![66
International Journal of Research and Innovation (IJRI)
CONCLUSION
A computational model has been developed to study the
performance of Tree shaped fins for varying geometry, fin
materials and the temperature distribution over the fin is
noted. It was found that the Tree shaped fin of 900
bifur-
cation angles is more effective than 600
bifurcation angled
fin due to the increased surface area. By adding the ma-
terial the surface area of the fin is increased further. So
the 900
tree fin with protrusion gives the better results
than the 900
tree fin without protrusion. By changing the
material the properties of the material gets changes , in
the investigation it was also found that the material with
less thermal conductivity gives the relatively lower base
temperature on the fin.
REFERENCES
[1] A. Aziz, Optimum dimensions of extended surfaces op-
erating in convective environment, Appl.Mech.Rev.45 (5)
(1992)155–173.
[2] A.D. Kraus, Developments in the analysis offinnedar-
rays, Int.J.Transp. Phenom. 1(1999)141–164.
[3] I. Mikk, Convective finofminimum mass, Int.J.Heat
Mass Transfer 23(5) (1980) 707–711.
[4] J. Mao, S.Rooke, Transient analysis of extended sur-
faces with convective tip, Int. CommunHeat Mass Trans-
fer 32(1) (1994)85–94.
[5] K.C. Leong, T.C.Kooi, Natural convection from a ver-
tical rectangular fin,Exp. Heat Transfer 9(4) (1996)287–
303.
[6] P.Razelos, E.Georgiou, Two-dimensional effects and
design criteria for convective extended surfaces, J.Heat
Transfer Eng.13 (3) (1992)36–48.
[7] D’A.W Thompson, OnGrowth and Form, Cambridge
University Press, Cambridge, 1942. [8] B.B. Mandelbrot,
the Fractal Geometry of Nature, Freeman, New York,
1982.
[9] M. Barnsley, Fractals Everywhere, Academic Press,
San Diego, 1988.
[10] C.D. Murray, The physiological principle of minimum
work.I.The vascular system and the cost of blood volume,
J.Physiol.12 (3) (1926)207–214.
[11] D.L. Cohn, Optimal systems: the vascular system,
Bull.Math.Biophys.16 (1954) 59–74. [12] D. Calamas,
J.Baker,Performanceofa biologically-inspired heat ex-
changer with hierarchical bifurcating flowpassages,
J.Thermophys.Heat Transfer 27 (1) (2013)80–90.
[13] H. Van Der Vyver (ValidationofaCFD model of a three-
dimensional tube-in tube heat exchanger),in: Proceedings
of the Third International Conference on CFD in the Min-
erals and Process Industries,Springer,Berlin,2003.
[14] J. Meyer,H.Van Der Vyver, Heat transfer character-
istics of quadratic Koch island fractal heat exchanger,
J.Heat Transfer Eng.26(9)(2005)22–29.
[15] J. Bonjour,L.A.O.Rocha,A.Bejan,F.Meunier,Dendritic
fins optimization for a coaxial two-stream heat exchanger,
Int.J.Heat Mass Transfer 47(1)(2004) 111–124.
[16] D.J. Lee, W.W.Lin, Second law analysis on fractal-like
fin under cross flow, AlChE J. 41(1) (1995)2314–2317.
[17] W.W. Lin, D.J.Lee,Diffusion–convection process in
branching fin, Chem.Eng. Commun. 158 (1) (1997)59–70.
[18] J.L. Plawsly, Transport in branched systems.I:
Steady-state response, Chem. Eng. Commun.123 (1)
(1993)71–86.
Author
K. Prudhvi Ravi Kumar,
Research Scholar,
Department of Thermal Engineering,
Aditya Engineering College, Surampalem,
Andra Pradesh, India.
A .Ravindra ,
Associate Professor,
Department of Mechanical Engineering,
Aditya Engineering College, Surampalem,
Andra Pradesh, India.
