IJSRD - International Journal for Scientific Research & Development Vol. 3, Issue 10, 2015 ISSN (online):

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1 IJSRD - Iteratioal Joural for Scietific Research & Developmet Vol. 3, Issue 10, 2015 ISSN (olie): CFD Aalysis of Ehacemet of the Forced Covectio Heat Trasfer over The Pi Fi with Trapezoidal Fi Ad Flow Structure Aalysis, usig Gaurav Kumar Gupta 1 Auraj Kulshrestha 2 Abhishek Arya 3 1,2,3 Scope College of Egieerig Bhopal/ R.G.P.V. Bhopal Abstract The proposed work is cocered with the aalysis of the improved heat trasfer by forced covectio o the pi fi with trapezoidal fi ad aalysis of the structure of flows i a CFD. This workig research thermal performace of the circular pi fi. The value of heat trasfer coefficiet obtaied for the surface of Nusselt umber of the pressure drop of the study, the heat resistace ad the pressure drop of the heat to the circular pi fi heat dissipatig fis trapezoidal fi iformatio at differet velocityes i differet heights is to examie the effect of a pi fi desig.thermal resistace, pressure drop, ad structure of the Nusselt umber are compared with experimetal results ad the simulatio results.parameters such as the geometry of the fi plate ad the pi height ad umber of the fi of the fis of the fi base height is regarded, i particular, the shape of the heat sik. the thermal model of the computer system with various fi heat sik desig of the geometry has bee selected ad the characteristics of the heat sik thermal fluid flow stream were studied. The pi fi plate ad trapezoidal heat siks of the fi geometry were used with base plate to improve heat dissipatio. Some features formed i a ifiite variety of geometries resultig i differet heat trasfer characteristics. The objective of the preset work is to fid the heat trasfer rate ad distributio of the airflow o surfaces istalled pi fis with differet parameters (height, speed) ad all results will be compared with each other. Key words: microchip Electroics, Computatioal Fluid Dyamics, Pi-ed heat sik, trapezoidal fi I. INTRODUCTION The most commo method for the trasfer of heat from the eviromet is to use a heat sik member. Estimate the juctio temperature of a compoet, is the value of the desired heat sik thermal resistace. The thermal resistace of the heat sik ca be determied by aalysis or experimet. I electroic systems, a heat sik is a passive elemet. I the computer, the heat sik for coolig the electroic compoets. Heat Siks for high-performace semi-coductors, such as power trasistors ad optoelectroic devices such as lasers ad light emittig diodes (LED), wherei the heat capacity of the etire device base isufficiet to regulate the temperature. Heat sik is coolig system. it is always lookig for ew techologies that improve the thermal performace without cost pealties. Heat dissipatio characteristics that icorporate the results of breakthroughs thermal re-research ad maufacturig are sought as ew product offerigs. pi fi heat sik is of iterest ad should be ivestigated. A isometric model is developed to ivestigate the heat trasfer rate ad the combied heat sik for ay item as electroic device. A series of umerical calculatios have bee carried out i commo ad the results are show i order to represet the effects of the temperature distributio, overall coefficiet of heat trasfer, ad thermal resistace surface Nusselt umber i the heat siks. II. OBJECTIVES OF THE WORK I this study, the fi pi arragemet is made to aalyze the effect o the trasfer of heat from outer surface without pi ad pi with circular fis with trapezoidal fi at differet velocity with differet dimesios of the pi fi is cosidered with the followig objectives. to obtai the uderstadig the flow structure. heat trasfer met i a heat sik pi-fi of a circular pi fis mouted o the trapezoidal surface fis. To study the performace of pi fis at differet air velocities. I order to study the performace of the circular