The experimental thermal and hydraulic performance analyses for the location of perforations and dimples on the twisted tapes in twisted tape inserted tube

2021 ◽  
Vol 167 ◽  
pp. 107033
Author(s):  
Toygun Dagdevir ◽  
Mahmut Uyanik ◽  
Veysel Ozceyhan
Keyword(s):  
Hydraulic Performance ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Performance Analyses

scholarly journals The Effect of Off-center Placement of Twisted Tape on Flow and Heat Transfer Characteristics in a Circular Tube

2020 ◽  
Author(s):  
Li Wang ◽  
Peiyong Ni ◽  
Guannan Xi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Circular Tube ◽  
Flow Distribution ◽  
Hydraulic Performance ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Plain Tube ◽  
And Performance ◽  
High Reynolds

Abstract This study is conducted to investigate the effect of off-center placement of twisted tape on flow distribution and heat transfer in a circular tube. The effect of tape width of 20, 18, 16, 14 and 12 mm on the heat transfer performance is discussed under the same twist ratio of 2.0. The numerical analysis of the flow field, average Nusselt number, friction factor and thermo-hydraulic performance parameter of the tube are discussed with Reynolds number ranged from 2600 to 8760. The results indicate that the Nusselt number of the tube fitted with center-placed twisted tapes at various width is 7~51% higher than the plain tube, and performance in low Reynolds region was found more effective than that in high Reynolds region. The heat transfer for circular tube with twisted tape attached to the wall shows better performance than that for the tube with center-placed twisted tape. With a smaller tape width, a higher increasing ratio of Nu-wall/Nu-center is obtained. The increasing ratio for Nusselt number ranged from 3 to 18%. However, the use of twisted tape inserts is not beneficial for energy saving. The thermo-hydraulic performance parameters for convective heat transfer of helium gas flowing in a circular tube are below unity for the calculated Reynolds region.

Effect of Various Twisted Tape and Tube Configurations on Thermal- Hydraulic Performance in a Roughened Heat Transfer Device: A Comprehensive Review

2021 ◽  
Vol 15 ◽  
Author(s):  
Rohit Khargotra ◽  
Raj Kumar ◽  
Rahul Nadda ◽  
Tej Singh
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Hydraulic Performance ◽  
Review Article ◽  
Energy Output ◽  
Twisted Tape ◽  
Current Review ◽  
Twisted Tapes ◽  
Similar Area ◽  
Transfer Device

: Turbulence promoters in the form of twisted tapes effectively improve heat exchangers thermal performance. The current review article summarizes the experimental and numerical behaviours of a heat exchanger. The experimental investigation reported in the literature of heat enhancement and fluid flowing characteristics with different twisted tape and tube configurations. Distant twisted tape configurations are employed to increase the heat enhancement rate in the different heat exchanger tubes. Based on the correlations developed by different investigators, an experiment has been made to differentiate the thermal-hydraulic performance of twisted tape configurations in heat exchanger tubes. A comparative study is also carried out to select the excellent twisted tape and tube configurations for superior thermohydraulic performance in the present work. This review article also provides a platform for researchers researching a similar area to design an improved heat enhancement rate apparatus using superlative twisted tape and tube configurations to increase the thermohydraulic performance by increasing the system's energy output.

scholarly journals The effect of off-center placement of twisted tape on flow and heat transfer characteristics in a circular tube

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li Wang ◽  
Peiyong Ni ◽  
Guannan Xi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Circular Tube ◽  
Flow Distribution ◽  
Hydraulic Performance ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Plain Tube ◽  
And Performance ◽  
High Reynolds

AbstractThis study is conducted to investigate the effect of off-center placement of twisted tape on flow distribution and heat transfer in a circular tube. The effect of tape width of 20, 18, 16, 14 and 12 mm on the heat transfer performance is discussed under the same twist ratio of 2.0. The numerical analysis of the flow field, average Nusselt number, friction factor and thermo-hydraulic performance parameter of the tube are discussed with Reynolds number ranged from 2600 to 8760. The results indicate that the Nusselt number of the tube fitted with center-placed twisted tapes at various width is 7–51% higher than the plain tube, and performance in low Reynolds region was found more effective than that in high Reynolds region. The heat transfer for circular tube with twisted tape attached to the wall shows better performance than that for the tube with center-placed twisted tape. With a smaller tape width, a higher increasing ratio of Nu-wall/Nu-center is obtained. The increasing ratio for Nusselt number ranged from 3 to 18%. However, the use of twisted tape inserts is not beneficial for energy saving. The thermo-hydraulic performance parameters for convective heat transfer of helium gas flowing in a circular tube are below unity for the calculated Reynolds region.

