# Thermal and Acoustic Design of a Shelter for High-Voltage Electrical Equipment
## 6 Conclusions  
The thermal and acoustic aspects necessary for a proper thermal and acoustic design of a shelter containing a high voltage system producing heat and impulsive noise were discussed. The system is to be installed in urban settlements to distribute power to various classes of consumers, such as residential, commercial and industrial. The heat produced by the electrical devices must be dissipated efficiently using natural convection, whereas the noise passing through the openings is to be mitigated to prevent the nearby residents from being disturbed. The article firstly deals with an FE thermal model of these electrical devices. The sources were replaced by an equivalent array of spheres with the same surface area and volume and placed at the same centre of mass inside the shelter. With sufficient mesh convergence, it was observed that the average air temperature in the shelter is below the temperature limit set by the switchgear supplier. To experimentally validate the CFD simulations and check the behaviour of the system in real-life conditions, a downscaled model was built. A heat source simulating the HV devices was placed inside the main volume, and this scaled model was placed outdoors, thus considering also the effects of solar radiation and wind. This experiment was simulated also in COMSOL Multiphysics(r) and it was shown that the temperature average computed for the stationary model agrees fairly well with that of the experimental downscaled model. Thus, it was shown that the thermal objectives can be attained by natural convection. As concerns the acoustic aspects, the switchgears acting as noise sources were characterised through an energy level determination carried out according to the standards. The shelter housing the sources and the aesthetic panels were modelled using literature data and the noise spreading simulated in SoundPLAN(r). Noise maps inside the shelter, outside the shelter, as well as various noise levels at a total of 24 point-receivers at different distances heights and directions were computed. It was shown that the nighttime emission, commission and differential levels respect the Class-II limits of the Italian legislation in most of the positions. In spite of the objective of this research being to model and simulate the switchgears and the shelter as close to reality as possible, there are a few limitations to achieving this objective. There needs to be an experimental validation of the full-scale COMSOL model. The acoustical simulations assume a completely flat ground covered by grass, which is not the case in any urban context. Hence, specific case-by-case modelling and simulation would provide better insight into the noise propagation and the noise levels at the receivers. There can be further research into optimising heat transfer by radiation with the help of coatings on the aesthetic panels and the shelter's roof. As pointed out before, variable parameters such as wind speed and direction, and the variance of ambient temperature and solar radiation throughout the day and the entire year can be modelled and simulated for a better and more precise insight into this problem. A future step of this research will be to validate the thermal and acoustic simulations with experimental campaigns after the assembly of the prototype system. Simulations, investigation, data curation, writing--original draft preparation, S.B. ; conceptualization, supervision, resources, writing--review and editing, E.P. ; methodology and validation, S.B. and E.P. All authors have read and agreed to the published version of the manuscript. This research was funded by MUR, fund PON \"Ricerca e Innovazione\" 2014-2020, Azione IV.4 \"Dottorati e contratti di ricerca su tematiche dell'innovazione\" and Azione IV.5 \"Dottorati su tematiche green\". Not applicable. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy.