Investigating the effects of different innovative turbulators on the turbulent flow field and heat transfer of a multi-p
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Investigating the effects of different innovative turbulators on the turbulent flow field and heat transfer of a multi‑phase hybrid nanofluid Roohollah Babaei Mahani1,2 · Amir Ahmadi3 · Hossein Mahdavi Hezaveh3 · Mohammad Sepehrirad3 · Pouyan Talebizadehsardari4,5 Received: 27 March 2020 / Accepted: 24 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract This study investigates the heat index by combining factors affecting the enhancement of heat transfer, including the modeling of three turbulators with 3D innovative geometries, hybrid nanofluid, including Cu and Al2O3, and high Reynolds numbers. Using the Eulerian method and the phase-coupled simple algorithm, a 3D tube in which turbulators with different sizes were embedded along with a hybrid nanofluid with a two-phase view were investigated. The geometry of rectangular turbulator is a = 1 cm, b = 3, 5, and 7 cm, and L = 40 cm, and geometry of twisted rectangular turbulator is like rectangular turbulator, and each part has a 5-cm length; also, the geometry of triangular turbulator is considered with b = 3, 5, and 7 cm, and L = 40 cm. In the two-phase view, because each phase can have a different velocity gradient and a different temperature gradient, the results were close to the experimental results. The results indicated that turbulators, hybrid nanofluid, and Reynolds number influenced heat transfer rate enhancement; for the rectangular turbulator, changing the turbulator size, volume fraction, and Reynolds number from the minimum values to the maximum values increased heat transfer by 49.17%. The same conditions increased heat transfer for the twisted rectangular and triangular turbulators by 44.28% and 45.19%, respectively. The proposed factors are practical and can be beneficial in heat transfer and fluid mechanics. Overall, at minimum conditions Re = 15,000 and φ = 0% up to maximum conditions Re = 25,000 and φ = 4% for rectangular, twisted rectangular, and triangular turbulators increasing heat transfer rates of 79.49%, 97.5%, and 82.45% have been observed, respectively. Keywords Nanofluid · Hybrid nanofluid · Two-phase · Turbulent flow · Turbulator · Heat transfer Abbreviations Cp Specific heat capacity (J Kg−1 K−1) D Pipe diameter (cm) * Roohollah Babaei Mahani [email protected] * Pouyan Talebizadehsardari [email protected] 1
Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
2
Faculty of Civil Engineering, Duy Tan University, Da Nang 550000, Vietnam
3
Department of Mechanical Engineering, Arak Branch, Islamic Azad University, Arak, Iran
4
Metamaterials for Mechanical, Biomechanical and Multiphysical Applications Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
5
Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
g Gravitational acceleration (m s−2) H Local heat transfer coefficient (W m−2 K−1) K Thermal conductivity (W m−1 K−1) L Length (cm) Nu Nusselt number P Pressure (Pa) q Phases Re Reynolds number R
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