pified by varyig the geometric size (diameter ad height) ad positio of pi fis. To reduce the material used to optimize the structure to dissipate heat maximum. To compare the potetial of ehacig a circular pi fis with ad without Pi fis ad fidig the reduced heat trasfer rates to differet air velocities. III. CONDUCTION IN THE PLANE WALL The heat trasfers through a wall of a coductio problem a dimesio where the temperature is a fuctio of the distace from oe of the wall surfaces. It is assumed that the rest of the wall surfaces are at a costat temperature. The heat trasfer from the surfaces of the wall is effected by covectio with ambiet air, causig them to have regular state of the temperatures of T 1 ad T 2 o their surfaces. Let assume that the fluid side of the wall with temperature T 1 is at T1 ad has a heat trasfer coefficiet h 1, ad that o the side of the wall with temperature T 2 is at T2 with heat trasfer coefficiet h 2, ad that T1. The hypothesis implies that h1 h2. Sice the surface does ot store ay heat eergy, all the eergy of heat, all the heat of the hot surface is formed to the coolig surface. eergy coservatio requires. for a body that geerates o heat or o heat stores. By applyig the same to the case 1 -D with the directio of the x axis perpedicular to the surface of the wall is obtaied O solvig ad puttig the appropriate boudary coditios, (At x=0, T = T 1 ad at x=l, T = T 2 ) we get a liear variatio for T withi the wall thickess. It is distributed withi the wall ad the temperature of varies liearly that the distace of the surface of a liear All rights reserved by 551

2 equatio chages sigificatly. Sice we have a chage of temperature, the thermal coductivity ca be calculated from the Fourier method. dt k q" S k A ( T 1 T2 ) dx L it ca be see from the above equatio, the heat flus is idepedet X is a costat. This example illustrates the stadard method of solvig a problem of coductio. First, the temperature profile with i the body is by usig the eergy coservatio equatio ad the temperature equatio is used to solve for the heat flux by pluggig it ito the right of the Fourier equatio IV. GOVERNING EQUATION Fig. 1: Goverig Equatio Time-Idepedet flow equatio of with the turbulece is resolved. the equatios goverig CFD used to mathematically solve for fluid flow ad heat trasfer therefore, the equatio goverig the flow of fluid ad heat trasfer are the followig form of the icompressible cotiuity equatio, the three-dimesioal Navier-Stokes turbulece ad eergy equatio are solved umerically (usig a scheme of fiite-differeces) combied with the cotiuity equatio to simulate the flow field eddy viscosity model.a heat ad turbulet is used to accout for turbulece effects of.the flow is assumed to be stable. Icompressible, ad i three dimesios. The heat trasfer effect ad buoyacy radiatio are eglected. The schematic diagram of the geometry ad of the computatioal domai is show i Fig. Ad these equatios to be solved through software fluet. The equatio goverig three-dimesioal mass mometum of the turbulet kietic eergy. A. Law Of Coservatio Of Mass B. Mometum equatio 1) X-mometum 2) Y-mometum 3) Z-Mometum 4) Eergy Equatio 5) Equatio Of state P= C. Computatioal Domai ad Boudary Coditios For The System The mathematical simulatio of the fied heat trasfer pi system ad the umerical simulatio of the udersized pi fi system, depedig o the dimesios of the pi fi heat sik, is studied usig a (CFD) computatioal fluid dyamics techique. Aalysis of the circular pi fi CFD aalysis based o the maximum rate of heat trasfer. V. MODELING AND ANALYSIS Modelig software Creo Parametric 1.0 creates geometry ad the geometry is imported to the established Asys 15.0, where the mesh is made ad exports Fluet mesh. The Boudary coditios, material properties, ad surroudig property is defied by the fluet file. Fixed a problem with the software to achieve the covergece limit is the umber specified by the user to be implemeted to achieve the iteratios The procedure to solve the problem is: 1) Create geometry. 2) Mesh the domai. 3) Defie the material properties ad boudary coditios. 4) Obtaiig the solutio A. Geometry Parameters of Heat Sik Fi No. N Fi height. H(mm) Fi Legth L. (mm) Fi thickess t. (mm) 1 to 0.8 as described i followig cases Table 1: Geometry Parameters of Heat Sik Fi-to-fi distace,ξ(mm) 12.5 Ca se Height of pi fi (10 mm) Velocity i (m/s) Velocity Base Temp. (K) Temp Differece. (k) Thermal Resistivity (K/W) Pressure Differe ce(pa) by e by U Nu All rights reserved by 552