V.V.Kamesh
Associate Professor ,
Department of Mechanical Engineering,
Aditya Engineering College, Surampalem,
Andra Pradesh, India.](https://image.slidesharecdn.com/ijri-te-02-006-160413090601/85/STUDY-AND-ANALYSIS-OF-TREE-SHAPED-FINS-BY-USING-FLUENT-6-320.jpg)
STUDY AND ANALYSIS OF TREE SHAPED FINS BY USING FLUENT
- 1. 61 International Journal of Research and Innovation (IJRI) STUDY AND ANALYSIS OF TREE SHAPED FINS BY USING FLUENT K. Prudhvi Ravi Kumar1 , A .Ravindra 2 ,V V Kamesh3 1 Research Scholar,Department of Thermal Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India. 2 Associate Professor,Department of Mechanical Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India. 3 Associate Professor , Department of Mechanical Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India. *Corresponding Author: K.Prudhvi Ravi Kumar Research Scholar, Department of Thermal Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India. Published: December 24, 2015 Review Type: peer reviewed Volume: II, Issue : IV Citation: K. Prudhvi Ravi Kumar, STUDY AND ANALYSIS OF TREE SHAPED FINS BY USING FLUENT INTRODUCTION The rejection of waste heat is vital in the design optimisa- tion of extended surfaces employed by electronic devices, industrial equipment and other mechanical devices. It is often desirable to maximise heat rejection while min- imising the mass and volume of extended surfaces. As convection is directly proportional to the surface area, it is important to maximise surface area while minimising system mass. The use of tree-like fins which are inspired from biology provides the larger surface area. Biological- ly inspired fins provide larger surface area for the same mass, base temperature as compared to traditionally em- ployed fins. Several experiments were investigated on rectangular fin with varying material and base temperature. Finally concluded that maximum heat transfer coefficient was at 22% and 45% of the fin height, when measured from the base. Measurement of temperature was found to be good with one-dimensional solution for convective type fin tips. By changing the bifurcation angle, the cross-sectional area of the fin also changes. Also by adding an extra ma- terial to the tree like fin increases the surface area, there by decreases the base temperature of the fin. BASICS OF HEAT TRANSFER The thermal energy exchange between physical systems depends upon the temperature and pressure by dissipat- ing heat is heat transfer. The modes of heat transfer are of three types 1. Conduction 2. Convection 3. Radiation Conduction An energy transfer across a system due to temperature difference by the mechanism of intermolecular interac- tions. Conduction needs matter and does not require any bulk motion of matter. Fourier Law gives the Conduction Rate: Where: q = heat flow, (W) k = thermal conductivity, (W/m K) A = Cross sectional area (m2) ΔT= Gradient of temperature (K/m) Abstract For increasing the efficiency of the system, extended surfaces like fins are used. The heat transfer rates of different shapes and cross sections like circular, rectangular, T-shaped and Tree shaped fins is compared. As per the data con- sidered from the previous works the heat transfer rate is depending on the surface area and the heat transfer coefficient, the surface area is increasing from circular to tree shaped fins. In this paper temperature distribution of the tree shaped fins is investigated by changing bifurcation angle, adding an extra element and the fin materials. Different cross section of the elements is considered and will be validated. Thermal analysis is enhanced by using Computational Fluid Dynamics ANSYS Workbench 15. Analysis will be done for different working conditions. International Journal of Research and Innovation (IJRI) 1401-1402
- 2. 62 International Journal of Research and Innovation (IJRI) Convection Theenergy transfer across a boundary due to temperature difference is Convection. It is a combined mechanism of intermolecular interactions and bulk transport. Convec- tion requires fluid matter. It is given by Newton’s Law of Cooling: q = h AsΔT Where: q = heat flow from surface, (W) h= heat transfer coefficient (W/m2 K) As = Surface area where convection takes (m2 ) ΔT = Temperature Difference between surface and cool- ant. (K) EXTENDED SURFACE HEAT TRANSFER Convection • Heat transfer between two surfaces will be governed by the Newton’s law of cooling: q = hA (Ts-T∞). Thus to increase the heat transfer rate by convection, •By increasing the temperature difference (Ts-T∞) be- tween the surfaces •By increasing convection coefficient.This is achievable by increasing the fluid flow over the surface. •By increasing the contact area. In general if we cannot vary the temperature difference between the surfaces and if the convection coefficient is already stretched to its limit, then the only alternative will be to increase the effective surface area by using fins or extended surfaces. Fins are extended surfaces from the base into the cooling fluid and in direct contact with the fluid. Most