## 3 Results and Discussion
### Morphology and Regime Map of Different Impact Behaviors
The ratio \(c_{\text{p,g}}/h_{\text{fg}}\) can be interpreted as the relative amount of energy available for evaporation compared to that being lost from the droplet to the surrounding gas [17]. The Leidenfrost temperatures calculated in this work are slightly larger than the results given by [PERSON] et al. [39]. This may be due to a slight difference in the saturation temperatures used for the calculations employed. As shown in Table 3, whereas propanol and water have comparable boiling points and specific heat of gas, the latent heat differs significantly. Thus, the Leidenfrost temperature of propanol is about 38 \({}^{\circ}\)C lower than that of water. Moreover, ethanol has a higher latent heat than propanol, and the specific heat of gas is similar. The difference in Leidenfrost temperature between the two alcohols is only 16 \({}^{\circ}\)C, while the difference in Leidenfrost temperature between ethanol and water is about 55 \({}^{\circ}\)C. Therefore, for ethanol/water binary droplets, changes in the content of ethanol have a significant effect on the Leidenfrost temperature. When the droplet reaches the transition boiling stage, nuclear boiling occurs in the early stages of evaporation. Then, the droplet retracts and rebounds to reach the Leidenfrost state. Upon reaching the Leidenfrost state, due to the persistence of the vapor film, droplets impact and retract after spreading to a maximum. The time interval between the moment when the droplet makes contact with the plate and the moment when the droplet first rebounds away from the surface is defined as the residence time (\(t_{\text{r}}\)). At a normal surface temperature, droplets stick to the hydrophilic aluminum plate after impact. Therefore, in the case of droplet impact on a heated wall, the residence time can be used to reflect the potential of vapor bubbles to accelerate the retraction and bouncing process of the droplet. Figure 5 illustrates that, for both types of binary droplets, the residence times are comparatively prolonged during the transition boiling phase, followed by a decrease as the surface temperature rises. Since the ethanol/propanol binary droplet reaches the Leidenfrost state very quickly, the residence time is essentially constant with various surface temperatures and liquid components. This is consistent with the findings of [PERSON] et al. [31],  
Figure 4: Regime map of droplet impact behaviors at different surface temperatures and liquid components, including film evaporation, nucleate boiling, transition boiling, and Leidenfrost levitation. The transition boiling regions are demarcated using dashed-line boxes. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Properties** & **Ethanol** & **Propanol** & **Water** \\ \hline \(T_{\text{b}}\) [\({}^{\circ}\)C] & 78.31 & 97.15 & 100.02 \\ \(c_{\text{p,g}}\) [kJ/(kg\({}^{\circ}\)C]) & 1.7174 & 1.7225 & 2.08 \\ \(h_{\text{fg}}\) [kJ/kg] & 849.91 & 670.211 & 2256.40 \\ \({}^{\bullet}T_{\text{L}}\) [\({}^{\circ}\)C] & 162.8 & 179.5 & 217.7 \\ \hline \hline \end{tabular} \({}^{\bullet}T_{\text{L}}\) is calculated using the relation given by [PERSON] et al. [39].  
\end{table} 
Table 3: Pure liquid properties at boiling points. who reported that the presence of iso-propanol and variations in surface temperature scarcely influence the residence time in the Leidenfrost state. For the ethanol/water droplet, the residence time is significantly reduced within a certain range of temperature in the transition boiling state, which is caused by the rapid breakup of the parent droplet. As the ethanol content increases, the temperature range that leads to a reduction in residence time gradually narrows, and the extent of the reduction in residence also diminishes due to the weakened breakup of parent droplets.