Thermo-Fluidic Modelling of a Heat Exchanger Tube with Conical Shaped Insert having Protrusion and Dimple Roughness

In the present work, thermo-fluidic behavior of a heat exchanger tube with conical shaped insert has been investigated with the help of finite volume method. To enhance the heat transfer rate, two different types of roughness has been used in conical insert i.e. protrusion and dimple roughness. A three-dimensional computational model with RNG turbulence model is used for the simulation and it has been performed for three different diameters (3 mm, 6 mm and 9 mm) and two different pitch space (120 mm and 180 mm) for both protrusion and dimple roughness. The present model has been validated with Dittus-Boelter equation and with Blasius equation for Nusselt number and friction factor, respectively. For a constant heat flux of 1200 W/m2, effect of roughness, diameter and pitch on Nusselt number and friction factor has been predicted for Reynold number range of 5000 to 30000. From the result, it is found that, the protrusion shaped roughness has better thermal performance factor than dimple shape and diameter of 6 mm has performed better than 3 mm and 9 mm for both the cases of roughness due to favorable flow dynamics.

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Correlations development for Nusselt number and friction factor in a dimpled surface heat exchanger tube

Experimental Heat Transfer ◽

10.1080/08916152.2019.1573863 ◽

2019 ◽

Vol 33 (2) ◽

pp. 101-122 ◽

Cited By ~ 8

Author(s):

Rajesh Maithani ◽

Anil Kumar

Keyword(s):

Nusselt Number ◽

Heat Exchanger ◽

Friction Factor ◽

Surface Heat ◽

Heat Exchanger Tube ◽

Surface Heat Exchanger ◽

Exchanger Tube

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Potential of gear-ring turbulator in three-dimensional heat exchanger tube from second law of thermodynamic viewpoint

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-05-2018-0250 ◽

2019 ◽

Vol 29 (4) ◽

pp. 1526-1543 ◽

Cited By ~ 8

Author(s):

Navid Moghaddaszadeh ◽

Saman Rashidi ◽

Javad Abolfazli Esfahani

Keyword(s):

Heat Exchanger ◽

Three Dimensional ◽

Second Law ◽

Bejan Number ◽

Heat Exchanger Tube ◽

Space Length ◽

Content Type ◽

Tooth Number ◽

Gear Ring ◽

Exchanger Tube

PurposeThis paper aims to use the second law of thermodynamic to evaluate the potential of gear-ring turbulator in a three-dimensional heat exchanger tube. Accordingly, a numerical simulation is performed to obtain the irreversibilities in a three-dimensional heat exchanger tube equipped with some gear-ring turbulators for turbulence regime.Design/methodology/approachA numerical simulation is performed to obtain the irreversibilities in a three-dimensional heat exchanger tube equipped with some gear-ring turbulators for turbulence regime. The analysis is carried out based on shear stress transport (SST) k-ω turbulent model. The influences of different parameters containing tooth number, free-space length ratios and Reynolds number on frictional and thermal irreversibilities and Bejan number are discussed.FindingsThe results indicated that the thermal irreversibility reduces by decreasing the tooth number. For example, the thermal entropy generation decreases about 25.81 per cent by decreasing the tooth number in the range of 24 to 0 at Re = 6,000. Moreover, the frictional entropy generation decreases by increasing the tooth number as the gear with more tooth number causes a lower flow disturbance.Originality/valueThe present study arranged a numerical work to study the potential of a gear-ring turbulator in a heat exchanger tube from first and second laws of thermodynamic viewpoint. The turbulent flow is considered for this problem. The literature review showed that the usage of a gear-ring turbulator in a heat exchanger tube is not investigated from the second law of thermodynamic viewpoint by previous studies. As a result, the influences of different parameters containing tooth number, free-space length ratios and Reynolds number on frictional and thermal irreversibilities and Bejan number are discussed.

