# Rates of High-Temperature Evaporation of Promising Fire-Extinguishing Liquid Droplets
## 4 Results and Discussion  
Figures 6-8 show the registered times of full evaporation of droplets of the investigated compositions under heating temperature variation at three schemes of energy supply. The values of the evaporation rates \(W_{\mathrm{e}}\) calculated using the recorded times \(t_{\mathrm{d}}\) are also presented. Nonlinear (described by power polynomials and exponential expressions) dependences of \(t_{\mathrm{d}}\) and \(W_{\mathrm{e}}\) on \(T_{\mathrm{a}}\) have been established for all compositions. They agree well with the results of experiments for water given in Reference [43]. When heating on a substrate and in a muffle furnace, the differences between the experimental values of \(W_{\mathrm{e}}\) for water and the data of Reference [12] generally correspond to the confidence intervals of the experiments. The greatest dispersion of values of evaporation rates of water droplets was registered when heating in an air stream (Figure 7). This is because, in the placement of droplets of the studied compositions on the holder in this work, the contact area was approximately 15% to 17% larger than in the experiments of Reference [12] (estimates were made by using the method from Reference [43]). Accordingly, the times of complete evaporation of droplets in the experiments of Reference [12] were higher and the evaporation rates were lower, as can be seen in Figure 7. The increase in this area was due to a small rounding of the end of the holder. The need to modify the tip was caused by different rheological characteristics of the droplets, in contrast to Reference [12]. When using a tip similar to Reference [12], droplets of foaming agent emulsion and EA-5 solution were separated from its surface, while being moved by the coordinate mechanism, or spread almost completely. Therefore, it was difficult to register the rates of reduction of the drop radii and, accordingly, the evaporation rates. The difference in area of the droplet contact with the holder from Reference [12] led to a difference in the shape and, accordingly, the average size in the conditions of the air flow. This was because the incoming air flow pressed the drop to the holder. Therefore, these features should be taken into account when comparing the data, previously obtained in Reference [12] for water and, in this research, in the scheme with heating in the air flow (Figure 7). In experiments with the muffle furnace, this factor was weak. The differences between the results of this work and the data of Reference [12] were insignificant (Figure 8) and within the random errors of the registration of varied and controlled parameters. Figure 6: Dependence of droplet lifetime (complete evaporation) (**a**) and evaporation rates (**b**) on the substrate temperature. Data for water without impurities from the experiments of Reference [12]. The experiments for all heating schemes and studied compositions have resulted in registering the general form of dependence \(t_{\text{d}}(T_{\text{a}})\) and dependence \(W_{\text{e}}(T_{\text{a}})\) (Figures 6-8). In particular, the maximum values of total evaporation times (and accordingly, the minimum values of evaporation rates) corresponded to water and salt solutions. The maximum values of evaporation rates have been registered in experiments with foaming agent emulsion and EA-5 solution. The bentonite suspension was characterized by average rates of vaporization relative to the emulsion, solutions, and water without impurities. These patterns can be explained by the influence of a group of properties and effects manifested in the experiments. Since different synergetic effects were registered depending on the studied heating scheme, it is advisable to comment on differences in the curves in Figures 6-8 for each of these schemes separately. Figure 6 demonstrates the results of experiments when placing droplets of the studied compositions on a heated substrate. Several significant results may be distinguished.