1. a ICE POWER POINT.ppt

Engr. Raymundo E. Feliciano, ME,MSME

Chapter 1. Introduction
1.1 Historical Development of an
Engine
The distinctive feature of our civilization today, one
that makes it different from all others, is wide use of
mechanical power . At one time , the primary source of
power for the work was chiefly man’s muscles. Later ,
animals were trained to help and afterwards the wind and
the running stream were harnessed . But, the great step
was taken in this direction when man learned the art of
energy conversion from one form to another. The
machine which does this job of energy conversion is called an
Engine .

1.1 Historical Development of an
Engine
The credit of inventing the Spark Ignition (SI)Engine
goes to Nicolaus A. Otto(1876), whereas Compression
Ignition (CI)Engine was invented by Rudolf Diesel (1892) and
Wankel Engine invented by Felix Wankel(1929) .

Engine
- An engine is the Device which transforms one form of energy
into another form.
However, while transforming energy from one form to another, the
efficiency of conversion plays an important role.
Heat Engine
- Is a device which transforms the chemical energy of a fuel into
thermal energy and utilizes this thermal energy to perform
useful work.

Classification of Heat Engine
- An engine whether Internal Combustion or External combustion
Are two types Rotary and Reciprocating.
Reciprocating
1. Gasoline Engine ( SI Engine)
2. Diesel Engine ( CI Engine)
Rotary
1. Wankel Engine

Classification of IC an Engine
- An engine whether Internal Combustion or External combustion
Are two types Rotary and Reciprocating.
Reciprocating
1. Gasoline Engine ( SI Engine)
2. Diesel Engine ( CI Engine)
Rotary
1. Wankel Engine

1.2. Main Components
Internal Combustion Engines
Cylinder Block- The Cylinder block is the main supporting structure for
the various component

IC Engine Components
Cylinder – It is a cylindrical vessel or space in which the piston makes
reciprocating motion.

Piston – It is a cylindrical component fitted into the cylinder

Inlet and exhaust Valves - – It is commonly mushroom shape d
poppet type.

Spark Plug - – It is the component that initiates the combustion
process in Spark Ignition (SI) Engines.

Intake Manifold- – It is The pipe which connects the intake system to
the inlet valve and through which air fuel mixture is drawn to the
cylinder.

Exhaust Manifold- – It is the pipe which connects the exhaust system
to the exhaust valve of the engine and through which the the product of
combustion escape into the atmosphere.

Piston Rings - – It provide a tight seal between piston and the cylinder
wall thus preventing leakage of combustion gases..

Gudgeon Pin - – It forms the link between the small end of the
connecting rod and the piston..

Connecting Rods - – It interconnects the piston and the crankshaft .

Crankshaft - – It converts the reciprocating motion of the piston into
useful rotary motion of the output shaft.

Combustion chamber – It is the space enclosed in the upper part of
the cylinder , by the cylinder head and the piston top during combustion
process.

camshaft- – Its associated parts control the opening and closing of the
two valves.

Cams- – It is made as integral parts of the camshaft and are designed in
such away to open the valves in correct timing.

Flywheel- – It is attached to the output shaft in order to achieve a
uniform torque .

Assembly of parts:

IC Engine Nomenclature's
Assembly of parts:

1.3 4 Stroke Spark Ignition (SI) Engine
It requires four stroke of the piston to complete one cycle
of operation in an engine cylinder .
The four stroke of SI Engine sucking fuel- air mixture in the carburettor
known as charge are described below:
1. Suction or Charging stroke( Intake Stroke)- in this stroke the
inlet valve opens and charged is sucked into the cylinder as the piston
moves downward form Top Dead Center (TDC) to Bottom Dead
Center (BDC).
2. Compression Stroke – in this stroke both inlet and exhaust valves
are closed and the charged is compressed as the piston moves
upwards from BDC to TDC. As a result of Compression , the pressure
and temperature of charge increases considerably this completes one
revolution of the crankshaft.

