scholarly journals KARAKTERISTIK TERMAL HIDRODINAMIK UNTUK ALIRAN LAMINAR DAN TURBULEN DI DALAM PIPA DENGAN BERBAGAI BENTUK SISIPAN PLAT BERGALUR

ROTASI ◽  
2015 ◽  
Vol 17 (4) ◽  
pp. 182
Author(s):  
Syaiful Syaiful ◽  
Faza Dzulhimam
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Three Dimensional ◽  
Working Fluid ◽  
Hydrodynamic Characteristics ◽  
Transfer Enhancement ◽  
Three Dimensional Flow ◽  
Laminar And Turbulent Flow ◽  
Heat Transfer Improvement

The purpose of this study is to investigate the thermal and hydrodynamic characteristics of air flowing in tubes with various inserts of grooved plate. Inserts of grooved plate with a variety of attack angles (a = 0°, 45° and 90°) has been studied in laminar and turbulent flow. Plate inserts are installed inside the tube intended to improve the heat transfer due to the mixing of the fluid. Numerical simulation of three-dimensional flow set as a model in the direction of fluid flow. The working fluid in the tube is cold, whereas hot wall temperature is kept constant. The results showed that the grooved plate inserts increases the heat transfer in the tube. For laminar flow, the highest heat transfer enhancement is obtained at the grooved plate inserts α = 45° i.e. from 4.46 to 20.34% with an increase in friction factor of 172.19 to 204.36%. As for the turbulent flow, the highest heat transfer improvement is found in a grooved plate inserts with α = 45° i.e. from 38.67 to 56.1% with an increase in friction factor of 183.5 to 262.29%.

Experimental Investigations on Heat Transfer Enhancement in a Horizontal Tube Using Converging and Diverging Conical Strip Inserts

2014 ◽  
Vol 592-594 ◽  
pp. 1590-1595 ◽  
Author(s):  
Naga Sarada Somanchi ◽  
Sri Rama R. Devi ◽  
Ravi Gugulothu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Turbulent Flow ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
Working Fluid ◽  
Experimental Investigations ◽  
Transfer Enhancement ◽  
Enhancement Of Heat Transfer

The present work deals with the results of the experimental investigations carried out on augmentation of turbulent flow heat transfer in a horizontal circular tube by means of tube inserts, with air as working fluid. Experiments were carried out initially for the plain tube (without tube inserts). The Nusselt number and friction factor obtained experimentally were validated against those obtained from theoretical correlations. Secondly experimental investigations using three kinds of tube inserts namely Rectangular bar with diverging conical strips, Rectangular bar with converging conical strips, Rectangular bar with alternate converging diverging conical strips were carried out to estimate the enhancement of heat transfer rate for air in the presence of inserts. The Reynolds number ranged from 8000 to 19000. In the presence of inserts, Nusselt number and pressure drop increased, overall enhancement ratio is calculated to determine the optimum geometry of the tube insert. Based on experimental investigations, it is observed that, the enhancement of heat transfer using Rectangular bar with converging and diverging conical strips is more effective compared to other inserts. Key words: Heat transfer, enhancement, turbulent flow, conical strip inserts, friction factor, pressure drop.

FORCED CONVECTION BASED HEAT TRANSFER ANALYSIS OF SPHERICAL DIMPLE AND PROTRUSION SURFACE IN TURBULENT FLOW

2017 ◽  
Vol 41 (5) ◽  
pp. 771-786 ◽  
Author(s):  
Ashif Perwez ◽  
Shreyak Shende ◽  
Rakesh Kumar
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Vortex Flow ◽  
Rectangular Channel ◽  
Heat Transfer Analysis ◽  
Flow Structures ◽  
Transfer Enhancement ◽  
Heat Transfer Augmentation ◽  
Thermal Boundary Conditions

