Investigating the effects of different innovative turbulators on the turbulent flow field and heat transfer of a multi-phase hybrid nanofluid

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 Al 2 O 3 , 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.

Improvement of Heat Transfer Through Use of Twisted Tape Inserts: A Review

“…Doubleperforated inclined elliptic (DPIE) ortex generators with d/ b = 0.25 and = 25 achieve the highest thermal performance parameter (η) of 1.849 at Re = 16,000.They have several advantages over active methods, including relative simplicity, lower manufacturing costs, and lower maintenance and repair costs (Gokulnathan, 2021;Wu, 2011;Liang et al, 2020).In passive techniques, increasing flow turbulence is the key to improving heat transfer, while pressure drop or friction factor is typically kept as low as possible. The most commonly used turbulators to improve thermal efficiency are baffles, ribs, winglets, perforated turbulators, louvered strips, inclined elliptical strips, twisted tapes , and different helical inserts, rectangular turbulators (Mahani, 2021), ring inserts, and springs (Kareem, 2015;Liu, 2013). Hatami et al (2015) used a turbulator of delta winglet to improve heat recovery from a diesel engine exhaust.…”

Experimental and numerical evaluation of the performances of type‐C and three‐segment demisters used in cooling towers

“…They found that the numerical results predicted by the SST k‐ω model were in better agreement with the experimental data for the droplet removal efficiency than the enhanced Reynolds stress model. Mahani et al [ 30 ] investigated a 3D tube embedded with turbulators by using the Eulerian method and the phase‐coupled simple algorithm. They found that the numerical results were close to the experimental results.…”