## 3 Results
Figure 2: Comparison between the experimental data measured (\(m\)) and the model predictions (\(p\)) of the dry-bulb temperature (\(T_{dh_{v}}\)) and relative humidity (\(\phi_{o}\)) of outlet air for all the pads analysed. (**a**) \(T_{dh_{v}}\) of \(CL\) pad. (**b**) \(T_{dh_{v}}\) of \(CS_{1}\) pad. (**c**) \(T_{dh_{v}}\) of \(CS_{2}\) pad. (**d**) \(\phi_{o}\) of \(CL\) pad. (**e**) \(\phi_{o}\) of \(CS_{1}\) pad. (**f**) \(\phi_{o}\) of \(CS_{2}\) pad. (**g**) \(T_{dh_{v}}\) of \(BC\) pad. (**h**) \(T_{dh_{v}}\) of \(PS_{1}\) pad. (**i**) \(T_{dh_{v}}\) of \(PS_{2}\) pad. (**j**) \(\phi_{o}\) of \(BC\) pad. (**k**) \(\phi_{o}\) of \(PS_{1}\) pad. (**l**) \(\phi_{o}\) of \(PS_{2}\) pad. Solid black line corresponds to the equality line. Dashed lines represent the interval of \(\pm\)0.5 \({}^{\circ}\)C and \(\pm\)2% around the equality line of \(T_{dh_{v}}\) and \(\phi_{o}\), respectively. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multirow{2}{*}{**Pad**} & \multicolumn{4}{c}{**Correlation Coefficients**} & \multicolumn{4}{c}{**RMSE**} \\  & \(\mathbf{a_{1}}\) & \(\mathbf{b_{1}}\) & \(\mathbf{c_{1}}\) & \(\mathbf{a_{2}}\) & \(\mathbf{b_{2}}\) & \(\mathbf{c_{2}}\) & \(\mathbf{T}\) [\({}^{\circ}\)C] & \(\mathbf{\phi}\) [\%] \\ \hline \(CL\) & 1.042 & 0.426 & 0.617 & 0.385 & 0.513 & 0.647 & 0.01 & 0.4 \\ \(CS_{1}\) & 0.093 & 0.935 & 1.300 & 0.727 & 0.589 & 0.748 & 0.02 & 0.7 \\ \(CS_{2}\) & 0.159 & 0.610 & 1.032 & 0.907 & 0.530 & 0.713 & 0.03 & 0.3 \\ \(BC\) & 0.196 & 0.700 & 0.998 & 0.554 & 0.629 & 0.809 & 0.03 & 0.3 \\ \(PS_{1}\) & 0.237 & 0.630 & 0.927 & 0.754 & 0.580 & 0.779 & 0.02 & 0.4 \\ \(PS_{2}\) & 0.186 & 0.890 & 1.064 & 0.689 & 0.641 & 0.864 & 0.01 & 0.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Coefficients of correlation (3) used to compute the convective heat and mass transfer coefficients. In Figures 3 and 4, the behaviour of the convective heat and mass transfer coefficients as functions of operative and constructive variables, such as air velocity (\(u\)), pad thickness (\(L\)), dry-bulb temperature (\(T_{db_{i}}\)) and relative humidity (\(\phi_{i}\)) of inlet air, are shown. For this matter, the other independent variables are considered constants (\(u\) = 1.5 m s\({}^{-1}\), \(L\) = 0.1 m, \(T_{db_{i}}\) = 30 \({}^{\circ}\)C, \(\phi_{i}\) = 60%). The relationship between the convective heat transfer coefficient (\(h_{H}\)) and the inlet air velocity is shown in Figure 3a. A linear relationship between them is presented, corresponding to an increase in the flow of heat transferred between the air crossing the pad and the wetted pad surface when the inlet air velocity increasing. Figure 3b shows the relation between \(h_{H}\) and the thickness of the pad; when \(L\) decreases, \(h_{H}\) rises to compensate for the decrease in the wet surface area. Figure 3c,d shows that \(h_{H}\) remains almost constant when the dry-bulb temperature and relative humidity of inlet air change. The effect of the inlet air velocity and pad thickness change were more relevant. With the exception of the \(PS_{2}\) pad, \(CL\) present the highest \(h_{H}\) values. The relationship between the convective mass transfer coefficient (\(h_{M}\)) and the inlet air velocity was shown in Figure 4a. An increase in \(h_{H}\) due to increasing the air velocity is presented. Thus, the evaporation rate increases according to the inlet air velocity. Figure 4b shows the relationship between \(h_{M}\) and the thickness of the pad. \(h_{H}\) also increases when the thickness of the pad decreases, to compensate for the reduction of the wet surface area. Figure 3c,d shows that \(h_{M}\) also remains almost constant when the dry-bulb temperature and relative humidity of inlet air change. The effect of the inlet air velocity and pad thickness changes was more significant than that caused by the dry-bulb temperature and relative humidity. In all the plots shown in Figure 4, \(h_{H}\) is inversely proportional to the specific surface area of each material.