3 e by e by e by e by e by e by e by e e 3 cases Height of pi fi(10 mm) 1to 3 Velocity i (m/s) 6.5,9.5 ad 12.5 Iitial Temp.(K) 300 VI. MODELLING AND ANALYSIS Table. 2: Dimesios of Circular Pi Fi Base Temp.(K) We have take 9 cases to show vary with height of pi fi. Ad fid out results from asys software R like Thermal Resistivity, Nusselt Number, Pressure drop with respect to air Velocity. Temp Differece.(k) Table 3: Theoretical Aalysis Table Thermal Resistivity(K/W) R= Pressure Differece (pa) P U Nu H= Nu= Fig. 4: (e 3) 3D Model Of Circular Pi Of 4mm Dia Trapezoidal Fi Of Height 2 By 3 (10 Mm ) Heat Sik Fig. 2: (e 1) 3D Model Of Circular Pi Of 4mm Dia Trapezoidal Fi Of Height 1 By 3 (10 Mm ) Heat Sik VII. MESHING OF THE DOMAIN Experimetal i the solid Para size ( :.x-t ) to the ANSYS 15.0 Workbech modular desig. The, defie the field of air ad the solid area. It for further processig. Defiitio of the mesh to the domai. The secod part of pre-processig is the mesh geeratio. After the model is imported to Asys Workbech 15.0 R, the it is lauched i the mesh module for the bulk of the mesh geeratio, medium, ad fie mesh types are available. Here, we chose the relevat ceter ad high fie mesh smoothig. CFD ad physical preferece. Mesh is the key elemet of a high quality solutio. There are three types of mesh algorithms. These are. 1) Hexahedral Cartesia 2) Hexahedral Ustructured 3) Tetrahedral mashers. Fig. 3: (e 2 ) 3D Model Of Circular Pi Of 4mm Dia Trapezoidal Fi Of Height 1 By 2 (10 Mm ) Heat Sik All rights reserved by 553

4 Table 4: Thermal Resistace The graph represets the relatio betwee the thermal resistace ad velocity of ie the cases, the lies shows the geometrical variatio we have take for the study. Series 1 is the validatio case it is plae fi, All the above geometrical variatio are compared the experimetal data. The miimum value of the Thermal resistace is 0.64.ad pi height 2 by 3 ad air velocity is Fig. 5: (e 1) Mesh Of Circular Fi Pi Heat Sik Model A. Steps i CFD Calculatio CFD umerical algorithms ca solve the problem code i the fluid. To facilitate access to their ow power to solve all the commercial CFD software, icludig the iput parameters of the problem, the complexity of the user iterface ad check the results. Therefore, all the code is composed of three mai factors: the CFD calculatios, there are three mai steps 1) Pre- treatmet 2) Resolutio 3) The post-processig. B. Solvig the CFD Problem The compoet that aalysis ad work the problem is called the CFD solver. It produces the required results i a oiteractive / batch process. A CFD problem is solved as follows. 1) The partial differetial equatios are itegrated over all cotrol volumes i the regio of iterest. This is equivalet to applyig a fudametal law of coservatio (for example, for mass or mometum) for each cotrol volume. 2) These itegral equatios are coverted ito a system of algebraic equatios by geeratig a set of approximatios for the terms i the itegral equatios. 3) The algebraic equatios are solved iteratively. A. Thermal Resistace Wid Velocit y (m/s) Fig. 6: Solvig The CFD Problem VIII. OBSERVATION TABLE Experimeta l Result(1) Results(2) Results(3) Results Table 4: Experimetal (1), (2) Ad (3), Result For The Plate Fi Heat Sik Fig. 6: Graph.1: Air Velocity-Thermal Resistace Pi fi height 10 mm Air velocity 1 by 3 1 by 2 2 by Fig. 7: Graph.2: Thermal Resistace ad Air Velocity B. Pressure Drop Wid Velocit y (m/s) Experimeta l Result(1) Results(2) Results(3) Results Table 5: Experimetal (1), (2) Ad (3), Result For The Plate Fi Heat Sik All rights reserved by 554

