International Conference on Global Trends in Engineering, Technology and Management (ICGTETM-2016)
―Experimental and Finite Element Analysis of Rectangular
Straight Fin and Rectangular Straight Fin with Variable Fin
Density”
Govind Sahebrao Badgujar#1, Dr. Atul A. Patil*2, Prof. V.H.Patil#3
#
M.E. Student, Department of Mechanical Engineering, GF’s Godavari College of Engineering, Jalgaon ,
Maharashtra, India.
*
Associate Professor, Dept. of Mechanical Engineering, GF’s Godavari College of Engineering, Jalgaon
,Maharashtra, India.
#
Associate Professor, Dept. of Mechanical Engineering, GF’s Godavari College of Engineering, Jalgaon
,Maharashtra, India.
Abstract— In the past decades, Due to the rapid
growth of electronic technology these microelectronic
systems have shown extraordinary growth. The most
common method for cooling electronic devices is by
finned heat sinks made of aluminium. The Test Model
having the Thermal Conductivity is Kf= 185 W/m°C.
Pressure drop across heat sink is one of the key
variables that govern the thermal performance of the
heat sink in forced convection environment. In order
to design an effective heat sink it having large heat
transfer rate, low pressure drop, simple construction,
and reasonable cost. The purpose of a heat sink is to
maintain the device temperature below the maximum
allowable temperature specified by the device
manufacturer. Thermoelectric coolers used in
applications where temperature stabilization or
cooling below ambient required. The present model
study to conduct for application of heat sink in
thermoelectric can cooler, where in the device shall be
used to cool beverage cans. The size of the device is
constraint due to this device is used as a portable
device hence to be compact. Thus the study is focused
on development and testing of heat sink with straight
fins and straight fins with variable fin density.
Keywords—Heat Sink, Straight fin, Thermal
Condutivity, Thermoelectric Coolers.
1. INTRODUCTIONA heat sink is a component or assembly that
efficiently transfers heat generated within a solid
material to a fluid medium, such as air or a liquid.
Heat sinks are primarily used to remove unwanted
heat from a device to keep it from overheating.
Examples of heat sinks is thermoelectric can cooler,
where in the device shall be used to cool beverage
cans. Rapid development in packaging technology
allows portable electronics to gain faster processing
speed and enhanced Capabilities. However, thermal
management in the portable electronics environment is
becoming increasingly difficult. Due to high heat load
and dimensional constraints. Proper selection of fans
and fin pitch in the heat sink is crucial to ensure the
thermal design of the system is optimized. In this
ISSN: 2231-5381
paper, the experimental conducted in Air duct is a
fabricated structure with the entry and exit section 160
x 160 mm cross-section with the central section 120 x
120 mm that include heater arrangement .ventureaction in provided for enhanced performance by a
gradual decreasing and gradually increasing section.
In that Test Model of fin heat sinks made of
aluminium having the Thermal Conductivity is
Kf=185 W/m°C. Study of the heat transfer to
enhancement obtained by Comparitatively study of
Rectangular Straight and Rectangular Straight with
variable Fin Density is the main objective of the
present work. In that Mass Flow of hot Air passing
through in Air Duct which content the Fins Test
Model. Due to Changing Density of Test model
Structure of Rectangular Straight and Rectangular
Straight with variable Fin Density .Finally we can find
out Comparatively study of Parameters of Pressure
Drop, Heat Flow ,Temperature gradient ,Overall Heat
transfer Coefficient by plotting on the Graph. And
just only changing the mass flow rate of Air passing
through in the Duct. The Main Application it is used
in portable device like heat sink in thermoelectric can
cooler. Here we are testing on two Test Models of fin
Structure 1) Rectangular Straight fin & 2) and
Rectangular Straight with variable Fin Density. The
parameters of sink can be derived for theoretical
validation a)Heat sink profile and geometry drawing
using 2-D AutoCAD .b) Solid modelling of the heat
sink models using NX Unigraphix. c) Thermal
analysis for temperature distribution using ANSYS
R14.5.
