This project about automotive coling system

1. AUTOMOTIVE COOLING SYSTEM
Group names
1) Yoonis Adan Abdulle ID: 98
2) Yaxye Maxamed Khaliif ID: 97
3) Abdullahi Abdukadir Sheikh Hassan ID: 40
Project submitted in partial fulfilment of the
Requirements for the machine tool
Course
Faculty of Engineering
Somali national university
December 2019

2. ii
ABSTRACT
The following paper deals with the topic of Engine Cooling System in Cars, these
systems are used in the cooling of the engines of the cars, was introduced around the early
1870s.It is mandatory in every engine to have its own cooling mechanism or system. The
operation of the cooling system is to remove the excess heat from the engine. The removal of
heat prevents the damage to parts and also keeps the engine at its normal pressure. The
radiator is the main part of the cooling system. The paper begins with a brief introduction of
cooling mechanism. The next part is about its components and its working. Then we study
about its various components in details and their uses. In the last part we discuss about the
fluids or coolant used in the system. Then finally we sum up to the Conclusion.

3. iii
CONTENTS
ABSTRACT.............................................................................................................................................i
CONTENTS........................................................................................................................................... iii
LIST OF FIGURES ............................................................................................................................... iv
1.Introduction..........................................................................................................................................1
2. Literature Review................................................................................................................................2
3.Working of a Cooling System..............................................................................................................8
4. Components of cooling System ........................................................................................................10
4.1. Water Jacket...............................................................................................................................10
4.2. Water Pump ...............................................................................................................................10
4.3. Engine Fan .................................................................................................................................10
4.4. Variable Speed Fan....................................................................................................................11
4.5. Flexible Blade Fan.....................................................................................................................11
4.6. Electric Fan................................................................................................................................11
4.7. Radiator......................................................................................................................................11
4.8. Expansion Tank .........................................................................................................................12
4.9. Thermostat .................................................................................................................................12
4.10. Cooling Bypass Passage ..........................................................................................................13
4.11. Radiator Cap ............................................................................................................................14
5. Antifreeze and Coolant .....................................................................................................................15
5.1. Antifreeze...................................................................................................................................15
5.2. Types of Antifreeze....................................................................................................................16
6. Conclusion ........................................................................................................................................17
REFERENCES .....................................................................................................................................18

4. iv
LIST OF FIGURES
Fig 1: Engine Cooling System ..........................................................................................1

5. 1
1. Introduction
The burning air-fuel mixture in the engine cylinders may reach 4000°F [2200 °C] or
higher. This means engine parts get hot. However, cylinder walls must not reach hotter than
about 500°F [260°C], higher temperatures causes lubricating oil to break down and lose its
lubricating ability. Other engine parts are also damaged. To prevent overheating, the cooling
system removes the excess heat. The cooling system keeps the engine at its most efficient
temperature at all speeds and operating conditions. It also helps bring the engine up to normal
operating temperature as quickly as possible. In addition, the cooling system provides a
source of heat for the passenger-compartment heaterand-air- conditioner.
Fig 1: Engine Cooling System
Cooling system uses five basic parts:-
1. Water Jacket
2. Water Pump
3. Thermostat
4. Radiator
5. Fan

6. 2
2. Literature Review
Oliet et al. (2007) studied different factors which influence radiator performance. It
includes air, fin density, coolant flow and air inlet temperature. It is catch that heat transfer
and performance of radiator strongly affected by air & coolant mass flow rate. As air and
coolant flow increases cooling capacity also increases. When the air inlet temperature
increases, the heat transfer and thus cooling quantity decreases. Smaller fin spacing and
greater louver fin angle have higher heat transfer. Fin density may be increased till it blocks
the air flow and heat transfer rate reduced.
Sulaiman et al. (2009) use the computational Fluid Dynamics (CFD) modeling
simulation of air flow distribution from the automotive radiator fan to the radiator. The task
undertook the model the geometries of the fan and its surroundings is the first step. The
results show that the outlet air velocity is 10 m/s. The error of average outlet air velocity is
12.5 % due to difference in the tip shape of the blades. This study has shown that the CFD
simulation is a useful tool in enhancing the design of the fan blade. In this paper this study
has shown a simple solution to design a slightly aerodynamic shape of the fan hub.
Chacko et al. (2005) used the concept that the efficiency of the vehicle cooling system
strongly rely on the air flow towards the radiator core. A clear understanding of the flow
pattern inside the radiator cover is required for optimizing the radiator cover shape to increase
the flow toward the radiator core, thereby improving the thermal efficiency of the radiator.
CFD analysis of the baseline design that was validated against test data showed that
indispensable area of re-circulating flow to be inside the radiator cover. This recirculation
reduced the flow towards the radiator core, leading to a reputation of hot air pockets close to
the radiator surface and subsequent disgrace of radiator thermal efficiency. The CFD make
able optimization led to radiator cover configuration that eliminated these recirculation area
and increased the flow towards the radiator core by 34%. It is anticipated that this increase in
radiator core flow would important to increase the radiator thermal efficiency.
Jain et al. (2012) presented a computational fluid dynamics (CFD) modeling of air
flow to divide among several from a radiator axial flow fan used in an acid pump truck Tier4
Repower. CFD analysis was executed for an area weighted average static pressure is variance
at the inlet and outlet of the fan.

