Packing ratio, definition

The constant is not a tme partition coefficient because of difference, — V, includes the soflds and the fluid associated with the gel or stationary phase. By definition, IV represents only the fluid inside the stationary-phase particles and does not include the volume occupied by the soflds which make up the gel. Thus is a property of the gel, and like it defines solute behavior independently of the bed dimensions. The ratio of to should be a constant for a given gel packed in a specific column (34). 

Soil specific weight is the measure of the concentration of packing of particles in a soil mass. It is also an index of compressibility. Less dense, or loosely packed, soils are much more compressible under loads. Soil specific weight may be expressed numerically as soil ratio and ptorosity (porosity for soils being basically the same definition as that for rocks discussed earlier in this section). Soil porosity e is... 

It can be shown that the ratio v3lvg is equal to the ratio of polymer packing densities coefficients in the amorphous and crystalline states, KJKC at Tg, because, by definition, Ka = NA V /va and Kc - NA Vi/yC)where vj is the Van der Waals volume of the chain repeat unit. The calculated values of (ATc)g correlate with the characteristic chain parameter a/o, the relationship between them being expressed by a linear equation... 

Based on the definition of density, two new terms are defined. Porosity is defined as the proportion of a powder bed or compact that is occupied by pores and is a measure of the packing efficiency of a powder and relative density is the ratio of the measured bulk density and the true density ... 

The review published by Ergun (E2) provides a definitive description of pressure drop in packed tubes when the ratio of particle diameter to tube diameter is sufficiently low. In addition, although the complicated relationship between the diameter ratio, the fraction void and the friction factor can not be accurately represented without some explicit dependence of the friction factor on the diameter ratio, Ergun showed that his correlation does work for a wide variety of experimental conditions. The friction factor is calculated from the expression... 

A very important form of such disturbances is caused by the presence of the wall of the tube containing the packed bed. Vortmeyer and Schuster (1983) have used a variational approach to evaluate the steady two-dimensional velocity profiles for isothermal incompressible flow in rectangular and circular packed beds. They used the continuity equation, Brinkman s equation (1947), and a semiempirical expression for the radial porosity profile in the packed bed to compute these profiles. They were able to show that significant preferential wall flow occurs when the ratio of the channel diameter to the particle diameter becomes sufficiently small. Although their study was done for an idealized situation it has laid the foundation for more detailed studies. Here CFD has definitely contributed to the improvements of theoretical prediction of reactor performance. 

Proposed standards of identity (10), which include all of the common frozen fruits except apples, specify definitely the ratios of fruit to sweeteners to be used and the labeling which should be used to indicate type, amount, and density of packing medium. 

Care must be taken with the definition of the velocity. S ne part of the obstruction factor can be explained by an inappropriate definition of the velocity. We must keep in mind that it refers to the residence time in the mobile phase of the sample compound whose diffusion is measured. This residence time is not necessarily identical to the residence time of an unretained sample compound, which is used to measure the linear velocity. Also, we implicitly assimied that the diffusion coefficient in the pores is the same as the diffusion coefficient in the interstitial mobile phase. This is also not necessarily the case. If me pore size is less than about 10 times larger than the size of the molecule, the diffusion coefficient depends on the ratio of the size of the sample molecule to w pore size of the packing. 

The compositions and chemical formulae for metal oxides and other inorganic compounds are usually written with a definite ratio of cations to anions, e.g. MaOb where a and b are usually small integers determined by the valence of the constituent atoms. In crystalline compounds this also reflects that the structure contains different types of sites (e.g. close-packed sites and tetrahedral or octahedral interstices) in simple ratios and that these are selectively and systematically filled with cations or anions. When the oxide MaOb contains M and O atoms in the exact ratio a b, it is said to have a stoichiometric composition. 

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