Cooling System-ic Engines

8/4/2019 Cooling System-ic Engines

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COOLING SYSTEM

Submitted by,

K. Chendil velan

A2326211009

M.Tech AutomobileEngineering



INTRODUCTION

• This heat is created when the gasoline and air mixture is

ignited in the combustion chamber.

• This explosion causes the piston to be forced down

inside the engine, levering the connecting rods, and

turning the crankshaft, creating power.

• Metal temperatures around the combustion chamber

can exceed 1000° F.



• Approximately 1/3 of the heat in combustion isconverted into power to drive the vehicle

• and its accessories.

• Another 1/3 of the heat is carried off into theatmosphere through the exhaust system.

• The remaining 1/3 of the heat is conducted by the Cylinder walls which will lead to preignition.

• So a suitable cooling system has to be providesto remove the heat from the cylinder walls.





AIR COOLING SYSTEM

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

• Important component of air cooling system are theFINS.

• Fins or extended surfaces are provided on thecylinder 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.





DIAGRAM OF AIR COOLING SYSTEM



LIQUID COOLING SYSTEM(WATER)

• In this method, cooling water jackets are providedaround the cylinder, cylinder head, valve seats etc.

• The water when circulated through the jackets, itabsorbs heat of combustion.

• This hot water will then be cooling in the radiatorpartially by a fan and partially by the flow developed

by the forward motion of the vehicle.

• The cooled water is again recirculated through the water jackets.







• The rate at which the water circulates isproportional to the heat output or the load onthe engine.

• Some of them contained Fans mounted behindthe radiator.

•

The fan is driven by belt and pulleys from thecrankshaft.



PUMP CIRCULATION SYSTEM

• This is similar to the thermosyphon system.

• The only difference is that a pump is used for thecirculation of coolant.

• Thermostat is also employed to control the flow of coolant.

•

The pump and fan are driven by means of beltfrom the engine crankshaft.





ADVANTAGES OF PUMP CIRCULATIONSYSTEM OVER THERMOSYPHON SYSTEM• Circulation of coolant is proportional to both

load and speed.

• Smaller water jackets can be used and hence can be employed in compact or small engines.

• The header tank is not necessary to be placed

above the engine level.• Radiator can be placed on the sides.



COMPONENTS• Water cooling system mainly consists of :

(a) Radiator,

(b) Thermostat valve,

(c) Water pump,

(d) Fan,

(e) Water Jackets, and

(f) Antifreeze mixtures.



RADIATOR

• A radiator is a type of heat exchanger.

•

It is designed to transfer heat from the hot flows through it tothe air blown through it by the fan.

• Most modern cars use aluminum radiators.

•

These radiators are made by brazing thin aluminum fins toflattened aluminum tubes.

• The fins conduct the heat from the tubes and transfer it to the

air flowing through the radiator.



RADIATOR-CONSTRUCTION

• It mainly consists of an upper tank and lowertank and between them is a core.

• The upper tank is connected to the water outletsfrom the engines jackets by a hose pipe and thelover tank is connect to the jacket inlet through

water pump by means of hose pipes.• There are 2-types of cores :

Tubular

Cellular



• In tubular type the coolant flows through thetubes and air passes around them.

• In the cellular type air passes through the tubesand coolant flows in the spaces between them.

• The thickness of tubes are made from 0.1 to

0.3 mm sheet.• Fins are made with thickness 0.1 mm.

• Core tubes and fins are made of thin copper and brass material.



CONSIDERATIONS FOR RADIATORCONSTRUCTION• CORROSION RESISTANT

• HIGH THERMAL CONDUCTIVITY

• SIZE

• WEIGHT

• COST



THERMOSTAT VALVE

• It is a valve which prevents flow of water fromthe engine to radiator, so that engine readily

reaches to its maximum efficient operatingtemperature.

• After attaining maximum efficient operating

temperature, it automatically beginsfunctioning.

• Generally, it prevents the water from flowing below 70°C.



THERMOSTAT VALVE IN OPEN ANDCLOSED CONDITION



TYPES OF THERMOSTAT

•

BELLOW TYPE THERMOSTAT

• WAX THERMOSTAT



BELLOW TYPE THERMOSTATCONSTRUCTION AND WORKING

• It contains a bronze bellow containing

liquid alcohol. Bellow is connected to the butterfly valve disc through the link.

• When the temperature of water increases,

the liquid alcohol evaporates.

• The bellow expands and in turn opens the

butterfly valve.

• Hence allows the hot water to the radiator,

where it is cooled.



WAX THERMOSTAT CONSTRUCTIONAND WORKING• There is a small cylinder located on

the engine-side of the device.

• This cylinder is filled with a wax that

begins to melt at around 180 F.

• A rod connected to the valve presses

into this wax.

• When the wax melts, it expands

significantly, pushing the rod out of

the cylinder and opening the valve.





COOLANT PUMP

• It is used to pump the circulating water.

• Impeller type pump will be mounted at the frontend.

• Pump consists of an impeller mounted on a shaftand enclosed in the pump casing.

•

The pump casing has inlet and outlet openings.• The pump is driven by means of engine output

shaft only through belts.

• When it is driven water will be pumped.



FAN

• It is driven by the engine

output shaft through same beltthat drives the pump.

• It is provided behind the

radiator and it blows air over

the radiator for cooling

purpose.



• For economic and efficient running it is requiredthat the fan must give adequate air flow at all

condition of vehicle speed and load.• At low speeds only minimum amount of air flow

is necessary and during high speeds more air

flow is necessary.• Unnecessary running of fan will consume nearly

5% of engine horse power and more noise.





AIR COOLING SYSTEM LIQUID COOLING SYSTEM

The design of this system is simple and

less costly

The design of this system is

complicated and more costly The mass of cooling system is very less. The mass of cooling system is much

more

The fuel consumption is more The fuel consumption is less

Its installation and maintenance is very easy and less costly

Its installation and maintenance isdifficult and more costly

There is no danger of leakage

or freezing of the coolant

There is a danger of leakage

or freezing of the coolantIt works smoothly and continuously.Moreover it does not depend on any coolant.

If the system fails, it may cause seriousdamage to the engine within a shorttime.





Cooling System-ic Engines

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