An experimental and numerical investigation is performed to study the effect of dimple and protrusion geometry on the heat transfer enhancement and the friction factor of surfaces with dimples and protrusions subjected to turbulent flow. The parameters used to compare the spherical dimples and protrusions are Nusselt Number, friction factor, and flow pattern. These parameters are obtained for a Reynolds number of 10500-60900. The spherical dimple results showed the greater heat transfer, which is about 6.97% higher and pressure loss which is 5.07% lower than the spherical protrusion. The realistic heat transfer augmentation capabilities of channels with dimples and protrusions can be studied from the experimental results. The comparison is made with respect to the smooth rectangular channel under the same flow and thermal boundary conditions. The numerical analysis is performed which shows the different vortex flow structures of the spherical dimples and protrusions channel.

Prandtl Number Influence on Heat Transfer Enhancement in Turbulent Flow of Water at Low Temperatures

1995 ◽  
Vol 117 (2) ◽  
pp. 276-282 ◽  
Author(s):  
T. S. Ravigururajan ◽  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Working Fluid ◽  
Enhanced Tubes ◽  
Influence Of Temperature On ◽  
Overall Performance ◽  
Prandtl Numbers ◽  
Application Specific

The paper presents the results of an experimental study that was carried out to determine the Prandtl number influence on the thermal-hydraulic performance of enhanced tubes. The enhanced tubes were identical in all aspects, except the roughness height. Emphasis was placed on turbulent flow, with water as the working fluid. Experiments were performed for Prandtl numbers from 10.2 to 5.8. Data for friction factor were obtained under both isothermal and heating conditions. The study confirmed the strong influence of rib roughness on heat transfer and pressure drop increase. In addition, the results of the investigation strongly suggest that the optimum roughness is application specific, because it is dependent on Reynolds and Prandtl numbers. The results show that the presence of entrance effects and the influence of temperature on the friction factor of enhanced tubes may be significant. The experiments show that a rib height-to-diameter ratio of 0.02 provides the best overall performance for water at Pr = 10; while at Pr = 6.0, the optimum e/d depends on the Reynolds number.

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.

Heat and Mass Transfer in 3D Non-Newtonian Nano and Ferro Fluids over a Bidirectional Stretching Surface

2015 ◽  
Vol 21 ◽  
pp. 33-51 ◽  
Author(s):  
Chakravarthula S.K. Raju ◽  
Naramgari Sandeep
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Friction Factor ◽  
Heat Transfer Performance ◽  
Three Dimensional ◽  
Transfer Performance ◽  
Stretching Surface ◽  
Three Dimensional Flow ◽  
Source Sink ◽  
Bidirectional Stretching

An analysis has been carried out for three-dimensional flow of magneto hydrodynamic Sisko ferro and nanofluids over a bidirectional stretching surface in porous medium with non-uniform heat source/sink. The set of nonlinear governing partial differential equations are transformed in to ordinary differential equations by using self-suitable transformations, and solved numerically using Runge-Kutta and Newton’s methods. The acquired results presents the effects of various non-dimensional governing parameters on velocity and temperature profiles. Also, determined and analyzed the friction factor coefficients and local Nusselt number. We have presented dual solutions for Sisko ferro and nanofluid cases. An excellent agreement of the present results has been found with existed literature under some special limited cases. Results depict that the material parameter have tendency to boost the friction factor coefficients along with the heat transfer rate. It is also observed that the heat transfer performance of Sisko nanofluid is high while compared with the heat transfer performance of the Sisko ferro fluid.

scholarly journals Two-way fluid-structure interaction study of twisted tape insert in a circular tube having integral fins with nanofluid

2021 ◽  
Vol 3 (8(111)) ◽  
pp. 25-34
Author(s):  
Mustafa Abdulsalam Mustafa ◽  
Atheer Raheem Abdullah ◽  
Wajeeh Kamal Hasan ◽  
Laith J. Habeeb ◽  
Maadh Fawzi Nassar
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Heat Transfer Enhancement ◽  
Circular Tube ◽  
Fluid Structure Interaction ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Laminar And Turbulent Flow

