ACKNOWLEDGEMENT

The present seminar report cannot see the light of the day unless it is blessed by

the benign assistance of eminent person. The help and co-ordination that I have

received from various quarters of in bringing this work to completion makes me

feel deeply indebted. This is not a work of individual but a number of persons

who helped me directly or indirectly in this journey. So, I wish to express great

fullness to all those who have helped & assisted me in bringing the final shape of

this report.

First of all, I wish to express my deep sense of gratitude to our Head of the

Department - Mr. Manoj Jha and Lecturer - Er. Ujjawal Madan for their

guidance and moral support all along the period of my study in the institute.

Last but not the least I wish to express my deep sense of gratitude to all those

who were knowingly or unknowingly with me during the seminar report.

CONTENT

1. Acknowledgement

2. Content

3. Introduction to Internal Combustion Engine

4. Classification

5. 2-Stroke Engine

a. Working Principal of 2-Stroke Engine

6. 4-Stroke Engine

a. Working Principal of 4-Stroke Engine

7. CI- Engine

a. Advantages of CI-Engine

b. Applications of CI-Engine

8. SI - Engine

INTRODUCTION

An internal combustion engine (ICE) is a heat engine where the combustion of

a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an

integral part of the working fluid flow circuit. In an internal combustion engine

the expansion of the high-temperature and high-pressure gases produced by

combustion apply direct force to some component of the engine. The force is

applied typically to pistons, turbine blades, or a nozzle. This force moves the

component over a distance, transforming chemical energy into useful mechanical

energy. The first commercially successful internal combustion engine was

created by Étienne Lenoir around 1859 and the first modern internal

combustion engine was created in 1864 by Siegfried Marcus.

The term internal combustion engine usually refers to an engine in which

combustion is intermittent, such as the more familiar four-stroke and two-stroke

piston engines, along with variants, such as the six-stroke piston engine and the

Wankel rotary engine. A second class of internal combustion engines use

continuous combustion: gas turbines, jet engines and most rocket engines, each

of which are internal combustion engines on the same principle as previously

described.[1][2] Firearms are also a form of internal combustion engine.

Internal combustion engines are quite different from external combustion

engines, such as steam or Stirling engines, in which the energy is delivered to a

working fluid not consisting of, mixed with, or contaminated by combustion

products. Working fluids can be air, hot water, pressurized water or even liquid

sodium, heated in a boiler. ICEs are usually powered by energy-dense fuels such

as gasoline or diesel, liquids derived from fossil fuels. While there are many

stationary applications, most ICEs are used in mobile applications and are the

dominant power supply for vehicles such as cars, aircraft, and boats.

Typically an ICE is fed with fossil fuels like natural gas or petroleum products

such as gasoline, diesel fuel or fuel oil. There's a growing usage of renewable

fuels like biodiesel for compression ignition engines and bioethanol or methanol

for spark ignition engines. Hydrogen is sometimes used, and can be made from

either fossil fuels or renewable energy.

CLASSIFICATION

There are several possible ways to classify internal combustion engines.

Reciprocating:

By number of strokes

Two-stroke engine

Four-stroke engine (Otto cycle)

By type of ignition

Compression-ignition engine

Spark-ignition engine

2- STROKE ENGINE

A two-stroke, or two-cycle, engine is a type of internal combustion engine

which completes a power cycle with two strokes (up and down movements) of

the piston during only one crankshaft revolution. This is in contrast to a "four-

stroke engine", which requires four strokes of the piston to complete a power

cycle. In a two-stroke engine, the end of the combustion stroke and the beginning

of the compression stroke happen simultaneously, with the intake and exhaust

(or scavenging) functions occurring at the same time.

Two-stroke engines often have a high power-to-weight ratio, usually in a narrow

range of rotational speeds called the "power band". Compared to four-stroke

engines, two-stroke engines have a greatly reduced number of moving parts, and

so can be more compact and significantly lighter.

