Numerical investigation of rectangular-cut twisted tape insert on performance improvement of heat exchangers

Nakhchi, M.E.; Esfahani, Javad Abolfazli

doi:10.1016/j.ijthermalsci.2018.12.039

Cited by 117 publications

(31 citation statements)

References 30 publications

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“…Suri et al [3] carried the same work by surface perforating the twisted tape and found that perforation gives better performance factor. Similarly, Nakhchi and Esfahani [4,5] in their study showed that Double V-cut insert has highest TPF as compared to other cut shapes. Nakhchi and Esfahani [6] in their further numerical investigation used perforated conical rings and studied the effect of geometrical parameters on heat transfer process.…”

Section: Introductionmentioning

confidence: 77%

“…These turbulators when placed inside the tube disturb the fluid flow and hence decrease the thermal resistance. Some inserts used by researchers are rings, twisted tapes, delta wings and strips [1][2][3][4][5][6][7][8][9][10]. Bhuiya et al [1] in their experimental investigation used double counter twisted tape and varied twist ratio of these tapes.…”

Section: Introductionmentioning

confidence: 99%

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CFD analysis for thermo-hydraulic properties in a tubular heat exchanger using curved circular rings

Singh

Kharkwal

Gautam

et al. 2020

J Therm Anal Calorim

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The never-ending demands of humans have led researchers to find more efficient energy conversion technologies. Enhancing heat transfer rate in a tubular heat exchanger through curved circular rings is one type of passive method that is studied in this work. The computational analysis has been done using "FLUENT" module of ANSYS 16.0. The tubular heat exchanger has internal diameter of 68.1 mm, length of 1.5 m and constant heat flux of 1000 W m −2. Air is the working fluid, which flows in Re varying from 3000 to 21,000. After reaching steady state conditions, the Nusselt number and friction factor are calculated for CCR rings. Furthermore, perforation has been done on these rings with perforation index 8, 12 and 16% and thermo-hydraulic properties are investigated. Computational results show that perforating the rings have a significant effect on heat transfer and friction factor. Greater the perforation index, greater is the Nu and TPF. The maximum enhancements obtained in Nu and TPF are 7.4 and 1.56 times, respectively (as compared to that of smooth tube), for PCCR-16%.

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Section: Introductionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

CFD analysis for thermo-hydraulic properties in a tubular heat exchanger using curved circular rings

Singh

Kharkwal

Gautam

et al. 2020

J Therm Anal Calorim

View full text Add to dashboard Cite

show abstract

“…Jedsadaratanachai, W. and A. Boonloi [2] conducted a numerical study on the influence of a twisted ratio on HT and flow thermal performance within a single twisted tape circle, resulting in HT in a tube with TT being more effective than that without TT and Re number decreasing with an increase in twist ratio. Nakhchi and Esfahani [3] inspected thermal-hydraulic behavior of the heat exchanger of a circular tube fitted with single-cut rectangular and twisted double-cut tape inserts in the regime of turbulent flow. The geometries of cuts are rectangular with different cut ratios 0.25<b/w<0.75, they revealed twisted band yield greater turbulence than single-cut band, and the Nusselt number increased by a maximum of 33.26 percent changes in the cut ratio were reported from 0.25 to 0.75.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Heat Transfer Enhancement by Turbulence Generator in Side Pipe

zaid

A.Hamza

Al-Zurfi

2021

Al-Furat Journal of Innovations in Mechanical and Sustainable Energy Engineering

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The enhancement of heat transfer exchangers is an important matter of concern for achieving more efficient thermal energy conversion systems. The use of modified twisted tape (TT) inserts as a passive heat transfer augmentation technique is an efficient way of improving heat transfer. Twisted tape insert is one of the passive heat transfer enhancement techniques that are widely used in various applications for heat transfer, such as air conditioning and cooling systems, heat recovery systems, Processes, procedures for food and milk, plants for chemical processes. To increase the heat transfer rate of the tubular heat exchanger, in this study a small-scale experimental setup was performed. The heat improvement of heat exchanger is done using twisted tape inserts with twist ratio (y=5.5). The effects of two dimensional parameters namely Nusselt number & friction factor on tubular heat exchanger effectiveness are studied. The turbulent flow was generated by the insertion into the test pipe of the twisted tape inserts, producing a high turbulence rate in the pipe, resulting in an increase in turbulence. And hence enhancement of heat transfer and drop in pressure. The length and width of insert was 1000 mm and 21.5 mm respectively. The diameter of the test pipe outside & inside is 23 mm and 22 mm respectively. The length of test section is 2000 mm. The study is carried out for the Reynold number regime (500-6500). The results show that The maximum enhancement for Nu number at Re 500 was 32% that of the plain tube.

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“…Several researchers conducted experimental and numerical simulations in the field of energy performance augmentation of turbulent and laminar flows by utilizing various active and passive methods, Such as twisted tapes [4][5][6], ribbed and corrugated channels [7][8][9], wavy surfaces [10,11], conical rings [12], louvered strips [13], hollow cylinders [14], asymmetric sinusoidal channels [15,16], nanofluids [17][18][19][20][21], baffle turbulators [22][23][24], helical screw tapes [25,26], rotating two-pass channels [27] and triangular obstacles [28].…”

Section: Introductionmentioning

confidence: 99%

Turbulent Flows Inside Pipes Equipped With Novel Perforated V-Shaped Rectangular Winglet Turbulators: Numerical Simulations

Nakhchi

Rahmati

2020

Journal of Energy Resources Technology

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In this study, computational simulations have been performed to investigate the turbulent characteristics and energy consumption through heat exchanger tubes equipped by new perforated V-shaped rectangular winglet (PVRW) turbulators. The effects of the holes intensity on the velocity and temperature contours are additionally investigated. The Reynolds number, hole diameter ratio, and the number of holes selected are in the range of 5000 ≤ Re ≤ 18,000, 0 ≤ DR ≤ 0.40, and 0 ≤ N ≤ 14, respectively. Renormalization group (RNG) k–ε turbulent model which is a finite volume solver is utilized for the computational fluid dynamics (CFD) simulation. It was noticed that the proposed perforated turbulators could considerably intensify the thermal performance compared to typical VRW inserts. It is found that the recirculating flow generated by the PVRW augments the fluid mixing and transfers the heat from the pipe walls to the core of the tube. The simulations illustrate that the amount of heat transfer enhances 25.2% reducing the DR from 0.4 to 0.13 at Re = 18,000 and N = 14. Also, using PVRW turbulators with N = 7 and DR = 0.26 augments the average Nusselt number around 354.3% compared to the circular pipe without inserts. The highest thermal efficiency parameter of η = 2.25 could be obtained at Re = 5000 for the heat exchangers fitted by vortex generators with N = 14 and DR = 0.26.

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Numerical investigation of rectangular-cut twisted tape insert on performance improvement of heat exchangers

Cited by 117 publications

References 30 publications

CFD analysis for thermo-hydraulic properties in a tubular heat exchanger using curved circular rings

CFD analysis for thermo-hydraulic properties in a tubular heat exchanger using curved circular rings

Experimental Study of Heat Transfer Enhancement by Turbulence Generator in Side Pipe

Turbulent Flows Inside Pipes Equipped With Novel Perforated V-Shaped Rectangular Winglet Turbulators: Numerical Simulations

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