20120140507005

International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN 0976 –

6480(Print), ISSN 0976 – 6499(Online) Volume 5, Issue 7, July (2014), pp. 47-56 © IAEME

47

ANALYSIS OF ELECTRONIC CHIPS MICROCHANNEL BY USING ANSYS

SOFTWARE

Ali Salah Ameen*, Dr. Ajeet Kumar Rai**

*Directorate of Telecommunications & post kirkuk, Iraqi Telecommunication& post company

Ministry of Communications, Republic of Iraq

**Department of Mechanical Engineering SSET, SHIATS- DU Allahabad (U.P) India

ABSTRACT

In this present work a three-dimensional fluid flow and heat transfer in a rectangular micro-

channel heat sink are analyzed numerically with the help of commercial CFD - ANSYS-FLUENT

14.0. The micro-heat sink model consists of a 10 mm long substrate material with rectangular micro

channels, 57µm wide and 180µm height, fabricated along the entire length. Two different materials

(silicon, copper) for rectangular micro channels are taken for our study. Water at 293K is taken as

working fluid. A comparison of heat transfer characteristics of liquid coolant is made in forced

convection cooling at a heat flux of 90W/cm2 in micro-heat sink with different pressure drops

(30kpa, 50kpa).

Keywords: Electronic Chips Cooling, Ansys, Micro Channel Heat Sink.

INTRODUCTION

Advance in micromachining technology in recent years has enabled the design and

development of miniaturized systems, which opens a promising field of applications, particularly in

the medical science and electronic-/bioengineering. Micro-channel cooling technology was first put

forward by Tuckerman, D.B. and Pease(1983) introduced a kind of water-cooled heat sink made of

silicon, used in very-large-scale integrated circuits (VLSI). The micro-channels were fabricated with

a 50 µm width and a 300 µm height so that heat fluxes as high as 790 W/cm2 could be removed with

the maximum temperature difference between substrate and inlet water of 71 K and the pressure drop

across the micro-channels of 31 Pa. The thermal performance is much better than presented by

conventional thermal dissipation technologies. After that, many researchers focused on such new

kind of chip cooling technology. Roy W. Knight (1992) The equations governing the fluid dynamics

and combined conduction/convection heat transfer in a heat sink are presented in dimensionless form

INTERNATIONAL JOURNAL OF ADVANCED RESEARCH

IN ENGINEERING AND TECHNOLOGY (IJARET)

ISSN 0976 - 6480 (Print)

ISSN 0976 - 6499 (Online)

Volume 5, Issue 7, July (2014), pp. 47-56

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48

for both laminar and turbulent flow. A scheme presented for solving these equations enables the

determination of heat sink dimensions that display the lowest thermal resistance between the hottest

portion of the heat sink and the incoming fluid.Judy. (2002) did pressure drop experiments on both

round and square microchannels with hydraulic diameters ranging from 15 to 150 µm. They tested

distilled water, methanol and iso-propanol over a Reynolds number range of 8 to2300. Their results

showed no distinguishable deviation from laminar flow theory for each case. Weilin Qu, Issam

Mudawar (2004) study, the three-dimensional fluid flow and heat transfer in a rectangular micro-

channel heat sink are analyzed numerically using water as the cooling fluid. The heat sink consists of

a 1-cm2 silicon wafer. The micro-channels have a width of 57 lm and a depth of 180 lm, and are

separated by a 43 lm wall. A numerical code based on the finite difference method and the SIMPLE

algorithm is developed to solve the governing equations. Harshal R. Upadhye , Satish G. Kandlikar

(2004) Direct cooling of an electronic chip of 25mm × 25mm in size is analyzed as a function of

channel geometry for single-phase flow of water through small hydraulic diameters. Fully developed

laminar flow is considered with both constant wall temperature and constant channel wall heat flux

boundary conditions. The effect of channel dimensions on the pressure drop, the outlet temperature

of the cooling fluid and the heat transfer rate are presented. J. Li , G.P. Peterson , P. Cheng (2004)

numerically simulated a forced convection heat transfer occurring in silicon based micro channel

heat sinks has been conducted using a simplified three-dimensional conjugate heat transfer model

(2D fluid flow and 3D heat transfer) consists of a 10 mm long silicon substrate, with rectangular

micro channel, 57 µm wide and 180 µm deep, fabricated along entire length with hydraulic diameter

86 µm. The influence of the geometric parameters of the channel and thermo physical properties of

the fluid on the flow and the heat transfer, are investigated using temperature dependent thermo

physical property method..Poh-Seng Lee, Suresh V. Garimella (2006) Three-dimensional numerical

simulations were performed for laminar thermally developing flow in micro channels of different

aspect ratios. Based on the temperature and heat flux distributions obtained, both the local and

average Nusselt numbers are presented graphically as a function of the dimensionless axial distance

and channel aspect ratio. J. Li, G.P. Peterson(2007) (3D) conjugate heat transfer model has been

developed to simulate the heat transfer performance of siliconbased, parallel micro channel heat

sinks. A semi-normalized 3-dimensional heat transfer model has been developed, validated and used

to optimize the geometric structure of these types of microheat sinks by the model were a pitch of