1.3 4 Stroke Spark Ignition (SI) Engine
3. Expansion or Working Stroke ( Power Stroke)- Shortly before the
piston reaches the TDC (during compression stroke). The charge is
ignited with the help of Spark plug. It suddenly increases the pressure
and temperature of the products of combustion. Due to the rise in
pressure the piston pushed down with great force.
4. Exhaust stroke – In this stroke, the Exhaust valve is open as the
piston moves from BDC to TDC . This movements of piston pushes
out the product of combustion from the cylinder and are exhausted
through the exhaust valve into the atmosphere this complete the
cycle and the engine cylinder is ready to suck the charge again .

1.6 Cylinder Arrangement of IC Engine

1.4 4 Stroke Compression Ignition
(CI) Engine or Diesel Engine
It is known to be Compression Ignition Engine because
the ignition takes place due to the heat produced in the engine
cylinder at the end of compression stroke.
The four stroke of Diesel Engine sucking pure air are described below:
1. Suction or Charging stroke( Intake Stroke)- in this stroke the
inlet valve opens and pure air is sucked into the cylinder as the piston
moves downwards from TDC to BDC.
2. Compression Stroke – in this stroke both inlet and exhaust valves
are closed and the air is compressed as the piston moves upwards
from BDC to TDC. As a result of Compression , the pressure and
temperature of air increases considerably this completes one
revolution of the crankshaft.

3. Expansion or Working Stroke ( Power Stroke)- Shortly before the
piston reaches the TDC (during compression stroke) fuel is injected
in the form of very fine spray into the engine cylinder through the
nozzle known as fuel injection valve. At this moment the
temperature of compressed air is sufficiently high to ignite the fuel.
It suddenly increases the pressure and temperature of the product of
combustion . Due to the increase of the pressure the piston is pushed
down in great force.
4. Exhaust stroke – In this stroke, the Exhaust valve is open as the
piston moves from BDC to TDC . This movements of piston pushes
out the product of combustion from the cylinder and are exhausted
through the exhaust valve into the atmosphere this complete the
cycle and the engine cylinder is ready to suck the air again .

1.5 2 Stroke IC Engine
The two stroke engine the cycle is completed in one revolution of
crankshaft . ( Invented by Dugald Clark ,1878)
The main difference between two stroke and four stroke is in the method
of filling the fresh charge and removing the burnt gases from the
cylinder. In the four stroke engine these operations are performed by
the engine piston during the suction and exhaust strokes respectively.
In the two stroke engine , the filling process is accomplished by the
charge compressed in crankcase or a blower. The Induction of the
compressed charge moves out the product of combustion through
exhaust ports. Therefore two strokes are sufficient to complete the
cycle one for compressing fresh charge and the other for power stroke.

Piston moves only twice in a two stroke engine. The first movement is
called the compression stroke and the second stroke is called the power
stroke.
1. Compression stroke: Compression stroke is an act of compressing
fuel. During compression stroke piston goes up compressing the fuel
in to the engine.
2. Power stroke: Compression stroke is followed by power stroke.
During a power stroke the fuel is ignited, which pushes the piston
down producing a lot of power and torque. It also involves in taking
new fuel and air to start compression again.

Comparison of Four Stroke and Two stroke Engines:
 As a 2 stroke engine receives power stroke twice than that of four
stroke engines they generate more power and torque. Also, 2 stroke
engines are noisier when compared to four stroke engines.
 2 stroke engines does all the act of exhausting and taking fuel in at a
single stroke i.e. power stroke, it is more polluting.
 2 stroke engines want more lubrication when compared to four stroke
engines. One will have to keep the engine lubricated frequently (oiling)
for smooth riding experience.
 2 stroke engines are not suitable for long term as they tend to produce
more noise and pollution simultaneously.

 4 stroke engines are fuel efficient, smoother riding experience, less
polluting and least noisy.
 4 stroke engines do not emit as much smoke as 2 stroke ones do. They
also have a long term life.
Conclusion:
Though a two stroke engine emits more power and torque,
they are not suited for the day to day activity. Moreover, they are
not fuel efficient, have a short life, polluting agent and also
noisier than 4 stroke ones. Therefore, 4 stoke engines should be
preferred as they are more fuel efficient, less polluting, and
affordable. 4 stroke bikes are ideal for day to day activities.

