Unit v Cooling System

8/17/2019 Unit v Cooling System

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Applied Thermodynamics

UNIT V

I.C. Engine Systems


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IC Engine Cooling System

• The cooling system is provided in the IC engine for thefollowing reasons:

• The temperature of the burning gases in the engine cylinder

reaches up to 1500 to 2000°C, which is above the melting

point of the material of the cylinder body and head of theengine !"latinum, a metal which has one of the highest

melting points, melts at 1#50°C, iron at 15$0°C and

aluminium at %5#°C& Therefore, if the heat is not dissipated,

it would result in the failure of the cylinder material• 'ue to very high temperatures, the film of the lubricating

oil will get o(idi)ed, thus producing carbon deposits on

the surface This will result in piston sei)ure


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IC Engine Cooling System

• The cooling system is provided in the IC engine for thefollowing reasons:

• 'ue to overheating, large temperature differences

may lead to a distortion of the engine components

due to the thermal stresses set up This ma*es it

necessary for, the temperature variation to be *ept

to a minimum

• +igher temperatures also lower the volumetric

efficiency of the engine


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REQUIREMENTS OF EFFICIENT

COOLING SYSTEM

The !o main re"#iremens o$ an e$$iciencoolin% sysem are&

1. t must be capable of removing only about $0- of

the heat generated in the combustion chamber Toomuch removal of heat lowers the thermal efficiency

of the engine

2 t should remove heat at a fast rate when the engine

is hot 'uring the starting of the engine, the cooling

should be very slow so that the different wor*ing

parts reach their operating temperatures in a short

time


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TY'ES OF COOLING SYSTEM

• There are two types of cooling systems.!i&/ir cooling system and

ii& atercooling system


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Cooling System

et the engine up to optimum operating Temperature as 3uic*ly as possible and maintains it at that temperature

Controls the heat produced in combustion chamber, so that the engine parts

are not damaged & the oil does not break down.


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Cooling System

TOTAL FUEL (URNE)1/3 cooling system

1/3 Ehaust system

1/3 !ropels the "ehicle


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Cooling System

AIR COOLE)

#a"e metal $I%S on the outer perimeter

o the engine.

'#eat is transerred rom the engine,

through these ins, into the atmosphere.


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Cooling System

+aer ,ac-es

'esigned to keep engine block and cylinder head

cool.

'pen spaces between the outside o cylinder and

inside o cylinder block and head.

'hen engine is running at normal operating

temperature, the coolant is orced through the

water -ackets in the engine block, through the

head gasket, into the head, and back to the

radiator.

Cylinder head %as-e sits between the short block and cylinder head.

'I damaged, the coolant enters the combustion chamber and

the combustion into the cooling system. It will allow acids to orm.

*#I0E S2E

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Cooling System

+aer '#mp *Impeller 0ype

'raws the coolant rom the radiator,

through the lower radiator hose, and

then orces it through the water -ackets,

back into the radiator.

'ater pumps gasket is placed between

the water pump and the engine block to

pre"ent leakage 4i let loose it might leak

and i tightened too much it might crack.

'I the clutch an can be wiggled up and down, most likely the water pump needs

to be replaced.

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Cooling System

'+aer p#mp is dri.en /y he cran-sha$ hro#%h

'0iming 5elt *Keeps Cam and Crank shafts in time)

'ri"e/accessory 5elt *6uns alternator, power7steering

pump, (C, etc.

Serpentine 5elt875elt


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Cooling System

En%ine Fan draws air through the radiator at low speeds *i.e. 0raic

Cl#ch $an is mounted on the water pump and

is dri"en by the dri"e belt.

'It slips at higher speed, in turn slowing the an

speed down.

'Should be able to turn when the engine is turned o.

'It locks up at slow speeds, in turn speeding

up the an 6!s.


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Cooling System

Elecric $an is mounted on the radiator

and is operated by battery power.

'Is controlled by the thermostat switch.

'Some modern cars ha"e the range between

1439 to :;


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Cooling System

Radiaor is a heat echanger that remo"es heat rom the coolant passingthrough it.

'8ertical or #ori+ontal core

'8ehicles e)uipped with automatic transmission

ha"e transmission cooler build into the radiator.

'Some "ehicles *towing purposes ha"e oil cooler

mounted to >or? build into the radiator.


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Cooling System

Thermosa placed between the cylinder head and top radiator hose.

'!urpose is to close o this passage when engine is cold.

'0he temperature that the thermostat opens is

called thermostat rating .

'I thermostat is stuck open the engine will run cool,

and i the thermostat is stuck closed the engine will

"erheat.

'Can be checked by placing in the boiling water.

'#igher temperature

thermostats are used

on the modern "ehicles.


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Cooling System

Radiaor 'ress#re cap seals the coolingsystem and pressuri+e it.

'ost caps insert 1:71@ lbs o pressure.

'Each pound o pressure inserted increases the boiling

point o coolant by 1.=9 C *39 $.

5oiling point o water is 1;;9 C *:1:9 $.

'#as a built in pressure relie "al"e to pre"ent ecessi"e pressure build7up.

'#as a "acuum "ent "al"e *when engine is shut o and it cools, the coolant "olume

is reduced

Ecess coolant goes to the epansion tank.

CAUTION ne"er open the radiator cap i you

canAt s)uee+e the top radiator hose.


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Cooling System0oses

0op 6adiator hose brings the coolant back to the radiator and are moldedSpeciically or indi"idual make and model.

Bower radiator hose draws the coolant into the

engine, rom the radiator and is attached to the

water pump. *sometimes a spring is inserted inorder to pre"ent collapsing


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Cooling System

(LOC1 0EATER

'$itted into the block to keep the enginewarm during etremely cold weather.

*iesel Engines

FREE2E 'LUG'!re"ents engine block cracking

i water ree+es inside.

'Common cause o ree+e plug ailure is

rust.


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Cooling System

Unit v Cooling System

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