scholarly journals Investigation of Overlapped Twisted Tapes Inserted in a Double-Pipe Heat Exchanger Using Two-Phase Nanofluid

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1656 ◽  
Author(s):  
Mehdi Ghalambaz ◽  
Hossein Arasteh ◽  
Ramin Mashayekhi ◽  
Amir Keshmiri ◽  
Pouyan Talebizadehsardari ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Evaluation Criterion ◽  
Twisted Tape ◽  
Performance Evaluation Criterion ◽  
Twisted Tapes ◽  
Double Pipe ◽  
Pipe Heat

This study investigated the laminar convective heat transfer and fluid flow of Al2O3 nanofluid in a counter flow double-pipe heat exchanger equipped with overlapped twisted tape inserts in both inner and outer tubes. Two models of the same (co-swirling twisted tapes) and opposite (counter-swirling twisted tapes) angular directions for the stationary twisted tapes were considered. The computational fluid dynamic simulations were conducted through varying the design parameters, including the angular direction of twisted tape inserts, nanofluid volume concentration, and Reynolds number. It was found that inserting the overlapped twisted tapes in the heat exchanger significantly increases the thermal performance as well as the friction factor compared with the plain heat exchanger. The results indicate that models of co-swirling twisted tapes and counter-swirling twisted tapes increase the average Nusselt number by almost 35.2–66.2% and 42.1–68.7% over the Reynolds number ranging 250–1000, respectively. To assess the interplay between heat transfer enhancement and pressure loss penalty, the dimensionless number of performance evaluation criterion was calculated for all the captured configurations. Ultimately, the highest value of performance evaluation criterion is equal to 1.40 and 1.26 at inner and outer tubes at the Reynolds number of 1000 and the volume fraction of 3% in the case of counter-swirling twisted tapes model.

Thermohydraulics of Laminar Flow Through Rectangular and Square Ducts With Transverse Ribs and Twisted Tapes

2006 ◽  
Vol 128 (10) ◽  
pp. 1070-1080 ◽  
Author(s):  
Debashis Pramanik ◽  
Sujoy K. Saha
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Laminar Flows ◽  
Short Length ◽  
Full Length ◽  
Twisted Tape ◽  
Twisted Tapes ◽  
Square Ducts ◽  
Better Than

The heat transfer and the pressure drop characteristics of laminar flow of viscous oil through rectangular and square ducts with internal transverse rib turbulators on two opposite surfaces of the ducts and fitted with twisted tapes have been studied experimentally. The tapes have been full length, short length, and regularly spaced types. The transverse ribs in combination with full-length twisted tapes have been found to perform better than either ribs or twisted tapes acting alone. The heat transfer and the pressure drop measurements have been taken in separate test sections. Heat transfer tests were carried out in electrically heated stainless steel ducts incorporating uniform wall heat flux boundary conditions. Pressure drop tests were carried out in acrylic ducts. The flow was periodically fully developed in the regularly spaced twisted-tape elements case and decaying swirl flow in the short-length twisted tapes case. The flow characteristics are governed by twist ratio, space ratio, and length of twisted tape, Reynolds number, Prandtl number, rod-to-tube diameter ratio, duct aspect ratio, rib height, and rib spacing. Correlations developed for friction factor and Nusselt number have predicted the experimental data satisfactorily. The performance of the geometry under investigation has been evaluated. It has been found that on the basis of both constant pumping power and constant heat duty, the regularly spaced twisted-tape elements in specific cases perform marginally better than their full-length counterparts. However, the short-length twisted-tape performance is worse than the full-length twisted tapes. Therefore, full-length twisted tapes and regularly spaced twisted-tape elements in combination with transverse ribs are recommended for laminar flows. However, the short-length twisted tapes are not recommended.

scholarly journals Heat Enhancement Effectiveness Using Multiple Twisted Tape in Rectangular Channels

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 188
Author(s):  
M. Ziad Saghir ◽  
Ayman Bayomy ◽  
Md Abdur Rahman
Keyword(s):  
Pressure Drop ◽  
Heat Removal ◽  
Energy System ◽  
Twisted Tape ◽  
Heat Exchanger Design ◽  
Twisted Tapes ◽  
Rectangular Channels ◽  
Flow Through ◽  
The Subject ◽  
Energy Coefficient

