Thermal 1unit3

8/10/2019 Thermal 1unit3

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Internal Combust ion Eng ine

(ICE)

It is an engine in which

the burning of a fueloccurs in a confined

space called a combustion chamber andthe products of combustion takes part

directly in power generation.

Eg: Petrol, Diesel, and Gas engines, opencyclegas turbines.
http://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Gas_turbinehttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Combustionhttp://en.wikipedia.org/wiki/Combustion


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ECE & ICE


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External Combust ion Eng ine

(ECE)

It is a heat enginewhich burns fuelto heat a

separate fluid (usually water) which then,

in turn, performs work.

Eg: Steam Engines, Steam turbines and

Stirling engines.
http://en.wikipedia.org/wiki/Heat_enginehttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Heat_enginehttp://en.wikipedia.org/wiki/Heat_enginehttp://en.wikipedia.org/wiki/Heat_engine


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Example

In steam engines,

the combustion processare used to produce steam

then, steam is used todo work on a steam piston.
http://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Steam_enginehttp://en.wikipedia.org/wiki/Steam_engine


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Comparison of ECE and ICEE.C Engine I.C. Engine

The combustion of fuel takes place

outs idethe engine working cylinder


ins idethe engine workingcylinder.

The working of ECE is smoo th and s i len t

running.

These engines are very noisy

The working pressure and temperature

inside the engine cylinder is low

The working pressure and temperature

inside the cylinder is very high

Because of low-pressure temperature,

ordinary al loyscan be used.

Because of very high pressure and

temperature special al loys must be

used.

It is heavy and cumbersome. It has low

efficiency about 20 -25 %

It has high efficiency about 35-40 %.

It can not be started instantaneously It can be started instantaneously.


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Components of ICE


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Components of ICE


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http://jschangsong.en.alibaba.com/offerdetail/53661689/Sell_Internal_Combustion_Engine_Parts/showimg.html


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Crank Shaft


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http://upload.wikimedia.org/wikipedia/commons/0/0c/Moore-single-cylinder-gasoline-engine.jpg


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Crank Shaft


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http://upload.wikimedia.org/wikipedia/commons/f/ff/Early-gasoline-engine-models.jpg


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http://upload.wikimedia.org/wikipedia/commons/b/ba/Colorized_car_engine.jpg


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Functions of COMPONENTS

Cylinder : Provides space for combustion

Cylinder liner :provides inner surface for CC.

Water Jacket :To cool the engine and to

prevent overheatingCylinder head : Covers the cylinder top andholds spark plug,

valves etc.

Piston : To develop mechanical energy

Piston rings : To lubricate the cylinder

andprevent gas leak into crank case


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Connecting rod : To convert reciprocatingmotion of the piston into oscillating

motion.

Crankshaft : To convert oscillating motion

into rotary motion.

Flywheel : To smoothen the turning moment.

Crank case : To hold crankshaft and luboil.


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Valves : To control air and gas flow

Spark Plug :To ignite air-fuel mixture

Fuel Injector :To inject fuel

Gudgeon pin :To connect small end of

connecting rod with piston

Crank pin : To connect big end ofconnecting rod with crank.

Timing gears :To transmit power from

crankshaft to cam shaft

Cam, Push Rod, Rocker arm:To operate valves


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CLASSIFICATION OF I.C.

ENGINES


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(I) According to the type of fuel

used

Petrol engine

Diesel engines or oil engine

and

Gas engine


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Petrol engine

A CAR ENGINE


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Petrol engine


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Petrol engine


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Petrol engine
http://www.west-wales-models.co.uk/images/shop/engines/da-50r%5b1%5d-b.jpg


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Petrol engine

Petrol+Air


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Water Cooled Diesel

Engine

Diesel Engine


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Diesel Engine


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Diesel Engine


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Gas Engine


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2-Stroke DTX 23 cc Gas Engine
http://www.duratrax.com/cars/dtxd97-engineb-2.jpg


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Gas engine

Gas + Air


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(II) According to the cycle of

operat ion

Otto cycle (constant volume cycle) engines

Diesel cycle (constant pressure cycle)

engines, and

Dual combustion cycle (semi diesel or

limited pressure cycle) engines


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Otto Cycle


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OTTO CYCLE


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Diesel Cycle


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Dual Cycle

(III) A di t th d f th


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(III) According to the speedof the

engine

Slow speed engines,

Medium speed engines, and

High speed engines


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16 HP 850 RPM Lister Type, Slow

Speed Diesel Engine


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High Speed Diesel Engine

(3000 rpm)
http://baldwindiesels.railfan.net/magazine-1936/page22pic1.jpg


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130-h.p., six cylinder, high speed Diesel engine,

illustrating the main components


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the interior of a 130-h.p., high speed Diesel

engine


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Thi i d l


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This engine develops

320 to 360 brake horsepower at 800 to 900 revolutions per

minute

(IV) A di t


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(IV) According to the cool ing

system

Air cooled engines

Water cooled engines, and

Evaporative cooling engines.


