scholarly journals Numerical study on the influencing mechanism of twisted ratio in outward convex corrugated tubes with a twisted tape insert

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 577-584
Author(s):  
Huaizhi Han ◽  
Longbin Yang ◽  
Yiran Hu ◽  
Ruitian Yu ◽  
Qun Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Numerical Study ◽  
Twisted Tape ◽  
High Twist ◽  
Numerical Investigations ◽  
Corrugated Tube ◽  
Influencing Mechanism ◽  
Flow And Heat Transfer ◽  
Twist Ratio

Numerical investigations were conducted on flow and heat transfer in an outward convex corrugated tube with various structural twisted tape inserts. The study investigated the influence of twisted ratio on thermodynamic regulation and mechanism in the corrugated tube. The results indicate that Nusselt number in the corrugated tube (Nuc) exceeds those in the corrugated tube and smooth tube by 120-136% and 171-317%, respectively. Meanwhile, the friction factor increases by 148-153% and 476-514%, respectively. The best overall thermal performance (h = 1.97) is obtained with a high twist ratio (y/w = 5). However, the highest thermal performance (Nuc/Nus = 4.78) is obtained with the lowest twist ratio (y/w = 1.25).

A Numerical Study of the Flow and Heat Transfer Characteristics of Outward Convex Corrugated Tubes With Twisted-Tape Insert

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Longbin Yang ◽  
Huaizhi Han ◽  
Yanjun Li ◽  
Xiaoming Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Performance ◽  
Swirling Flow ◽  
Numerical Study ◽  
Twisted Tape ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Corrugated Tube ◽  
Flow And Heat Transfer ◽  
Flow Heat

This work presents a mathematical model for simulating the swirling flow in an outward convex corrugated tube with twisted-tape insert (CT). The synergistic effect on the flow, heat transfer, and friction loss behaviors between the surface-based and fluid-based enhancements is numerically investigated. Renormalized group (RNG) k-ε turbulence model applied in our paper is verified by comparing with experimental results investigated by Manglik and Bergles. Comparisons of the CT and smooth tube with twisted-tape insert (ST) plots are confirmed to investigate the performance differences between them. When comparing the performance of the CT against the ST, the maximum ratio of Nusselt number (Nuc/Nus), ratio of friction factor (f/fs), and overall heat transfer performance (η) values realized in the CT are 1.36, 1.53, and 1.15 times higher, respectively, than the maximum values for those same variables in the ST.

scholarly journals Numerical Investigation of the Effect of Inserted Twisted Tape inside Submerged Bundle Tubes on its Thermal Performance

2018 ◽  
Vol 24 (3) ◽  
pp. 42
Author(s):  
Kamal Mohammed Ali ◽  
Abdalrazzaq K. Abbas
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Reynolds Numbers ◽  
Twisted Tape ◽  
Ansys Fluent ◽  
Twist Ratio ◽  
Plain Tube ◽  
Exit Temperature ◽  
Inner Diameter ◽  
Film Heat Transfer

Twisted tape insertion in smooth plain tube is one of types of passive methods that is used to enhance heat transfer. Swirl fluid flow inside tube and related heat transfer characteristics are very complex. ANSYS FLUENT (V 16.1) and ASPEN industrial program are used in analyzing this technique for enhancement heat transfer. A circular plain tube has length L=8534mm and 17 mm inner diameter with twisted tape has twist ratio of y = (H/D) = (150/17) =8.8 along with a plain tube were considered for this study. Eight Reynolds numbers (Re) of 784, 1000, 2000, 3000, 4000, 5000, 6000 and 7000 are used to analyze the response of thermal performance. Crude oil API 28 exit temperature, film heat transfer coefficient, Nusselt number and overall enhancement ratio results are presented for both empty and inserted plain tube with comparison between the two cases. An increase of 0.76 to 2.36 overall enhancement is predicted with twist ratio 8.8 for Reynolds number 784 to 7000 respectively.  

