Thermo-convective behavior and entropy generation studies on Alumina and Titania nanofluids flowing through polygonal ducts

• Published in: International journal of thermal sciences Vol. 186; p. 108123
• Main Authors: Prabakar, K.S., Nagarajan, P.K., Venkatesan, J., Suseel Jai Krishnan, S., Sharifpur, Mohsen
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.04.2023
• Subjects: Entropy generation; Hexagonal duct; Nanofluid; Square duct; Triangular duct; Hexagonal duct; Triangular duct; Nanofluid; Square duct; Entropy generation
• ISSN: 1290-0729; 1778-4166
• DOI: 10.1016/j.ijthermalsci.2022.108123

The current study emphasizes the thermal performance of 0.05, 0.1, and 0.2% volume concentrated Al2O3/DI water and TiO2/DI water nanofluids flowing through three different ducts (equilateral triangle, square, and hexagonal shaped) were compared with circular tubes. The thermo-convective experiments were carried out in the turbulent regime (5000≤ Re ≤ 10,000) at iso-heat flux conditions. The experimental outcome reveals that the maximum Nusselt number of 78, 74, and 71 were achieved when 0.2% Al2O3/DI water flowed through hexagonal, square, and triangular ducts, respectively. Similarly, the desired lowest friction factor of 0.03692, 0.03688, and 0.03686 was achieved by the same nanofluid through those orientations, which ensured that the Al2O3/DI water outperformed TiO2/DI water. The maximum Performance Evaluation Criteria (PEC) was 1.102 when comparing the 0.2% Al2O3/DI water nanofluid flow through a hexagonal duct with water through a circular tube, and 1.169 when the flow through the duct is compared with DI water flow through the same hexagonal duct. When evaluating the performance of all these augmented flow orientations by Entropy Performance Evaluation Factor (EPEF), the maximum values of 665, 572, 635, and 654 were achieved by 0.2% Al2O3/DI water and 660, 531, 561, and 628 by 0.2% TiO2/DI water while flowing through the circular tube, triangular, square, and hexagonal ducts, respectively. Correlations for Nusselt number and friction factor employable to these orientations were derived based on the dominant dependant parameters.