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Using the Macrofluid Model to Calculate Limits of Performance

3 Using the Macrofluid Model to Calculate Limits of Performance [Pg.403]

All of the analyses in Chapter 4 were focused on the best arrangement of CSTRs and PFRs of different sizes in series. We did not recognize at the time that the external-age distribution for a given number, size, and type of reactors is the same, no matter how they are ordered. We saw a simple illustration of this in Example 10-2. [Pg.403]

Although it was not stated explicitly, the question that we really addressed in Chapter 4 was If the extemal-age distribution is fixed, shouldmvdng take place early in the reaction or late in the reaction, in order to maximize conversion The answer was [Pg.403]

For a first-order system, earliness or lateness of mixing does not affect reactor performance, for a given residence time distribution. Therefore, when the residence time distribution is known, the exact performance of a system of first-order reactions can be calculated from the macrofluid model. [Pg.403]

The macrofluid model represents the latest possible mixing/or a given residence time distribution. There is no mixing between fluid elements until the reaction is over, i.e., until the fluid has left the reactor. For a reaction with an effective order greater than 1, the macrofluid model represents the best possible situation. It provides an upper bound on conversion. If some mixing takes place before the fluid has left the reactor, the actual conversion will be less than predicted by the macrofluid model. [Pg.403]




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Calculation of model

Limitations of Use

Limited use

Limits of modeling

Limits of use

Macrofluid

Model calculations

Model limitations

Modeling limitations

Modeling, use

Performance calculations

Performance modeling

Performance models

The Use of Models

Using the Model

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