100 lm, a channel width of 60 lm and a channel depth of about 700 lm. Afzal Husain and Kwang-

Yong Kim A numerical(2013) investigation of 3-D fluid flow and heat transfer in a rectangular

micro-channel has been carried out using water as a cooling fluid in a silicon substrate. Navier–

Stokes and energy equations for laminar flow and conjugate heat transfer are solved using a finite

volume solver. Nivesh Agrawal1 (2013) he is study the comparison of heat transfer characteristics

of liquid coolants in forced convection cooling in a micro-heat sink with different pressure drops

such as (35, 50 and 65kPa).The heat transfer characteristics of water and Propylene Glyco.l

Numerical results of a fluid flow micro-heat sink are obtained using commercial CFD software

ANSYS-CFX.

MATHEMATICAL FORMULATION

The microchannels heat sink model modeling in ANSYS FLUENT 14.0 its consists of a 10

mm long and dimension of rectangular single micro-channel have a width of 57 µm and a depth of

180 µm as shown in Fig(1). The heat sink substrate is (silicon, copper) and water is used as the

cooling fluid. The electronic component is idealized as a constant heat flux boundary condition at the

heat sink bottom wall. Heat transport in the unit cell is a conjugate problem which combines heat

conduction in the solid and convective heat transfer to the coolant (water). Here we consider a



49

rectangular channel of dimension (900µx100µmx10mm) applied constant heat flux of 90 W/cm2

from bottom.

Fig(1):Modeling Structure of a rectangle micro-channels heat sink and Computational domain of

single micro-channel heat sink and the unit with a constant heat flux in ANSYS FLUENT 14.0

Governing Equations

The governing equations are continuity, momentum and energy equations, which are derived from

fundamental principles of heat and fluid flow. The equations are posed to implement SIMPLE

(Semi-Implicit Method for Pressure Linked equation) algorithm.

length required to fully developed laminar flow entrance length = 0.057Re× Dh (1)

= (0.057× 106.8× 86.58) µm= 527.064 µm it is less than 10 mm So fully developed laminar flow is

valid.



50

Continuity Equation

(2)

Momentum Equation (Navier-stokes Equation)

X-momentum equation

(3)

Y-momentum equation

(4)

Z-momentum equation

(5)

Energy Equation

(6)

The hydrodynamic boundary condition can be stated as at the inner bottom wall surface of

channel (no-slip condition)

(7)

(7.1)

(7.2)



51

(7.3)

(8)

(9)

Table (1): Thermophysical Properties of fluid

Fluid

liquid ƿ f

kg/m3

cp

j/ kg-k

µ f

kg/m-s

Kf

W/m-K

T

k

P

kpa

water 998.2 4182 0.001003 0.6 293 30-50

Table (2): Geometric dimensions of the single microchannel

H

(µm)

h

(µm)

W

(µm)

w

(µm)

St

(µm)

Sb

(µm)

t

(µm)

L

(mm)

900 180 100 57 450 270 21.5 10

Table (3): Thermo physical Properties of solid

Table (4): Relaxation factors- Solution controls

Pressure 0.3

Density 1

Momentum 0.7

Body force 1

RESULT AND DISCUSSION

This present numerical simulation and mishing has been done using ANSYS FLUENT-CFD

14.0 after putting Table (1,2,3,4) the boundary conditions and flow conditions in micro-channel

Fig(2), iteration will be start. The model of the micro-channel heat sink has been converged in 100

iteration. Fig(3).

Solid ƿ s

Kg/m3

c p

J/Kg-K

k s

W/m-K

Silicon 2330

712 148

copper 8978 381 387.6



52

Fig (2): The boundary names and meshing Optimum grid system for single micro channel heat sink

in ANSYS FLUENT 14.0

Fig (3): Convergence graph

Simulation of Single Micro channel The fluid is entered through the micro channel made of (silicon, copper) at pressure 50

kPa,30kpa with constant inlet temperature 293k. After passing through the channel, the fluid

discharged to the atmosphere. A constant heat flux q"=90 W/cm2is applied at the bottom wall of heat

sink. Fig(4).