The first commercial two-stroke engine

involving in-cylinder compression is attributed

to Scottish engineer Dugald Clerk, who patented

his design in 1881. However, unlike most later

two-stroke engines, his had a separate charging

cylinder. The crankcase-scavenged engine,

employing the area below the piston as a

charging pump, is generally credited to

Englishman Joseph Day. The first truly practical two-stroke engine is attributed

to Yorkshireman Alfred Angas Scott, who started producing twin-cylinder water-

cooled motorcycles in 1908.

Gasoline (spark ignition) versions are particularly useful in lightweight or

portable applications such as chainsaws and motorcycles. Despite that, they are

also used in diesel compression ignition engines operating in large, weight-

insensitive applications, such as marine propulsion, railway locomotives and

electricity generation. In a two-stroke engine, the heat transfer from the engine

to the cooling system is less than in a four-stroke, which means that two-stroke

engines are more efficient. However, crankcase-compression two-stroke engines,

such as the common small gasoline-powered engines, create more exhaust

emissions than four-stroke engines because their petrol lubrication mixture is

also burned in the engine, due to the engine's total-loss oiling system.

Working principle of two stroke engine

1st stroke(Upward stroke):

1st stroke: The piston is at the

bottom of the cylinder. A pipe at the

left side is opened and lets the fuel

mixture, which is already

compressed a bit, flow from the

lower to the upper part of the

cylinder. The fresh gases expulse

now the exhaust through an

ejection pipe, which is not closed by

the piston at this moment

2nd stroke(Downward stroke):

2nd stroke: After being hurried upward, the piston now covers the pipe on the

left side and the ejection pipe. Because there is no way out any more, the upper,

fresh gas mixture gets compressed now. At the same time in the part below fresh

gas is taken in by the piston driving upward through the open suction pipe. At

the upper dead-center, the compressed fuel mixture is ignited by the sparking

plug, the piston is pressed downward while he compresses at the same time the

fresh gas below. The process begins again as soon as the piston arrives at its

lowest point.

4-STROKE ENGINE

A four-stroke engine (also known as four cycle) is an internal combustion (IC)

engine in which the

piston completes four

separate strokes while

turning a crankshaft. A

stroke refers to the full

travel of the piston

along the cylinder, in

either direction. The

four separate strokes are termed:

1. Intake: This stroke of the piston begins at top dead center (T.D.C.) and

ends at bottom dead center (B.D.C.). In this stroke the intake valve must

be in the open position while the piston pulls an air-fuel mixture into the

cylinder by producing vacuum pressure into the cylinder through its

downward motion.

2. Compression: This stroke begins at B.D.C, or just at the end of the suction

stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel

mixture in preparation for ignition during the power stroke (below). Both

the intake and exhaust valves are closed during this stage.

3. Power: This is the start of the second revolution of the four stroke cycle.

At this point the crankshaft has completed a full 360 degree revolution.

While the piston is at T.D.C. (the end of the compression stroke) the

compressed air-fuel mixture is ignited by a spark plug (in a gasoline

engine) or by heat generated by high compression (diesel engines),

forcefully returning the piston to B.D.C. This stroke produces mechanical

work from the engine to turn the crankshaft.

4. Exhaust: During the exhaust stroke, the piston once again returns to T.D.C

from B.D.C while the exhaust valve is open. This action expels the spent

air-fuel mixture through the exhaust valve.

Working principle of four stroke engine

The operation of the engine is divided into 4 parts, which are called

strokes:

1st stroke (Intake or suction):

The piston sucks in the fuel-air-

mixture from the carburetor into

the cylinder.

2nd stroke (Compression):

The piston compresses the

mixture.

3rd stroke (Combustion or

power):

The spark from the spark plug

inflames the mixture. The

following explosion presses the

piston to the bottom, the gas is

operating on the piston.

4th stroke (Exhaust):

The piston presses the exhaust

out of the cylinder.

COMPRESSION-IGNITION ENGINE

The diesel engine (also known as a compression-ignition or 'CI' engine) is an

internal combustion engine in which ignition of the fuel that has been injected

into the combustion chamber is initiated by the high temperature which a gas

achieves when greatly compressed (adiabatic compression). This contrasts with

spark-ignition engines such as a petrol engine (gasoline engine) or gas engine

(using a gaseous fuel as opposed to petrol), which use a spark plug to ignite an

air-fuel mixture.

