Heat Transfer Enhancement from Heat Sinks using Perforated Fins: A Review

Heat Transfer Enhancement from Heat Sinks using Perforated Fins: A Review A A Kanaskar V M Kriplani PV Walke Student, MTech Professor, Professor, (Heat Power Engineering) Mechanical Engineering Dept Mechanical Engineering Dept GH Raisoni College of Engineering GH Raisoni College of Engineering GH Raisoni College of Engineering Nagpur-16, Maharashtra, India Nagpur-16, Maharashtra, India Nagpur-16, Maharashtra, India Abstract - The present review paper contribute the experimental analysis of the heat transfer growth and the respective pressure drop below a flat surface embedded with ring shaped or circular square perforated fins in a rectangular manner Extended surfaces (fins) are frequently used as heat exchange appliances to enhance the heat transfer between the primary surface and surrounding liquid Fins are extensively usage as heat exchange appliances The fins are widely usage for various industrial applications Other modes of fins are rectangular, rounded, narrowing, ring shaped pin fins or mixture of other geometries has been used Gas turbines of the blades, electronic cooling, and aerospace application are the few application of short fins Long fins have applications where attainment of high heat transfer is major concerned Fins provide large total surface area without the use of a large primary surface area Keywords: Perforated fins, Fin performance, Thermal performance I INTRODUCTION The augmentation of the heat transfer is very essential to thermal engineering The heat transfer from the surface may in general be enhanced by rising the heat transfer between a surface and its surrounding by rising the heat transfer area of the surface Rectangular fins, square fins and rounded fins are used for both natural and forced convection of heat transfer Other modes of heat exchanging fins, ranging from similarly shapes, like orthogonal, ring shaped, cylindrical, narrowing or pin fins, to a mixture of other geometries have been used In engineering applications, heat generation can cause overheating, cooling electronic equipment, heating and cooling in evaporator, radiator in vehicles, refrigerator, gas turbine blade, as well as aerospace industry efficient surface area They normally use geometrical changes to the flow channel by compilation inserts or extra appliances They promote higher coefficient of heat transfer by interrupting or to changing the existent flow behavior except for extended surfaces Heat transfer enhances by this method can be accomplished by using these surfaces are treated, rough, and swirl flow like techniques Following are generally used in passive heat transfer augmentation tools a) Ribs b) fins c) pits d) coils of the wire C Compound techniques: Compound technique is a hybrid technique in which both active as well as passive techniques are used in combination The compound technique needs composite design II REVIEW OF WORK CARRIED OUT Bayram Sahin, Alparslan Demir [1]carried out the performance of heat transfer Augmentation with related pressure drop through a rectangular channel with circular fins attached to a flat surface Reynolds number ranges are selected for this experiment 13500 42,000 They defined the clearance ratio of space above fins to the height of fin in rectangular channel They found that average Nusselt number and friction factor enhanced with reducing clearance ratio and interfin spacing ratio Rise of the efficiencies varied at middle 11 and 19 reliant for both the ratio Various methods of heat transfer augmentation A Active method This system needs external power to the growing of the heat transfer There are various specimens of active techniques are that which produces effect pulsating by cams, reciprocating pump-piston etc B Passive method These techniques do not need any external power Fins are specimen of passive techniques that are popularly used in variety of industrial usage to augment the rate of heat transfer centrally initial surface and ambient liquid Convective heat transfer increases the heat transfer rate as to increase the Fig1 Experimental set up (1) 726 wwwijaegtcom

