Cooling System Design and Analysis: ENRP20001 Engineering Report

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ENRP20001 - COOLING SYSTEM
SCOPE DOCUMENT
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Contents
Background information..................................................................................................................3
Objective..........................................................................................................................................3
Scopes of the study..........................................................................................................................4
Milestone.........................................................................................................................................4
Deliverables.....................................................................................................................................5
Conclusion.......................................................................................................................................8
Bibliography..................................................................................................................................10

Background information
The cooling system can be defined as the process that helps the system in removing thermal
energy that is being generated in the engine during its processing. This process redirects and
exerts the flow of excess heat generated in an engine due to its operation process and maintains
the optimum internal temperature of the system for it's successful and smooth operating. The
cooling system basically requires a coolant medium for their process of cooling which is
generally fluid based including air, water, or oil-based liquid. Based on the coolant medium,
there are two types of cooling system-
Air cooling system- In this process of the cooling system, the coolant is an air-based fluid. This
process is also known as direct cooling. In this process of the cooling system, the cooling
medium i.e. air is directly circulated to the engine system for its process of cooling.
 The operation process of air cooling system- In this type of cooling system, the coolant
medium (air) is directly passed through the components of the engine system so as to
minimize the heat generated in the engine. Since the cooling medium in this type of cooling
system is directly in contact with the components of the engine, hence is termed direct
cooling system (Zaidan, 2018).
Liquid cooling system- In this process of the cooling system, the coolant medium is a liquid-
based fluid which can include water, oil, or other viscous liquid media. The process of cooling in
the liquid cooling system uses an indirect type of cooling method in which the actual process of
cooling i.e. air is not circulated in the engine system for cooling rather is used in cooling of the
coolant medium.
 The operation process of the liquid cooling system- In this type of cooling system, the
components of an engine are surrounded by a layer of liquid also called water jackets. The
liquid present in the water jacket is circulated using pumps that are incorporated in the design
of the engine. The heat generated in the engine during its operational process is absorbed by
the flowing liquid in the jackets. The heated liquid flows via a radiator which helps in the
cooling of the heated liquid. Using fans, cold air is circulated in the radiator for the liquid to
be cooled down. This cycle of cooling, circulating, and heating is continuously repeated
during the processing of the engine to maximize engine performance and reduce risks related
to heating of components (Terzi, 2018).
Objective
The cooling system is a vital addition to the engines as by using this process, the engine can
perform various tasks smoothly and for elongated hours. Liquid cooling is the later designed
cooling system that is designed to enhance the performance of cooling in the engines. This type

of cooling system benefits the engine in various aspects such as the design of the liquid cooling
system is compact, thus incorporates portability factor in their design. Using a liquid cooling
system, the components of the engine system is evenly cooled which manage the operation
ability of all the components in the engine system. The process of direct cooling system also
benefits the engine system as the design is simple and the process of maintenance and repairing
becomes easier. In this cooling system, there is no liquid medium, thus the risk of leakage of
coolants in the engine is totally eliminated. The cooling system enhances engine performance by
keeping the system cooled down to enhance the processing of more tasks. The cooling system
also increases the efficiency of an engine by keeping its component cool and also improves
production ability. The cooling system manages the heat of the engine and enhances its long-term
sustainability (Lekbir, 2018).
Scopes of the study
This study focuses on the cooling system of an engine. The cooling system is used in various
engines that exhibit heat generation. Current incorporating the cooling system in such engines
helps the engine to perform multiple tasks easily without the risks of damaging any vital or non-
vital components of an engine. Incorporating the cooling system has developed a new margin of
threshold in the performance of the engine and also in its sustainability aspect. The
advancements in the cooling system include automation which manages the flow of heat in the
processing of the engine by automatically circulating coolants when the engine displays certain
set threshold of heat generation to cool the system back to optimum running temperature. It also
deactivates the process when low heat is being generated by the engine. This process of the
automated system helps the engine in sustaining power consumption as well as reduces the cost
of management of the engine system. This system enhanced the output of services and products
in various organization thus implementing benefits in various sectors of the industrial process as
well. Future implementation of this cooling system includes the use of fluids with high cooling
efficiencies in the engine integrated cooling systems to enhance performance and output.
Currently, liquid-based cooling systems are incorporated even in portable devices such as laptops
to enhance performance output (Llopis, 2016).
Milestone
It is difficult to make generalizations about air-cooled and liquid-cooled engines. Air-cooled
diesel engines are chosen for reliability even in extreme heat, because air-cooling would be
simpler and more effective at coping with the extremes of temperatures during the depths of
winter and height of summer, than water cooling systems, and are often used in situations where
the engine runs unattended for months at a time.