7. 3
Pressure contours, path line and velocity vectors were plotted for detailing the flow
characteristics for dissimilar orientations of the fan blade. This study showed how the flow of
air was intermittent by the hub obstruction, thereby resulting in unwanted reverse flow
regions. The different orientation of blades was also considered while operating CFD
analysis. The study revealed that a left oriented blade fan with counterclockwise rotation 5
performed the same as a right oriented blade fan with rotating the clockwise direction. The
CFD results were in accord with the experimental data measured during physical testing.
Singh et al. (2011) studied about the issues of geometric parameters of a centrifugal
fan with backward- and forward-curved blades has been inspected. Centrifugal fans are used
for improving the heat dissipation from the internal combustion engine surfaces. The
parameters studied in this study are number of blades, outlet angle and diameter ratio. In the
range of parameters considered, forward curved blades have 4.5% lower efficiency with 21%
higher mass flow rates and 42% higher power consumption compared to backward curved
fan. Experimental investigations suggest that engine temperature drop is significant with
forward curved blade fan with insignificant effect on mileage. Hence, use of forward fan is
recommended on the vehicles where cooling requirements are high. The results suggest that
fan with different blades would show same an action below highpressure coefficient. Increase
in the number of blades increases the flow coefficient follow by increase in power coefficient
due to better flow guidance and reduced losses.
Kumawat et al. (2014) illustrated about the axial flow fans, while incapable of
increasing high pressures, they are well relevant for handling large volumes of air at
comparatively low pressures. In general, they are low in cost, possess good efficiency and
can have blades of airfoil shape. Axial flow fans show good efficiencies, and can to work at
high static pressures if such operation is necessary. The presentation of an axial fan was
simulated using CFD results were presented in the form of velocity vector and streamlines,
which provided actual flow characteristics of air around the fan for different number of fan
blades. The different parameters similar temperature, pressure, fan noise, turbulence and were
also considered while performing CFD analysis. The study exposed that a fan with an
optimum number of fan blades performed well as compared to the fan with less number of
fan blades. In general, as a compared between the efficiency and cost, five to 12 blades are
good practical solutions.

8. 4
Barve et al. (2014) illustrated about design the fan and analyze it for its strength in
structure using the Finite Element Method (FEM) and the flow of air all side it using
Computational Fluid Dynamics (CFD) approach. The design of the fan was conducted in
phases, starting with calculating to need all dimensions followed by analytical models to
prove the concept. The results obtained from the analytical studies determined a potential for
a successful design that met greatest of the above outlined parameters. The calculations of the
Flow Rate, Static Pressure, Velocity Vectors, and Safety in Structural were made. The
structural analysis of the fan represents its strength structurally. The shear stress, Von-Misses
stresses approve the safety of the design in structural. Torque Optimization: The maximum
torque is optimized for the fan. Its value is 42.5 Nm.
Jama et al. (2014) The airflow distribution and non-uniformity across the radiator of a
full size Results from these tests have shown the best method for shielding the front end of
the vehicle in terms of airflow equality to be the horizontal way followed by the vertical
method. These shielding methods also produced the high average airflow velocity across the
radiator which is analogous to better cooling. The results showed that the method to shield
the front-end of a passenger vehicle would be to employ a flat method. This shielding method
produced the high uniform cooling airflow distribution matched to the other methods. By
extension it should also produce the lesser reduction in cooling capacity for a given intake
area.
Leong et al. (2010) described use of Nano fluids based coolant in the engine cooling
system and its effect on cooling capacity. It is found that Nano-fluid having higher thermal
conductivity than base coolant like 50% water and 50% ethylene glycol. It increases heat
transfer. So for same heat transfer, radiator core area can be decreased matched to base one. It
finds better solution to minimize area. Thermal performance of a radiator using Nano fluids is
increased with increase in pumping power required compared to same radiator using ethylene
glycol as coolant.
Sai et al. (2014) an experimental study of performance of Al2O3 Nano fluid in a car
radiator was studied in the present work. Nano fluids were tested in a car radiator by varying
the percentage of nanoparticles mix with the water. Pure water is used in a radiator and its
performance was studied. Al2O3 Nano particles are mixed with the water in 0.025%, 0.05%
and 0.1% volume concentration and the performance was studied. The performance
comparison has made between pure water and Nano fluids tested in a radiator.