1.1 Basic Heat Sink Heat Transfer Principle:Heat sink is an object that transfers thermal
energy from a higher temperature to a lower
temperature in fluid medium. To understand the
principle of a heat sink, consider Fourier's law of heat
conduction. Fourier’s law of heat conduction,
simplified to a one-dimensional form in the x-direction,
shows that when there is a temperature gradient in a
body, heat will be transferred from the higher
temperature region to the lower temperature region.
The rate at which heat is transferred by conduction, Q
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International Conference on Global Trends in Engineering, Technology and Management (ICGTETM-2016)
is proportional to the product of the temperature
gradient and the cross-sectional area through which
heat is Q=-k×A× (∂T/∂x).
Fig.1: Sketch of a heat sink in a duct used to calculate the governing
equations from conservation of energy and Newton’s law of cooling.
Consider a heat sink in a duct, where air flows through
the duct, It is assumed that the heat sink base is higher
in temperature than the air. Applying the conservation
of energy, for steady-state conditions, and Newton’s
law of cooling to the temperature nodes shown in
Fig.1 gives the following set of equations. Where,
Is the air mass flow rate in kg/s.
=
2.2 Rectangular Straight with variable Fin Density-
Fig.3 2D Geometry of Rectangular Straight Fin with variable fin
density Heat Sink.
Measurement Mass Properties is
Volume
= 55656.00 mm3
Area
= 24306.00 mm2
Mass
= 0.435822100 kg
Weight
= 4.273958651 N
Density
= 0.000007831 kg/ mm3
2.3 Analytical Calculations for finding the different
parameters for Test Model1) Discharge (Q) –
Q= Cd × (π/4) × d2 ×
Cp, in (Tair, out- Tair, in)
, m3/sec.
2) Mass flow of air = Density x discharge, Kg/min.
3) Heat flow = m x Cp x ΔT, Watt
4) Overall H.T Coefficient (U)= (heat flow / A x ΔT),
W/m2K.
2. HEAT TRANSFER RATE OF
RECTANGULAR FINS:here we are testing on two Test Models of fin
Structure 1) Rectangular Straight fin & 2)Rectangular
Straight with variable Fin Density having the Mass
Properties from NX Unigraphix & geometry drawing
using 2-D AutoCAD given below
2.1 Rectangular Straight fin-
3. EXPERIMENTATION USING AIR DUCTStart the heater by switching on the power. Maintain
the Power same as100 watts, Voltage - 230 Volt AC.
for all readings. Start the blower and adjust and
maintain speed at level-1.Take manometer reading (h1)
mm of water using this reading to find pressure drop
across the test model. Take manometer reading (h2)
mm of water using this reading to find velocity of air
and discharge of speed of blower. Note down
thermocouple temperature reading (T f) .Gradient of
temperature (ΔT) = (Tf- Ta). Repeat the same set of
reading for different levels of manometer readings
level-2. Level-3. Level-4, level-5& level-6.
3.1 Experiment Set-up-
Fig.2 2D Geometry of Rectangular Straight Fin Heat Sink.
Measurement Mass Properties
Volume
= 56088.00 mm3
Area
= 24738.00 mm2
Mass
= 0.156709872 kg
Weight
= 1.536800253 N
Radius of Gyration = 30.731330231 mm
Centroid
=36.098844673, 33.401155327, 2.418485237 mm
Density
= 0.000002794 kg/ mm3
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International Conference on Global Trends in Engineering, Technology and Management (ICGTETM-2016)
20
18
Pressure Drop
16
14
12
Temp
gradient
10
8
6
Heat flux
4
Fig.4 Experiment Set-up
2
3.2 Test Model of Rectangular Straight Fins –
0
Overall heat
transfer coeff.
Mass Flow Rate (Kg/min)
Graph no.1 Different Parameters Vs Mass Flow rate of Rectangular
Straight fin.
Fig .5 Test Model of Rectangular Straight Fins in NX Unigraphix.
3.3 Test Model of Rectangular Straight Fins with
variable fin density –
Fig.6 Test Model of Rectangular Straight Fins with variable density
in NX Unigraphix.
3.3 Combine Parameters of Rectangular Straight fin
on Graph from Result Table-
From graph no.1 Pressure drop across fins increases
with increase in Mass flow rate. Temperatures
gradient increases with increase in Mass flow rate.