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Air Cooled Petrol Engine


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http://shengqisport.en.alibaba.com/product/50185425/50588370/Dirt_Bikes/Dirt_Bike__Air_Cooled_Stunt_Bike___Aluminum_Frame_.html


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Ai C l d P t l E i


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Cooling System: Air

cooling by a fan fixed

on flywheel and

through streamline

designed cowling.



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Air Cooled Diesel Engine

13 hp

aircooledfour stroke

diesel

engine.


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Compressor unit, air cooled, with Diesel engine, 2

stages, for working pressures up to 40 bar.


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Water Cooled Petrol Engine


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Di t Bik (GAS 114) (W t C l d E i


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Dirt Bike (GAS-114) (Water Cooled Engine;

Front And Rear Disc Breaks)


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Cooling : Engine can be cooled with the help of runthrough water supply arrangement or with radiator / tank

cooling in water cooled engine.

Diesel Engine And Engine Pumpset

ISUZU 6BD1T Water Cooled


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ISUZU 6BD1T Water-Cooled

Diesel Engine
http://engine.en.alibaba.com/product/10105578/50944821/ISUZU_Series/ISUZU_6BD1T_Water_Cooled_Diesel_Engine.html


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India tractor with water cooled 2 cylinder 4 stroke Diesel engine. 10

gears forward and 2 gears reverse are for 1 to 22 km/h speed.

(V) According to the method o f


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(V) According to the method o f

fuel inject ion

Carburettor engines,

Air injection engines

Airless or solid injection engines

(VI) According to the method of


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(VI) According to the method of

igni t ingthe fuel

Spark ignition engines (brieflywritten as S.I. engines)

Compression ignition engines

(briefly written as C.I.engines), and

(VII) According to the number of


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(VII) According to the number of

st rokes per cycle

Four stroke cycle engines,

and

Two stroke cycle engines


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(IX) According to the or ientation of


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(IX) According to the or ientation of

cyl inders

Vertical engines

Horizontal engines


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Vertical engines


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Vertical engines


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Vertical engines


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Horizontal engines


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Horizontal engines


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Horizontal engines


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Horizontal engines


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(X) According to the arrangement


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(X) According to the arrangement

of Mu lt i cyl inder eng ines

In-line multi-cylinder engines

Vertical engines,

Horizontal engines

Radial engines,

V-type multi-cylinder engines

Opposite cylinder engines and

Opposite piston engines

V ti l I li i


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Vertical In line engines

V ti l I li i


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V ti l I li i


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Vertical Inline engines

Volvos 5-cylinder (in-line) aluminium


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y ( )

block Petrol Engine (1991)

I li lti li d i


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A i li 4 li d i


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An inline 4 cylinder engine

I li lti li d i


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H i t l I li i


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Horizontal Inline engines

Radial Engine


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Radial Engine
http://upload.wikimedia.org/wikipedia/commons/2/2e/Radial_engine_large.gif


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http://upload.wikimedia.org/wikipedia/commons/a/a4/Emile_Salmson_watercooled_radial_engine_1915.jpg


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http://upload.wikimedia.org/wikipedia/commons/a/a4/Emile_Salmson_watercooled_radial_engine_1915.jpg


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Twentyfour Cylinder multibanked, six bank radial,


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petrol engine, four strokes, liquid cooled Engine

V type multi cylinder engines


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V-type multi-cylinder engines


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V Engine - the cylinders are arranged in two


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banks set at an angle to one another
http://auto.howstuffworks.com/engine-v.htm


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Flat (also known as horizontally opposed or a

boxer) -- the cylinders are arranged in two banks


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boxer) the cylinders are arranged in two banks

on opposite sides of the engine

A V-6 cylinder engine

Opposite Cylinder Engine


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Opposite Piston engines
http://auto.howstuffworks.com/engine-flat.htm


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Opposite Piston engines

Opposed Piston Engine


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(XI) According to the valve


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mechanism

Overhead valve engines

IHead engines

T-Head Engines

F Head Engines

Side valve engines



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IHead

engines


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T-Head Engines


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T Head Engines

L - Head


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L Head

F - Head


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F Head

(XII) According to the type of

ti f ki l t


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motion of working element

Reciprocating IC engines

Rotary IC engines


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(XIII) According to the method of

governing


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governing

Hit and miss governed engines

Quantitatively governed engines, and

Qualitatively governed engines


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4 Processes in all IC

Engines


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(i) Suction Process,

(ii) Compression Process,

(iii) Expansion or working Process,

(iv) Exhaust Process

An inline 4 cylinder engine


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y g


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2S and 4S Engine


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4S Engine

FOUR STROKE CYCLE ENGINE


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In a four stroke engine,the working cycle is completed in four

st rokes of the piston or two revolut ions

of the crankshaft.