important applications of fins are cooling fins on air-cooled engines, electronic equipment (CPUs), auto- mobile radiators, and air conditioning equipment. Extended Surface Analysis An area Aof the surface is shown in Figure 1 where heat transfers from the surface to the surrounding fluid with a heat transfer coefficientof h. The heat transfer rate can be varied by varying the convection coefficient h, reducing the fluid temperature T∞ and by adding extra material. fins to enhance heat transfer TREE SHAPED FIN Heat transfer rate is directly proportional to the surface area; the base temperature of the fin gets decreases by adding the extra material and by increasing the bifurca- tion angle. Tree shaped fin with bifurcation angles 600 Tree shaped fin without protrusion 600 Tree shaped fin without protrusion by considering the dimensions By changing the values of the bifurcation angle the fin temperature at the fin tip gets decreases. The 600 Tree shaped fin without protrusion. The temperature distribu- tion and thermal analysis on tree shaped fin will be dis- cussed in the next chapter. 900 Tree shaped fin without protrusion
- 3. 63 International Journal of Research and Innovation (IJRI) 600 Tree shaped fin with protrusion 900 Tree shaped fin with protrusion ANSYS WORK BENCH INTRODUCTION: ANSYS Workbench, developed by ANSYS Inc., is a Com- puter Aided Finite element Modeling and Finite Element Analysis tool. In the graphical user Interface (GUI) of ANSYS Workbench, the user can generate 3-dimensional (3D) and FEA models, perform analysis and generate re- sults of analysis. It can perform a variety of tasks rang- ing from Design Assessment to finite Element Analysis to complete product optimization analysis. ANSYS Fluent Fluent is the most powerful computational fluid dynam- ics (CFD) software tool available, empowering you to go further and faster as you optimize your product perfor- mance. Fluent includes well-validated physical modelling capabilities to deliver fast, accurate results across the widest range of CFD and multi-physics applications. Built for Multiphysics Gain deeper insight into the complex, often counterin- tuitive interactions caused by multiple physics such as fluid–structure interaction (FSI). ANSYS Fluent is fully in- tegrated with ANSYS Workbench to provide full two-way interactivity with ANSYS Mechanical, ANSYS Maxwell and other simulation technologies. Solve Complex Models with Confidence ANSYS Fluent can solve your most sophisticated models for multiphase flows, chemical reaction and combustion. Even complicated viscous and turbulent, internal and ex- ternal flows, flow-induced noise predictions, heat transfer with and without radiation can be modelled with ease. Go Faster with High Performance Computing (HPC) With HPC, ANSYS Fluent delivers CFD simulation solu- tions faster so that engineers and designers can make better decisions sooner in the design cycle. While ANSYS HPC provides linear scalability on systems with tens of thousands of processors, there is more to HPC than just the number of cores. ANSYS also optimizes processor ar- chitecture, algorithms for model partitioning, optimized communications and load balancing between processors to deliver results in breathtaking speed on a wide variety of simulation models. Turbulence Modelling ANSYS Fluent software places special emphasis on pro- viding a wide range of turbulence models to capture the effects of turbulence accurately and efficiently. Several in- novative models such as the Menter–Langtry γ–θ laminar– turbulent transition model™ are available only in Fluent. Heat Transfer & Radiation Fluent handles all types of radiative heat exchange in and between fluids and solids, from fully and semi-transpar- ent to radiation, or opaque. You can choose from a variety of spectral models to account for wavelength dependen- cies in a simulation and to account for scattering effects. Multiphase Flow A complete suite of models capture the interplay between multiple fluid phases like gasses and liquids, dispersed particles and droplets, and free surfaces. Reacting Flow Whether simulating combustion design in gas turbines, automotive engines, or coal-fired furnaces, or assessing fire safety in and around buildings and other structures, ANSYS Fluent software provides a rich framework to mod- el chemical reactions and combustion associated with flu- id flow. ANSYS Fluent handles non-premixed, partially- premixed, or premixed combustion models to accurately predict parameters like the flame speed, flame location, and the post-flame temperature. Acoustics ANSYS Fluent computes the noise resulting from un- steady pressure fluctuations to solve acoustical simula- tions. Fluid-Structure Interaction Fluent models the effects of solid motion on fluid flow by coupling with ANSYS structural mechanics solutions through the Workbench unified user environment. Flu- ent users enjoy robust and accurate two-way FSI without the need to purchase, administer or configure third-party coupling and pre- and post-processing software. Optimize Your Design - Automatically •Fluent’s shape optimization tools can automatically ad- just the geometric •Parameters until your optimization goals are met. For example, aerodynamics of a car or aircraft wing and the