Ahmad Khoshnevis et al [2] carried out the study of the outcome of lateral surface perforation on heat transfer intensification of a 3-D channel with a ground attached heater Hole and slot were two types of perforation are studied Ranges of work: Re number 6000-40000 and 005 to 015 that is open area perforation ratio Their results significantly augmentation in the heat transfer and pressure drop by rising the perforation area due to disorganizing the thermal traps distinguish the ribs Ahmad Khoshnevis et al [2] carried out the effect of extended surface perforation on heat transfer augmentation of a 3-D channel with a ground attached heater Two types of perforation are studied, ie Hole and slot Ranges of work: Re number 6000-40000 and open area perforation ratio 005 to 015 perforation inclination angle: 0<o<45 t Their results show significant augmentation in heat transfer and pressure drop by increases the perforation area due to disorganizing the thermal traps between the ribs MR Shaeri, M Yaghoubi [3] carried out on the heat transfer augmentation and for 3-D liquid flow from grouping of solid as well as perforated fins that are attached to a horizontal sheet Air as effective liquid is used in both the equation like Navier- Stokes and RNG Reynolds number ranges are based on the fin length from 2 10 4 to 4 10 4 and Prandtl number Pr=071 Outcome show that fins with longitudinal pores have remarkable heat transfer augmentation in addition to the decrease in weight by comparison with solid fins EAM Elshafei [4], in this experiment they were performed on heat transfer from the rounded pin fin attached to a flat plate Heat sinks were generally spaced both the solid as well as perforated rounded pin fins with zigzagged or staggered combination, attached into a heated base of constant area Range of Reynolds no considered was 38x10 6 to 165x10 7 Perforated fins showing better performance than solid fins in the heat transfer analysis ON Sara [5] the paper shows that the convective heat transfer through a rectangular channel with square cross-section fins mounted below a flat surface The experimental outcomes showed that use of square fins may cause to benefit on the basis of heat transfer augmentation For higher heat transfer performance, less inter-fin distance ratio clearance ratio so that comparatively less Reynolds numbers should be important for the zigzagged arrangement They found that the average Nusselt number enhancing with reducing -fin distance clearance ratio and inter ratio, the friction factor enhancing with reducing clearance as well as inter-fin distance ratio Fig 2 experimental set up (5) Md Farhad Ismail et al, [6] in this experiment numerical study was performed to investigate the turbulent convection heat transfer on a rectangular plate mounted over a flat surface The extended surfaces were of various types of lateral perforations like rectangular, circular, hexagonal cross sections RANS based modified K-W turbulence model is usage to calculate the fluid flow and heat transfer parameters Reynolds number considered from 2000 to 5000 basis on the thickness of the fins Shape of lateral perforation has significant effects on the heat transfer behavior of heat sinks below turbulent flow conditions Rectangular perforated fins have the lowest and solid fins getting higher Nu number Hexagonal perforated fins have the highest fin usefulness Triangular perforated fins have lowest skin friction coefficient Fig 3: Three perforation of rounded, hexagonal, square, trilateral arrangement [6] 727 wwwijaegtcom

Rasim Karabacak, Gülay Yakar [7] In this experimentally studied, diameter holes were 6 mm on each circular fin on a heating tube that inline arrangement in order to growth of the heat transfer The holes invented turbulence in a region nearby the heating tube surface on the bottom of the fin They observe the differences between, perforated finned heaters along with imperforate finned heater with both additions Perforated finned locations are 12% more than the imperforate state in the Nusselt numbers Mohammad Reza Shaeri, Tien-Chien Jen [8],in their merical investigation they selected fin with greater porosity and with no change of its porosity, the number were varied to study the effects of perforation sizes on laminar heat transfer characteristics of the fins In this experiment they were using the Navier Stokes and energy equations are solved finite volume with the help of SIMPLE algorithm Fin with less perforation is more efficient to increase the heat transfer rate compared with a fin with more perforations Fig 4: Configuration of fin group [8] Tzer-Ming Jeng, Sheng-Chung Tzeng, [9] carried out the heat transfer performance analysis with seven square pin fins fitted to a flat surface with different arrangement are studied The outcomes show that lower part facing orientation yields the less coefficient of heat transfer It is observed that the sideward arrangement outcome of the upward one for small finning factors below 27 The optimal heat sink porosity for both upward and sideward arrangement is around 83%and 91% the addition of surface higher effective for the downward as well as lower effective for the sideward arrangement Ren-Tsung Huang el at, [10] experimentally studied the heat transfer of a square pin fin of a square fin array in a rectangular channel with the help of the transient single-blow method Longitudinal pitch the relative transverse pitch as well as the both zigzagged or staggered and line arrangement are the variable parameters The performance of the square fins as the cooling appliances is compared with that of the circular pin fns The optimal inter-fin pitches along with the largest Nu number under the similar pumping power, then XT = 2 and XL = 15 as well as XT = 15 and XL = 15 for the arrays in line as well as staggered arrangements (Relative longitudinal and transversal pitch were denoted as XT and XL) Monoj Baruah el at, [11] they carried out the computational investigation to assess the heat transfer characteristic of elliptical pin fins organized in a rectangular duct in a zigzagged manner They considered solid as well as perforated elliptical pin fins with three perforations They claimed that by changing the solid elliptical fin into the perforated elliptical pin fin, the pressure drop decreases by an average of 12% and heat transfer increases by 23% by introducing perforations and this performance may be further improved by increasing the numbers of perforations in elliptical pin fin Kavita H Dhanawade et at, [12] experimental to investigate the heat transfer Enhancement over horizontal flat plate surface with rectangular fin arrays will lateral square and circular perforation by force convection They varied sizes of perforation as well as Re from 21x10 4 to 87x10 4 They found that average of percentage improvement of square perforated fin is more than that of the fin array of circular perforated fin of same size Friction factor slightly increases with increase in the size of perforation This type of arrays can becomes for air cooling of IC engines and other industrial application A) Fig 5 Schematic of the experimental set up [9] 728 wwwijaegtcom B)

