## 8 Conclusions  
The primary goal of this experimental investigation was to determine the ideal geometric shape and dimension of the hole for the air cooler tubes that can be printed without supports and used after the printing without any additional technological modifications. If there were any imperfections in the tubes, such as a corrugated hole shape or sharp edges and protrusions where contaminants could accumulate, they could ultimately cause problems with airflow and circulation in the air cooler.  
The three samples with different aperture shapes were printed on the aluminum 3D printer, which uses powerful ytterbium laser beams to melt fine metal powders to produce fully functional 3D parts. The results obtained by measuring the shape deviation and observing the surface microstructure and numerical analysis are summarized as follows:  
* It is clear from the samples tested that the most suitable shape for the air cooler design is a set of holes with rhombic and circular cross-sections, with shape deviations ranging from 0.1 mm to 0.4 mm for all hole diameters. A 45-degree angle of the rhombic hole surface is most accurately extruded. Accuracy is more pronounced when designing apertures with a rhombic cross-section and a larger edge angle. It is necessary to emphasize that one of the parameters of additively produced surfaces that is also  
Figure 22: Airflow in the air cooler with rhombic aperture system.  
influenced by the inclination angle is wettability. Usually, decreasing the inclination angle allows obtaining surfaces that are more hydrophobic [47].
* The least suitable cross-sectional shape of the air cooler tube was found to be a square. The sample with square-shaped holes was printed without supports and had a significant shape deviation from 0.81 mm to 1.2 mm after printing.
* When examining the microstructure of the cross-sectioned sample using an Olympus SZX 16 microscope, it was found that the sample manufactured at the selected 3D printer settings had a porosity of 2.06% in the surface structure.
* The highest temperature of the air cooler with rhombic tubes was almost 20% lower than the temperature of the air cooler with circular tubes.
* The experimental results and the numerical results were relatively consistent.  
The subject of further research will consist of new samples with hexagonal and triangular tube openings. The samples will be printed from the same AlSi10 Mg powder material as used in this experiment to be able to compare the results with a similar study [48], where an experimental comparison is presented for duct flow with optimized hexagonal heatsinks using ANSYS Icepack software.  
Further research results can then be used not only in conventional air conditioners or air coolers but also in the development of more efficient and well thermally regulated battery boxes for electric vehicles. However, as stated in the study [49], despite the advantages of AM, several disadvantages need to be addressed. Only after these drawbacks have been addressed can technology be applied across industries.  
Conceptualization, R.M. and R.K.; methodology, R.M.; software, R.K.; validation, R.K. and M.V.; formal analysis, R.M.; investigation, M.V.; resources, F.B.; data curation, M.V.; writing--original draft preparation, R.M.; writing--review and editing, F.B.; visualization, M.V.; supervision, R.K.; project administration, F.B.; funding acquisition, F.B. All authors have read and agreed to the published version of the manuscript.  
This article was funded in the context of the project KEGA 02 ZU-4/2024 supported by the Ministry of Education, Research, Development and Youth of the Slovak Republic.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.