State of segregation

Segregrated flow Occurs when all molecules that enter together also leave together. A state of segregation is associated with every RTD. Each aggregate of molecules reacts independently of every other aggregate, as in an individual batch reactor. 

As an example consider free-radical polymerization. When an occasional free radical is formed here and there in the reactor it triggers an extremely rapid chain of reactions, often thousands of steps in a fraction of a second. The local reaction rate and conversion can thus be very high. In this situation the immediate surroundings of the reacting and growing molecules—and hence the state of segregation of the fluid—can greatly affect the type of polymer formed. 

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

When indeed the state of segregation is a small-scale segregation, then each particle at a certain point will, on the average, be surrounded by-other particles which have an average concentration which is characteristic for the point in consideration. When c is the concentration in a particular particle and c is the average concentration in all of the particles at the point of interest, then... 

If only a single fast (or instantaneous) reaction is involved, relatively slow mixing and state of segregation may cause a change in the apparent reaction rate (reduction in plant capacity), but no... 

Examples of these methods can be found in ref. [28] and [333-4 5. Experimental determination of the state of segregation... 

Still with the aim of having mathematical expressions for the representation of the solution, Redlich and Kister offered a representation that provides an expansion of the excess Gibbs energy, a pure-substance reference in the same state of segregation as the solution (reference (I)), the equivalent of ihe Margules expansion for the activity coefficients. For a two-component solution, the pol5momial expansion up to order m is written ... 

The reference chosen for convention (I) is components in the pure state in the same state of segregation as the solution (this reference is called the pure-substance reference), in which case, = 1. We chose to use it in... 

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