9. 5
The convective heat transfer performance and flow characteristics of Al2O3
nanofluids flowing in an automotive radiator have been experimentally investigated.
Impotent increase in heat transfer was observed with the used different volume foci of
nanoparticles mixed with water. The experimental result have shown that the heat transfer
enhancement was about 4.56% for 0.025% Al2O3 nanofluid at 80ºC and this is about 12.4%
for 0.1% Al2O3 nanofluid at 80ºC.The results have shown that Al2O3 nanofluid has a high
potential for hydrodynamic flow and heat transfer enhancement in an automotive radiator.
Trivedi et al. (2012) illustrated the effect of pitch tube for best configured radiator for
optimum presentation. Heat transfer increases as the surface area of the radiator core is
increased. This leads to change the geometry by modifying the order of tubes in automotive
radiator to increase the surface area for greater heat transfer. The modification in order of
tubes in radiator is carried out by studying the effect of tube pitch by CFD analysis. Results
Shows that as the tube pitch this decreased or increased than optimum pitch of tubes, the heat
transfer rate increases. So it can suggest that optimum efficiency is coming at the pitch of 12
mm.
Yadav et al. (2011) presented parametric study on automotive radiator. In the action
evaluation, a radiator is installed into a test setup. The various parameters including inlet
coolant temperature, mass flow rate of coolant, and etc. are varied. Following remarks are
observed during learning. Influence of coolant mass flow cooling capacity of the radiator has
straightforward relation with the coolant flow rate. With an increase in the value of cooling
flow rate, corresponding increase in the value of the effectiveness and cooling capacity.
Influence of coolant inlet temperature is increase in the inlet temperature of the coolant the
cooling capacity of the radiator increases.
Bozorgan et al. (2012) This paper presented a numerical investigation of the use of
copper oxide water nanofluid as a coolant in a radiator of Chevrolet Suburban IC engine with
a given heat exchange and pumping power for Cuowater capacity. The local convective
overall heat transfer coefficients Nano fluid at different volume fractions (0.1% to 2%) was
of the coolant Reynolds number and the studied under turbulent flow conditions. Also the
effects automotive speed on the radiator performance are consider in the work. The
simulation results indicate that the total heat transfer coefficient of Nano fluid is better than
that of water alone and therefore the total heat transfer area of the radiator can be decrees.

10. 6
Nguyen et al. (2007) studied we have experimentally studied the heat transfer
enhancement delivered by a particular nanofluid, Al2O3 water mixture, for a water closed
system that is destined for cooling of microprocessors and another heated electronic
components. Data obtained for distilled water and Nano fluid with various component
concentrations, namely 0.95% and 2.2% & 4.5% have eloquently shown that the use of such
a Nano fluid appears especially advantageous for cooling of heated component. For the
particular concentration of 4.5%, a heat transfer improvement as much as 23% with respect to
that of distilled water has been achieved.
Satyamkumar et al. (2006) in this cooling system of automotive engine the water is
evaporate at more temperature, so we need to add water and also water is low capacity of
absorb the heat. By using nano fluids in radiator alternative of water, we can improve the
thermal efficiency of the radiator. So cooling effect of the radiator is improve and the overall
efficiency of engine willpower increased. As heat transfer can be improving by nanofluids, in
Automotive radiators can be made energy efficient and compact.
Vajjha et al. (2010) have been numerically studied a 3D laminar flow and heat
transfer with two different nanofluid, Al2O3 and CuO, in the ethylene glycol/water mixture
circulating through the flat tubes of an automotive radiator to evaluate their control over the
base fluid. Convective heat transfer coefficient along the flat tubes with the nanofluid flow air
considerable improvement over the base fluid.
Peyghambarzadeh et al. (2011) have recently investigated the application of
Al2O3/water nanofluids in the radiator by calculating the tube side heat transfer co-efficient.
They have recorded the interesting enhancement of 45% contrasting with the pure water
application under highly turbulent flow condition. Peyghambarzadeh et al. have used diverse
base fluids including pure water, pure ethylene glycol and their binary mixtures with Al2O3
nanoparticles and once again it was proved that nanofluids enhances the cooling efficiency of
the car radiator extensively.
Kim et al. (2009) Investigated effect of nanofluids on the performances of convective
heat transfer coefficient of a circular straightforward tube having laminar and turbulent flow
with consistent heat flux. This studied have create that the convective heat transfer coefficient
of alumina nanofluids enhanced in comparison to base fluid by 15% & 20% in laminar and
turbulent flow, separately.

