Mixing earliness

Arrington C A, Morse M D and Doverstal M 1995 Spectroscopy of mixed early-late transition metal diatomics ScNi, YPd, and ZrCo J. Chem. Rhys. 102 1895... 

Win(ts,t) = 1 - F , fraction of material entering at time t which will remain in the reactor for a duration greater than tg, and Wout (ts,t) = 1 - Fout, fraction of material leaving at time t which remained in the reactor for a duration greater than tg. From these functions, two RTD can be defined, namely E n = 9F n/3tg and out = 3Fout/ats which have all the classical properties of steady state RTD except that they vary with time. In particular, chemical conversion can be calculated in the two limits of mixing earliness (see next Section). For minimal mixedness ... 

Figure 3. The two limiting cases for mixing earliness. Left, Min. Mix. particles having the same age are close together (on the same vertical) right, Max. Mix. particles having the same life expectancy are close together (on the same vertical).

Playing a project or part of a project hack is something that will quickly become second nature as you work with ACID. Mixing, on the other hand, is a surprisingly complex concept that cannot be overlooked in any project. It is pretty important to work with volume and panning to control the mix early in a project, but mixing is also probably the last and most important variable to finalize before a song is published or committed to a CD. 

The complementary fraction in the L.E. is 1 - s. s(X,t ), which may also be written s(X,a), is known as the "segregation function". This term is somewhat confusing as the process above is concerned with segregation of ages (mixing earliness). However, s(X,a) also describes the decay of segregation in the physical sense under the additional (and often made) assumption that E.E. = macrofluid and L.E. = microfluid. In the particular tube considered above, the... 

Mixing earliness may be experimentally determined by injecting two tracers A and B which can react with each other. Close to Minimum Mixedness, the best discrimination is obtained by injecting two sharp pulses of A and B separated by a short interval. Close to Maximum Mixedness, the recommended injection is a square pulse containing both A and B. The reaction extent at the reactor outlet is then strongly dependent on micromixing. The determination is simple if the reaction products are coloured (e.g., hydrolysis of p-nitrophenyl acetate) [22 [23. ... 

When chemical reactions with orders different from one are involved the residence time alone is no longer sufficient to predict conversion since this also depends on the history of concentrations encountered by the reactants in the reactor. Additional information about mixing earliness and segregation must be known. 

Flow models presented in Sec. 2.4 may be used for predicting chemical conversion. Elementary patterns involved in the model are generally assumed to behave as ideal well micromixed reactors. Mixing earliness is implicitly accounted for by the arrangement of these elementary zones with respect to each other and the internal streams connecting them. This method is very popular and is successful for representing and scaling up chemical reactors provided the model has a sound physical basis. 

Since CSTRs and PFRs represent the extremes of mixing, the best order wUl depend on whether it is better to mix when the reactant concentrations are high or when they are low. Stated differently, is it better to mix early in the reaction (when the conversion is low) or to mix late in the reaction (when the conversion is high) The answer depends on the rate equation. 

These generalizations apply to a situation where the amount ofmixing is fixed, and the only question is whether to mix early or late in the reaction. The generalizations do not mean that mixing is beneficial. Obviously, based only on the total volume required, mixing is undesirable in all three of these cases. We would use a PFR in all three situations, if that were allowable. 

A variety of acetylide complexes have been reported with mixed early-late transition metal or mid-late transition metal complexes. The synthetic procedures either... 

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