## 3 Results
### Pressure Drop across the Pad  
Table 10 summarized the statistical description of the pressure drop measured across the pads (\(\Delta P\)). Larger differences of the average values of \(\Delta P\) between the cellulose and the alternative pads were evident. Even at high speeds (\(u_{7}\approx\) 3.5 m s\({}^{-1}\)), the cellulose \(\Delta P\) is around the obtained for the air velocity tested in the other materials (for \(u\leq\) 1 m s\({}^{-1}\)). The variability of the measured \(\Delta P\) also shows big differences. This is mainly due to an increase in resistance to air flow caused by increasing water flow through the pads. For each air velocity, up to three water flows were evaluated. The low variability of the \(CS_{2}\) material for the inlet air velocity \(u_{3}\) was because, in this test, only the lowest flow of water was evaluated; when water flow was increased, liquid water came out of the pads. The \(PS\) pads present the lowest variability from the alternative pads, indicating that water flow does not considerably affect the air flow resistance in them. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Pad** & **Test** & \(\overline{\Delta P}\) & \(\overline{\Delta P}\) & \(\sigma\) & \(\sigma^{2}\) \\ \hline \multirow{8}{*}{\(CL\)} & \(u_{1}\) & 1.2606 & 1.2700 & 0.0955 & 0.0091 \\  & \(u_{2}\) & 3.5558 & 3.6100 & 0.2227 & 0.0496 \\  & \(u_{3}\) & 6.9345 & 6.9500 & 0.2199 & 0.0484 \\  & \(u_{4}\) & 12.3764 & 12.3800 & 0.3067 & 0.0941 \\  & \(u_{5}\) & 18.2361 & 18.2700 & 0.4733 & 0.2240 \\  & \(u_{6}\) & 24.0571 & 24.2300 & 0.5083 & 0.2584 \\  & \(u_{7}\) & 31.5677 & 31.8500 & 0.9008 & 0.8114 \\ \hline \multirow{2}{*}{\(CS_{1}\)} & \(u_{1}\) & 20.7298 & 10.5400 & 20.3817 & 415.4150 \\  & \(u_{2}\) & 109.3886 & 115.4700 & 22.1462 & 490.4554 \\ \hline \multirow{2}{*}{\(CS_{2}\)} & \(u_{1}\) & 22.2006 & 21.0000 & 2.7782 & 7.7182 \\  & \(u_{2}\) & 89.9411 & 78.3650 & 19.5662 & 382.8370 \\  & \(u_{3}\) & 133.2440 & 132.3500 & 3.7064 & 13.7374 \\ \hline \multirow{2}{*}{\(BC\)} & \(u_{1}\) & 33.6239 & 30.7100 & 8.5841 & 73.6868 \\  & \(u_{2}\) & 134.8465 & 131.6900 & 24.7958 & 614.8340 \\ \hline \end{tabular}
\end{table} 
Table 10: Statistics of pressure drop across the cooling pad (\(\Delta P\)) for the wind tunnel tests. \(\overline{\Delta P}\) is the mean [Pa], \(\overline{\Delta P}\) is the median [Pa], \(\sigma\) is the standard deviation [Pa] and \(\sigma^{2}\) is the variance [Pa\({}^{2}\)]. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Pad** & \(\eta\) (\(\Delta\eta\)) [\%] & **THI (\(\Delta THI\))** & \(\Delta T\) [\({}^{\circ}\)C] & \(\Delta\phi\) [\%] \\ \hline \(CL\) & 66.3 & 74.5 (5.3) & \(-\)5.1 & 28.1 \\ \(CS_{1}\) & 56.4 (\(-\)9.9) & 75.9 (3.9) & \(-\)4.3 & 29.5 \\ \(CS_{2}\) & 61.1 (\(-\)5.2) & 75.6 (4.2) & \(-\)4.7 & 32.2 \\ \(BC\) & 52.4 (\(-\)13.9) & 76.1 (3.7) & \(-\)4.0 & 27.5 \\ \(PS_{1}\) & 40.7 (\(-\)25.6) & 76.8 (3.0) & \(-\)3.1 & 21.8 \\ \(PS_{2}\) & 39.6 (\(-\)26.7) & 77.1 (2.7) & \(-\)3.0 & 22.7 \\ \hline \end{tabular}
\end{table} 
Table 9: Cooling efficiency (\(\eta\)), Temperature–Humidity Index (THI), dry-bulb temperature drop (\(\Delta T\)) and relative humidity increment (\(\Delta\phi\)) for average input variables: inlet air velocity (\(u\) = 1.5 m s\({}^{-1}\)), pad thickness (\(L\) = 0.1 m), dry-bulb temperature (\(T_{db_{i}}\) = 30 \({}^{\circ}\)C) and relative humidity of inlet air (\(\phi_{i}\) = 50%). \(\Delta\eta\) is the difference between \(\eta\) of the alternative pads and the \(CL\) pad. \(\Delta THI\) is the difference between the THI compute with the outlet and inlet (79.8) air thermal conditions. The average values of water flow presented in Table 11 were around 2, 6.2 and 10 L min\({}^{-1}\) m\({}^{-1}\) values as defined before. The variability of the water flow measurements was below 0.7 L min\({}^{-1}\) m\({}^{-1}\), being considerably lowest for the cellulose pad tests.