scholarly journals Heat Transfer Enhancement of Laminar Nanofluids Flow in a Circular Tube Fitted with Parabolic-Cut Twisted Tape Inserts

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Sami D. Salman ◽  
Abdul Amir H. Kadhum ◽  
Mohd S. Takriff ◽  
Abu Bakar Mohamad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Swirl Flow ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Twist Ratio ◽  
Cut Depth

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 depthw= 0.5 cm offered 10% enhancement of the average Nusselt number with significant increases in friction factor than those of Classical twisted tape.

scholarly journals Internal Flow Analysis of a Heat Transfer Enhanced Tube with a Segmented Twisted Tape Insert

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 207 ◽  
Author(s):  
Gan Liu ◽  
Chen Yang ◽  
Junhui Zhang ◽  
Huaizhi Zong ◽  
Bing Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
Dominant Role ◽  
Length Ratio ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Advantages And Disadvantages ◽  
Twist Ratio

A heat exchanger is a device that transfers unneeded heat from one region to another, and transferred heat may be fully reused, thus improving energy efficiency. To augment this positive process, many studies and investigations on automation technologies have been performed. Inserts are widely used in pipe flow for heat transfer enhancement, since they can break the boundary layer and promote the heat exchange. Segmented twisted tape, which is applicable in 3D printing, is a novel insert and has potential in heat transfer enhancement. To clarify its advantages and disadvantages, this research presents a numerical investigation of vortex flow and heat enhancement in pipes containing one segmented twisted element. Flow state and heat transfer behaviour are obtained by simulation under constant wall temperature with different Reynolds numbers, ranging from 10,000 to 35,000. The effects of geometric parameters, including twist ratio (P/D = 2.0, 3.3 and 4.6) and length ratio (L/P = 0.3, 0.5 and 0.7), on the Nusselt number (Nu) and friction factor (f) are investigated. Streamline and temperature distribution are presented. Meanwhile, local and overall heat transfer performance is compared with those of a smooth tube, and the overall performance is evaluated by performance evaluation factor (η). The results indicate that the twist ratio (P/D) plays a dominant role in heat transfer enhancement while the length ratio (L/P) also has considerable influence. It is shown that a segmented tape insert can increase the overall heat transfer rate by 23.5% and the friction factor by 235%, while local improvement along the tube can be 2.8 times more than the plain tube.

scholarly journals CFD Analysis of Heat Transfer and Friction Factor Characteristics in a Circular Tube Fitted with Quadrant-Cut Twisted Tape Inserts

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Sami D. Salman ◽  
Abdul Amir H. Kadhum ◽  
Mohd S. Takriff ◽  
Abu Bakar Mohamad
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Cfd Simulation ◽  
Swirling Flow ◽  
Circular Tube ◽  
3D Models ◽  
Twisted Tape ◽  
Twist Ratio ◽  
Plain Tube ◽  
Cut Depth

This paper reports numerical investigations of heat transfer and friction factor characteristics in swirling flow conditions using CFD simulation. A commercial CFD package, FLUENT 6.3.26, was used in this study. 3D models for circular tube fitted with classical and quadrant-cut twisted tape (QCT) inserts with three twist ratios (y= 2.93, 3.91, and 4.89) and different cut depths (w= 0.5, 1.0, and 1.5 cm) were generated for the simulation. The data obtained from the CFD simulation were verified with the literature correlations of plain tube with the discrepancy of less than ±8% for Nusselt number and ±10% for friction factor. The results show that there was a significant increase in heat transfer coefficient and friction factor in the tube fitted with quadrant-cut twisted tape (QCT) with decreasing of twist ratio (y) and cut depth (w). Furthermore, the configuration of QCT insert with a twist ratio ofy= 2.93 and a cut depth ofw= 0.5 cm offered higher heat transfer rate and friction factor than other twist ratios.

CFD simulation of heat transfer enhancement in circular tube with twisted tape insert by using nanofluids

2020 ◽  
Vol 21 ◽  
pp. 572-577 ◽  
Author(s):  
A. Natarajan ◽  
R. Venkatesh ◽  
S. Gobinath ◽  
L. Devakumar ◽  
K. Gopalakrishnan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Cfd Simulation ◽  
Circular Tube ◽  
Twisted Tape ◽  
Transfer Enhancement

scholarly journals CFD Analysis for Heat Transfer Enhancement inside a Circular Tube with Half-Length Upstream and Half-Length Downstream Twisted Tape

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
R. J. Yadav ◽  
A. S. Padalkar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Circular Tube ◽  
Swirl Flow ◽  
Twisted Tape ◽  
Turbulent Regime ◽  
Cfd Analysis ◽  
Transfer Enhancement ◽  
Plain Tube ◽  
Half Length

CFD investigation was carried out to study the heat transfer enhancement characteristics of air flow inside a circular tube with a partially decaying and partly swirl flow. Four combinations of tube with twisted-tape inserts, the half-length upstream twisted-tape condition (HLUTT), the half-length downstream twisted-tape condition (HLDTT), the full-length twisted tape (FLTT), and the plain tube (PT) with three different twist parameters (, 0.27, and 0.38) have been investigated. 3D numerical simulation was performed for an analysis of heat transfer enhancement and fluid flow for turbulent regime. The results of CFD investigations of heat transfer and friction characteristics are presented for the FLTT, HLUTT, and the HLDTT in comparison with the PT case.

scholarly journals Augmentation of Heat Transfer in a Duct with Rotating Turbulator using Al2o3 Nanofluid

2019 ◽  
Vol 8 (3) ◽  
pp. 3059-3062
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Twist Ratio ◽  
Al2o3 Nanofluid

