Page 1 of 18
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 04
April 2019
Available online:https://ejbss.org/ P a g e | 1252
Study Of Plate Fin Heat Sinks For Cpu Cooling
Gnanakalimuthu.S
ABSTRACT
Experimental work of the thermal performance of a variety of heat
sinks with different base plates for enhancing heatdissipation rates in CPU have
been undertaken. In this project work the fin thickness is varied from 3mm to
5mm and also the fin pitch is varied from 1.5mm to 3.5mm. The aluminum,
copper and carbon carbon composite (ccc) materials are used as base plate of
heat sink. The base plate thickness of 2.5mm and 5mm are used. Experimental
results show that among the many design parameters, the base plate material ccc
has the most significant influenceon the thermal performance of heat sinks. The
thermal performance of the heat sinks is increased up to 42.3% by employing
ccc base plate. The resultsalso show that heat sinks with copper base plate are
superior to aluminum base. The best heat sink geometry is selected and
modified in order to reduce maximum temperature distribution and hot spots of
heat sink at center by varying fin pitch, fin thickness, base plate thickness and
changing the base plate materials. In this study a complete computer chassis
with different base plate heat sinks has been investigated. Although the
performance of heat sink is good, the temperature of heat sink at center is high.
1. INTRODUCTION
Microelectronic devices such as transistors, capacitors, inductors,
transformers and resistors are the building blocks of all electronic equipment.
For such electronics to function, a passage of electrical current is required. A
portion of this energy is dissipated as heat due to inefficiencies in a device or
the nonzero resistance to electrical current. The heat dissipation in transistors is
due to switching, dynamic short circuit and leakage power dissipations. Before
Page 2 of 18
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 04
April 2019
Available online:https://ejbss.org/ P a g e | 1253
the invention of transistors, vacuum tubes have been used instead. The vacuum
tube efficiency has been very low and has consumed a lot of electrical energy
that has been wasted as heat. Their life expectancy has also been very short. The
invention of transistors has been a breakthrough in the electrical industry and it
is consuming less electrical energy and dissipating significantly lower heat. The
early electronic circuits have been built by connecting a few transistors,
capacitors, inductors and resistors on a single layer printed board. These circuits
which dissipate little heat have limited functionality. Later on, using
semiconductor manufacturing processes, more complex electronic circuits have
been created by building many transistors on a single semiconductor piece
called a chip. Over a period of about 30 years, integrated circuits and large scale
integrated circuits with up to a few thousand to a few million transistors have
been introduced by different manufactures.Being introduced by Intel in 1971,
the Intel’s introduced 4004 microprocessors have about 2300 transistors while
the Intel Pentium 4 processor introduced in 2000 have about 42 million
transistors. During the same period, the transistor size has been reduced and
transistor density of the chip has been increased.
The performance levels of electronic systems such as computers are increasing
rapidly, while keeping the temperatures of heat sources under control has been a
challenge. All electronic equipments depend on the flow and control of electrical
current to perform a variety of functions. Whenever electrical current flows
through a resistive element, heat is generated. The heat dissipation is one of the
most critical aspects to be considered in order to maintain the continuous
operation. The electronic industry requires increased forced-air cooling limits to
cool heat sources of CPUs adequately. Improving the air -cooled heat sink thermal
performance is one of the critical areas for increasing the overall air-cooling limit.
Page 3 of 18
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 04
April 2019
Available online:https://ejbss.org/ P a g e | 1254
Experimentalsetup
This test setup is not done for the whole computer chassis system. It is
set for a smaller domain in order to simplify the experiments. The power supply is
connected to the constant voltage regulator and also given to temperature scanner.
Power is distributed to DC regulator supply from the constant voltage regulator.
The experimental setup is arranged with an electrical heater of size 30 x 30 mm as
a heat source to imitate a processor and it is supplied by direct current power
supply. A heater strip is mounted on a piece of circuit board which in turn, is
mounted on a piece of insulation. The insulationis machined so that the top
surface of the heater lies just below the top surface of the insulation.
The insulation is drilled or milled to allow routing of power and
thermocouple wires to minimize free stream interference in the vicinity of the
heat sink. The heater is fixed with heat sink using anabondcompound with
thermal conductivity of 0.437 W/m°Cand Wakefield thermal compound with
thermal conductivity of 0.735 W/m°C to make proper surface contact between the
heat sink and the heater. The heat sink rejects the heat into air the flow of which is
enhanced by theblower.
Theareacoveredbytheresistancecoils(ontheheatstrip)islessthan the area
of the base of the heat sink, so that the base of the heat sink completely covers the
active heater section. This ensures that the entire power output of the heater is
dissipated through the heat sink. Fig.1 shows the schematic representation of the
arrangement for the experimentation.
As a heat source to imitate a processor a 30 x 30 mm strip is attached to
different heat sinks models and heated with heat loads of 100W. Since the test
setup is an open domain, the
atmospherictemperatureisthetemperatureoftheairblowntotheheatsink.The
atmospheric air is passed around the heat sink which is heated and then is