A Diesel engine built by MAN AG in 1906

The diesel engine has the highest thermal efficiency (engine efficiency) of any

practical internal or external combustion engine due to its very high

compression ratio and inherent lean burn which enables heat dissipation by the

excess air. A small efficiency loss is also avoided compared to two-stroke non-

direct-injection gasoline engines since unburnt fuel is not present at valve

overlap and therefore no fuel goes directly from the intake/injection to the

exhaust. Low-speed diesel engines (as used in ships and other applications

where overall engine weight is relatively unimportant) can have a thermal

efficiency that exceeds 50%.

Diesel engines are manufactured in two-stroke and four-stroke versions. They

were originally used as a more efficient replacement for stationary steam

engines. Since the 1910s they have been used in submarines and ships. Use in

locomotives, trucks, heavy equipment and electricity generation plants followed

later. In the 1930s, they slowly began to be used in a few automobiles. Since the

1970s, the use of diesel engines in larger on-road and off-road vehicles in the

USA increased. According to the British Society of Motor Manufacturing and

Traders, the EU average for diesel cars account for 50% of the total sold,

including 70% in France and 38% in the UK.

The world's largest diesel engine is currently a Wärtsilä-Sulzer RTA96-C

Common Rail marine diesel, which produces a peak power output of 84.42 MW

(113,210 hp) at 102 rpm.

Major advantages

Diesel engines have several advantages over other internal combustion engines:

They burn less fuel than a petrol engine performing the same work, due to

the engine's higher temperature of combustion and greater expansion

ratio.[1] Gasoline engines are typically 30% efficient while diesel engines

can convert over 45% of the fuel energy into mechanical energy.

They have no high voltage electrical ignition system, resulting in high

reliability and easy adaptation to damp environments. The absence of

coils, spark plug wires, etc., also eliminates a source of radio frequency

emissions which can interfere with navigation and communication

equipment, which is especially important in marine and aircraft

applications, and for preventing interference with radio telescopes.

The longevity of a diesel engine is generally about twice that of a petrol

engine due to the increased strength of parts used. Diesel fuel has better

lubrication properties than petrol as well. Indeed, in unit injectors, the

fuel is employed for three distinct purposes: injector lubrication, injector

cooling and injection for combustion.

Diesel fuel is distilled directly from petroleum. Distillation yields some

gasoline, but the yield would be inadequate without catalytic reforming,

which is a more costly process.

Diesel fuel is considered safer than petrol in many applications. Although

diesel fuel will burn in open air using a wick, it will not explode and does

not release a large amount of flammable vapor. The low vapor pressure of

diesel is especially advantageous in marine applications, where the

accumulation of explosive fuel-air mixtures is a particular hazard. For the

same reason, diesel engines are immune to vapor lock.

For any given partial load the fuel efficiency (mass burned per energy

produced) of a diesel engine remains nearly constant, as opposed to

petrol and turbine engines which use proportionally more fuel with

partial power outputs.

They generate less waste heat in cooling and exhaust.

Diesel engines can accept super- or turbo-charging pressure without any

natural limit, constrained only by the strength of engine components. This

is unlike petrol engines, which inevitably suffer detonation at higher

pressure.

The carbon monoxide content of the exhaust is minimal.

Biodiesel is an easily synthesized, non-petroleum-based fuel (through

transesterification) which can run directly in many diesel engines, while

gasoline engines either need adaptation to run synthetic fuels or else use

them as an additive to gasoline (e.g., ethanol added to gasohol).

Applications

The characteristics of diesel have different advantages for different applications.

Passenger cars

Diesel engines have long been popular in bigger cars and have been used in

smaller cars such as superminis like the Peugeot 205, in Europe since the 1980s.

Diesel engines tend to be more economical at regular driving speeds and are

much better at city speeds. Their reliability and life-span tend to be better (as

detailed). Some 40% or more of all cars sold in Europe are diesel-powered where

they are considered a low CO2 option. Mercedes-Benz in conjunction with Robert

Bosch GmbH produced diesel-powered passenger cars starting in 1936 and very

large numbers are used all over the world (often as "Grande Taxis" in the Third

World). Diesel-powered passenger cars are very popular in India too, since the

price of diesel fuel there is lower as compared to petrol. As a result,

predominantly petrol-powered car manufacturers including the Japanese car

manufacturers produce and market diesel-powered cars in India. Diesel-

powered cars also dominate the Indian taxi industry.

