Rough disperse

Organic particles are also observed in the rough-disperse fraction of... 

The organic component is also present in marine aerosol. It is also characterized by a complicated chemical composition. Over remote oceanic regions the concentration of organic matter in the rough-disperse aerosol fraction can reach 2-4 mg/m [41], but in other cases it does not exceed 0.15-0.47 mg/m [18]. 

The concentration of rough-disperse particles with r > 0.14 pm constituted about 0.5 cm" These particles contribute most to the aerosol mass. Undoubtedly, they are driven from remote regions. Covering the surface, these particles form aerosol insertions into polar ice. Their long-term concentration variations can serve as indicators of paleoclimate changes. 

Suspension Monomer with dissolved initiator roughly dispersed in a continuous phase with a bw amount of surfactant Polymerisation initiated in monomer droplets droplets converted into polymer particles Large polymer particbs (diameter 10-1000 pm)... 

Lanthanum promoted supports with 7% of copper and higher thermally treated at 773 and 973 K contain a roughly-dispersed copper oxide, while the spinel form is not found probably because of its high dispersity and disorder. At 1273 K, unlike the cerium system, lanthanum exhibits a stabilizing effect only at 15% of Cu, all alumina appears to be in the form of a-Al203. 

When 2 and 7% of (Cu+Cr) mixture are introduced, the cerium modified support pretreated at 773 K, exhibits only its own lines, while when 15% of (Cr+Cu) is supported, the lines of roughly dispersed copper oxide are observed. According to X-ray patterns, the lines intensity of the spinel-based solid solutions increases with the increase of the supported components concentration. At 1273 K, all the studied samples reveal the presence of a-Al203 with the increased cell parameter and the spinel-type solid solution with a parameter typical for Cu(Alx,8Cro.2)04. Concentration of components introduced determine a-Al203 content. The content of a-oxide is considerably lower in the sample promoted with a 7% (Cu+Cr) mixture than in the pure alumina. 

These results combined with those obtained by TEM show that the resin with the highest EP/PP viscosity ratio present heterogeneous surface elastic properties corresponding to the rough dispersion of almost spherical EP nodules below the surface. On the contrary, the low viscosity ratio resin presents homogeneous surface elastic properties at the resolution of our measurements (> 100 nm). The measured surface rigidity is comparable to that measured above EP nodules on the high viscosity ratio resin. This could be explained by the easier deformation of the EP nodules into platelets and by their fine dispersion below the thin PP surface layer. 

Dispersion In tubes, and particiilarly in packed beds, the flow pattern is disturbed by eddies diose effect is taken into account by a dispersion coefficient in Fick s diffusion law. A PFR has a dispersion coefficient of 0 and a CSTR of oo. Some rough correlations of the Peclet number uL/D in terms of Reynolds and Schmidt numbers are Eqs. (23-47) to (23-49). There is also a relation between the Peclet number and the value of n of the RTD equation, Eq. (7-111). The dispersion model is sometimes said to be an adequate representation of a reaclor with a small deviation from phig ffow, without specifying the magnitude ol small. As a point of superiority to the RTD model, the dispersion model does have the empirical correlations that have been cited and can therefore be used for design purposes within the limits of those correlations. 

Colloid mills which are employed for dispersion or for emulsification fall into four main groups the hammer or turbine, the smooth-surface disk, the rough-surface type, and valve or orifice devices. 

The dispersion coefficient is orders of magnitude larger than the molecular diffusion coefficient. Some rough correlations of the Peclet number are proposed by Wen (in Petho and Noble, eds.. Residence Time Distribution Theory in Chemical Tngineeiing, Verlag Chemie, 1982), including some for flmdized beds. Those for axial dispersion are ... 

Comparison of Models Only scattered and inconclusive results have been obtained by calculation of the relative performances of the different models as converiers. Both the RTD and the dispersion coefficient require tracer tests for their accurate determination, so neither method can be said to be easier to apply The exception is when one of the cited correlations of Peclet numbers in terms of other groups can be used, although they are rough. The tanks-in-series model, however, provides a mechanism that is readily visualized and is therefore popular. 

Similarly, contaminant concentrations in rivers or streams can be roughly assessed based on rate of contaminant introduction and dilution volumes. Estuary or impoundment concentration regimes are highly dependent on the transport mechanisms enumerated. Contaminants may be localized and remain concentrated or may disperse rapidly and become diluted to insignificant levels. The conservative approach is to conduct a more in-depth assessment and use model results or survey data as a basis for determining contaminant concentration levels. 

Clouds cover roughly two-thirds of our earth s surface and play an important role in influencing global climate by affecting the radiation budget. Cirrus clouds are one example of a cloud type whose optical properties are not accurately known. Cirrus clouds form in the upper troposphere and are composed almost exclusively of non-spherical ice crystal particles. The impact of cloud coverage on dispersion of pollution in the atmosphere is an area of great concern and intensive study. 

Bubble flow - The gas is roughly uniformly distributed in the form of small discrete bubbles in a continuous liquid phase. The flow pattern is designated as bubble flow (B) at low liquid flowrates, and as dispersed bubble (DB) at high liquid flow rates in which case the bubbles are finely dispersed in the liquid. 

The criterion for the validity of Equation 8-141 is Npg 1.0. A rough rule-of-thumb is Npg > 10. If this condition is not satisfied, the correct equation depends on the boundary conditions at the inlet and outlet. A procedure for determining dispersion coefficient Dg [ is as follows ... 

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