International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 3, March 2013
ISSN 2319 - 4847
OPTIMUM DESIGN AND SELECTION OF
HEAT SINK
1
Mukesh Kumar 2 Anil Kumar 3 Sandeep Kumar
1
Asst.Prof. in Shivalik Institutes of Engg. & Tech.-Aliyaspur
23
, Asso. Prof. in Modern Institute of Engg. & Tech. - Mohri
ABSTRACT
The study of heat sink is an important field for the last decade. The reason is mainly the possibilities of reducing the size,
weight and cost as compared to current designs. Also, new applications, heat sinks have been gradually developed so as to
satisfy these needs. The continual development of faster desktop computers being sold at lower prices into the market place has
demanded that thermal management engineers develop and optimize thermal management devices that not only perform better,
but are at the same or lower cost than previous generations. The ever shrinking form factor has also increased the burden
placed on today's thermal management devices.
Keywords: Heat sink, CFD, fins, heat transfer
1. INTRODUCTION
Advancements in semiconductor technology have led to the significant increase in power densities encountered in
microelectronic equipment [1]. As the amount of heat that needs to be dissipated from electronic devices constantly
increases, the thermal management becomes a more and more important element of electronic product design. Both the
performance reliability and life expectancy of electronics equipment are inversely related to the component temperature
of the equipment. Therefore, long life and re li able performance of a component may be achieved by effectively
controlling the device. Operating temperature within the limits set by the device design engineers. With the increase in
heat dissipation from the electronic de vices and the reduction in over all form factors, it became an essential practice to
optimize heat sink de -signs with least trade-offs in material and
Manufacturing costs. A study of heat sink fin technologies has given in formation towards important design criteria for
practical cooling of electronic components. Significant work has been carried out by various researchers in the thermal
analysis of heat sink design. Ellison [2], Kraus et al. [3] have presented the fundamentals of heat transfer and
hydrodynamics character is tics of heat sinks including the fin efficiency, forced convective correlations, applications in
heat sinks, etc. Sasaki [4] optimized, with criteria of fin to channel thickness ratio of unity, the dimensions of water
cooled micro-channels at a given pressure. Azar et al. [5] reported a method of design optimization and presented con
tour plots showing the thermal performance of an air cooled narrow channel heat sink in terms of fin thickness and
channel spacing parameters and employed Poiseuille’s equation in relating the channel flow velocity to the pressure
drop, and the optimization method was presented, as summing the pressure drop across the heat sink is known. An
analytical method of optimizing forced convection heat sinks was proposed by Knight et al. [6, 7] for fully developed
flow in closed finned channelsThey presented normal ized non-dimensional thermal resistances as a function of the
number of channels, again for a fixed pressure drop. Wirtz et al. [8] investigated experimentally the effect of flow by
pass on the performance of longitudinal fin heat sinks and Devised a set of expressions for determining the optimum
fin density for different fin geometry and flow conditions. Keyes [9] analytically examined the fin and channel
dimensions to provide optimum cooling under various forced convection cooling conditions. Bartilson [10]
investigated, using both experimental and numerical techniques, air jet impingement cooling on a rectangular pin fin
heat sink. Various shapes of longitudinal straight fin heat sinks were experimentally examined, and the thermal
performance measurements were compared with existing correlations [11]. Seri Lee [12] observed that the actual
convection flow velocity through fins is usually un -known to designers, yet, is one of the parameters that greatly affect
the overall thermal performance of the heat sink and developed a simple method of determining the fin flow velocity
and the Development of the overall model of the heat sink. Different types of heat sink are examined, and their relative
performances are presented. The analytical simulation model is validated by comparing the results with the
experimental data, and sample cases are presented with discussions on the parametric behavior and optimization of bidirectional heat sinks with the heaters placed symmetrically. Chris to pher et al. [13] studied on elliptical pin fin heat
sink. Comparative thermal tests have been carried out using aluminum heat sinks with extruded fins, cross cut
Volume 2, Issue 3, March 2013