- 4. 64 International Journal of Research and Innovation (IJRI) optimized flow rate in nozzles and ducts. •Fluent’s ground-breaking ad joint solver modifies the mesh from within to see the effect of a recommended change. The ad joint solver provides recommendations to improve geometries that are difficult and expensive to get any other way PROCEDURE FOR TREE SHAPED FIN ANALYSIS Select models >Viscous-laminar > K-€ (2 eqn) Select materials > Fluid >air RESULTS AND DISSCUSION The dimensional computational model has been devel- oped in commercially available computational fluid dy- namics. In fluid dynamics, analysis is carried out by fi- nate volume method. 600 Tree shaped fin without protrusion Static Temperature contour for 600 Fin without protrusion Contours of wall temperature (K) Contours of Enthalpy 900 Tree shaped fin without protrusion Static Temperature contour for 900 Fin without protrusion
- 5. 65 International Journal of Research and Innovation (IJRI) Contours of wall temperature (K) Contours of Enthalpy 600 Tree shaped fin with protrusion Static Temperature contour for 600 Fin with protrusion 900 Tree shaped fin with protrusion Contours of wall temperature (K) COMPARISION OF RESULTS Comparison of Tree shaped fin geometry 600 Fin without protrusion Fin temperature drops from 600k to 483K 900 Fin without protrusion Fin temperature drops from 600k to 483K 600 Fin with protrusion Fin temperature drops from 600k to 477K 900 Fin with protrusion
- 6. 66 International Journal of Research and Innovation (IJRI) CONCLUSION A computational model has been developed to study the performance of Tree shaped fins for varying geometry, fin materials and the temperature distribution over the fin is noted. It was found that the Tree shaped fin of 900 bifur- cation angles is more effective than 600 bifurcation angled fin due to the increased surface area. By adding the ma- terial the surface area of the fin is increased further. So the 900 tree fin with protrusion gives the better results than the 900 tree fin without protrusion. By changing the material the properties of the material gets changes , in the investigation it was also found that the material with less thermal conductivity gives the relatively lower base temperature on the fin. REFERENCES [1] A. Aziz, Optimum dimensions of extended surfaces op- erating in convective environment, Appl.Mech.Rev.45 (5) (1992)155–173. [2] A.D. Kraus, Developments in the analysis offinnedar- rays, Int.J.Transp. Phenom. 1(1999)141–164. [3] I. Mikk, Convective finofminimum mass, Int.J.Heat Mass Transfer 23(5) (1980) 707–711. [4] J. Mao, S.Rooke, Transient analysis of extended sur- faces with convective tip, Int. CommunHeat Mass Trans- fer 32(1) (1994)85–94. [5] K.C. Leong, T.C.Kooi, Natural convection from a ver- tical rectangular fin,Exp. Heat Transfer 9(4) (1996)287– 303. [6] P.Razelos, E.Georgiou, Two-dimensional effects and design criteria for convective extended surfaces, J.Heat Transfer Eng.13 (3) (1992)36–48. [7] D’A.W Thompson, OnGrowth and Form, Cambridge University Press, Cambridge, 1942. [8] B.B. Mandelbrot, the Fractal Geometry of Nature, Freeman, New York, 1982. [9] M. Barnsley, Fractals Everywhere, Academic Press, San Diego, 1988. [10] C.D. Murray, The physiological principle of minimum work.I.The vascular system and the cost of blood volume, J.Physiol.12 (3) (1926)207–214. [11] D.L. Cohn, Optimal systems: the vascular system, Bull.Math.Biophys.16 (1954) 59–74. [12] D. Calamas, J.Baker,Performanceofa biologically-inspired heat ex- changer with hierarchical bifurcating flowpassages, J.Thermophys.Heat Transfer 27 (1) (2013)80–90. [13] H. Van Der Vyver (ValidationofaCFD model of a three- dimensional tube-in tube heat exchanger),in: Proceedings of the Third International Conference on CFD in the Min- erals and Process Industries,Springer,Berlin,2003. [14] J. Meyer,H.Van Der Vyver, Heat transfer character- istics of quadratic Koch island fractal heat exchanger, J.Heat Transfer Eng.26(9)(2005)22–29. [15] J. Bonjour,L.A.O.Rocha,A.Bejan,F.Meunier,Dendritic fins optimization for a coaxial two-stream heat exchanger, Int.J.Heat Mass Transfer 47(1)(2004) 111–124. [16] D.J. Lee, W.W.Lin, Second law analysis on fractal-like fin under cross flow, AlChE J. 41(1) (1995)2314–2317. [17] W.W. Lin, D.J.Lee,Diffusion–convection process in branching fin, Chem.Eng. Commun. 158 (1) (1997)59–70. [18] J.L. Plawsly, Transport in branched systems.I: Steady-state response, Chem. Eng. Commun.123 (1) (1993)71–86. Author K. Prudhvi Ravi Kumar, Research Scholar, Department of Thermal Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India. A .Ravindra , Associate Professor, Department of Mechanical Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India. V.V.Kamesh Associate Professor , Department of Mechanical Engineering, Aditya Engineering College, Surampalem, Andra Pradesh, India.