Pedet number

In Figure 2.9.8(b), the mean traveling time of a neutral tracer across the percolation duster is plotted versus the Pedet number [43]. Two regimes can be identified, namely isotropic dispersion (Pe C 1) and mechanical dispersion (Pe > 1) with a crossover dose toPe 1. In the latter case, the data can be represented by a power law... 

Choquet, C., and Mikelic, A. "Laplace Transform Approach to the Upscaling of the Reactive Flow under Dominant Pedet Number", accepted for publicahon in "Applicable Analysis" (2008). 

Comparing the solution of this equation to a Gaussian distribution shows that an estimate of the Pedet number can be obtained from the variance of the N distribution Pe = 2L2/a2. To obtain estimates of Peclet numbers in the bed alone the assumption was made that the mixing at the ends of the bed and the dispersion within the bed are independent in the sense that the variances of the N profiles are additive. Figure 3 shows data both with and without the bed, and the result of subtracting the variance due to end mixing from the total variance. 

When the Pedet number equals about R3, or when Ad < 1 and Brownian motion is negligible, the radial concentration profile displays a maximum value greater than unity. Then a generalized form of transformation (11a)... 

Hashimoto I,Deshpande KB, Thomas HC (1964) Pedet numbers and retardation factors for ion exchange columns. Ind Eng Chem Fund 3 213-218... 

Example 10.3 Determine the Pedet number for 0.25-p.m-diameter spheres being mixed in a room 10 ft wide, 20 ft long, and 10 ft high if air is circulating in the room at a rate of 6 air changes per hour. 

A decrease in gas-phase Pedet number PeG, an increase in gas velocity, a... 

In this range Nagata et al. [0.6] found for the exponent a of the Pedet number... 

Consequently, we see that the Pedet number, Pe (and hence DJ. can be found experimentally by determining and [Pg.968]

Bar a Pedet number of 0.1 based on the PFR length, how much bigger than a PFR must the real reactor be to achieve the 99% conversion predicted by the PFR ... 

If the reactor is modeled by a dispersion mode , what are the Pedet numbers for an open system and for a dosed system. What is the conversion for a first-order reaction with k = 0.1 min" for each case ... 

P14>180 Load the laminar flow with dispersion example on the FEMLAB CD-ROM. Keep Da and L/R constant and var> the reaction order n, (0.5 < n < 5) for different Pedet numbers. Are there any combinations of n and Pe where dispersion is more important or less imponam on the exit concentration What generalizations can you make Hint for n < 1 use r = -k (AbsiC )) P14-19c Revisit the FEMLAB Example 14-3 for laminar flow with dispersions. 

Fig. 18. Pedet numbers in large scale gas—liquid contactors using 2.54-cm Bed saddles (----) or 2.54 cm (---) or 5.08 cm (----) Raschig rings (51).

Pedet number specifically defined for phase i,i = x orj hI I I), dimensionless HTU Pedet number, see equation 75... 

Figure 10.4 [4] shows the results for theoretical calculations [5] for the ratio n, the number of viable cells leaving the holding section of a continuous sterilizer, to n0, the number of viable cells entering the section, as a function of the Pedet number (Pe), as defined by Equation 10.7, and the dimensionless Damkohler number (Da),... 

Assuming a length of the holding section of 36 m, the Pedet number is given as... 

NA molar flux of A relative to stationary coordinates nA mass flux of A relative 10 stationary coordinates Pe Pedet number... 

Using the dispersion model, find the Pedet number, VNH at is the conversion of a first order reaction where A = 0.1 min" ... 

Qiung and Wen (1968) and Wen and Fan (1975) proposed a dimensionless equation using the dependency of the dispersion coefficient on the (particle) Reynolds number Re (Equation 6.171) for fixed and expanded beds. It is an empirical correlation, based on published experimental data and correlations from other authors, which covers a wide range of Rqmolds numbers Re. Owing to two different definitions of the Reynolds number, actual forms of the correlations vary in the literature. Since the particle diameter dp is the characteristic value of the packing. Equation 6.170 based on the (particle) Pedet number PCp (Equation 6.172) is given as follows ... 

Notably, the particle Pedet number differs from the axial Pedet number defined in Equation 6.108 by the ratio of partide diameter to column length ... 

In Section 7.1.2 it is shown that in case of high efficient chromatography the number of dimensionless parameters reduces and instead of Stanton and Pedet numbers the number of plates is the dominating parameter. In order to proof these findings for CLRC, Scherpian and Schembecker (2009) measured the elution profiles for three different process setups for which the number of plates, the loading factor, and the recycle number are constant. The characteristic data of these experiments are presented in the reference. 

The key parameter is the intrapartide Pedet number defined as the ratio between the time constant for pore diffusion and the time constant for intrapartide convection. There are two limiting situations ... 

Conservation Laivs and Equations of State 4. The Pedet number... 

The formulated boundary value problem has an analytical solution [46], but it is unwieldy and is not presented here. It should be noted that the necessary condition for the considered approximation is Pej> 1, otherwise it would be impossible to formulate the condition at the infinity. At centrifugation, the characteristic values of the Pedet number are 10 -10, therefore this assumption is justified. Another assumption refers to the short time intervals. Time enters the expression for the Strouhal number... 

A way to relate particle size of hard spheres (solid or colloidal particles, or very viscous drops) to shear rate and themnal energy (Brownian motion) is by means of a dimensionless parameter, the Pedet number (Pe). which is... 

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