1.5 Cylinder Arrangement
1. In- line
2. U- Cylinder
3. V- Cylinder
4. X- cylinder
5. Radial
6. H- Type
7. Opposed Cylinder
8. Opposed Piston
9. Delta Type

Chapter 2 Thermodynamics of
IC Engines

2.1 Introduction
 State
equation and
Constants
 Entropy
change of a
process
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Ideal Gas Isentropic Relations
 State
equation and
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2.2 Ideal Air Standard Cycles
Carnot Cycle

Brayton CycLe
 Dual Cycle Thermal Efficiency
where: γ = Cp/Cv

2.4 Actual Cycles and Engine Efficiencies

Performance Equations and Engine
Characteristics

Chapter 4. Fuels
Introduction :
Internal combustion engine can be operated on
different kind of fuels, including liquid , gaseous, and even
solid materials. The character of the fuels used may have
considerable influence on the design, output , efficiency of
fuel consumption, reliability and durability of the engine.
Therefor , more research has been carried out in this field
than in any other aspect of engine development.
Over 99% of the worlds internal combustion engines
use liquid fuels
Derived from petroleum and some countries use similar fuels
derived by hydrogenation of coal.

Chapter 4. Fuels
Important fuels for IC engines are listed below :
A. Liquid Fuels- Gasoline , Kerosene, Diesel
B. Gaseous Fuels- Blast Furnace gas, Coal gas , Natural Gas
C. Solid Fuels- Powdered Coal
D. Non- Petroleum Fuels- Methyl Alcohol , Ethyl Alcohol

Chapter 4. Fuels
Important Qualities of SI Engine Fuels
A. Volatility
B. Detonation and Pre ignition Characteristics (Anti Knocking
Characteristics)
C. Heat of Combustion
D. Heat of Evaporation
E. Chemical stability, neutrality and Cleanliness
F. Safely
G. Cost and availability

Chapter 4. Fuels
Volatility
-is one of the most important characteristics of liquid fuel.
It is defined as the tendency of liquid to evaporate and
controls the fuel air ratio.
Detonation
-It is a loud pulsating noise heard within the engine cylinder (
also known as knocking or pinking).It is the propagation of a
high speed pressure wave created by the auto ignition of end
portion of unburnt fuel. The blow of this pressure wave may be
sufficient enough to break the piston. Thus detonation is
harmfulto the engine and must be avoided.

Chapter 4. Fuels
Factors that causes detonation:
a. The shape of combustion chamber
b. The relative position of the spark plug in case of petrol
engine.
c. The chemical nature of the fuel
d. The initial pressure and temperature of the fuel
e. The rate of combustion of that portion the fuel first ignite.
This portion of the fuel in heating up, compresses the
remaining unburnt fuel, thus producing the condition of
auto ignition to occur.

Chapter 4. Fuels
The following are the chief effects due to detonation:
a. A loud pulsating noise accompanied by vibration of the
engine.
b. An increase of heat lost to the surface of combustion
chamber.
c. An increase in Carbon deposits.

Chapter 4. Fuels
Sulphur Content
- A good fuel must possess low sulphur content because
formation of sulphuric acids causes corrosion. Other sulphur
compounds formed slowdown the action of tetraethyl lead
and decrease the anti knock quality of fuel.
Cleanliness
- The fuel must be clean and should not contain dirt or dust.
The corrosion can cause pitting in the valve faces there Can
therefore, be leakage of hot gasese and lowering of
compression ratio.

Chapter 4. Fuels
Ratings of SI Engine Fuels
- the quality of fuels is judged on the basic of its fuel ratings .
There are different methods in adopting for fuel ratings:
a. Highest Useful Compression Ratio ( HUCR)
b. Octane Number
c. Performance Number

Chapter 4. Fuels
A. Highest Useful Compression Ratio ( HUCR)
- If the compression ratio is increased for a particular fuel ,
detonation starts at some compression ratio. This
compression ratio is called HUCR . This test is carried out on a
variable compression engine. The HUCR is 10.96 for iso-
octane and 3.75 for N- Heptane . This method is no longer
popular.