Railroad rolling stock

Diesel engines have eclipsed steam engines as the prime mover on all non-

electrified railroads in the industrialized world. The first diesel locomotives

appeared in the early 20th century, and diesel multiple units soon after. While

electric locomotives have replaced the diesel locomotive for some passenger

traffic in Europe and Asia, diesel is still today very popular for cargo-hauling

freight trains and on tracks where electrification is not feasible. Most modern

diesel locomotives are actually diesel-electric locomotives: the diesel engine is

used to power an electric generator that in turn powers electric traction motors

with no mechanical connection between diesel engine and traction. After 2000,

environmental requirements has caused higher development cost for engines,

and it has become common for passenger multiple units to use engines and

automatic mechanical gearboxes made for trucks. Up to four such combinations

might be used to get enough power in a train.

Other transport uses

Larger transport applications (trucks, buses, etc.) also benefit from the Diesel's

reliability and high torque output. Diesel displaced paraffin (or tractor

vaporising oil, TVO) in most parts of the world by the end of the 1950s with the

U.S. following some 20 years later.

Aircraft

Marine

Motorcycles

In merchant ships and boats, the same advantages apply with the relative safety

of Diesel fuel an additional benefit. The German pocket battleships were the

largest Diesel warships, but the German torpedo-boats known as E-boats

(Schnellboot) of the Second World War were also Diesel craft. Conventional

submarines have used them since before World War I, relying on the almost total

absence of carbon monoxide in the exhaust. American World War II Diesel-

electric submarines operated on two-stroke cycle, as opposed to the four-stroke

cycle that other navies used.

Non-road diesel engines

Non-road diesel engines include mobile equipment and vehicles that are not

used on the public roadways such as construction equipment and agricultural

tractors.

Military fuel standardization

NATO has a single vehicle fuel policy and has selected diesel for this purpose.

The use of a single fuel simplifies wartime logistics. NATO and the United States

Marine Corps have even been developing a diesel military motorcycle based on a

Kawasaki off road motorcycle the KLR 650, with a purpose designed naturally

aspirated direct injection diesel at Cranfield University in England, to be

produced in the USA, because motorcycles were the last remaining gasoline-

powered vehicle in their inventory. Before this, a few civilian motorcycles had

been built using adapted stationary diesel engines, but the weight and cost

disadvantages generally outweighed the efficiency gains.

Non-transport uses

Diesel engines are also used to power permanent, portable, and backup

generators, irrigation pumps, corn grinders, and coffee de-pulpers.

SPARK-IGNITION ENGINE

The term spark-ignition engine refers to internal combustion engines,

generally petrol engines, where the combustion process of the air-fuel mixture is

ignited by a spark from a spark plug. This is in contrast to compression-ignition

engines, typically diesel engines, where the heat generated from compression

together with the injection of fuel is enough to initiate the combustion process,

without needing any external spark.

Fuels

Spark-ignition engines are commonly referred to as "gasoline engines" in

America, and "petrol engines" in Britain and the rest of the world. However,

these terms are not preferred, since spark-ignition engines can (and increasingly

are) run on fuels other than petrol/gasoline, such as autogas (LPG), methanol,

ethanol, bioethanol, compressed natural gas (CNG), hydrogen, and (in drag

racing) nitromethane.

Working cycle

The working cycle of both spark-ignition and compression-ignition engines may

be either two-stroke or four-stroke.

A four-stroke spark-ignition engine is an Otto cycle engine. It consists of

following four strokes: suction or intake stroke, compression stroke, expansion

or power stroke, exhaust stroke. Each stroke consists of 180 degree rotation of

crankshaft rotation and hence a four-stroke cycle is completed through 720

degree of crank rotation. Thus for one complete cycle there is only one power

stroke while the crankshaft turns by two revolutions.