Effect of Flow Pattern

The effect of flow pattern in a reactor was investigated with ethylene as the monomer by changing the position of monomer inlet and pumping exit of the system. A relatively high flow rate of about 9.8 seem, which showed a conspicuous minimum at the location near the monomer inlet, was used throughout this series of experiments. 

Whether or not the monomer is fed through the radio frequency coil also has an important influence on the distribution of polymer deposition. When 

These experimental data indicate that three major factors influence the polymer deposition in a plasma reactor the locations of (1) the energy input (radio frequency coil in these cases), (2) the monomer flow inlet, and (3) the monomer flow outlet. The local deposition rate di observed at a location is expressed as a function of the location of polymer deposition. These experimental data indicate that the major parameter that determines d is the distance from the energy input. Other factors (i.e., monomer inlet and outlet) determine the direction of flow, which can be either along or against the direction of the energy input to the point of polymer deposition. The direction of monomer flow has less influence on the polymer deposition than the distance from the energy input. 

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Figure 3. Effect of flow pattern on rate analysis.

COMBINED EFFECT OF FLOW PATTERN AND ENERGY INPUT... 

Bakker, A. Fasano, J.B. Myers, K.J. Effects of flow pattern on the solids distribution in a stirred tank. I. Chem. E. Symp. Ser. 1994, 136, 1-8. Gadala-Maria, F. Acrivos, A. Shear-induced structure in a concentrated suspension of solid spheres. J. Rheol. 1980, 24, 799-814. 

Pribyl, Bar-Cohen and Bergles [3] have studied the effect of flow pattern on CHF, based on water data obtained in three independent test facilities with a total number of experimental points of 4109. The tube diameters ranged from 1.0 to 37.0 mm, heated lengths from 31 to 3,000 mm and mass... 

V P Serwinski, The effect of flow patterns and gate parameters on fiber orientation , Proceedings ANTEC 92, Detroit, MI. Society of Plastics Engineers, Brookfield, CT, USA. May 1992, Volume 1, pp 1277-1278. 

Explain and analyze the effects of flow patterns on the separation achieved in membrane systems... 

Omoijan, R. P., Clnic, G. M., Tekic, M. N. (1996). A simple analytical analysis of the performance of a two-membrane reactor. Journal of Membrane Science, 118, 17—22. Omoijan, R. P., Gordana, M. C., Miodrag, N. T., Ratomir, N. P. (1997). Applicability of two-membrane reactors for reversible gas phase reaction. Effects of flow patterns and inerts. Journal of Membrane Science, 128, 213—221. 

Bakker A., Fasano J.B., Myers K.J. Effects of flow patterns on the soUd distribution in a stirred tank. 

Bakker, A., J. B. Fasano, and K. J. Myers (1994). Effect of flow pattern on solids distribution in a stirred tank, Inst. Chem. Eng. Symp. Sen, 136, 65-72. 

Figure 13-33. The yields for the two scales are closer together for equal N, but there is still significant deviation, suggesting that for this chemical reaction there is an effect of flow pattern on yield.

Emulsions. Because emulsions are different from dispersions, different viscosity—concentration relationships must be used (71,87). In an emulsion the droplets are not rigid, and viscosity can vary over a wide range. Several equations have been proposed to account for this. An extension of the Einstein equation includes a factor that allows for the effect of variations in fluid circulation within the droplets and subsequent distortion of flow patterns (98,99). 

The mechanism of suspension is related to the type of flow pattern obtained. Suspended types of flow are usually attributable to dispersion of the particles by the action of the turbulent eddies in the fluid. In turbulent flow, the vertical component of the eddy velocity will lie between one-seventh and one-fifth of the forward velocity of the fluid and, if this is more than the terminal falling velocity of the particles, they will tend to be supported in the fluid. In practice it is found that this mechanism is not as effective as might be thought because there is a tendency for the particles to damp out the eddy currents. 

Tinker, T. Proceedings of the General Discussion onHeat Transfer, September, 1951, p. 89. Analysis of the fluid flow pattern in shell and tube exchangers and the effect of flow distribution on the heat exchanger performance, (Inst, of Mech. Eng. and Am, Soc. Mech. Eng.). 

The effect of flow obstructions on the flow pattern transitions in horizontal two-phase flow was studied by Salcudean and Chun (1983). The practical importance of the problem is related to the use of rod spacing devices in water-cooled nuclear reactors. In general, these devices are expected to affect the flow distribu-... 

Salcudean, M., J. H. Chun, and D. C. Groeneveld, 1983a, Effect of Flow Obstructions on the Flow Pattern Transitions in Horizontal Two-Phase Flow, Int. J. Multiphase Flow, P( 1) 87. (3) Salcudean, M., D. C. Groeneveld, and L. Leung, 1983b, Effects of Flow Obstruction Geometry on Pressure Drops in Horizontal Air-Water Flow, Int. J. Multiphase Flow 9(l) 73-85. (3)... 

Govier and Omer, in a recent article in the Canadian Journal of Chemical Engineering, have summarized the present (G4) state of knowledge concerning the calculation of pressure drop and other quantities in two-phase flow The principal flow patterns are understood in a qualitative way and the effect on flow pattern of the major variables, mainly the lineal or maffi velocities of the phases, is recognized. In nearly all cases the real significance of the viscosities of the phases, the possible separate roles of the densities of the phases, and the influence of the diameter of the pipe is not known. 

Kosterin (K3) investigated the effect of tube inclination on flow patterns for air-water systems. As tube inclination increases, the flow patterns become more dispersed tube slope is an important variable at the lower liquid or gas rates. At high gas rates, when annular or dispersed flow normally occurs in horizontal tubes, tube inclination has little effect on flow-pattern. 

The sum of both effects, the flow-pattern switch and the entrance flow effects, is achieved when the sign of curvature is simply altered [152], The respective design is that of a meander channel. At large Dean numbers, chaotic flow can be induced in this way, as evidenced by cross-sectional views of different segments of the meander channel. 

Relying on the knowledge of flow pattern generated by the Coanda effect inplane micro valves and micro pumps, it was envisaged to transfer this technique to a micro-mixer device [55], In the latter case, using a Tesla structure (see [163] for geometric details), the flow is redirected and collision of streams occurs. 

With the establishment of the primary phototriplet reduction mechanism we now turn to the explanation for the effect of flow rates and the formation of polarized phenoxy radicals. Since reaction [2] is a relatively fast secondary process it is readily understood that the observation of the primary ketyl radicals will be dependent upon flow rate. The triplet polarization (E) of the secondary phenacyl radical should not have been affected but the increased contribution of the E/A Radical-Pair polarization altered the overall appearance of the polarization pattern. The diffusion model of the Radical-Pair theory relates the E/A polarization magnitude to the radical concentration within the reaction zone. Since the phenacyl radical is considered to be very chemically reactive, and the product phenol "accumulated" within the reaction zone is also a much better hydrogen donor, the following reactions will proceed within the reaction zone ... 

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