Degree of segregation

A CSTR is a deliberately backmixed reactor and, in principle, its effluent temperature and composition are the same as the reactor contents. With an ideal CSTR, the feed blends instantaneously with the uniform reactor contents. In actual practice, of course, we find that feed blending time may be protracted, and varying degrees of segregation, short circuiting and stagnation exist in the reactor contents. 

The monomer conversion in this seeded polymerization system is independent of the degree of segregation as long as an exponential residence time distribution function is maintained. 

Deactivating catalyst 319 Dead zones 159, 162, 163 Degree of segregation 471 Density influences 492 Desorption of solute 578, 579 Difference differential equation 579 Difference formulae for partial differential equations 268 Differential column 167... 

From Example 14-4, we conclude that the performance for a first-order reaction in a CSTR is independent of the degree of segregation. This conclusion does not apply to any other order (value of n). The results for n = 0, 1, and 2 are summarized in Table 14.1, which includes equations 14.3-22 to -25. 

The nature of mixing of fluid elements during flow through the vessel as characterized, so far, by the degree of segregation (Section 13.5) thus, in a CSTR (i.e., a... 

In this case, the results for /A2 are different, and this is typical for nonlinear processes. The lower result is for case (ii) in which earlier mixing occurs that is, when the CSTR precedes the PFR. Thus, although the kinetics, RTD, and degree of segregation (microfluid) are the same, a different mixing pattern in terms of location of mixing may result in a different performance. 

In most systems the variation of the surface tension with composition is much lower. Data for some binary liquids are shown in Figure 6.23. A limited degree of segregation is expected in these systems. 

The concept of segregation and its meaning to chemical reactors was first described by Danckwerts (1953). The intensity or degree of segregation is given the symbol I, which varies between one and zero. Shown in Fig. 1 is a tank with two components, A and B, which are separated into volume fractions, qA and l-qA this condition represents complete initial segregation (1 = 1). Stirring or... 

The technique of self-nucleation [75] can be very useful to study the nucleation and crystallization of block copolymer components, as already mentioned in previous sections. In block copolymers, factors like the volumetric fraction and the degree of segregation affect the type of confinement and therefore modify the self-nucleation behavior. In the case of semicrystalline block copolymers, several works have reported the self-nucleation of either one or both crystallizable components in PS-fc-PCL, PS-b-PB-b-PCL, PS-b-PE-b-PCL, PB-fr-PIB-fr-PEO, PE-fr-PEP-fr-PEO, PS-fc-PEO, PS-h-PEO-h-PCL, PB-b-PEO, PB/PB-fc-PEO and PPDX-fc-PCL [29,92,98,99,101-103,134] and three different kinds of behavior have been observed. Specific examples of these three cases are given in the following and in Table 5 ... 

Conventional tracer tests can reveal nothing of the extent of micromixing present in a chemical reactor. In theory, a choice of reacting tracers could be made which would enable the degree of segregation to be determined but, in practical situations, the complexities of such techniques... 

SELF-MKING OF A SINGLE FLUID Degree of Segregation... 

Batch Reactor. Let the batch reactor be filled with a macrofluid containing reactant A. Since each aggregate or packet of macrofluid acts as its own little batch reactor, conversion is the same in all aggregates and is in fact identical to what would be obtained with a microfluid. Thus for batch operations the degree of segregation does not affect conversion or product distribution. 

This equation is identical to that obtained for a microfluid for example, see Eq. 5.14a. Thus we conclude that the degree of segregation has no effect on conversion for first-order reactions. 

Danckwerts defined a degree of segregation J based on the fluctuations in concentration which occur. He studied a chemical reaction in a binary mixture of two components A and B, in which a is the volume fraction of A at a certain point and (1 — a) the volume fraction of B at this same... 

For the case of more or less parallel streams Danckwerts defined the degree of segregation by means of the age of a point. 

System Interaction rate State of segregation (here defined) Degree of segregation (Danckwerts) State of mixedness (Zwietering)... 

It must be stressed that this equation holds for every degree of segregation but only when the order of drop conversion is equal to zero. 

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