Resfriamento psicro-ciclônico: Revisão sistemática e efeito da geometria dos ciclones

Abstract

With the increasing environmental impacts of human activities and the demand for new air cooling alternatives, indirect evaporative cooling stands out as a sustainable option. This study investigated the thermal variation and performance of 25 geometric configurations of cyclones as indirect evaporative heat exchangers. Due to their centrifugal flow nature, cyclones enhance convective heat transfer through tangential velocity. This feature enables the development of geometries that are more efficient in cooling and economically accessible, particularly advantageous for hot and arid regions, as well as for communities with limited resources. The investigation adopted an experimental approach, where cyclones coated with a wet cotton fabric were subjected to indirect evaporative cooling tests under various geometric and operational conditions. The results revealed a wide thermal variation among the cyclones, with significant impact from all geometric and operational variables, especially the total length of the cyclone, relative humidity, air temperature, and air volumetric flow rate. Thermal efficiency varied considerably, with total length and volumetric flow rate being the most influential factors. Additionally, the analysis of Euler values highlighted the importance of cyclone geometry in selecting configurations that minimize energy costs. Cyclones 8 and 16, which have some of the longest geometries tested, showed remarkable performance in terms of thermal efficiency. Cyclone 8 exhibited the best thermal performance, while Cyclone 16 achieved the best balance between thermal efficiency and energy consumption, as indicated by the highest thermal-energy performance ratio. The key difference between these two configurations lies in their inlet diameters. Cyclone 8 features a smaller inlet diameter (DI/DC = 0.16), which results in a higher tangential flow velocity. This promotes better heat transfer and enhances thermal efficiency. In contrast, Cyclone 16 has a larger inlet diameter (DI/DC = 0.26), leading to a lower pressure drop and a reduced Euler number, which contributed to its overall superior thermal-energy performance. As a result, Cyclone 8 is better suited for applications that prioritize high thermal efficiency, while Cyclone 16 emerges as a more efficient option with lower energy consumption. The findings of this study have the potential to guide the development of more efficient and sustainable indirect evaporative cooling systems, contributing to the reduction of energy consumption and environmental impacts.