Abstract
Numerical investigation has been carried out on heat transfer and friction factor characteristics of copper-water nanofluid flow in a constant heat-fluxed tube with the existence of new configuration of vortex generator using Computational Fluid Dynamics (CFD) simulation. Two types of swirl flow generator: Classical twisted tape (CTT) and Parabolic-cut twisted tape (PCT) with a different twist ratio (y = 2.93, 3.91 and 4.89) and different cut depth (w = 0.5, 1.0 and 1.5 cm) with 2% and 4% volume concentration of CuO nanofluid were used for simulation. The effect of different parameters such as flow Reynolds number, twist ratio, cut depth and nanofluid were considered. The results show that the enhancement of heat transfer rate and the friction factor induced by the Classical (CTT) and Parabolic-cut (PCT) inserts increases with twist ratio and cut depth decreases. The results also revealed that the heat transfer enhancement increases with an increase in the volume fraction of the CuO nanoparticle. Furthermore, the twisted tape with twist ratio (y = 2.93) and cut depth w = 0.5 cm offered 10% enhancement of the average Nusselt number with significant increases in friction factor than those of Classical twisted tape.
Highlights
The applications of heat transfer augmentation techniques can significantly increase the performance of heat exchanger, leading to the reduction of heat exchanger size as well as operating cost
Computations data of the Nusselt number and friction factor was first performed for water in a plain tube to validate the model against data developed by Stephan and Preußer correlations [22]
The results revealed that the twist tape with twist ratio y = 2.93 and cut depth
Summary
The applications of heat transfer augmentation techniques can significantly increase the performance of heat exchanger, leading to the reduction of heat exchanger size as well as operating cost. Salman et al [18] reports an application of a mathematical model of the heat transfer enhancement and friction factor characteristics of water in constant heat-fluxed tube fitted with elliptical cut twisted tape inserts using FLUENT version 6.3.26. The results show that the elliptical cut twisted tape with twist ratio (y = 2.93) and cut depth (w = 0.5 cm) offered higher heat transfer rate with significant increases in friction factor. The results show that the V-cut twisted tape with twist ratio (y = 2.93) and cut depth (w = 0.5 cm) present a maximum heat transfer rate with significant increases in friction factor. A numerical investigation of heat transfer enhancement in a tube induced by new configuration of vortex generator (Parabolic-cut twist tape) with 2% and 4% volume fractions of CuO nanofluid is reported using CFD simulation. The result obtained by this configuration offered about 10% enhancement of the Nusselt number with significant increases in friction factor than those of Classical twisted tape
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