Numerical Study on the Flow and Heat Transfer Characteristics in Rectangular Channels With Grooves and Different Protrusions

2017 ◽  
Author(s):  
Feng Zhang ◽  
Xinjun Wang ◽  
Jun Li ◽  
Daren Zheng ◽  
Junfei Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Rectangular Channels

The present work represents a numerical study on the flow and heat transfer characteristics in rectangular channels with protrusion-grooved turbulators. The Reynolds averaged Navier-Stokes equations, coupled with SST turbulence model, are adopted and solved. In this paper, six geometric protrusion shapes (circular, rectangular, triangular, trapezoidal, circular with leading round concave and circular with trailing round concave) are selected to perform the study. The flow structure, heat transfer enhancement, friction factor as well as thermal performance factor of the rectangular channel fitted with combined groove and different protrusions have been obtained at the Reynolds number ranging from 5000 to 20000. The results indicate that the protrusion shapes affect the velocity distribution near the groove surface. The case of circular protrusion with leading round concave provides the highest overall heat transfer enhancement, while it also causes the highest pressure loss penalty. The case of rectangular protrusion has the lowest overall heat transfer enhancement with high pressure loss penalty. The case of circular protrusion has similar overall heat transfer enhancement with cases of trapezoidal protrusion as well as circular protrusion with trailing round concave, but the pressure loss penalty of the case of circular protrusion is the lowest. In addition, the best overall thermal performance can be observed for circular protrusion-grooved channel.

Characterization of Heat Transfer by Overlapped-Quadruple Counter Tapes

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
S. Eiamsa-Ard ◽  
P. Samravysin
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Twisted Tape ◽  
Flux Boundary Condition ◽  
Turbulent Flow Regime ◽  
Thermal Enhancement ◽  
Twist Ratio ◽  
Enhancing Heat Transfer ◽  
Uniform Wall

This paper deals with the influence of overlapped-quadruple twisted tape (OQT) and typical quadruple twisted tape (QT) on the enhancing heat transfer rate in a heat exchanger tube. The effects of tube orientation (co-tapes and counter tapes), tape arrangement (cross and parallel arrangements), and overlapped twist ratio (yo/y = 0.625, 0.75, and 0.875) were investigated. The experiments were performed in the turbulent flow regime (5000 ≤ Re ≤ 20,000) under uniform wall heat flux boundary condition, using air as the testing fluid. The experimental results indicates that all OQTs consistently yield higher Nusselt number and thermal performance than QTs. The tapes in cross arrangement show better heat transfer enhancement and thermal performance than the ones in parallel arrangement. Heat transfer, friction loss, and thermal performance increase with decreasing overlapped twist ratio. The maximum thermal enhancement factor (TEF) of 1.58 is achieved by the use of overlapped-quadruple counter tapes in cross arrangement (CC-OQTs) with yo/y = 0.625 at the lowest Reynolds number of 5000.

Parametric Numerical Study of Flow and Heat Transfer in Microchannels With Wavy Walls

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Liang Gong ◽  
Krishna Kota ◽  
Wenquan Tao ◽  
Yogendra Joshi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Numerical Study ◽  
High Heat ◽  
High Heat Flux ◽  
Laminar Fluid Flow ◽  
Flow And Heat Transfer ◽  
Wavy Channels

Wavy channels were investigated in this paper as a passive scheme to improve the heat transfer performance of laminar fluid flow as applied to microchannel heat sinks. Parametric study of three-dimensional laminar fluid flow and heat transfer characteristics in microsized wavy channels was performed by varying the wavy feature amplitude, wavelength, and aspect ratio for different Reynolds numbers between 50 and 150. Two different types of wavy channels were considered and their thermal performance for a constant heat flux of 47 W/cm2 was compared. Based on the comparison with straight channels, it was found that wavy channels can provide improved overall thermal performance. In addition, it was observed that wavy channels with a configuration in which crests and troughs face each other alternately (serpentine channels) were found to show an edge in thermal performance over the configuration where crests and troughs directly face each other. The best configuration considered in this paper was found to provide an improvement of up to 55% in the overall performance compared to microchannels with straight walls and hence are attractive candidates for cooling of future high heat flux electronics.

Parametric Numerical Study of Flow and Heat Transfer in Microchannels With Wavy Walls

2010 ◽  
Author(s):  
Liang Gong ◽  
Krishna Kota ◽  
Wenquan Tao ◽  
Yogendra Joshi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Numerical Study ◽  
High Heat ◽  
High Heat Flux ◽  
Laminar Fluid Flow ◽  
Flow And Heat Transfer ◽  
Wavy Channels

Wavy channels are investigated in this paper as a passive scheme to improve the heat transfer performance of laminar fluid flow as applied to microchannel heat sinks. Parametric study of three-dimensional laminar fluid flow and heat transfer characteristics in micro-sized wavy channels was performed by varying the wavy feature amplitude and wavelength at different Reynolds numbers between 50 and 150. Two different types of wavy channels were considered and their thermal performance for a constant heat flux of 47 W/cm2 was compared. Based on the comparison with straight channels, it was found that wavy channels can provide improved overall thermal performance. In addition, it was observed that wavy channels with a configuration in which crests and troughs face each other alternately (serpentine channels) were found to show an edge in thermal performance over the configuration where crests and troughs face each other. The best configuration considered in this paper was found to provide an improvement of up to 55% in the overall performance compared to microchannels with straight walls and hence are attractive candidates for cooling of future high heat flux electronics.