This is achieved by carrying out

suction, compression expansion andexhaust processes in each stroke.


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Working of

a

4S Petrol Engine

Intake (Suction) Process


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( )


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Compression Process


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Power Process


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Exhaust Process


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Theoretical Valve Timing Diagram

for 4S Cycle Petrol Engine


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for 4S Cycle Petrol Engine

Actual Valve Timing Diagram for

4S Cycle Petrol Engine


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SI engine


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LOW SPEED HIGH SPEEDIVO 10 bTDC 10 bTDC

IVC 10 aBDC 60 aBDC

IGN 15 bTDC 30 bTDC

EVO 25 bBDC 55bBDC

EVC 05 aTDC 20aTDC

Ideal P-V Diagram of 4S Cycle

Petrol Engine


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Petrol Engine

Actual p-V Diagram for



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Working of

4S Cycle Diesel Engine


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Actual Valve Timing Diagram for



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Ideal p-V Diagram for



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Actual p-V Diagram for



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IMPORTANT NOTE


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From the thermodynamic pointof view there is no d i fference

between two stroke and fourstroke cycle engines,

The difference is purely

mechanical.

ADVANTAGES of

2S OVER 4S CYCLE ENGINES


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2S OVER 4S CYCLE ENGINES

It gives tw ice the number of power st rokesthan the four stroke cycle engine at the sameengine speed.

In actual practice, a two stroke cycle

engine develops 1.7 to 1.8 times (greatervalue for slow speed engines) the powerdeveloped by four stroke cycle engine ofthe same dimensions and speed.

This is due to lower compression ratio andeffective stroke being less than thetheoretical stroke.

Disadvantages of

2S over 4S Cycle Engines


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2S over 4S Cycle Engines Low thermal eff ic iency

because of lower compressionratio.

Low overal l eff ic iency, due to more loss of fuel due tovalve overlap.

High pol lu t ing em iss ions.

High Cyl inder temperature because of high rate ofpower stroke.

Greater wear and tear due to High Cylindertemperature

High capaci ty of the coo l ing sys temis required.

Large consumption of lubricating oil because of highoperating temperature.

Noisy exhaust because of short time available for theirdelivery.


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2S Engine

TWO STROKE CYCLE ENGINE


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The working cycle is completed in two st rokes

of the piston or one revolut ion of thecrankshaft.

This is achieved by carrying out

the suction and compression processes inone stroke (or more precisely in inward

stroke),

expansion and exhaust process in thesecond stroke (or more precisely in outward

stroke).


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Working of 2S Cycle Petrol Engine


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Theoretical Port Timing Diagram of



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TPO, EPOTPC,

EPC

y g

Actual Port Timing Diagram of 2S

Cycle Petrol Engine


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y g


Petrol Engine


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g

Actual P-V Diagram of 2S Cycle

Petrol Engine


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g

Working of 2S Cycle Diesel Engine


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Actual Port Timing Diagram of 2S

Cycle Diesel Engine


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y g


Diesel Engine


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g

Actual P-V Diagram of 2S Cycle

Diesel Engine


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PE and DE

Working of a Petrol Engine


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WORING of a 4S Diesel Engine


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PETROL ENGINES DIESEL ENGINES

A petrol engine draws a i t of A diesel engine draws l i during suction

Comparison of PE with DE


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A petrol engine draws a mixture of

petrol and air during suction stroke

A diesel engine draws only air during suction

stroke

The carburet tor is employed to mix air

and petrol in the required proportion

and to supply it to the engine during

suction stroke

The in jector or atomiser is employed to inject

the fuel at the end of compression stroke

Pressure at the end of compression is

about 10 bar

Pressureat the end of compression is about 35

75 bar

The charge (i.e., petrol and air mixture

is ignited with the help of spark

plug.

The fuel is injected in the form of fine spray. The

temperature of the compressed air (about

600C) at a pressure of about 35 bar is

sufficiently high to ignite the fuel.


approximately at constant vo lum e.In other words. It works on Otto

cyc le


approximately at constant pressure. Inother words, it works on Diesel cy cle

A petrol engine has compression ratio

approximately from 6 to 10.

A diesel engine has compression ratio

approximately from 15 to 25

The starting is easy due to low

compression ratio.

The starting is little dif f icul tdue to high

compression ratio

As the compression ratio is low, As the compression ratio is high, the


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p ,

the petrol engines are l ighter

and cheaper

p g ,

diesel engines are heavier and cost l ier

The runn ing cost of a petrol

engine is highercost of petrol.

The runn ing cost of diesel engine is

low because of the lowercost of diesel

The maintenancecost is less The maintenance cost is more

The thermal eff icienc y is about25%

The thermal eff ic iencyis about 35%

Overheat ing trouble is more

due to low thermal efficiency

Overheating trouble is lessdue to high

thermal efficiency

These are high speedengines The are relatively low speedengines

The petrol engines are generally The diesel engines are generally

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