## 2 Experiments
### Data Reduction and Uncertainty Analysis  
The heat loss analysis for the plain copper surface at different heat-flux intervals is shown in Table 5. As a baseline check for the experimental data, the heat loss percentages were less than 10% in the experiments. ### Data Reduction and Uncertainty Analysis  
The heat loss analysis for the plain copper surface at different heat-flux intervals is shown in Table 5. As a baseline check for the experimental data, the heat loss percentages were less than 10% in the experiments. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{4}{c}{**Static Contact Angle**} \\ \hline \multirow{2}{*}{**Surface Condition**} & \(\theta_{1}\) & \(\theta_{2}\) & \(\Delta\theta_{12}\) \\  & **(Parallel)** & **(Normal)** & **(Anisotropy)** \\ \hline S1 & \(18\pm 0^{\circ}\) & \(15\pm 0.3^{\circ}\) & \(\sim\)3\({}^{\circ}\) \\ \hline S2 & \(26\pm 1^{\circ}\) & \(12\pm 0.3^{\circ}\) & \(\sim\)14\({}^{\circ}\) \\ \hline S3 & \(25\pm 1^{\circ}\) & \(13\pm 0.3^{\circ}\) & \(\sim\)12\({}^{\circ}\) \\ \hline S4 & \(22\pm 1^{\circ}\) & \(15\pm 1^{\circ}\) & \(\sim\)7\({}^{\circ}\) \\ \hline \multicolumn{4}{c}{Receding Contact Angle} \\ \hline \multirow{2}{*}{Surface Condition} & \(\theta_{\text{rec1}}\) & \(\theta_{\text{rec2}}\) & \(\Delta\theta_{\text{rec12}}\) \\  & (Parallel) & (Normal) & (Anisotropy) \\ \hline S1 & \(17\pm 0.3^{\circ}\) & \(15\pm 0.3^{\circ}\) & \(\sim\)2\({}^{\circ}\) \\ \hline S2 & \(27\pm 1^{\circ}\) & \(13\pm 0.2^{\circ}\) & \(\sim\)14\({}^{\circ}\) \\ \hline S3 & \(24\pm 1^{\circ}\) & \(14\pm 0.5^{\circ}\) & \(\sim\)10\({}^{\circ}\) \\ \hline S4 & \(23\pm 0.7^{\circ}\) & \(16\pm 0.6^{\circ}\) & \(\sim\)7\({}^{\circ}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Static and receding CA results measured in parallel and normal directions on S1–S4 surfaces. Figure 10: Images of (**a**) static CA and (**b**) receding CA measured in parallel and normal directions on S1–S4 surfaces. Owing to the good insulation condition during the experiments, the heat transfer mode was considered as 1D heat conduction. The temperature gradient, \(\frac{dT}{dx}\), was calculated using the linear property of the heat conduction, defined in Equation (1) as follows:  
\[\frac{dT}{dx}=\frac{T_{1}-T_{3}}{2\Delta x} \tag{1}\]  
where \(\Delta x\) is the distance between the \(T_{1}\) and \(T_{2}\) thermocouples. The heat flux, \(q^{\prime\prime}\), was derived using [PERSON]'s heat conduction law, expressed in Equation (2) as follows:  
\[q^{\prime\prime}=-k_{Cu}\frac{dT}{dx} \tag{2}\]  
where \(k_{Cu}\) is the thermal conductivity of copper (400 W/m\(\cdot\)K). The surface temperature, \(T_{w}\), was estimated through back-calculation, given by Equation (3) as follows:  
\[T_{w}=T_{1}-q^{\prime\prime}(\frac{d_{Cu}}{k_{Cu}}+\frac{d_{gresase}}{k_{gresase }}) \tag{3}\]  
where \(k_{gresase}\) is the thermal conductivity of the thermal grease (79 W/m\(\cdot\)K), \(d_{Cu}\) is the distance between the \(T_{1}\) thermocouple and the upper surface, and \(d_{gresase}\) is the thickness of the applied thermal grease. The wall superheat, \(\Delta T_{w}\), was estimated using Equation (4) as follows:  
\[\Delta T_{w}=T_{w}-T_{sat} \tag{4}\]  
where \(T_{sat}\) represents the saturation temperature of the working fluid. The saturation temperature for Novec-7100 is 61 \({}^{\circ}\)C.  
Finally, the boiling heat transfer coefficient, \(h\), was evaluated using Equation (5) as follows:  
\[h=\frac{q^{\prime\prime}}{\Delta T_{w}} \tag{5}\]  
The estimation of uncertainties within specific heat-flux intervals was conducted using [PERSON]'s method [48]. The uncertainty analysis of the S1 surface is presented in Table 6. The subsequent equations are the general formulae of the uncertainty calculation. Equation (6) is the general formula for determining uncertainties for various parameters, including the heat flux, wall superheat, and HTC.