table 1.22. Weight the carbon and hydrogen in accordance with the number of atoms in the benzene molecule (six each), then add the diffusion increment for the aromatic ring (note that it is a negative number). The sum is the diffusion volume for benzene ... 

Molecule Diffusion volume Molecule Diffusion volume... 

As for air, its diffusion volume can be read directly from the table 20.1. 

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