This work deals with fluid-structure interaction (FSI), one of the emerging areas of numerical simulation and calculation. This research shows a numerical study investigating heat transfer enhancement and fluid-structure interaction in a circular finned tube by using alumina nanofluid as a working fluid with a typical twisted tape that has a twisting ratio of 1.85. The studied nanofluid volumes of fraction are φ=0, 3, 5 % under conditions of laminar and turbulent flow. The solution for such problems is based on the relations of continuum mechanics and is mostly done with numerical methods. FSI occurs when the flow of fluid influences the properties of a structure or vice versa. It is a computational challenge to deal with such problems due to complexity in defining the geometries, nature of the interaction between a fluid and solid, intricate physics of fluids and requirements of computational resources. CFD investigations were made based on the numerical finite volume techniques to solve the governing three-dimensional partial differential equations to get the influence of inserted twisted tape and concentration of nanofluid on heat transfer enhancement, friction loss, average Nusselt number, velocity profile, thermal performance factor characteristics, and two-way interaction in a circular tube at laminar and turbulent flow. The governing continuity, momentum and energy transfer equations are solved using Ansys Fluent and Transient Structural. The simulation results show that the deformations of two-way coupling fluctuate from side to side, with 0.004 mm, as maximum amplitude, located at the typical twisted tape center. Heat transfer dissipation improved by adding fins and as Reynolds numbers increase the heat transfer behavior increases.

On Fields Synergism and Convective Heat Transfer Enhancement and Control in Centrifugal Force Field

2004 ◽  
Author(s):  
Honghu Ji
Keyword(s):  
Heat Transfer ◽  
Centrifugal Force ◽  
Three Dimensional ◽  
Mathematical Expression ◽  
Cavity Flows ◽  
Transfer Enhancement ◽  
Three Dimensional Flow ◽  
Temperature And Pressure ◽  
Dot Product ◽  
And Control

In this article the mathematical expression of field synergy theory for three-dimensional flow with centrifugal force was derived by integrating the energy equation in the concerned volume. This expression contains the terms of dot product of velocity vector U and temperature gradient ∇T, and the dot product of U and the pressure gradient ∇P. This means that heat transfer is not only related to the magnitude of U, ∇T and ∇P, but also related to their directions. To augment and control heat transfer, the effort is directed to understand the synergetic relation among the fields of velocity, temperature and pressure. Theoretical analysis shows that the patterns of these fields can be adjusted by means of changing the boundary condition of inlet and outlet of the system. This method was verified by numerically calculation of three disk cavity flows.

Investigation of Turbulent Flow and Heat Transfer in Periodic Wavy Channel of Internally Finned Tube With Blocked Core Tube

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Qiu-Wang Wang ◽  
Mei Lin ◽  
Min Zeng ◽  
Lin Tian
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Wave Height ◽  
Three Dimensional ◽  
Finned Tube ◽  
Diameter Ratio ◽  
Hydraulic Diameter ◽  
Core Tube ◽  
Flow And Heat Transfer

Three-dimensional complex turbulent flow and heat transfer of internally longitudinally finned tube with blocked core tube and streamwise wavy fin are numerically investigated. The numerical method is validated by comparing the calculated results with corresponding experimental data. The effects of both wave height and wave distance on heat transfer performance are examined. The range of wave height to hydraulic diameter ratio is from 0.61 to 2.45, and that of wave distance to hydraulic diameter ratio is from 3.06 to 14.69, while that of Reynolds number is from 904 to 4520. The computational results demonstrate that the Nusselt number and friction factor increase with the increase of the wave height, while they decrease with the increase of the wave distance. Furthermore, general correlations are proposed to describe the performance of the wavy configuration for 904⩽Re⩽4520, 0.61⩽s∕de⩽2.45, 6.12⩽l∕de⩽11.02, with the mean deviations for heat transfer and friction factor correlations being −2.8% and −1.9%, respectively.

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