Heat enhancement and heat removal have been the subject of considerable research in the energy system field. Flow-through channels and pipes have received much attention from engineers involved in heat exchanger design and construction. The use of insert tape is one of many ways to mix fluids, even in a laminar flow regime. The present study focused on the use of different twisted tapes with different pitch-to-pitch distances and lengths to determine the optimum design for the best possible performance energy coefficient. The results revealed that twisted tape of one revolution represented the optimal design configuration and provided the largest Nusselt number. The length of the tape played a major role in the pressure drop. The results revealed that the insertion of a shorter twisted tape can create mixing while minimizing the changes in the pressure drop. In particular, the best performance evaluation criterion is found for a short tape located towards the exit of the channel. The highest performance energy coefficient was obtained for the half-twisted tape for a Reynolds number varying between 200 and 600.

Analytical Prediction of Heat Transfer in Tape Generated Swirl Flow

2017 ◽  
Author(s):  
R. J. Yadav ◽  
Sandeep Kore ◽  
V. N. Riabhole
Keyword(s):  
Heat Transfer ◽  
Circular Tube ◽  
Swirl Flow ◽  
Twisted Tape ◽  
Analytical Prediction ◽  
Transfer Coefficients ◽  
Numerical Predictions ◽  
Twisted Tapes ◽  
Wide Range ◽  
Prandtl Numbers

Heat transfer and pressure drop characteristics in a circular tube with twisted tapes have been investigated experimentally and numerically using different working fluids by many researchers for wide range of Reynolds number. The swirl was generated by tape inserts of various twist ratios. The various twist ratios are considered Many researchers formed generalized correlations to predict friction factors and convective heat transfer coefficients with twisted tapes in a tube for a wide range of Reynolds numbers and Prandtl numbers. Satisfactory agreement was obtained between the present correlations and the data of others validate the proposed correlations. The experimental or numerical predictions were compared with earlier correlations revealing good agreement between them. From the literature review it is observed that most studies are mainly focused on the heat transfer enhancement using twisted tape by experimental or numerical solution. An investigation with analytical approach is rarely reported. Therefore, the main aim of the present work is to form a correlation from theoretical approach for Nusselt number for circular tube with twisted tape. Application of dimensional analysis to heat transfer in tape generated swirl flow is carried out.

Non-Linear Characteristics of Subcooled Water Flow Boiling CHFS Versus Outlet Subcoolings for Flow Velocities at Pressures in Various Tubes

2008 ◽  
Author(s):  
Katsuya Fukuda ◽  
Qiusheng Liu
Keyword(s):  
Flow Velocity ◽  
Water Flow ◽  
Flow Boiling ◽  
Vertical Tube ◽  
Twisted Tape ◽  
Outlet Pressure ◽  
Subcooled Water ◽  
Twisted Tapes ◽  
Non Linear ◽  
Bare Tube

Non-linear characteristics of the subcooled water flow boiling CHF versus outlet subcooling for a flow velocity with outlet pressure as a parameter in a horizontal or vertical tube with a twisted tape having flowing subcooled water was clarified using the existing databases expanding quite recently derived the CHF correlations based on two CHF mechanisms for the bare tubes with various inside diameters and length-to-diameter ratios for a flow velocity with outlet pressure as a parameter. The databases were applied measured using, the horizontal tubes with inside diameters of 8 and 12 mm, having length-to-diameter ratios of 6.25 and 4.17 respectively with twisted-tapes having a twist ratio of 2.0, for flow velocities of 7 and 10 m/s, at pressures ranging from 0.2 to 1.1 MPa. The nonlinear characteristics of subcooled water flow boiling CHFs for outlet subcoolings in the tubes having helically coiled 1 mm diameter wires of the coil pitches of 12, 24 and 36 mm, with flowing subcooled water of a flow velocity of 7 m/s at outlet pressures of 0.2, 0.3 and 1.1 MPa were investigated based on the subcooled water flow boiling CHF correlations for bare tubes previously derived. The following results were derived that (1) the non-linear characteristic of CHF versus outlet subcooling, for a horizontal or vertical tube having a twisted tape, divided into three regions for middle, transition, and high outlet subcooling was clarified. The characteristics were similar to that for a identical bare tube, with higher CHF values for middle and high outlet subcooling values respectively, and (2) the enhanced CHF values for middle and high outlet subcooling values being dependent on outlet pressuret and being independent of one respectively, were described by the same CHF correlations derived for a identical bare tube, with higher coefficients of the correlations depending on the tubes with twisted tapes of twist ratios.

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