Pressure-gradient correction factor

Net retention volume. VN- The adjusted retention volume multiplied by the pressure gradient correction factor. 

Pressure gradient correction factor. j. The factor that... 

Since a finite pressure drop exists over the length of the column, the adjusted retention volume is often multiplied by the pressure gradient correction factor, j, to give a net retention volume, VN. 

Figure 10.5. Plot of James-Martin pressure-gradient correction factor / as a function of the compression ratio P = pjp0 for a GC column.

Where j is the James-Martin pressure-gradient correction factor... 

Prove that the James-Martin pressure-gradient correction factor j approaches zero as P- oo and approaches unity as 1. Deduce these limits on a physical basis using the result j = u/v0. 

The net retention volume V is equal to the retention volume minus the column dead space, V — where both V and are corrected for the pressure-gradient correction factor (see below). If the noncolumn contributions to the dead space are insignificant relative to the total dead space, and if the sample size is small enough so that the velocity of the mobile phase within the band is not increased by the solute in the mobile phase, then the net retention volume is equal to kV, and the partition ratio is (V — F )/F . The relative retention for two solutes is the ratio of their net retention volumes (V2 — or Fj/Fj this is usually expressed by a... 

Strongly dependent on temperature for both gases and liquids. For gases the effective flow rate also may change with temperature, owing to changes in the pressure-gradient correction factor. 

Capacity factor based on tower area, ft/sec Capacity fector at flood, ft/sec Liquid gradient vapor load correction factor or Discharge coefficient (see accompanying table) or Gas phase loading factor, ft/sec. Equation 8-281 Eddy loss coefficient, dimensionless. Table 8-22 Wet cap pressure drop correction factor. Figure 8-115... 

Pressure Gradient Correction Coefficient j. This factor corrects for the compressibility of the mobile phase in a homogeneously filled column of uniform diameter ... 

For parallel plates, Co = 1, this equation reduces to Eq. 6.3-19 with pressure drop replacing pressure gradient. Hence, the terms containing Co can be viewed as correction factors of the parallel plate model for tapered geometries. 

The former vanishes when the velocity of the moving plate is zero, and the latter vanishes in the absence of a pressure gradient, (a) Explain on physical and mathematical grounds why the solution of the same flow problem with a non-Newtonian fluid, for example, a Power Law model fluid, no longer leads to the same type of expressions, (b) It is possible to define a superposition correction factor as follows... 

Figure 2 — Use this chart to find the correction factor for pressure-gradient values obtained from Figure 1...

Conversely, the correct approach to formulate the diffusion of a single component in a zeolite membrane is to use the MaxweU-Stefan (M-S) framework for diffusion in a nonideal binary fluid mixture made up of species 1 and 2 where 1 and 2 stands for the gas and the zeohtic material, respectively. In the M-S theory it is recognized that to effect relative motions between the species 1 and 2 in a fluid mixture, a force must be exerted on each species. This driving force is the chemical potential gradient, determined at constant temperature and pressure conditions [68]. The M-S diffiisivity depends on coverage and fugacity, and, therefore, is referred to as the corrected diffiisivity because the coefficient is corrected by a thermodynamic correction factor, which can be determined from the sorption isotherm. 

In the case of macro- and mesoporous supports their flow resistance should be as small as possible. If the transport resistance is not negligible corrections must be applied in the study of the separation properties of the separating layers. It is shown that even small pressure gradients across the support can cause a considerable decrease of the permeation and of the separation factor of the top layer, especially in the case of adsorbing gases. The absolute value of the permeate pressure is important in addition to the pressure ratio of feed and permeate streams. Increasing support resistance causes an increase of the permeate pressure on the interface between support and separation (top) layer in the case of supported membranes. 

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