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
Volume 2, Issue 3, March 2013
ISSN 2319 - 4847
rectangular fins in low air flow environments. Be sides the thermal measurements, the effect of air flow by pass
characteristics in opened duct configuration was investigated. The testing described in the study incorporates several
possible performance factors into two terms; flow by pass and over all thermal resistance. These simplified terms
represent a combination of several factors, such as material conductivity, lateral fin conduction, boundary layer
formation, effective surface area, and pres -sure drop. The cross cut heat sink of fersease of production assembly where
misalignment of heat sink with respect to the direction of the air flow will result in failure. Vollaro et al. [14] and
Culham et al. [15] studied the optimization of the parallel plate heat sink and at tempted to define general rules for
optimizing it. Park et al. [16] proposed the progressive quadratic response surface model to obtain the optimal values of
design variables For a plate fin type heat sink Park et al. [17, 18] performed an investigation of numerical shape
optimization for high performance of a heat sink with pin fins. Yu et al. [19] developed a plate pin fin heat sink and
compared its performance with a plate fin heat sink. Chiang et al. [20] developed the procedure of response surface
methodology for finding the optimal values of designing parameters of a pin fin type heat sink under constraints of
mass and space limitation to achieve the high cooling efficiency. From the above literatures, it can be concluded that
Significant work needs to be carried out in optimizing the heat sink de sign. Plate fin and pin fin heat sinks are
commonly used heat sinks for electronic cooling applications. This makes the selection of heat sink a difficult task for a
particular application. In the present work, cross cut pin fin heat sink is developed and its performance is compared
with the parallel plate heat sink in micro electronics cooling. In most of the electronic components the heat duty
involved is high and also the heater is placed symmetrically about the axis, thereby leading to space con straints. An
effort is made in the experiment by placing the heating element asymmetrically for the study of heat transfer characters
tics and the thermal performance. The fan distance is also varied in the experimental work to find the optimum
distance for maximum efficiency for both parallel plate and cross cut pin fin heat sinks.
Heat-Sink Types: Heat sinks can also be classified in terms of manufacturing methods and their final form shapes.
The most common types of air-cooled heat sinks include [8]
1. Stampings: Copper or aluminum sheet metals are stamped into desired shapes. They are used for air cooling of
electronic components at low cost and low thermal density problems. They are suitable for a high volume production
and advanced cooling with high speed stamping
Stamping Heat sink
2. Extrusions: The formation of elaborate two-dimensional shapes capable of dissipating large heat loads [16]. They
may be cut, machined and options are added. A cross-cutting will produce unidirectional, rectangular pin fin heat sinks
and incorporating serrated fins improves the performance by approximately 10 to 20% at the expense of extrusion rate.
Extrusion limits, such as ratio of the fin height-to-gap aspect ratio. The minimum fin thickness-to-height and
maximum base to fin thicknesses usually dictate the flexibility in design options.
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Extrusion Heat sink
3. Bonded/Fabricated Fins: Air cooled heat sinks are convection limited and the overall thermal performance of an air
cooled heat sink can be improved by exposed more surface area to the air stream can be provided even at the expense of
conduction paths [16].These high performance heat sinks utilize thermally conductive aluminium-filled epoxy to bond
planar fins on to a grooved extrusion base plate. This process allows for a much greater fin height-to gap aspect ratio of
20 to 40, greatly increasing the cooling capacity without increasing volume requirements.
Bonded/ fabricated fins
4. Castings: Sand, lost core and die casting processes are available with or without vacuum assistance, in aluminum or
copper/bronze. This technology is used in high density pin fin heat sinks which provide maximum performance when
using impingement cooling.
Casting fins
5. Folded Fins: Corrugated sheet metal in either aluminum or copper increases surface area and, hence, the volumetric
performance. The heat sink is then attached to either a base plate or directly to the heating surface via epoxying or
brazing. It is not suitable for high profile heat sinks due to the availability and from the fin efficiency point of view.