11. 7
This showed that the thermal boundary layer played a dominant role in the laminar
flow while thermal conductivity played a dominant role in turbulent flow. Be that as it may
no development in convection heat transfer coefficient was noticed for amorphous molecule
nanofluids.
Naraki et al. (2013) found that thermal conductivity of CuO/water nanofluids much
higher than that of base liquid water. Author found that the total heat transfer coefficient
increases with the improvement in the nanofluid focus from (0 - 0.4) vol. %. Conversely, the
enactment of nanofluid increases the overall heat exchange coefficient up to 8% at nanofluid
focus of 0.4 vol % incomparison with the base fluid.

12. 8
3. Working of a Cooling System
The cooling system is a system of parts and fluid that work together to control an
engine’s operating temperature for optimal performance. The system is made up of passages
inside the engine block and heads, a water pump and drive belt to circulate the coolant, a
thermostat to control the temperature of the coolant, a radiator to cool the coolant, a radiator
cap to control the pressure in the system, and hoses to transfer the coolant from the engine to
the radiator. The liquid that flows through a cooling system, antifreeze, or commonly referred
to as coolant, withstands extreme hot and cold temperatures and contains rust inhibitors and
lubricants to keep the system running smoothly.
Coolant follows a circulation path that begins with the water pump. The water pump’s
impeller uses centrifugal force to draw coolant from the radiator and push it into the engine
block. Pumps are usually fan, serpentine timing belt, or timing chain driven. Nowadays, they
may even be driven electrically. If the water pump experiences a leak from the seal, a cracked
housing, broken impeller or a bearing malfunction, it can compromise the entire cooling
system, causing the vehicle to overheat. As coolant flows through the system, it picks up heat
from the engine before arriving at the thermostat. The thermostat is a valve that measures the
temperature of the coolant and opens to allow hot fluid to travel to the radiator. If the
thermostat becomes ‘stuck’ and quits working, it will affect the entire cooling system.
Once released by the thermostat, hot coolant travels through a hose to be cooled by
the radiator. The antifreeze passes through thin tubes in the radiator. It is cooled as air flow is
passed over the outside of the tubes. Depending upon the speed of the vehicle, airflow is
provided by the vehicle’s movement down the road (ram air effect) and/or cooling fans.
Radiator restrictions can compromise its ability to transfer heat. These can be either external
air flow or internal coolant flow restrictions. A malfunctioning electric cooling fan or fan
clutch can limit air flow across the radiator. Check/replace the fan clutch…the life
expectancy of water pumps and fan clutches are about the same and share a common shaft. A
failed fan clutch can cause severe damage to the water pump.
As coolant temperature increases, so does the pressure in the cooling system. This
pressure is regulated by the radiator cap. Correct system pressure is required for proper water
pump seal lubrication. Increasing the cooling system pressure raises the boiling point of the
coolant. Each one pound of increased pressure raises the boiling point by 3˚F. If the pressure

13. 9
builds up higher than the set pressure point, a spring-loaded valve in the cap will release the
pressure. If an engine has overheated, the radiator cap and thermostat should be replaced. It is
important to regularly inspect the condition of your cooling system’s belts and hoses. Soft
hoses, oil soaked belts or cracked belts and hoses can have dire effects on the entire cooling
system. Proper belt tension is also important.
Always refer to your manufacturer’s manual to determine the recommended coolant
type for your vehicle. This and the proper mixture of coolant and distilled water are the
lifeblood towards keeping your system running cool. Most parts retailers now offer a solution
of premixed coolant and distilled water. While it may seem like an unnecessary added
expense, the cleanliness of the premixed solution will pay off over time.
Mineral deposits and sediments from corroded or malfunctioning parts accumulate in
the cooling system. Before performing a cooling system repair, it is recommended to flush
the cooling system prior to installing any new parts. This is a task made even easier by using
a flush-fill kit. Failure to flush the system will contaminate the new parts being installed and
could lead to premature component failure.