53

Fig (4): Pressure contours of channel for ∆ p = 50 kPa, 30kpa and q"=90 W/cm

2

The temperature of fluid at the inlet is initially uniform (293k). The temperature Profiles

shown is due to the assumption of hydrodynamic fully developed Flow. The temperature rise along

the flow direction in the solid and fluid regions of the micro channel heat sink. Fig(5,6,7,8)

Fig (5):Temperature contours inside channel of heat sink (silicon, copper) for inlet and outlet for

∆ p = 30 kPa q"=90 W/cm2



54

Fig (6): Temperature contours inside channel of heat sink (silicon, copper) for inlet and outlet for

∆ p = 50 kPa q"=90 W/cm2

Fig (7): Temperature contours inner wall channel of heat sink (silicon, copper) for inlet and outlet

for ∆ p = 30 kPa q"=90 W/cm2

Fig(8): Temperature contours along channel of heat sink (silicon, copper) for inlet and outlet for

∆ p = 50 kPa q"=90 W/cm2



55

Fig(9): Velocity vectors at outlet of channel for ∆ p = 30 kPa, 50kPa, q"=90 W/cm

2

Fig(10): Comparison of temperature difference (silicon, copper) based of micro channel heat sink for

different pressure drop q"= 90 W/cm2

Fig (11): Average heat transfer coefficient and Average Nusselt number distributions inside the

channel for different pressure drop at q"=90 W/cm2

290

295

300

305

310

315

320

325

0 2 4 6 8 10 12

50 kpa - cu

50 kpa - si

30 kpa- cu

30 kpa- si

Z - (mm)

T

(k)

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

0 2 4 6

30 kpa- si

30 kpa- cu

50 kpa- cu

50 kpa- si

Z- (mm)

H a

vg

(w/m

2.k

)

0

2

4

6

8

10

12

14

16

18

0 2 4 6

30 kpa- cu

50 kpa- cu

50 kpa- si

30 kpa- si

Z- (mm)

Nu

a

vg

e



56

CONCLUSION

In the present study it has been observed that the temperature of cooling fluid at the outlet of

micro channel is maximum when the pressure drop is 30 kPa. It is further observed that the water

temperature is maximum at the outlet when substrate Silicon is used. The outlet temperature of water

when substrate copper is used is observed to be 316 K and 305 K for respective pressure drop of 30

kPa and 50 kPa. Whereas it is 321 K and 310 K for respective pressure drop of 30 kPa and 50 kPa.

REFERENCES

[1] D. B. TUCKERMAN AND R. F. W. PEASE (1981), High-Performance Heat Sinking for

VLSI, IEEE ELECTRON DEVICE LETTERS, VOL. EDL-2, NO. 5, MAY 1981,

pp 126-129.

[2] Roy W. Knight, Donald J. Hall, John S. Goodling, and Richard C. Jaeger (1992), Heat

Sink Optimization with Application to Microchannels, IEEE TRANSACTIONS ON

COMPONENTS, HYBRIDS, AND MANUFACTURING TECHNOLOGY, VOL. 15,

NO. 5, OCTOBER 1992, pp 832-842

[3] J. Judy, D. Maynes, B.W. Webb (2002), Characterization of frictional pressure drop for

liquid flows through microchannels, International Journal of Heat and Mass Transfer 45

(2002) pp 3477–3489.

[4] Weilin Qu, Issam Mudawar (2002), Analysis of three-dimensional heat transfer in micro-

channel heat sinks, International Journal of Heat and Mass Transfer 45 (2002) PP 3973–3985.

[5] Harshal R. Upadhye , Satish G. Kandlikar (2004), Optimization of Microchannel

Geometry for Direct Chip Cooling Using Single Phase Heat Transfer, ASME 2004 2nd

International Conference, ICMM2004-2398, pp. 679-685.

[6] J. Li ,G.P. Peterson , P. Cheng (2004), Three-dimensional analysis of heat transfer in a

micro-heat sink with single phase flow, International Journal of Heat and Mass Transfer 47

(2004) pp4215–4231.

[7] Poh-Seng Lee, Suresh V. Garimella (2006), Thermally developing flow and heat transfer in

rectangular microchannels of different aspect ratios, International Journal of Heat and Mass

Transfer 49 (2006), pp 3060–3067.

[8] J. Li, G.P. Peterson (2007), 3-Dimensional numerical optimization of silicon-based high

performance parallel microchannel heat sink with liquid flow, International Journal of Heat

and Mass Transfer 50 (2007), pp 2895–2904.

[9] Nivesh Agrawal, Mahesh Dewangan (2013), Heat Transfer Analysis of Micro Channel

Heat Sink, International Journal of Science and Research, ISSN: 2319-7064 pp 177-181.

[10] Afzal Husain and Kwang-Yong Kim A numerical (2013), Shape Optimization of Micro-

Channel Heat Sink for Micro-Electronic Cooling, IEEE TRANSACTIONS ON

COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 31, NO. 2, JUNE 2008,

pp 322-330.

[11] Isam Jasim Jaber and Ajeet Kumar Rai (2014), Design and Analysis of I.C. Engine Piston

and Piston-Ring Using Catia and Ansys Software, (IJMET), Volume 5, Issue 2, pp. 64 - 73,

ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

[12] Haider Shahad Wahad, Ajeet Kumar Rai and Prabhat Kumar Sinha (2013), Modeling

And Analysis of Involute Helical Gear Using Catia5 and Ansys Softwares, Volume 4,

Issue 5, pp. 182 - 190, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.

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