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Investigation of the convective heat transfer and friction factor of magnetic Ni nanofluids within cylindrical pipes

International Journal of Thermofluid Science and Technology ◽

10.36963/ijtst.2021080101 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

M. Abdelkader ◽

H. Ameur ◽

Y. Menni

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Nusselt Number ◽

Friction Factor ◽

Turbulent Flows ◽

Volume Fraction ◽

Particle Volume Fraction ◽

Constant Heat Flux ◽

Particle Volume ◽

Number Range

The current paper reports the results of numerical research on the magnetic Ni nanofluid flowing in a tube, developing turbulent flows under constant heat flux conditions. The numerical investigations are conducted for a Reynolds number range from 3,000 to 22,000, and a particle concentration range of 0% to 0.6%. The effects of the Reynolds number on the friction factor and Nusselt number are computed and compared satisfactorily with the experimental results of the literature. The classical correlations of Gnielinski, Notter – Rouse, and Pak and Cho are verified by predicting the Nusselt number of the Ni nanofluid. The obtained results revealed an enhancement in the heat transfer with the increase of magnetic Ni particle volume fraction and Reynolds number.

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Numerical simulation of vortex induced vibration in heat exchanger tube bundle at low Reynolds number

Journal of Naval Architecture and Marine Engineering ◽

10.3329/jname.v14i2.25894 ◽

2017 ◽

Vol 14 (2) ◽

pp. 77-91

Author(s):

Asif Khan ◽

Shahab Khushnood ◽

Najum Ul Saqib ◽

Imran Sajid Shahid

Keyword(s):

Reynolds Number ◽

Heat Exchanger ◽

Stokes Equations ◽

Tube Bundle ◽

Lift Coefficient ◽

Flow Analysis ◽

Cross Flow ◽

Heat Exchanger Tube ◽

Number Range ◽

Exchanger Tube

It is sound recognized that when the tube is forced to vibrate or is naturally excited to sufficient amplitudes by flow-induced forces, cyclones peeling phenomena arises at downstream of a tube which clues to vibration in the tube. Two-dimensional numerical recreation model for the computation of flow induced vibration of heat exchanger tube bundle imperiled to cross- flow is proficient in current research. Computational Fluid Dynamics (CFD) tool, GAMBIT (grid generation) and ANSYS FLUENT (fluid flow analysis) are operated during numerical investigations. k-epsilon model is used to solve the Navier Stokes equations. Lift coefficient graph derived from analysis is used to predict the vortex shedding frequency using Fast Fourier Transform (FFT). The results of flow rate, Strouhal number, Reduced velocity, Natural frequency of tube as found from the experimental data has been verified numerically for a Reynolds number range of 4.45 × 104<Re <4.65 × 104 . It is concluded that experimental results are well in agreement with the numerical results.

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Numerical Simulation of Flow-Induced Vibration of Three-Dimensional Elastic Heat Exchanger Tube Bundle Based on Fluid-Structure Coupling

Shock and Vibration ◽

10.1155/2022/8980562 ◽

2022 ◽

Vol 2022 ◽

pp. 1-17

Author(s):

Shiqin Ai ◽

Chao Sun ◽

Yuechan Liu ◽

Yuelin Li

Keyword(s):

Heat Exchanger ◽

Natural Frequencies ◽

Tube Bundle ◽

Three Dimensional ◽

Vibration Characteristics ◽

Heat Exchanger Tube ◽

Flow Induced Vibration ◽

Vibration Displacement ◽

Tube Bundles ◽

Exchanger Tube

The reliability of the heat exchanger tube bundle not only affects the economic efficiency of production but also relates to the normal development of production safety and health. To study the flow-induced vibration of tube bundles, a three-dimensional finite element model of heat exchange tubes and watersheds inside and outside the tubes was established to explore the flow-induced vibration characteristics of tube bundles and analyze the natural frequencies of single-span and multispan heat exchange tubes. Considering the randomness of the effective support between the tube bundle and the support plate of the heat exchanger, the natural frequency and vibration mode of the four-span tube with failure of the tube bundle support are analyzed. On this basis, the vibration caused by the two-way coupling flow between tube and tube outflow is calculated. Finally, the flow-induced vibration characteristics of the five-tube bundle with two different pitch-diameter ratios are analyzed. The calculation results show that the error between the calculated natural frequencies and the theoretical values is less than 3%, and within the allowable error range, the natural frequencies of the same order decrease with the increase of the number of support failures. The vibration frequencies of single-span and multispan tube bundles are consistent with the lift and drag frequencies, the vibration displacement curves show typical Strouhal modes, and the amplitude increases with the increase of fluid velocity. Vibration displacement curves of symmetrical spans of multispan tube bundles are similar in shape and amplitude. With the increase of tube bundle spacing, the vibration characteristics become more obvious.

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