14. 10
4. Components of cooling System
4.1. Water Jacket
The water jackets are open spaces between the cylinder walls and the outside shell of
the block and head. Coolant from the water pump flows first through the block water jackets.
Then the coolant flows up through the cylinder-head water jackets and back to the radiator.
4.2. Water Pump
Water pumps are impeller pumps. They attach to the front of the engine and are
driven by a belt from the crankshaft pulley. The pump circulates as much as 7500 gallons
(28,390 L) of coolant an hour. As the impeller rotates, the curved blades draw coolant from
the bottom of the radiator. They force the coolant through the pump outlet to the water
jackets.
The impeller shaft is supported on sealed bearings which never need lubrication. Seals
prevent the coolant from leaking past the bearings. The water pump is driven by the fan belt.
The water pump may also be driven by a single serpentine belt that also drives other
components.
4.3. Engine Fan
The radiator sometimes needs additional airflow through it to prevent the engine from
overheating. This usually occurs at idle and slow speed. At higher vehicle speeds, the air
rammed through the radiator by the forward motion of the vehicle provides all the cooling
that is needed. An engine fan or cooling fan pulls the additional air through the radiator. The
fan may be either a mechanical fan or an electric fan.
Engines mounted longitudinally in rear-drive vehicles usually have a mechanical fan
that mounts to the water-pump shaft. The fan is made of sheet steel or molded plastic. It has
four to seven blades and turns with the waterpump impeller. A fan shroud around the fan
directs the airflow. This increases the efficiency of the fan.

15. 11
4.4. Variable Speed Fan
Many longitudinal engines use a variable-speed fan driven through a fan clutch. The
fan clutch is a temperature-controlled fluid coupling that mounts between the water-pump
pulley and the fan.The air passing through the radiator strikes a thermostatic blade or spring
on the front of the clutch. The temperature of the air causes the thermostatic device to bend.
This operates a valve that allows silicone oil to enter or leave the fluid coupling. When the
engine is cold, the fluid coupling slips so the fan is not driven. This reduces noise and saves
engine power. As the engine warms up, the thermostatic device causes more oil to enter the
fluid coupling. Then the fan clutch begins to drive the fan.
4.5. Flexible Blade Fan
Another way to reduce the power needed to drive the fan and reduce fan noise is to
use flexible blades on the fan. In operation, the blades slant or pitch of the blades decreases as
fan speed increases. Centrifugal force flattens the blades so they take a smaller bite of air.
This reduces noise and airflow, and the power needed to turn the fan.
4.6. Electric Fan
Transverse engines in front-drive vehicles usually have an electric fan. An electric
motor turns the blades. A thermostatic switch turns on the fan only when needed. For
example, in one engine, the switch turns on the fan when the coolant reaches 200°F [93°C]. It
turns off the fan if the coolant drops below this temperature. On vehicles with air
conditioning, turning on the air conditioning bypasses the thermostatic switch. The fan runs
all the time when the air conditioner is on. The fan is turned on and off by the electronic
control module (ECM) in many vehicles with an electronic engine control system.
Most fans, mechanical and electric, are pull-type fans. They mount behind the radiator
and pull air through it. Some cars also have a push-type fan. It mounts in front of the radiator
and pushes air through it. An electric fan drains less power from the engine and creates less
noise than a mechanical fan. Also, there is no fan belt to inspect, adjust, or replace.
4.7. Radiator
The radiator is a heat exchanger that removes heat from engine coolant passing
through it. The heat transfers from the hot coolant to the cooler outside air. An automotive

16. 12
radiator has three main parts. These are a radiator core, and inlet and outlet tanks. The cores
are usually made of aluminium. The tanks may be made of plastic or metal. The core has two
sets of passages, a set of tubes, and a set of fins attached to the tubes.
The tubes run from the inlet tank to the outlet tank. Coolant flows through the tubes
and air flows between the fins. The hot coolant sends heat through the tubes to the fins. The
outside air passing between the fins picks up and carries away the heat. This lowers the
temperature of the coolant. The coolant flows from the upper tank down through the tubes to
the lower tank. Most cars use a cross-flow radiator. The tubes are horizontal so the coolant
flows from the inlet tank horizontally to the outlet tank. The cross-flow radiator takes up less
space from top to bottom. A car with a cross- flow radiator can have a lower hood line.
A typical radiator in a car with factory-installed air conditioning has seven fins per
inch [25.4 mm]. Heavy-duty radiators may have more fins and more rows of tubes. These
provide greater cooling capacity to handle additional heat loads such as those caused by the
air conditioner or turbocharger. On vehicles with an automatic transaxle or transmission, the
outlet tank has a transmission oil cooler. Many radiators have a drain valve in the bottom.
Radiators with filler neck in the top seal the opening with a radiator pressure cap.
4.8. Expansion Tank
Most cooling systems have a separate plastic reservoir or expansion tank. It is partly
filled with coolant and connected by an overflow or transfer tube to the radiator filler neck.
As the engine heats up, the coolant expands and flows through the transfer tube into the
expansion tank. When the engine is turned off and cools, the coolant contracts. This creates a
partial vacuum in the cooling system. Then the vacuum siphons coolant from the expansion
tank back through the transfer tube and into the radiator.
The cooling system with an expansion tank is a closed system. Coolant can flow back
and forth between the radiator and the expansion .tank as the engine heats and cools, this
keeps the cooling system filled for maximum cooling efficiency. The expansion tank also
eliminates air bubbles from the coolant. Coolant without air bubbles can handle more heat.
4.9. Thermostat
The thermostat is a heat-operated valve that regulates coolant temperature. It does this
by controlling coolant flow from the engine to the radiator. The thermostat is in the coolant

