cooling system 16,18.pptx

8/10/2019 cooling system 16,18.pptx

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COOLING SYSTEM


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Cooling System in IC Engine

1)Need for cooling system: A large portion of the heat formed due to combustion is

transferred to the cylinder head and walls, piston and valves.

Unless this excess heat is carried away and these parts are

adequate cooled, the engine will be damaged.

The duty of cooling system, is to keep the engine from getting

not too hot and at the same time not to keep it too cool either to

get maximum performance from engine.

2) Characteristics of efficient cooling system:

capable of removing about 30% of heat generated in the

combustion chamber

During starting of the engine the cooling should be minimum, so

that the working parts of engine reach their operating temperature

in short time


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Types of cooling system:

1) Liquid or indirect cooling system

2) Air or direct cooling system


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Liquid cooled systems:

Mainly water is used and made to circulate

through the jackets provided around the

cylinder, cylinder-head, valve ports

and seats

It consists of a long flat, thin-walled tube

with an opening, facing the water pump

outlet and a number of small openings

along its length that directs the water against the

exhaust valves.

The liquid becomes heated in its passage

through the jackets and is in turn cooled

by means of an air-cooled radiator system


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Water cooling can be carried out by any of the following

Methods:

1) Direct or non-return system

2)Thermosyphon system

3)Forced circulation cooling system

4)Evaporative cooling system

5)Pressure cooling system

1)Direct or non-return system:

useful for large installation where plenty of water is available.

Water is directly supplied through the inlet valve to the enginecooling jacket. The hot water is not cooled for reuse but simply

discharged.


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2)Thermosyphon system:

The fluid circulates through the system in the form of

convective current.

For engine application the tank A represent the cylinder jacket

while tank B represent a radiator and water act as a circulating

fluid

Fig. Principal of thermosyphon system


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3) Forced circulating cooling system

Used in large number of automobile like cars, buses and even

heavy trucksflow of water from radiators to water jacket is by convection

assisted by pump.

Fig. Principle of forced circulation cooling system using

thermostat


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water or coolant is circulated through jacket around the part of

engine, is kept in motion by a centrifugal pump .

The water is passed through the radiator where it is cooled by the

air, A thermostat is used to control the water temperature requiredfor cooling.


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4)Evaporative Cooling System

predominately used in stationary engine, cooling is because of

the evaporation the water in the cylinder jackets into the steam.


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Air cooled system is generally used in small enginessay up to 15-20 kW and in aero plane engines.

In this system fins or extended surfaces are providedon the cylinder walls, cylinder head, etc.

Heat generated due to combustion in the enginecylinder will be conducted to the fins and when theair flows over the fins, heat will be dissipated to air.

The amount of heat dissipated to air depends upon :

(a) Amount of air flowing through the fins.

(b) Fin surface area.

(c) Thermal conductivity of metal used for fins

AIR COOLED SYSTEM


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motor cycles

Air planes

Combat tanks


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Advantage of liquid cooling system

Compact design of engine

The fuel consumption of high compression liquidcooled engine is rather lower than for air cooled ones.

Because of the even cooling of the cylinder barrel and

due to jacketing makes it possible to reduce thecylinder head and valve seat temperature.

In case of water cooled engines, installation is notnecessarily at the front of the mobile vehicle, aircraft

etc. as the cooling system can be conveniently locatedwherever required. This is not possible in case of aircooled system.


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Limitation of liquid cooling system

This is a dependent system in which water circulation

in the jackets is to be ensured by additional.

Power absorbed by the pump for water circulation is

considerable and this affects the power output of theengine.

Cost of the system is considerably high.

System requires considerable maintenance of its

various parts.


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Limitations of Air-cooling System

Can be applied only to small and medium sizedengines.

Cooling is not uniform.

Higher working temperature compared to water-

cooling.

Produce more aerodynamic noise.

Specific fuel consumption is slightly higher.

Lower maximum allowable compression ratios.


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NEW INNOVATION

THERMODYNE

No need of mechanical moving parts like

belt, water pump , thermostat Utilize waste heat energy of engine

Less in cost

It is applicable in all gasoline and diesel carengine.


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THANK YOU

Documents

cooling system 16,18.pptx