Numerical Study of Laminar Flow and Heat Transfer Characteristic in Wave Tubes Based on Sine Curve

2011 ◽  
Vol 322 ◽  
pp. 349-352
Author(s):  
Zheng Ming Tong ◽  
Kai Zhu ◽  
Jia Lei Lu ◽  
Gen Li
Keyword(s):  
Heat Transfer ◽  
Flow Resistance ◽  
Numerical Study ◽  
Transfer Characteristic ◽  
Flow State ◽  
Field Synergy Principle ◽  
Corrugated Tube ◽  
Flow And Heat Transfer ◽  
New Type ◽  
Computational Fluid Dynamics Cfd

A new type of corrugated tube based on sine function is proposed by introducing a parameter of sine camber in this paper. Computational Fluid Dynamics (CFD) was used to analysis flow state and sine camber of tube influence on the heat transfer and flow. The heat transfer and flow around sinusoidal corrugated tubes with different sine camber e are investigated. According to the numerical calculus result, correlation equations of Nu (Nusselt) =f(Re) is given. At last, the theoretical comparative analysis with field synergy principle is carried out for the heat transfer and flow resistance in smooth tube and sinusoidal corrugated tube.

scholarly journals Numerical Investigation of the Effect of Inserted Twisted Tape inside Submerged Bundle Tubes on its Thermal Performance

2018 ◽  
Vol 24 (7) ◽  
pp. 1
Author(s):  
Kamal Mohammed Ali ◽  
Abdalrazzaq K. Abbas
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Reynolds Numbers ◽  
Twisted Tape ◽  
Ansys Fluent ◽  
Twist Ratio ◽  
Plain Tube ◽  
Exit Temperature ◽  
Inner Diameter ◽  
Film Heat Transfer

Twisted tape insertion in the smooth plain tube is one of the types of passive methods that are used to enhance heat transfer. Swirl fluid flow inside the tube and related heat transfer characteristics are very complex. ANSYS FLUENT (V 16.1) and ASPEN industrial program are used in analyzing this technique for enhancement heat transfer. A circular plain tube has length L=8534mm and 17 mm inner diameter with a twisted tape of twist ratio of y = (H/D) = (150/17) =8.8 along the plain tube were considered for this study. Eight Reynolds numbers (Re) of 784, 1000, 2000, 3000, 4000, 5000, 6000 and 7000 are used to analyze the response of thermal performance. Crude oil API 28 exit temperature, film heat transfer coefficient, Nusselt number and overall enhancement ratio results are presented for both empty and inserted plain tube with a comparison between the two cases. An increase of 0.76 to 2.36 overall enhancement is predicted with twist ratio 8.8 for Reynolds number 784 to 7000 respectively.  

scholarly journals Comparative Studies on Thermal Performance of Conic Cut Twist Tape Inserts with SiO2and TiO2Nanofluids

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Sami D. Salman ◽  
Abdul Amir H. Kadhum ◽  
Mohd S. Takriff ◽  
Abu Bakar Mohamad
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Thermal Performance ◽  
Volume Concentration ◽  
Twisted Tape ◽  
Maximum Heat ◽  
Performance Factor ◽  
Thermal Performance Factor ◽  
Maximum Heat Transfer ◽  
Twist Ratio

This paper presents a comparison study on thermal performance conic cut twist tape inserts in laminar flow of nanofluids through a constant heat fluxed tube. Three tape configurations, namely, quadrant cut twisted tape (QCT), parabolic half cut twisted tape (PCT), and triangular cut twisted (VCT) of twist ratioy= 2.93 and cut depthde= 0.5 cm were used with 1% and 2% volume concentration of SiO2/water and TiO2/water nanofluids. Typical twist tape with twist ratio ofy= 2.93 was used for comparison. The results show that the heat transfer was enhanced by increasing of Reynolds number and nanoparticles concentration of nanofluid. The results have also revealed that the use of twist tape enhanced the heat transfer coefficient significantly and maximum heat transfer enhancement was achieved by the presence of triangular cut twist tape insert with 2% volume concentration of SiO2nanofluid. Over the range investigated, the maximum thermal performance factor of 5.13 is found with the simultaneous use of the SiO2nanofluid at 2% volume concentration VCT at Reynolds number of 220. Furthermore, new empirical correlations for Nusselt number, friction factor, and thermal performance factor are developed and reported.

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