## 3 Results and Discussion
### Mixing Process Tracking
#### 3.1.2 Diffusional Model  
The concentration profiles of the model and the diffusional coefficients were obtained thanks to the optimization process in Scilab. The concentration profiles of the binary mixtures are plotted in Figure 4. The 95% confidence interval of the experimental values is indicated. The B-40H mixture showed broader confidence intervals than the binary mixtures of PFK5. The concentration of all binary mixtures reached stabilization after 10 h. The molar concentrations at the end of the experiments were 4.1 and 8.2 mol m\({}^{-3}\) for the PFK5 mixtures and 17.1 mol m\({}^{-3}\) for the HFO3E mixture. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Line** & **Linear Regression** & \(\mathbf{r^{2}}\) & \(\mathbf{\epsilon_{M}\) (m\({}^{3}\) mol\({}^{-1}\) cm\({}^{-1}\))} \\ \hline \multirow{4}{*}{PFK5} & T & \(y=0.0811x\) & 0.997 & 9.9 \\  & MT & \(y=0.0852x\) & 0.999 & 10.4 \\  & MB & \(y=0.0827x\) & 0.999 & 10.1 \\  & B & \(y=0.0826x\) & 0.994 & 10.1 \\ \hline \multirow{4}{*}{HFOSE} & T & \(y=0.0081x\) & 0.991 & 0.99 \\  & MT & \(y=0.0081x\) & 0.989 & 0.99 \\ \cline{1-1}  & MB & \(y=0.0079x\) & 0.988 & 0.97 \\ \cline{1-1}  & B & \(y=0.0081x\) & 0.989 & 0.98 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Linear regression equations, correlation coefficients (\(r^{2}\)), and molar absortivities (\(\varepsilon_{M}\)), of PFK5 and HFO3E. Figure 4: Experimental (\(C_{cap}\), dots) and estimated (\(C_{model}\), solid lines) concentration profiles of the binary mixtures over time. T (Top, \(\circ\)), MT (Medium Top, \(\triangle\)), MB (Medium Bottom, \(\square\)), and B (Bottom, \(\diamond\)) correspond to the different heights of the measurement lines. The model fitted the experimental data of B-10P and B-20P mixtures correctly. The concentration profiles from the mixture B-40H show that the model deviated in lines T and B at the beginning of the experiment. The molar absorptivity of HFO3E is ten times lower than that of PFK5 in the UV spectrum. T is the line that shows the lowest concentration and B is the line that shows the highest molar flux, as will be discussed later. The concentration profiles obtained for the T-10P/40H mixture are shown in Figure 5. In general, the ternary mixture showed greater confidence intervals than the binary mixtures. Line MB exhibited less variation in both components than the others. Even though the whole mixture stabilized after 12 h, the concentration of HFO3E was stable after 10 h. The compound PFK5 is the one that determines the duration of the mixing process, as it is the one with the lower effective diffusion coefficient. The molar concentrations at the end of the experiments were 4.4 mol m\({}^{-3}\) for PFK5 and 16.6 mol m\({}^{-3}\) for HFO3E. The model fitted the experimental data correctly, although the concentration profile of HFO3E also deviated from the confidence interval in lines T and B, like in mixture B-40H. The optimized diffusion and convective coefficients, the theoretically estimated coefficients, and relative standard error for the binary mixtures are shown in Table 5. As diffusion does not depend on concentration, the \(D\) of mixtures B-10P and B-20P should be equal, and they are similar. Additionally, the \(K\) values are very low. It can be assumed that the convection mechanism had little effect on the mixing process. The \(RSE\) for all binary mixtures is lower than 6%, and the mixture whose model best fitted the experimental data was B-20P, which also has the lowest diffusion coefficient. The optimized coefficients of the PFK5 mixtures are more similar to the estimated one than the HFO3E mixture, and the error increases with the concentration. Figure 5: Experimental (\(C_{exp. }\) dots) and estimated (\(C_{model}\), solid lines) concentration profiles of the components of the ternary mixture over time. T (Top, \(\odot\)), MT (Medium Top, \(\triangle\)), MB (Medium Bottom, \(\square\)), and B (Bottom, \(\diamond\)) correspond to the different heights of the measurement lines.