The heat transfer enhancement is one of the essential factors to be considered in the design of heat exchangers. The rate of heat transfer can be enhanced by inserting and modifying the geometric configuration of the turbulators in the tube of heat exchangers. In our present work we conducted the experiment to investigate the rate of heat transfer enhancement in a tubular in a heat exchanger by using rotating twisted tape turbulator of twist ratio 3.27 using water and Al2O3 nanofluid as a testing fluid at the flow rate of 1, 2, and 3 LPM. The range of Reynolds number used is 2000<Re<10000, the heat transfer rate calculated for each case of rotating TTT with the speed of 0 to 300 RPM with the step of 100 RPM. The obtained results are compared between water and Al2O3 nanofluid, with and without rotating TTT. From the comparisons, it was found that the TTT with U-cut and the use of Al2O3 nanofluid gives the better rise in the heat transfer rate of about 39.63%. The augmented rate of heat transfer is due to the more turbulence when the rotating TTT is used and replacing the water with nanofluid as the testing fluid which of high thermal properties.

Numerical Studies on Heat Transfer and Friction Factor Characteristics of a Tube Fitted With Helical Twisted Tape Without Core-Rod Inserts

2010 ◽  
Author(s):  
Zhichun Liu ◽  
Xiaoyu Zhang ◽  
Wei Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
High Efficiency ◽  
Three Dimensional ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Turbulence Analysis ◽  
Core Rod

The principles of heat transfer enhancement in the core flow of tube have been proposed to improve the temperature uniformity and reduce flow resistance, which is different from that of heat transfer enhancement in the boundary flow of tube. Helical twisted tape inserts with four different widths (w = 7.5mm, 12mm, 15mm and 20mm) have been investigated for different inlet volume-flow rates ranging from 200L/h to 500L/h. A three-dimensional turbulence analysis of heat transfer and fluid flow is performed by numerical simulation. The simulation results show that the average overall heat transfer coefficients in circular plain tubes are enhanced with helical twisted tape of different widths by as much as 220∼390% at a constant tube-side temperature and the friction factor are enhanced by as much as 50% to 790%. The PEC value of the helical twisted tape inserts of different width varies between 1.60 and 3.15. Physical quantity synergy analysis is also performed. The synergy angles α, β, γ and θ are calculated, and the numerical results verify the synergy regulation among physical quantities of fluid particle in the flow field of convective heat transfer, which can guide the optimum design for better heat transfer units and high-efficiency heat exchangers.

Numerical Analysis for Performance Evaluation of Round Tubes Inserted With Corrugated Twisted Tape

2019 ◽  
Author(s):  
Kalpana Gupta ◽  
Raj Kumar Singh ◽  
Naman Choudhary ◽  
Subham Mukhopadhyay
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
Evaluation Criteria ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Round Tube ◽  
Heat Transfer Augmentation ◽  
Plain Tube

Abstract Varieties of heat transfer enhancement techniques developed by different researchers. Heat transfer augmentation techniques refer to different methods used to increase rate of heat transfer and basically divided into active, passive and compound heat transfer enhancement technique. Use of twisted tape is one such promising passive heat transfer augmentation technique. In this work a novel design of twisted tape is introduced. An attempt has been made to analyze the effect of newly designed twisted tape on heat transfer enhancement using computational Fluid Dynamics (CFD) Techniques. Physical time and energy considered for experimentation will be more so in present work simulation has been carried out using ANSYS FLUENT software to find performance of novel twisted tape. The tape considered here is corrugated twisted tape in which corrugations are given longitudinally with fixed angle of corrugation then it is twisted. Comparison in performance of tube without tape, with plain twisted tape and twisted corrugated tape has been done. Verification of model has been done using available correlations for plain tube and tube with plain twisted tape. Range of Reynolds varied from 10,000 to 60,000. Heat transfer and pressure drop characteristics studied using computational analysis. Nusselt Number and friction factor of round tube with CTT insert is found to be 1.79–1.94 times and 2.5–3.5 times higher respectively compared to round tube without any insert. Thermal performance factor chosen as performance evaluation criteria keeping pumping power constant. Performance of tube with corrugated twisted tape insert found to be better than plain tube (improvement in TPF up to 31%) taking into account both heat transfer and friction factor.

scholarly journals Review on Heat Transfer Enhancement by Insert Devices

2020 ◽  
Vol 5 (4) ◽  
pp. 130-147
Author(s):  
Md. Shamim Ahmed ◽  
Mohammad Zoynal Abedin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Helical Tube ◽  
Twist Ratio ◽  
Different Types ◽  
Considerable Impact ◽  
Wire Coil ◽  
Pitch Ratio

The scientists revise the heat transfer enhancement techniques time to time to achieve better performance and to obtain optimized designs of heat exchangers. The present study reviews the performance and techniques of heat transfer enhancement using various insert devices such as twisted tape and wire coil insert as well as completely different forms of other inserts like air-foil shape inserts, X-shaped twisted tape inserts, baffles and V-winglets inserts with various types of medium and nanofluids. According to the summary of recent significant researches  on the heat transfer enhancement by using different types of  inserts and combinations of these inserts with various nanofluids showed that insert can indicatively enhance the heat transfer rate by modifying its geometry or configurations like twist ratio, length ratio, pitch ratio, segmented tape, perforated tape, angle of arrangements and insert quantities and so on which caused a considerable impact on performance characteristics of heat transfer enhancement along with the pressure drop and friction factor. It is revealed through reviewing the related literature that the highest value of equivalence heat transfer enhancement is as maximum as 400%, 300% and 9% for the twisted tape insert with helical tube, the air foil shaped inserts and for the wire coil inserts, respectively when compared with the smooth tube. In the case of baffles in nanofluids, as maximum as 255% equivalence heat transfer enhancement could be achieved when compared with that of baffles without nanofluids.

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