# Rates of High-Temperature Evaporation of Promising Fire-Extinguishing Liquid Droplets
## 4 Results and Discussion
Therefore, this film acts as a buffer zone between the external gas medium and the internal liquid layers. The film reduces the evaporation rate. The higher the heating temperature, the greater the difference of \(W_{\mathrm{e}}\) is. Therefore, it can be concluded that, for intensive evaporation of EA-5, it is expedient to increase the dynamics of transformation of the surface of droplets and layers. In this case, evaporation rates can be even higher than those of suspensions, salt solutions, and water without impurities, as shown in the substrate and air flow schemes. The key feature of the application of the EA-5 solution is the formation of a buffer steam zone between the envelope, material, or substance, and the heating source. In addition to the above film, the formation of a vapor layer was observed on the videograms with conductive heating. The temperature diffusivity of vapors is an order of magnitude lower than that of liquids and solid materials. Therefore, the heat flux was significantly reduced after the passage of radiation through the vapor layer. In the analysis of Figure 8, it can be concluded that the most significant differences in the times of complete evaporation and vaporization rates are characteristic of the foaming agent emulsion compared to other studied component compositions. However, these differences are significant at low heating temperatures (up to 100 \({}^{\circ}\)C). The higher the heating temperature is, the smaller the difference in total evaporation times is. This result characterizes the fact that the rates of radiation heating of most extinguishing agents are close. However, due to different areas of the droplet contact with the holder and different areas of its free surface (the dynamics of droplet spreading is different, as mentioned above), the values of evaporation rates also differed even with an increasing temperature (Figure 8). If the key parameters of radiation heat transfer are taken into account, the determinant should be the emissivity of droplets of extinguishing agents. Therefore, the values of the heat fluxes to the surface of the studied droplets are comparable. When generalizing the experimental data obtained for each of the dependent factors in Figures 6-8, approximation expressions are formulated to most closely describe the experimental data. A similar work has been carried out to determine the approximation expressions for the dependence of the evaporation rates on the heating temperature. A general form of the approximation expression has been obtained for the evaporation rate dependence on the heating temperature by taking into account the scheme of heat supply to the drop: \(W_{e}=a\cdot T^{2}+b\cdot T+c\). Table 3 shows the values of empirical constants and the approximation confidence value (R\({}^{2}\)). In all cases, it was possible to most closely describe the dependence of the evaporation rates of liquids on the heating temperature using a polynomial of the second degree. This allows concluding that the determining influence on the evaporation rate is exerted not only by the heating temperature or the heat flux, but several more factors, i.e., at least two (otherwise, it would be possible to apply exponential and power functions or polynomials of the first order). We have attempted to describe an experimental dependence with approximation expressions based on exponential, power, and polynomial dependent factors. The best correspondence has been found when applying the polynomial of the second degree. If a polynomial of the third or fourth degree is applied, the approximation curves may be approached to the experimental values. However, these refinements will be insignificant in comparison with the use of the polynomial of the second degree. The analysis of the studied processes has shown that the key ones are: the contact area with the heating medium, the temperature of the medium, the heat flux, and the thermophysical and rheological characteristics of the liquid.