However, it allows obtaining high performance heat sinks in applications where it is impractical or impossible to use
extrusions or bonded fins.
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Folded fins
To quantify the effectiveness of different types of heat sinks, the volumetric heat transfer efficiency can be defined as:
Design Parameters
In designing or selecting an appropriate heat sink that satisfies the required thermal and geometric criteria, one needs
to examine various parameters that affect not only the heat-sink performance itself, but also the overall performance of
the system. Option of choosing a particular type of heat sink depends largely on the thermal budget
Allowed for the heat sink and external conditions surrounding the heat sink. In any type of heat sink, one of the most
important external parameters in air cooling is the flow condition which can be classified as natural, low flow
definition or consensus on the flow velocity that separates the mixed and forced flow regimes.
A list of design constraints for a heat sink may include parameters, such as
 induced approach flow velocity
 available pressure drop
 cross sectional geometry of incoming flow
 amount of required heat dissipation
 maximum heat sink temperature
 ambient fluid temperature
 maximum size of the heat sink
 orientation with respect to the gravity
 appearance and cost
Given a set of design constraints, one needs to determine the maximum possible performance of a heat sink within the
envelope of constraints. The parameters, over which a designer has a control for optimization, typically include,








fin height
fin length
fin thickness/spacing
number/density of fins
fin shape/profile
base plate thickness
cross-cut patterns
heat sink material
Characterization and Optimization of Heat Sinks
In view of achieving an optimum thermal performance, most of the parameters discussed in the previous section are
interdependent of the others. It is often true that the impact one parameter has on the performance of a heat sink cannot
be generalized, or even foreseen without
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Volume 2, Issue 3, March 2013
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Specification of heat sink without cut
Specification
Length
78mm
Width
60mm
Height H f
25mm
Height H b
08mm
Thickness W W
01mm
Channel width W c
02mm
Volume 2, Issue 3, March 2013
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Heat sink without cut
Heat sink with one cut
Concurrently considering the consequences exhibited in the other parameters. For example; a longer fin height
provides additional surface area for greater heat dissipation and improves the overall thermal performance. However, if
the available volumetric flow rate is fixed, the overall performance may deteriorate with the fin height; if the available
pressure drop is fixed, a longer heat sink in the direction of flow may have an adverse effect on the performance by
decreasing the actual velocity over the fin surfaces, and; an option of having more fins is generally viewed as a way to
improve the performance. This is a very dangerous generalization, because, in most cases, having excessive fins induce
a higher pressure drop across the heat sink, resulting in a severe reduction in flow velocity and/or a significant increase
in flow bypass over the heat sink.
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EXPERIMENTAL SETUP
Following type heat sinks are tested.
Heat sink without cut
Heat sink with one cut
Schematic diagram of experimental setup
Heat sink made of Aluminium alloy 6061. Aluminium alloy 6061 is one of the most extensively used of the 6000 series
aluminium alloys. 6061 is a precipitation hardening aluminium alloy, containing magnesium and silicon as its major
alloying elements. It has good mechanical properties and exhibits good weld ability. It is one of the most common
alloys of aluminium for general purpose use. It is a versatile heat treatable extruded alloy with medium to high strength
capabilities Physical and Thermal properties of alloys 6061
RESULTS AND DISCUSSION
Comparison of temperature for a heat sink without cut and with one cut for 120 W consumption
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Comparison of temperature for a heat sink without cut and with one cut for 100 W consumption
Experimental analysis was made for the heat transfer for a heat sink having two profiles. The following conclusions
were made throughout the experimentation:
 It was observed that the temperature variation was more for a heat sink with cut as compare to heat sink without
cut leading to higher heat transfer.
 An optimum selection of heat sink is to be made depending upon its industrial application
Similar trends were also observed in for various heat inputs of 80 W, 100 W and 120 W leading to that heat transfer
equations and methodologies hold well for various heat sinks.
