**16. Conclusions**

The injection zone 1 (Tracer 1) allows a lower mixing time compared with the injection zone 2. However, mixing times of Monitors C and E are less sensitive to changes in stirrer speed.

The SM and ROT stirring models were discarded because the calculated mixing time does not correspond to the experimental data, as seen in **Figures 20** and **21**. Experimental mixing time

**Figure 20.** Tracer 1 curves, Monitor C (100 rpm) with 3 different models: MRF, SM, and ROT.

**Figure 21.** Tracer 2 curves, Monitor E (100 rpm) with 3 different models: MRF, SM, and ROT.

Once MRF model was selected, a stirring speed swept from 100 to 300 rpm was done. Monitor C mixing time presents minor variations between 100 to 200 rpm; however, at 300 rpm the mixing time is drastically reduced (**Figure 22**). In contrast, in Monitor E the mixing time is reduced by increasing the stirring speed. An increase in the stirring speed leads to a reduced mixing time, allowing better contact among chemical species. Nevertheless, in the case of polymerization, a high stirring speed (above 300 rpm) can produce mechanical degradation

**15. Effect of the stirring speed**

of the formed chains.

is well fitted by MRF calculations.

288 Modeling and Simulation in Engineering Sciences

Chemical product design requires the development of standardized procedures to ensure reproducibility and quality of the synthetized product. If this is possible, then the impact of any experimental variation on the product properties can be properly analyzed and eventually, the optimization of the designed product can be reached.

To set up a procedure for the synthesis of an AAm-AMPSNa copolymer in a batch reactor, we have used CFD-simulations and rheokinetics. These tools were used to research the relation‐ ship between the polymerization reaction kinetics and the mixing process.

The AAm-AMPSNa copolymer properties (Mv, Tg and kp/kt 1/2) increase according to the shear rate (better mixing) in the synthesis. Specifically, the molecular weight of the polymer synthetized at the highest stirring speed (C7) increases up to 317% with respect to the lowest stirring speed in the stirred tank (C2), showing a direct relation between the mixing stirring times and the chemical kinetics.

MRF and realizable *k*- satisfactorily model the mixing process in the stirred tank. The tracer curves obtained numerically from CFD were experimentally validated using a 1 M NaOH tracer. The simulated mixing time differs by 0.4% with regard to the experimental value of Monitor E (Tracer 2).

According to the tracer analysis and the rheokinetics of the polymerization, it is recommended that reagents be injected (e.g. initiators or REDOX pairs) in the region defined as "Tracer 1," operating the reactor at 217 rpm (200 s−1) and controlling the temperature at 60°C.

To give continuity to this work, we suggest to include the rheokinetics model in the transport phenomena equations, to consider rheology progression and its effect on the flow pattern, as a consequence of the growing polymer chains.