Similarly, it is usually desirable to minimize the number of heat transfer stages in order to
maximize the temperature difference at each stage. However, Detroit Diesel two-stroke cycle
engines commonly use oil cooled by water, with the water in turn cooled by air.
The coolant used in many liquid-cooled engines must be renewed periodically and can freeze at
ordinary temperatures thus causing permanent engine damage when it expands. Air-cooled
engines do not require coolant service and do not suffer damage from freezing, two commonly
cited advantages for air-cooled engines. However, coolant based on propylene glycol is liquid to
−55 °C, colder than is encountered by many engines; shrinks slightly when it crystallizes, thus
avoiding damage; and has a service life over 10,000 hours, essentially the lifetime of many
engines.
A special class of experimental prototype internal combustion piston engines have been
developed over several decades with the goal of improving efficiency by reducing heat loss.
These engines are variously called adiabatic engines, due to a better approximation of adiabatic
expansion, low heat rejection engines, or high-temperature engines. They are generally diesel
engines with combustion chamber parts lined with ceramic thermal barrier coatings. Some make
use of titanium pistons and other titanium parts due to its low thermal conductivity and mass.
Some designs are able to eliminate the use of a cooling system and associated parasitic losses
altogether. Developing lubricants able to withstand the higher temperatures involved has been a
major barrier to commercialization.
There are many demands on a cooling system. One key requirement is to adequately serve the
entire engine, as the whole engine fails if just one part overheats. Therefore, it is vital that the
cooling system keeps all parts at suitably low temperatures. Liquid-cooled engines are able to
vary the size of their passageways through the engine block so that coolant flow may be tailored
to the needs of each area. Locations with either high peak temperatures (narrow islands around
the combustion chamber) or high heat flow (around exhaust ports) may require generous cooling.
This reduces the occurrence of hot spots, which are more difficult to avoid with air cooling. Air-
cooled engines may also vary their cooling capacity by using more closely spaced cooling fins in
that area, but this can make their manufacture difficult and expensive.
Deliverables
Radiators are heat exchangers used for cooling internal combustion engines, mainly in
automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary
generating plant or any similar use of such an engine.

Internal combustion engines are often cooled by circulating a liquid called engine coolant
through the engine block, where it is heated, then through a radiator where it loses heat to the
atmosphere, and then returned to the engine. Engine coolant is usually water-based, but may also
be oil. It is common to employ a water pump to force the engine coolant to circulate, and also for
an axial fan to force air through the radiator.
Radiator construction
Automobile radiators are constructed of a pair of header tanks, linked by a core with many
narrow passageways, giving a high surface area relative to volume. This core is usually made of
stacked layers of metal sheet, pressed to form channels and soldered or brazed together. For
many years radiators were made from brass or copper cores soldered to brass headers. Modern
radiators have aluminum cores, and often save money and weight by using plastic headers. This
construction is more prone to failure and less easily repaired than traditional materials.
An earlier construction method was the honeycomb radiator. Round tubes were swaged into
hexagons at their ends, then stacked together and soldered. As they only touched at their ends,
this formed what became in effect a solid water tank with many air tubes through it.
Some vintage cars use radiator cores made from coiled tube, a less efficient but simpler
construction.
Coolant pump
Radiators first used downward vertical flow, driven solely by a thermosyphon effect. Coolant is
heated in the engine, becomes less dense, and so rises. As the radiator cools the fluid, the coolant
becomes denser and falls. This effect is sufficient for low-power stationary engines but
inadequate for all but the earliest automobiles. All automobiles for many years have used
centrifugal pumps to circulate the engine coolant because natural circulation has very low flow
rates.
Heater
A system of valves or baffles, or both, is usually incorporated to simultaneously operate a small
radiator inside the vehicle. This small radiator and the associated blower fan is called the heater
core and serves to warm the cabin interior. Like the radiator, the heater core acts by removing
heat from the engine. For this reason, automotive technicians often advise operators to turn on
the heater and set it to high if the engine is overheating, to assist the main radiator

Temperature control
Waterflow control
The engine temperature on modern cars is primarily controlled by a wax-pellet type of
thermostat, a valve which opens once the engine has reached its optimum operating temperature.
When the engine is cold, the thermostat is closed except for a small bypass flow so that the
thermostat experiences changes to the coolant temperature as the engine warms up. Engine
coolant is directed by the thermostat to the inlet of the circulating pump and is returned directly
to the engine, bypassing the radiator. Directing water to circulate only through the engine allows
the engine to reach optimum operating temperature as quickly as possible whilst avoiding
localized "hot spots." Once the coolant reaches the thermostat's activation temperature, it opens,
allowing water to flow through the radiator to prevent the temperature rising higher.
Airflow control
Other factors influence the temperature of the engine, including radiator size and the type
of radiator fan. The size of the radiator (and thus its cooling capacity) is chosen such that it
can keep the engine at the design temperature under the most extreme conditions a vehicle
is likely to encounter.
Airflow speed through a radiator is a major influence on the heat it loses. Vehicle speed affects
this, in rough proportion to the engine effort, thus giving crude self-regulatory feedback. Where
an additional cooling fan is driven by the engine, this also tracks engine speed similarly.

Conclusion
Different cooling structures for the cylinder head and block and the corresponding thermal status,
thermal dissipation and frictional power dissipation were investigated in this study. A controlling
model for the cooling system of an engine was developed in order to reduce fuel consumption
and engine emissions through the use of controllable engine cooling components including an
electric water pump, an electrical fan, and a heater thermostat. The analysis indicated that the
top-bottom flow cooling structure can effectively reduce the cylinder head thermal load and
slightly increase the temperature of the cylinder liner. The combined split and top-bottom cooling
structure are proven as the optimal solution with the advantages of lower thermal and frictional
power dissipation compared with that of the conventional cooling structure.

Bibliography
Lekbir, A. H. (2018). Improved energy conversion performance of a novel design of a
concentrated photovoltaic system combined with a thermoelectric generator with advance
cooling system. Energy Conversion and Management, 177, 19-29.
Llopis, R. N.-A.-G. (2016). Experimental evaluation of a CO2 transcritical refrigeration plant
with dedicated mechanical subcooling. International Journal of Refrigeration, 69, 361-
368.
Terzi, E. C. (2018). Modeling and predictive control of a recirculating cooling water system for
an industrial plant. Journal of Process Control, 68, 205-217.
Zaidan, M. K. (2018). Thermal analysis of a solar absorption cooling system with hot and cold
storage tanks. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences,
50, 67-80.