## 3 Results and Discussion  
### The Effect of Volume Flow Rate and Temperature on Conversion  
The experimental measurements for the ethyl acetate saponification reaction were conducted in different reactor systems (Figures 7-9). The experimental data are given as points with error bars. Horizontal error bars represent inaccuracies in the experimental determination of the volumes of the whole reactor system: the reactor, the residence time unit, the tube connectors, and the conductivity cell. Vertical error bars consider uncertainties of conductivity measurements and inaccuracies of conductivity measurements for 0% and 100% conversion solutions from Figure 6. The dashed lines represent the reactor model, based on the kinetic modeling using the Arrhenius parameters which were obtained from the kinetic study. Since the experimental points lie very close to each other, a zoomed in view at low space times is shown. The measured conversion values in different reactor systems indicate the differences from the kinetic model. The reactor performance is considered as poor if the experimental points lie below the model curve. Otherwise, if the experimental points coincide, or are above the model curve the reactor system shows a good reactor performance. The reactor system with a T-shaped reactor gives a good reactor performance only at high volume flow rates from 0.8 to 20 mL/min (space time from 8.3 to 55.5 s  
Figure 7: Experimental data (crosses) and kinetic model (dashed lines) at different temperatures in the reactor system with a T-shaped reactor. Figure 8: Experimental data (crosses) and kinetic model (dashed lines) at different temperatures in the reactor system with an interdigital microreactor. Figure 9: Experimental data (crosses) and kinetic model (dashed lines) at different temperatures in the reactor system with a chicane microreactor. This corresponds to a low degree of mixing grade and indicates a strongly stratified flow, which is completely insufficient for mixing purposes [34]. Since the T-shaped reactor serves as the main mixing element in this system, further mixing can only be enhanced by molecular diffusion and weak secondary flow formations in the residence time unit. Therefore, the mixing time at low volume flow rates is relative long, thus having a negative effect on sodium hydroxide conversion. At higher flow rates, a significant intensification of the mixing process can be observed (Figure 10b). The flow consists of alternating layers of both solutions due to the formation of vortices in the cross-section. This flow is called vortex flow [34]. The interfacial area between solutions becomes significantly larger, which results in enhanced molecular diffusion which takes place in the residence time unit. Conversion at a volume flow rate of 5 mL/min or higher (space time less than 33 s) is equal to the results according to the kinetic model at the same space time because of weak vortices. Moreover, higher volume flow rates cause more intensive secondary flow vortices inside the residence time unit. At a volume flow rate of 20 mL/min, an extremely fast mixing process takes place, due to a vortex manifold of different length scales (Figure 10c). Therefore, mixing quality at 20 mL/min higher flow rate seems to be more efficient than at 5 mL/min. There are differences between the experimental data and the model in the reactor system with a T-shaped reactor, and they can be observed at low flow rates and the highest investigated temperature (32 \({}^{\circ}\)C). At higher temperatures, the value of the diffusion constant increases. Since the primary mixing process occurs through molecular diffusion, the value of the diffusion constant may have a significant influence on the diffusion rate. At high flow rates or short space times, several measurement points lie slightly above the model curve. A possible reason for this behavior is the fact that the hydrodynamics inside the conductivity cell can differ at various flow rates.