Effective diameter

The fimctiong(ri is central to the modem theory of liquids, since it can be measured experimentally using neutron or x-ray diffraction and can be related to the interparticle potential energy. Experimental data [1] for two liquids, water and argon (iso-electronic with water) are shown in figure A2.4.1 plotted as a fiinction ofR = R /a, where a is the effective diameter of the species, and is roughly the position of the first maximum in g (R). For water, a = 2.82 A,... 

Let us focus our adention for the moment on a small volume in space, dr, and on particles in the volume with a given velocity v. Let us sit on such a particle and ask if it might collide in time t with another particle whose velocity is v, say. Taking the effective diameter of each particle to be a, as described above, we see... 

To be specific let us have in mind a picture of a porous catalyst pellet as an assembly of powder particles compacted into a rigid structure which is seamed by a system of pores, comprising the spaces between adjacent particles. Such a pore network would be expected to be thoroughly cross-linked on the scale of the powder particles. It is useful to have some quantitative idea of the sizes of various features of the catalyst structur< so let us take the powder particles to be of the order of 50p, in diameter. Then it is unlikely that the macropore effective diameters are much less than 10,000 X, while the mean free path at atmospheric pressure and ambient temperature, even for small molecules such as nitrogen, does not exceed... 

Molecular sieves 4X Molecules with effective diameter >4A 0.001 0.18 250... 

Effective Diameters (a) for Selected Inorganic Cations and Anions... 

The same type catalyst modified with boron (41), magnesium (42), or phosphoms (43) to reduce the pore size can be used to alkylate toluene with ethylene to produce predominantly -ethyltoluene. Since -ethyltoluene [622-96-8] has the smallest effective diameter of the ethyltoluene isomers, the selectivity to this isomer is favored because it can most easily escape the ZSM-5 pore stmcture. For the same reason, the alkylation of toluene [108-88-3] to xylene [106 2-3] also is favored over the usual acid catalyzed equiHbrium mixture of isomers when it is carried out over magnesium- or phosphoms-modified ZSM-5 (44). 

While the axial position of multistage impellers to their diffusers is not critical, they should line up reasonably well. Impellers are not extremely sensitive to leading-edge dings and minor damage, but anything, such as erosion on the exit tips, that tends to decrease the effective diameter of the impeller is more serious. Front shroud clearance on open impellers should be maintained close to the design values to minimize capacity loss. 

Deduct 4 inches from effective diameter for 2-inch support ring inside. 

The main problem of hydrate formation will arise in pipelines transporting natural gas, because gas hydrates are solids and will leave deposits. The solid deposits reduce the effective diameter of the pipeline and can therefore restrict or even clog the flow properties. Furthermore, the formation of condensates, hydrates, or ice may occur in the course of decompression of natural gas stored in natural reservoirs (e.g., in salt caverns). The operation of oil and gas pipelines in the deep sea is significantly complicated by the formation of gas hydrates [1204]. Experience indicates that large gas hydrate plugs in gas and oil pipelines form most actively during the period of an unforeseen long shut-down. In static conditions, three types of hydrate crystals can be formed [1153] ... 

Deff Effective diameter of column for wind loading L... 

The root mean square (rms) radius for the electron distribution is (3/5)mra and the corresponding rms effective diameter of the molecule is then given by ... 

Many particles are not spherical and so will not have the same drag properties as spherical particles. The effective diameter for such particles is often characterized by the equivalent Stokes diameter, which is the diameter of the sphere that has the same terminal velocity as the particle. This can be determined from a direct measurement of the settling rate of the... 

An alternative description of nonspherical particles is often represented by the sphericity factor (tfi), which is the number that, when multiplied by the diameter of a sphere with the same volume as the particle (ds), gives the particle effective diameter (dp) ... 

For a gas of density p, viscosity 17, flowing at a mass rate m in a pipe of effective diameter D and length L, the pressure drop is ... 

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