Future Scope
Present study deals with heat transfer and pressure drop at inlet and outlet of a wind tunnel with heat sink placed inside
it. This study has the following future scopes:

Present experimental set up may be extended for the study of various other types of industrial heat sinks. All
the process may be repeated for evaluating the variation in friction factor, temperature drop across the heat
sink, fanning factor and pressure drop.

Whole experimentation to be repeated for varying gap between the fins of the heat sink and their effects on
temperature drop and pressure drop are to be studied.

Effects of dimensions on heat transfer rate, i.e. width and depth may be studied using, different heat sinks
having different dimensions.

The effect of different kind of materials of heat sink on heat transfer rate can be studied.
REFERENCES
[1] Bar-Cohen,A., Thermal management of Electronics components with Dielectric Liquids, Proceedings,
ASME/JSME Thermal engg joint conference, Maui, Hawaii USA, Vol 2 ,1996,pp 15-39
[2] Ellison, G. N., Thermal Computations for Electronic Equipment, 2nd ed., Van Nostrand Reinhold Corporation,
New York, USA, 1989
[3] Kraus, A. D., Bar-Co hen, A., Thermal Analysis and Control of Electronic Equipment, Hemi sphere Publishing
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[4] Sasaki, S., Kishimoto, T., Optimal Structure for Microgroove Cooling Fin for High Power LSI Devices, Electronics
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Components, Proceed ings, 8th Annual IEEE Semi-Therm Symposium, Aus tin, Tex., USA, 1992, pp. 12-19
[6] Knight, R. W., Goodling, J .S., Hall, D. J., Optimal Thermal De sign of Forced Convection Heat Sinks-Analytical,
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[7] Knight, R. W., Hall, D. J., Goodling, J. S., Jae ger, R. C., Heat Sink Optimization withApplication to Microchannels, IEEE Transactions on Components, Hybrids and Manufacturing Technology, 15 (1992),5, pp. 832-842
[8] Wirtz, R. A., Chen, W., Zhou, R., Ef fect of Flow By pass on the Performance of Longitude nal Fin Heat Sinks,
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International Journal of Application or Innovation in Engineering & Management (IJAIEM)
Web Site: www.ijaiem.org Email: editor@ijaiem.org, editorijaiem@gmail.com
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[9] Keyes, R. W., Heat Trans fer in Forced Con vec tion through Fins, IEEE Transactions on Electronic Devices, ED31 (1984), 9, pp. 1218-1221
[10] Bartilson, B. W., Air Jet Impingement on a Miniature Pin-Fin Heat Sink, ASME Pa per No.91-WA-EEP-41, 1991
[11] Matsushita, H., Yanagida, T., Heat Transfer from LSI Packages with Longitudinal Fins in a Free Air Stream,
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[15] Culham, J. R., Muzychka, Y. S., Optimization of Plate Fin Heat Sinks Using Entropy Generation Minimization,
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[19] Yu, X., et al., Development of a Plate-Pin Fin Heat Sink and its Performance Com par i sons with a Plate Fin Heat
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AUTHOR
MUKESH KUMAR ANIL KUMAR received the B.TECH. And M.TECH. Degrees in Mechanical
Engineering from Amravati University and Punjab Technical University in 1998 and 2012. He is now
asst. prof. In Shivalik Institutes of Engg. & Tech.-Aliyaspur
ANIL KUMAR received the B.TECH. And M.TECH. Degrees in Mechanical Engineering from
Aurangabad University and NIMS University in 1998 and 2012. PHD Pursuing from Mewar University.
He is now asso. Prof in MIET Kurukshetra.
ANIL KUMAR received the B.TECH. And M.TECH. Degrees in Mechanical Engineering from
National Institute of Technology Kurukshetra in 2010 and 2012. He is now asst prof in MIET
Kurukshetra
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