Influence of geometric and operational variables on indirect evaporative cooling using cyclone as heat exchanger

• Published in: Applied thermal engineering Vol. 257; p. 124298
• Main Authors: Dias, Daiane Ribeiro, Oliveira Silva, Danylo de, Gustavo Martins Vieira, Luiz
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-12-2024
• Subjects: Cyclone separator; Cyclone-psychrometric cooling; Heat exchanger; Heat transfer; Mass transfer; Sustainability; Cyclone separator; Cyclone-psychrometric cooling; Sustainability; Heat exchanger; Heat transfer; Mass transfer
• DOI: 10.1016/j.applthermaleng.2024.124298
• ISSN: 1359-4311

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•Higher temperatures and lower relative humidity enhance thermal variation.•Longer cyclones and smaller inlet diameters increase thermal variation.•Convective coefficient rises with airflow rate, enhancing heat transfer efficiency.•Turbulent airflow in cyclones enhances convective heat transfer.•Longer cyclones achieve lower Euler numbers.
With the increasing environmental impacts of human activities and the demand for new air cooling alternatives, indirect evaporative cooling (IEC) emerges as a sustainable alternative. However, there is a gap in the literature regarding examining cyclone configurations in this context. Despite being good separator devices, cyclones can be used as heat exchangers, enhancing convective heat transfer through turbulence. This opens the possibility of developing improved and economically accessible geometries of IEC systems, especially beneficial for hot and arid regions, and communities with limited resources. This study aimed to investigate the performance of 25 geometric configurations of cyclones used as indirect evaporative heat exchangers. The researchers employed an experimental approach by subjecting cyclones covered with a wet cotton fabric to IEC tests under various geometric and operating conditions, followed by statistical analyses to identify relationships between the variables. The results showed significant thermal variation in the cyclones, with a considerable impact on all variables, particularly the cyclone’s total length, relative humidity, air temperature, and flow rate. The thermal efficiency of the cyclones varied widely, with total length and flow rate being the most significant factors. Additionally, an analysis of the Euler values revealed the importance of the cyclone geometry in selecting the one that reduces energy costs. Among the cyclones tested, the configuration with the optimal geometric design (Cyclone 8) achieved the highest thermal performance and lowest Euler number. The findings of this study could help developing more efficient and sustainable IEC systems, helping to reduce energy consumption and environmental impacts.