Heat flux increases with increase in flow rate with
maximum of 3.28 W/mm2. Overall heat transfer
coefficient of fins is best at elevated flow rates.
3.4 Combine Parameters of Rectangular Straight
with variable fin density on Graph from Result
Table18
16
14
12
10
8
6
4
2
0
Pressure Drop
Temp gradient
Heat flow
mass flow rate (kg/min)
Overall heat
transfer
coefficient .
Graph no.2 Different Parameters Vs Mass Flow rate of Rectangular
Straight with variable fin density.
From graph no.2 Pressure drop across fins increases
with increase in flow rate. Temperature gradient
increases with increase in flow rate of air. Heat flux
increases with increase in flow rate with maximum of
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International Conference on Global Trends in Engineering, Technology and Management (ICGTETM-2016)
3.177 W/mm2. Overall heat transfer coefficient of fins
is best at elevated flow rates.
4.
FINITE
ELEMENT
ANALYSIS
OF
RECTANGULAR FINS4.1Finite Element Analysis of Rectangular Straight
FinsIn Finite Element Analysis of Rectangular Straight Fin
& Rectangular Straight Fin with variable fin density is
draw in ANSYS of R14.5 Version.
Geometry-
Fig. 10 Directional heat flux in X –direction of Test Model of
Rectangular Straight Fins.
4.2Finite Element Analysis of Rectangular Straight
Fin with variable fin densityGeometry-
Fig.11 Geometry of Test Model of Rectangular Straight Fins with
variable density in ANSYS R14.5
Meshing -
Fig.7 Geometry of Test Model of Rectangular Straight Fins in
ANSYS R14.5
Meshing -
Fig.12 Meshing of Test Model of Rectangular Straight Fins with
variable density.
Total Heat Flux -
Fig. 8Meshing of Test Model of Rectangular Straight Fins.
Total Heat Flux -
Fig.13 Total heat flux Test Model of Rectangular Straight Fins with
variable density
Directional Heat flux-
Fig. 9Total heat flux of Test Model of Rectangular Straight Fins.
Directional Heat flux-
Fig.14 Directional heat flux in X direction of Test Model of
Rectangular Straight Fins with variable density.
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International Conference on Global Trends in Engineering, Technology and Management (ICGTETM-2016)
5.COMPARISON BETWEEN RECTANGULAR
STRAIGHT & RECTANGULAR STRAIGHT
FINS WITH VARIABLE DENSITYAnalysis resultsSr.
No
Parameter
Rectangular
straight fins
Rectangular
straight
fins
with Variable
density
30.547
1.9703
0.83676
1
2
3
Max. Tip temp
31.89
Total heat flux
1.9816
Directional
heat 0.96929
flux
Table no.1 Analysis results Rectangular Straight & Rectangular
Straight Fins with variable density.
The Rectangular Straight fins show marginally better
performance than the Rectangular Straight fins with
variable fin density
Experimental resultsSr.
No
Parameter
Rectangular
straight fins
1
Pressure drop across
fin
Temperature gradient
(max)
Heat flow ( max)
Overall
Heat
Transfer Coefficient
0.35
Rectangular
straight fins with
Variable density
0.36
19
17
3.287
6.9215
3.177
6.85
2
3
4
Table no .2 Analytical results Rectangular Straight & Rectangular
Straight Fins with variable density.
The rectangular straight fins show less pressure drop
across fins hence they will be preferred over variable
density fins as they will lead to less cross heating of
components. Overall heat transfer coefficient and heat
flow of the straight fins is marginally better than the
variable density fins hence they perform slightly better
than the variable density fins.
variable fin density.& from Experimental results the
Conclusion is The rectangular straight fins show less
pressure drop across fins hence they will be preferred
over variable density fins as they will lead to less
cross heating of components. Overall heat transfer
coefficient and heat flow of the straight fins is
marginally better than the variable density fins hence
they perform slightly better than the variable density
fins.
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6. CONCLUSIONFrom Analysis results the Conclusion is the
Rectangular Straight fins show marginally better
performance than the Rectangular Straight fins with
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