## 3 Results
The \(BC\) material had a value (338.8 m\({}^{-1}\)-0.34 m\({}^{2}\) kg\({}^{-1}\)) higher than that of the \(CS_{2}\) material (304.7 m\({}^{-1}\)-0.56 m\({}^{2}\) kg\({}^{-1}\)); although both materials had the same particle size, the \(BC\) had thicker particles. For the \(PS\) materials, their values were much lower: 137.6 m\({}^{-1}\) (0.36 m\({}^{2}\) kg\({}^{-1}\)) and 107.4 m\({}^{-1}\) (0.30 m\({}^{2}\) kg\({}^{-1}\)) for \(PS_{1}\) and \(PS_{2}\), respectively. Table 8 shows the coefficients of Equation (3) fitted to the experimental data using the specific surface area found for each pad, and the RMSE values computed between the experimental and the predicted values of the dry-bulb temperature and the relative humidity of the outlet air, which were obtained using the mathematical model proposed by [PERSON] et al. [32]. \begin{table}
\begin{tabular}{l c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Pad**} & \multicolumn{3}{c}{**Entering**} & \multicolumn{3}{c}{**Leaving**} & \multicolumn{3}{c}{\(\Delta\mathbf{T}_{w}=\mathbf{T}_{wb_{i}}-\mathbf{T}_{w_{e}}\)} \\  & \(\overline{T}_{w_{i}}\) & \(\sigma\) & \(\sigma^{2}\) & \(\overline{T}_{w_{e}}\) & \(\overline{T}_{w_{e}}\) & \(\sigma\) & \(\sigma^{2}\) & \(\overline{\Delta T}_{w}\) & \(\Delta\overline{T}_{w}\) & \(\sigma\) & \(\sigma^{2}\) \\ \hline \(CL\) & 20.9 & 20.3 & 1.1 & 1.2 & 19.2 & 19.2 & 0.3 & 0.1 & 0.24 & 0.27 & 0.29 & 0.09 \\ \(CS_{1}\) & 21.7 & 20.8 & 1.5 & 2.2 & 18.7 & 18.4 & 1.4 & 1.9 & \(-\)0.24 & 0.18 & 0.72 & 0.09 \\ \(CS_{2}\) & 19.9 & 19.3 & 1.7 & 3.0 & 17.1 & 17.0 & 0.3 & 0.1 & 0.59 & 0.73 & 0.33 & 0.11 \\ \(BC\) & 18.5 & 18.0 & 1.4 & 1.8 & 16.3 & 16.3 & 0.2 & 0.5 & 0.91 & 0.91 & 0.22 & 0.05 \\ \(PS_{1}\) & 20.3 & 20.2 & 1.3 & 1.7 & 17.8 & 17.6 & 0.9 & 0.8 & 0.31 & 0.50 & 0.58 & 0.34 \\ \(PS_{2}\) & 21.1 & 21.0 & 0.8 & 0.6 & 19.2 & 19.1 & 0.5 & 0.3 & 0.31 & 0.31 & 0.56 & 0.32 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Statistical analysis of the water temperature (\(T_{w}\)) entering (\(i\)) and leaving (\(o\)) the pad in the wind tunnel tests. The difference between the inlet air wet-bulb temperature (\(T_{wb_{i}}\)) and the water temperature leaving the pad (\(\Delta T_{w}=T_{wb_{i}}-T_{w_{e}}\)) is also shown. \(\overline{T}\) is the mean [\({}^{\circ}\)C], \(\overline{T}\) is the median [\({}^{\circ}\)C], \(\sigma\) is the standard deviation [\({}^{\circ}\)C] and \(\sigma^{2}\) is the variance [\({}^{\circ}\)C]. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Pad** & **Test** & \(\overline{u}\) & \(\overline{u}\) & \(\sigma\) & \(\sigma^{2}\) \\ \hline  & \(u_{1}\) & 0.554 & 0.570 & 0.041 & 0.002 \\  & \(u_{2}\) & 1.067 & 1.070 & 0.049 & 0.002 \\  & \(u_{3}\) & 1.534 & 1.530 & 0.042 & 0.002 \\ \(CL\) & \(u_{4}\) & 2.032 & 2.030 & 0.046 & 0.002 \\  & \(u_{5}\) & 2.534 & 2.540 & 0.053 & 0.003 \\  & \(u_{6}\) & 2.994 & 2.990 & 0.057 & 0.003 \\  & \(u_{7}\) & 3.537 & 3.530 & 0.068 & 0.005 \\ \hline \(CS_{1}\) & \(u_{1}\) & 0.299 & 0.220 & 0.145 & 0.021 \\  & \(u_{2}\) & 0.888 & 0.840 & 0.091 & 0.008 \\ \hline  & \(u_{1}\) & 0.503 & 0.500 & 0.030 & 0.001 \\ \(CS_{2}\) & \(u_{2}\) & 1.046 & 1.050 & 0.068 & 0.005 \\  & \(u_{3}\) & 1.398 & 1.410 & 0.059 & 0.004 \\ \hline  & \(u_{1}\) & 0.472 & 0.470 & 0.034 & 0.001 \\ \(BC\) & \(u_{2}\) & 0.969 & 0.970 & 0.049 & 0.002 \\ \hline  & \(u_{1}\) & 0.507 & 0 Figure 2 shows a comparison between the predictions obtained with the mathematical model and the experimental data. For all the pads, a linear relation around the equality line (black solid line) was presented. The Wilcoxon signed rank statistical test found no statistically significant difference between the predictions and the experimental data (\(p\)-value \(>\) 0.05). \(\phi_{o}\) was slightly overestimated for the alternative materials but with a bias deviation of less than 5% (dashed lines). Those results allow us to consider that the model is suitable for predicting the behaviour of the pads for other operative and constructive conditions.