17. 13
passage between the cylinder head and the radiator. The valve in the thermostat opens anti
doses as coolant temperature changes. When the engine is cold, the thermostat closes. As the
engine warms up, the thermostat opens. This prevents or allows coolant to flow through the
radiator.
By closing the passage to the radiator when the engine, is cold, the engine warms up
more quickly. Engine heat stays in the engine instead of being carried to the radiator. This
shortens warmup time, wastes less fuel, and reduces exhaust emissions. After warmup, the
thermostat keeps the engine running at a higher temperature than it would without a
thermostat. The higher operating temperature improves engine efficiency and reduces exhaust
emissions.
There are several types of automotive thermostats. A heat-sensitive wax pellet
operates most thermostats; it expands with increasing temperature to open the valve. The
thermostat opens at a specific temperature or thermostat rating. This number is usually
stamped on the thermostat. Two common ratings are 185°F [85°C] and 195°F |91°C], most
thermostats begin to open at their rated temperature. They are fully open about 20°F [11°C]
higher. For example, a 195°F [91°C] starts to open at that temperature. It is fully open about
215°F [102°C].
4.10. Cooling Bypass Passage
Most engines have a small coolant bypass passage. The bypass may be an external
bypass hose on the top of the water pump, or an internal passage. It permits some coolant to
circulate within the cylinder block and head when the engine is cold and the thermostat
closed. This provides equal warming of the cylinders and prevents hot spots. Some engines
use a blocking-bypass thermostat. It has a bypass valve that restricts or closes the bypass
passage as the thermostat opens after engine warmup. This prevents coolant from continuing
to flow through the bypass.

18. 14
4.11. Radiator Cap
Cooling systems are sealed and pressurized by a radiator pressure cup. Sealing
reduces coolant loss from evaporation and allows the use of an expansion tank. Pressurizing
raises the boiling temperature of the coolant, thereby increasing cooling efficiency. At normal
atmospheric pressure, water boils at 212°F [100°C], if air pressure increases, the boiling point
also increases. For example, if the pressure is raised by 15 psi [103 kPa) over atmospheric
pressure, the boiling point is raised to about 260°F | I27°C], Every I psi [7 kPa| increase in
pressure raises the boiling point of water about 3 1/4°F [ 1,8°CJ. This is the principle on
which the pressurized cooling system works.
As the pressure in the cooling system goes up, the boiling point of the coolant goes
higher than 212 F |100°C|. There is a greater difference between coolant temperature and
outside air temperature. The hotter the coolant, the faster heat moves from the radiator to the
cooler passing air. Pressurizing the cooling system also increases water-pump efficiency.
Normal pressure in the cooling system is determined by the vehicle manufacturer. Less than
normal pressure allows coolant to be lost and may cause boiling. Too much pressure can
damage the radiator and blow off hoses. The radiator cap has a pressure-relief valve (Fig. 25-
20) to prevent excessive pressure. When the pressure goes too high, it raises the valve. Excess
pressure and coolant then escape into the expansion tank.
The radiator cap also has a vacuum-relief valve. It protects the system from
developing a vacuum that could collapse the radiator. When the engine is shut off and begins
to cool, the coolant contracts. Cold coolant takes up less space than hot coolant. As the
volume of coolant decreases, a vacuum develops in the cooling system. This pulls open the
vacuum valve. Coolant from the expansion tank then flows back into the cooling system. The
radiator pressure cap must seal tightly if the pressurized cooling system is to work properly.
When the cap is put on the filler neck, the locking lugs on the cap fit under the filler-neck
flange. The cam locking surface of the flange tightens the cap as it is turned clockwise. This
also preloads the pressure-relief valve spring.

