Mass transport correlations

Generally, diffusion coefficients strongly depend on viscosities and densities as well as molar volumes. The surface tension represents another important factor in calculations of mixture properties and mass transport correlations. Thus, possibly accurate determination methods are required. 

IV. USE OF MASS TRANSPORT CORRELATIONS FOR UNDERSTANDING MASS TRANSPORT CONTROLLED CORROSION... 

V. MASS TRANSPORT CORRELATIONS FOR SELECTED GEOMETRIES OF INTEREST... 

This section describes selected mass transport correlations for laboratory devices such as the rotating disk and cylinder. These mass transport correlations may be used in order to establish the same mass transport conditions (diffusional boundary layer thicknesses) as those obtained in a pipe or under impinging flow. Essentially, the experimenter may vary the rotation rate and geometry of the cylinder or disk to dial in the same mass transport conditions as obtained in the field for pipes or impinging jets. The user should also verify that the same hydrodynamic conditions also exist through use of Reynolds numbers, as shown above. 

The rotating disk electrode (RDE) is an important system in electrochemistry. Axial followed by radial flow across the disk brings fresh solution to all points across the disk (Fig. 6). The surface is therefore uniformly accessible to reacting species. The RDE operates under laminar flow for Re < 1.7 X 105. Flow is turbulent above 3.5 X 105 and is transitional in between (4). Thus the system is less practical for the study of corrosion under turbulent conditions but enjoys widespread use in research electrochemistry. For the rotating disk electrode, the laminar mass transport correlation obtained in the literature is given by Levich (10) ... 

Table 4.27 gives dimensionless mass transport correlations for different geometries and flow regimes. More complete compilations can be found in the literature [9,10]. 

Table 4.33 Dimensionless mass-transport correlations for free convection systems [9].

This approach permits for example to apply dimensionless mass transport correlations as discussed in section (4.3.2). However, the value of Dgff must be determined experimentally for each electrolyte composition because it depends on the concentration of all ions present. The reasoning presented here for the cathodic reduction of a cation can be easily extended to the reduction of anions and to anodic reactions. 

Estimation of Aeolian Mass Transport Correlations and Parameters.469... 

ESTIMATION OF AEOLIAN MASS TRANSPORT CORRELATIONS AND PARAMETERS... 

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