## 4 Conclusions  
The constructed and studied air pressure nozzle system achieved an improvement in the cooling process compared to a conventional fan. The results showed that the nozzle system fully replaces the fan in the cooling process and even achieves improved heat dissipation, making the cooling process significantly shorter and more efficient. In addition, the air nozzle system can also be used as an additional equipment for intensification of heat dissipation in combination with the fan. The most significant results of the research can be summarised as follows:  
* Inline arranged nozzles with a spacing of 130 to 170 mm achieved an improvement in the cooling process of about 5 \({}^{\circ}\)C compared with the fan in a time of 46 min. * Staggered nozzle arrangement solves the problem of empty spots on the cooler that are not covered by air in the case of an inline arrangement. The staggered arrangement of the nozzles with spacing of 80 mm to 170 mm have reached a more effective cooling efficiency throughout the entire cooling process compared to the fan. At a spacing of 160 mm of the staggered arranged nozzles, the cooling process was improved by more than 6 \({}^{\circ}\)C compared with the fan in 46 min. When compared with the minimum spacing of 60 mm, the spacing of 160 mm of staggered arranged nozzles showed an improvement in the cooling process of nearly 10 \({}^{\circ}\)C.
* The combination of the inline arrangement of the nozzles and fan provided a decrease in the cooler outlet temperature of 17.38 \({}^{\circ}\)C for a spacing of 160 mm in a time of 46 min compared to fan-only cooling. * The combination of the staggered arrangement of the nozzles and fan provided a cooler outlet temperature reduction of 17.61 \({}^{\circ}\)C for a 140 mm spacing in a time of 46 min compared to fan-only cooling. Further increase in the spacing was already causing an increase in the cooler outlet temperature and deterioration of the cooling process. * As the distance of the nozzles from the cooler increases, complete coverage of the heat exchange surface by the air flow is ensured, which leads to a reduction in the cooling time of the coolant and an increase in the temperature difference. * When comparing the temperature differences for the fan and nozzle over a time of 46 min, the maximum \(\Delta T=16.9\)\({}^{\circ}\)C and 16.49 \({}^{\circ}\)C are achieved by the nozzles at a spacing of 160 mm in the staggered and inline arrangements, respectively. A minimum spacing of 60 mm is even less efficient than using only the fan. * When comparing the temperature differences for the fan and combination fan and nozzles over a time of 46 min, the maximum \(\Delta T=28.84\)\({}^{\circ}\)C and 28.72 \({}^{\circ}\)C are achieved by the combination of fan and nozzles at a spacing of 160 mm in the staggered and inline arrangements, respectively. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **Nozzles** & **Nozzles** & **Fan with** & **Fan with** & **Nozzles** & **Nozzles** & **Fan with** & **Fan with** & **Nozzles** \\  & **Inline** & **Staggered** & **Inline** & **Staggered** & **Inline** & **Staggered** & **Inline** & **Staggered** \\ \hline Temperature & & & & & & & & \\ difference & 15.09 & 17.62 & 32.97 & 33.84 & 25.41 & 26.96 & 34.31 & 33.93 \\ \(\Delta T\) [\({}^{\circ}\)C] & & & & & & & \\ \hline Heat transfer rate \(Q\) & 35,842 & 41,851 & 78,311 & 80,377 & 60,354 & 64,036 & 81,494 & 80,591 \\ \hline Maximum heat & & & & & & & & \\ transfer rate \(Q_{\text{max}}\) & 134,627 & 135,577 & 131,136 & 133,535 & 133,345 & 132,941 & 128,499 & 131,397 \\ \hline Thermal & & & & & & & & \\ performance & 0.266 & 0.309 & 0.597 & 0.602 & 0.453 & 0.482 & 0.634 & 0.613 \\ \(\varepsilon\) [-] & & & & & & & \\ \hline Spacing between & & & & & & & & \\ nozzles and cooler & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Thermal performance of the investigated combinations for spacing between the air nozzles and cooler of 60 mm and 160 mm.