5 higher tha (case o 9) but thermal resistace is 0.76 i place of Fig. 8: Graph.3: Pressure drop ad differet air velocity C. Nusselt Number Wid Velocit y (m/s) Experime tal Result(1) Simulati o Results(2 ) Simulati o Results(3 ) Simulati o Results Table. 6: Experimetal (1), (2) Ad (3), Result For The Plate Fi Heat Sik Fig. 9: Graph.4: Nussail umber ad differet air velocity IX. CONCLUSION As we have realized i the results above thermal resistivity, Nusselts umber, the heat trasfer coefficiet, pressure drop, we are here to coclude that the maximum pressure drop is (e No. 9) Pascal ad the miimum pressure drop that is Pascal (case 1), ad as we saw with the maximum thermal resistace is i (case o 1) ad the miimum thermal resistace of to (e No. 9). Also oe of our cocetratio by Nusselt umber, the maximum value of Nusselt umber i (case 3).ad Nusselt Mi value ot i 1,655,456 (case o 1).Similarly Max. value of the heat trasfer coefficiet is (case o 3) ad a miimum heat trasfer coefficiet i (e o 1). This discussio will lead us to uderstad the best combiatio of fi arragemet. Most values i our favor arrives (case 3). That is Pi height 1 by 3 at 12.5 m/s velocity with small cosideratio of Pressure drop 50 Pascal X. REFERENCES [1] [2] [3] mr. Yue-Tzu Yag-2009 INVESTIGATION OF PLANTED PIN FINS FOR HEAT TRANSFER ENHANCEMENT IN PLATE FIN HEAT SINK Elsevier Ltd, (2009) Elsevier Ltd [4] mr. Irfa Vohra1, Mohammad Azim Aijaz, Dr. B. B. Saxea CFD ANALYSIS OF CYLINDRICAL PIN WITH TRAPEZOIDAL FIN HEAT SINK USING ANSYS FLUENT 14.0 Iteratioal Joural of Emergig Techology ad Advaced Egieerig Volume 4, Issue 5, May 2014 [5] yue-tzu yag, Hau-se peg-2009 NUMERICAL STUDY OF THE HEAT SINK WITH UN-UNIFORM FIN WIDTH DESIGN Elsevier Ltd, (2009) Elsevier Ltd [6] R.Moha ad Dr. P. Govidaraja-2010 THERMAL ANALYSIS OF CPU WITH COMPOSITE PIN FIN HEAT SINKS Iteratioal Joural of Egieerig Sciece ad Techology Vol. 2(9), 2010, [7] Amol B. Dhume, Hemat S. Farkade-2013 HEAT TRANSFER ANALYSIS OF CYLINDRICAL PERFORATED FINS IN STAGGERED ARRANGEMENT Iteratioal Joural of Iovative Techology ad Explorig Egieerig (IJITEE) ISSN: , Volume-2, Issue-5, April [8] B.Sri Aravidh Dr.T.R.Gopalakrisha Nair-2008 HEAT SINK PERFORMANCE ANALYSIS THROUGH NUMERICAL TECHNIQUE IEEE Symposium (NSSP08), Bagalore, 2008 [9] Bill L. Schmidt Christopher L. Chapma, ad Seri Lee- Thermal Performace Of A Elliptical Pi Fi Heat Sik [10] Sukhvider Kag Aavid Thermalloy NH Maurice Holaha-2003 THE THERMAL RESISTANCE OF PIN FIN HEAT SINKS IN TRANSVERSE FLOW Iteratioal Electroic Packagig Techical Coferece ad Exhibitio, iter Pack [11] W. A. Kha, J. R. Culham, ad M. M. Yovaovich OPTIMIZATION OF PIN-FIN HEAT SINKS USING ENTROPY GENERATION MINIMIZATION Microelectroics Heat Trasfer Laboratory Departmet of Mechaical Egieerig. [12] Yoav Peles, Ali Kos_ar, Chada Mishra, Chih-Jug Kuo, Brado Scheider-2005 FORCED CONVECTIVE HEAT TRANSFER ACROSS A PIN FIN MICRO HEAT SINK Elsevier Ltd,Iteratioal Joural of Heat ad Mass Trasfer 48 (2005) [13] A Diai, S Maci, C Zilio1 ad L Rossetto EXPERIMENTAL AND NUMERICAL ANALYSES OF DIFFERENT EXTENDED SURFACES departmet of Igegeria Idustriale, uiversity of Padova, via Veezia 1, [14] Michael E. Lyall-2006 HEAT TRANSFER FROM LOW ASPECT RATIO PIN FINS All rights reserved by 555

6 [15] Abel M. Siu-Ho, Weili Qu-2006 PRESSURE DROP AND HEAT TRANSFER IN A SINGLE-PHASE MICRO-PIN-FIN HEAT SINK 2006 ASME Iteratioal Mechaical Egieerig Cogress ad Expositio, IMECE [16] Seri Lee 1995 OPTIMUM DESIGN AND SELECTION OF HEAT SINKS ieee-1995 [17] S. Ragadiesh, M. Rajasekar, S. Arukumar ad M. Vekatesa,-2014 EXPERIMENTAL AND NUMERICAL ANALYSIS ON HEAT TRANSFER CHARACTERISTICS OF SHOE BRUSH-SHAPED FINS SCIENCE, VOL. 106, NO , 25 MAY 2014 All rights reserved by 556