19. 15
5. Antifreeze and Coolant
5.1. Antifreeze
Antifreeze is a chemical additive which lowers the freezing point of a waterbased
liquid. An antifreeze mixture is used to achieve freezing-point depression for cold
environments and also achieves boiling-point elevation ("anti-boil") to allow higher coolant
temperature Most automotive engines are "water"-cooled to remove waste heat, although the
"water" is actually antifreeze/water mixture and not plain water. The term engine coolant is
widely used in the automotive industry, which covers its primary function of convective heat
transfer for internal combustion engines. When used in an automotive context, corrosion
inhibitors are added to help protect vehicles' radiators, which often contain a range of
electrochemically incompatible metals (aluminium, cast iron, copper, brass, solder, et cetera).
Water pump seal lubricant is also added.
Antifreeze was developed to overcome the shortcomings of water as a heat transfer
fluid. In some engines freeze plugs (engine block expansion plugs) are placed in areas of the
engine block where coolant flows in order to protect the engine from freeze damage if the
ambient temperature drops below the freezing point of the antifreeze/water mixture. These
should not be confused with core plugs, whose purpose is to allow removal of sand used in
the casting process of engine blocks (core plugs will be pushed out if the coolant freezes,
though, assuming that they adjoin the coolant passages, which is not always the case).
On the other hand, if the engine coolant gets too hot, it might boil while inside the
engine, causing voids (pockets of steam), and leading to localized hot spots and the
catastrophic failure of the engine. If plain water were to be used as an engine coolant, it
would promote galvanic corrosion. Proper engine coolant and a pressurized coolant system
can help obviate the problems which make plain water incompatible with automotive
engines. With proper antifreeze, a wide temperature range can be tolerated by the engine
coolant, such as −34 °F (−37 °C) to +265 °F (129 °C) for 50% (by volume) propylene glycol
diluted with water and a 15 psi pressurized coolant system.

20. 16
Early engine coolant antifreeze was methanol (methyl alcohol), still used in
windshield washer fluid. As radiator caps were vented, not sealed, the methanol was lost to
evaporation, requiring frequent replenishment to avoid freezing of the coolant. Methanol also
accelerates corrosion of the metals, especially aluminium, used in the engine and cooling
systems. Ethylene glycol was developed, and soon replaced methanol as an engine cooling
system antifreeze. It has a very low volatility compared to methanol and to water.
Fluid - Freezing Point - Boiling Point
Pure Water: 0 C / 32 F - 100 C / 212 F
50/50 mix of C2H6O2/Water: -37 C / -35 F - 106 C / 223 F
70/30 mix of C2H6O2/Water: -55 C / -67 F - 113 C / 235 F
5.2. Types of Antifreeze
There are two types of ethylene-glycol antifreeze, high silicate and low silicate. This
refers to the amount of silicone silicate inhibitor added to the ethylene glycol. Most
automotive engines use high-silicate antifreeze. It protects aluminium parts. Without this
protection, aluminium flakes from the water jackets of an aluminium cylinder head may clog
the radiator. Low-silicate antifreeze is used in diesel or gasoline engines with cast-iron
cylinder block and heads. The recommended antifreeze is listed in the vehicle owner’s
manual.

21. 17
6. Conclusion
Cooling system is one of the most important parts of the automobile; it dissipates the
extra heat out of the engine which can damage the various components of the engine. The
temperature of the engine reaches high enough to weld the piston with the cylinder which can
damages the engine. So there is a provision of cooling system which keeps the various
components of the engine cool and safe. Cooling system is of two type : Air cooling and
Liquid cooling system. Air cooling system is mostly used in old cars and bikes. It is not
suitable for the engines which dissipates large amount of heat whereas liquid cooling is the
most reliable cooling system used mostly in modern cars. The mixture of water and ethylene
glycol is used in the system. Ethylene glycol is mixed in water because water freezes in
winters or in the region having temperature below freezing point, so ethylene glycol increases
the freezing point of the water. So cooling system plays a vital role as a part of an
automobile to keep it working with full efficiency.