C) Fig 6Schematic of the square, circular, solid fin in line arrangement [12 ABGanorkar, VMKriplani [13] studied whole performance of suitable designed lateral perforated fins in a rectangular channel, Different type of perforated fins are used in the rectangular channel Effect of perforated fins in a rectangular channel is observed for other Reynolds numbers In respect of the Nusselt numbers as well as heat transfer coefficient were analyzed Reynolds number range taken 2500-10000, diameter range of holes 6-10 mm As Re number raises the ratio of (Nu perforated/nu solid) fin increases Increase in no Of holes, the ratio (Nu perforated/nu solid) increases Increase in diameter of holes the ratio (Nu perforated/nu solid) increases The enhancement of (Nu perforated/nu solid) is not significant with increase in no Of holes Advances in electronic engineering have significant changes in size and density of high performances chips Advances in electronic engineering have significant changes in size and density of high performances in size and density of high performances chips Thermal management of these small, high flux dissipater chips is an important issue in order to keep them in order Active method consists of certain external power for the augmentation of the heat transfer Some specimens of active method cause pulsating by cams, reciprocating pumppiston etc Passive techniques normally usage surface or geometrical conversions to the flow channel by compilation inserts or extra appliances, for few specimens, wire coils, extended surface appliances, mesh inserts References [1] Bayram Sachin, Alparslan Demir, Performance analysis of a heat exchanger having perforated square fins Applied Thermal Engineering28(2008)621-632 [2] Ahmad khoshnevis, faramarze talati, maziyar jalaal, esmaeil esmaeilzadeh, Heat transfer enhancement of slot & hole shape perforation in rectangular ribs of a 3-D channel, 17 th Annual (International) conference on mechanical engineering- ISME2009, university of Tehran, Iran [3] MR Shaeri, M Yaghoubi, Numerical analysis of turbulent convection heat transfer from an array of perforated fins, International Journal of Heat and Fluid flow 30 (2009) 218-228 [4] EAM Elshafei, Natural convection heat transfer from a heat sink with hollow/perforated circular pin fin, thermal issues in emerging technologies, Theta 3, Cairo, Egypt, Dec 19-22 nd 2010 Fig7Experimental set up [13] Abdullah H Alessa, Mohamad I Al-Widyan, [14] studied augmentation of heat transfer from a horizontal rectangular fin inserted with wedge shaped or triangular perforations below natural condition Geometrical measurement of fin and perforations are the parameters considered In this experiment, the heat wastage from the perforated fin for definite distance of wedge shaped or triangular perforation measurement, spaces between perforations the outcome in improvement in heat transfer ended the corresponding solid fin Growth of the heat transfer of the perforated fin rises as fin thermal conductivity is increased Advances CONCLUSION Augmentation of heat transfer is very useful in many industrial purposes Very quick heat extraction from heated surface, lowering material weight as well as cost has become a greater task for design for heat exchanger equipment Modernize of heat exchangers needs efficient techniques fabrication of heat exchangers to exchange great amount of heat between extended surfaces and ambient liquid [5] ONSara, Performance analysis of rectangular ducts with staggered square pin fins, Energy conversion and management 44(2003)1787-1803 [6] Md Farhad Ismail,Muhammad Noman Hasan,Suvash Csaha Numerical study of turbulent fluid flow and heat transfer in lareral perforated extended surfaces Energy 64(2014)632-639 [7] Rasim Karabacak,Gulay Yakar, Forced convection heat transfer and pressure drop for a horizontal cylinder with vertically attached imperforate and perforated circular fins Energy conversion and management 52(2011)2785-2793 [8] Mohammad Reza Shaeri,Tin-Chien Jen, The effect of perforation Sizes on laminar heat transfer characteristics of an array of perforated fins [9] Ren-Tsung Huang, Wen-Junn Sheu,Chi-Chuan Wang, Orientation Effect on natural convection convective performance of square pin fin Heat sinks International Journal of heat and mass transfer51(2008) 2386-2376 mastransfer51(2008)2386-2376 [10] Tzer-mingjeng,Sheng-chung Tzeng, Pressure drop and heat Transfer of square pin-finarrays in-line and staggere arrangment International Journal of Heat and Mass Transfer 50 (2007) 2364-2375 [11] Monoj Baruah,Anupam Dewan, PMahanta Performance of elliptical Pin heat exchanger with three elliptical perforations Deparmental of Mechanical engg,indian instistute of technology 729 wwwijaegtcom

guwahati, Vol 3(2) 2011 [12] Kavita H Dhanwade, Vivek K Sunnapwar,Hanamant SDhanawade, Theraml analysis of square and circular perforated fin arrays by Forced Convection International Journal of current Engineering 26 (2006) 1990 1997 [13] AB Ganorkar, VMKriplani Experimental study of Heat transfer Rate by Using lateral perforated fins in a rectangular channel MIT International Journal of Mechanical engineeringvol 2, No 2, Aug 2012, pp (91-96)ISSN No2230-7680 [14] Abdullah H Alessa, Mohamad I Al-Widyan, Enhancement of Natural convection heat transfer from a fin by triangular perforation of bases parallel and toward its tip Jordan University of Science and Technology, Irbid, JordanAppl Math Mech -EnglEd2008, 29(8):1033 1044 730 wwwijaegtcom