Flow resistance factor

The certified flow resistance factor, K[, is a dimensionless factor used to calculate the velocity head loss that results from the... 

FIGURE 6.1 A Poppe plot for the required plate number in conventional HPLC. The parameters are taken from Poppe s original paper (Poppe, 1997). The parameters are maximum pressure AP = 4x 107 Pa, viscosity / = 0.001 Pa/s, flow resistance factor

diffusion coefficient D= lx 1CT9 m2/s, and reduced plate height parameters using Knox s plate height model are A — 1, B— 1.5, C = 0.05. 

In pHPLC, there are numerous types of columns used. The comparison and characterization of these columns are often discussed in terms of thermodynamic properties and kinetic characteristics. The retention factor, k, selectivity, a, and the peak asymmetry are believed to be representative parameters for the thermodynamic properties, while the kinetic characteristics are often expressed in dimensionless magnitudes of reduced plate height, h, separation impedance, E, and flow resistance factor, ( ). 3... 

Figure 18. Influence of the ionic strength Is of the solvent (NaCl addition) on the flow resistance factor for solutions of HPAA 30.5% hydrolysis, 8.7 x...

An 18-20% hydrolyzed polyacrylamide was used in all tests. In all 300 ppm polymer solutions a radioactive C14 tagged polyacrylamide was used. At higher polymer concentrations (600 and 1200 ppm) a commercial product called Calgon Polymer 454 was added to the base 300 ppm radioactive solution. A special study was conducted to develop a radioactive polymer which has properties identical to the commercial product. Several experiments were run on both polymers to check these properties such as, viscosity measurements, friction reduction flow tests, and flow tests in porous media. These special studies showed that performance of the radioactive product was equivalent to that of the commercial product. A typical result of these tests is shown in Figure 1. The small differences in the polymer flow resistance factors are due to small differences in the textures of different sandpacks, rather than to differences in the chemical structures of the polymers. Friction reduction, viscosity, and retention experiments showed even closer agreements between properties of the radioactive and commercial product. 

Polymer flow resistance factors were computed from the equation below ... 

Figure 10 shows the polymer flow and residual resistance factor curve related to the experiments described in Figure 8. As can be seen, the polymer flow resistance factors stabilized at both 100% water saturation, and at residual oil saturation. The small differences in polymer flow resistance factors in these two experiments are probably due to small differences in pore structure from one pack to another.

The unsteady-state polymer flow resistance factors for any moment and distance can be determined from laboratory experiments, provided that the pressures are measured at an adequate number of locations. Combining these experiments with the determination of the flowing polymer concentration at difierent locations, the value of C it. or the absolute quantities of retained polymer can be determined for any location and for any time. 

The polymer flow resistance factor vs flow rate curve has a minimum in many cases [10]. It was also shown earlier [11] that over a critical flow rate an unsteady-state polymer flow can develop. In such a case, only the first value of the measured resistance factor will be on the resistance factor versus flow rate curve on its imaginary section (Figure 33). 

The polymer flow resistance factor shows a characteristic distribution as a function of distance in steady-state flow. This uniform distribution is due to the first invasion... 

Steady-state and unsteady-state polymer flow resistance factors at different distances from the injection face as a function of time. 

However, the exact values of the polymer flow resistance factors for any given distance coordinate can be determined if the pressure drops are measured in at least three segments of the porous body. The analytical solution of this problem is given in Appendix C. 

The average excess polymer flow resistance factor between 0—1 distance can be expressed as follows ... 

Q = volumetric flow, Sm /s Y = expansion factor, dimensionless K = flow resistance factor of pipes and fittings d = diameter, m Ap = differential pressure, kPa Pi = vessel pressure, kPaA T = temperature, K Sg = specific gravity (air = 1)... 

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