22. 18
REFERENCES
1) Cooling Systems in Automobiles & April 2013 Cars(IJEAT)-ISSN: 2249 – 8958,
Volume-2, Issue-4,
2) Automotive Mechanics William by H Crouse and Donald L Anglin
3) Golakiya Satyamkumar, Sarvaiya Brijrajsinh, Makwana Sulay. (2006), ‘Analysis of
Radiator with Different types of Nano fluids’, Engineering Research and Studies, vol.
6, no. 1, pp. 1-3.
4) Jain S and Deshpande Y. (2012), ‘CFD Modeling of a Radiator Axial Fan for Air
Flow Distribution’, World Academy of Science, Engineering and Technology, vol. 6,
no. 11, pp. 1085–1090.
5) Jama H, Watkins S, Dixon C. (2004) ‘Airflow Distribution through the Radiator of a
Typical Australian Passenger Car’, Australasian Fluid Mechanics Conference, vol. 15,
pp. 1-4.
6) Kim D, Kwon Y, Cho Y, Cheong S, Hwang Y. (2009) ‘Convective heat transfer
characteristics of nanofluids under laminar and turbulent flow conditions’, Current
Applied Physics, vol. 9, no 2, pp. 119-123.
7) Kumawat H. (2014), ‘Modeling and Simulation of Axial Fan Using CFD’,
Mechatronic and Manufacturing Engineering, vol. 8, no. 11, pp. 1858–1862.
8) Leong K.Y, Saidur R, Kazi S.N and A.H. (2010), ‘Performance investigation of an
automotive car radiator operated with nanofluid- based coolants (nanofluid as a
coolant in a radiator)’, Applied Thermal Engineering , vol. 2, pp. 1-10.
9) Mohd Yusoff Sulaiman, Shamsul Bahari Azraai and Wan Mokhtar Wan Abdullah.
(2009), ‘CFD Modelling of Air Flow Distribution from a Fan’, Proceeding of
International Conference on Applications and Design in Mechanical Engineering, pp.
11-13.
10) Naraki M, Peyghambarzadeh S. M, Hashemabadi S, Vermahmoudi, Y. (2013)
‘Parametric study of overall heat transfer coefficient of CuO/water nanofluids in a car
radiator’, International Journal of Thermal Sciences, Vol. 66, pp. 82-90.
11) Navid Bozorgan, Komalangan Krishnakumar, Nariman Bozorgan. (2012),
‘Numerical Study on Application of CuO-Water Nanofluid in Automotive Diesel
Engine Radiator’, Modern Mechanical Engineering, vol. 2, pp. 130-136.

23. 19
12) Nguyen C.T, Roy G, Gauthier C, Galanis N. (2007) ‘Heat transfer enhancement
using Al2O3-water nanofluid for an electronic liquid cooling system’, Applied
Thermal Engineering, vol. 27, pp. 1501-1506.
13) Oliet C, Oliva A, Castro J and Pérez-Segarra C.D. (2007), ‘Parametric studies on
automotive radiators’ Applied Thermal Engineering, vol. 27, no. 11–12, pp. 2033–
2043.
14) Peyghambarzadeh S, Hashemabadi S, Hoseini S, Seifi Jamnani. (2011)
‘Experimental study of heat transfer enhancement using water/ethylene glycol based
nanofluids as a new coolant for car radiators’, International Communication in Heat
and Mass Transfer, vol. 52, no 1, pp. 1283–1290.
15) Sai Sasank P and Naik G. (2014), ‘Experimental Studies on Automotive Radiator
Performance using Water and Al2O3 Nanofluid’, International Journal of Engineering
Research & Technology, vol. 3, no. 9, pp. 1347–1350.
16) Salvio Chacko, Biswadip Shome and Vinod Kumar. (2005), ‘Numerical Simulation
for Improving Radiator Efficiency by Air Flow Optimization’, Engineering Research
Center, pp.1-10.
17) Singh O. P, Khilwani R, Sreenivasulu T and Kannan M. (2011), ‘Parametric Study of
Centrifugal Fan Performance : Experiments and Numerical Simulation’, International
Journal of Advances in Engineering & Technology, vol. 1, no. 2, pp. 33–50.
18) Trivedi P. K and Vasava N. B. (2012), ‘Effect of Variation in Pitch of Tube on Heat
Transfer Rate in Automobile Radiator by CED Analysis’, vol. 1, no. 6, pp. 180–183.
19) Tushar C. Ambedkar, Shivaprakash B. Brave, Kothavale and Nilesh Dhokane.
(2014), ‘Design and Analysis of Engine Cooling Fan’, vol. 3, pp. 114–118.
20) Vajjha R. S, Das D. K, Namburu P. K. (2010) ‘Numerical study of fluid dynamic and
heat transfer performance of Al and CuO nanofluids in the flat tubes of a radiator’,
International Journal of Heat Fluid Flow, vol. 31, no 4,
21) Yadav JP and Bharat Raj Singh. (2011), ‘Study on Performance Evaluation of
Automotive Radiator’, Applied Thermal Engineering, vol. 2, no. 2, pp. 1122–1125.
22) www.howacarworks.com/basics/how-an-engine-cooling-system-works
23) http://westislandgarage.com