Chapter 4. Fuels
B. Octane Number
- This method was introduced by CFR ( Cooperative Fuel
Research ) committee , USA.
Normal heptane is arbitrarily placed at O.N.= 0 due to its worst
anti knock characteristics and iso – octane is placed at O.N.=
100 due to its best anti knock characteristics. The octane
number of any fuel is the percentage of iso-octane by volume
in the mixture of iso- octane and normal heptane which gives
the same anti knock characteristics as the fuel under
standard test conditions.

Chapter 4. Fuels
C. Performance Number
- With the advancement of fuel technology many
hydrocarbons have been found to have octane number more
than 100. For example , aviation fuels have O.N. > 100 . To
express their relative rating, another scale has been devised
which is called Performance Number (PN).
It is based on the indicated power produced by the engine
operating under standard conditions. It indicates the
maximum power produced by an engine without knocking in
the fuel used over the maximum power produced by an
engine with out knocking using iso –octane.

Chapter 4. Fuels
Dopes or Additives:
- Various dopes or additives are mixed with petrol to achieve
desirable properties . These maybe hydrocarbons , non
hydrocarbons, organic or inorganic compounds.
important additives are:
a. Benzole
b. Ethyl Alcohol
c. Tetra Ethyl Lead (TEL)
d. Tetra Methyl Lead (TML)

Chapter 4. Fuels
Purpose of Dopes or Additives:
1. Oxidation Inhibitors- these are meant to avoid reaction of
some components of petrol with each other and with
oxygen thus controlling deposit formation during storage.
2. Rust Inhibitors – These are added to protect components
of the fuel supply system against rusting.
3. Metal Deactivators- These are added to inhibit reactions
between the petrol and metals in the fuel supply system.
4. Detergents – Keeps the carburettor jets clean and prevent
their clogging.
5. TEL ( Tetra Ethyl Lead) – It is added toincrease the octane
ratings.

Chapter 4. Fuels
S.I. Engine Fuels:
I. Present Fuels.
a. Gasoline or Petrol
b. L.P.G. (Liquified Petroleum Gas)
II. Alternative Fuels
a. Alcohol
b. Benzol
c. hydrogen

Chapter 4. Fuels
1. Gasoline or Petrol
- It is the mixture of hydrocarbons , manufactured by crude
distillation followed by refining process. The composition is not
fixed. These are prepared by blending different refinery
gasolines and additives to obtain desired quality of fuel having
desired octane number, volatility, stability and antiknock
qualities
2. LPG ( Liquefied Petroleum gas)
- It contains mainly butane and propane and is also used as
engine fuel. The engine is provided with special fuel system.

Chapter 4. Fuels
Alternative fuels:
1. Alcohol
- Ethyl Alcohol is mainly used as a fuel. It has high anti knock
rating ( above 100) and is used as blending agent. It has Low
calorific value ( 27,000 KJ/Kg) and higher cost per liter than
gasoline.
2. Benzol
- It is obtained by distillation of coal. It has very high octane
number( above 115) and is valuable blending component. But it
has high freezing and not suitable for uses in cold climate. High
aroma content leads to large carbon deposits.

Chapter 4. Fuels
Alternative fuels:
3. Hydrogen
- It is a perfect fuel . Hydrogen is used in liquid form . It emits
less pollution . The power output of hydrogen air engine is
lower then petrol engine due to lower volumetric efficiency
and back fire.

Chapter 4. Fuels
Important Quality of CI Fuels:
a. Ignition Quality
b. Viscosity
c. Heat of combustion
d. Volatility
e. Cleanliness
f. Non corrosiveness

Chapter 4. Fuels
Ignition Quality
- The term ignition quality is used to cover loosely the ignition
temperature vs. delay characteristics of fuel when used in
engine. Good ignition quality means short delay angle at
given speed , compression ration, air inlet and jacket
temperature.
Viscosity
- Diesel fuel is injected into the combustion chamber. High
viscosity fuel is not finely atomized and requires more injection
pressure.

Chapter 4. Fuels
Ignition Quality
- The term ignition quality is used to cover loosely the ignition
temperature vs. delay characteristics of fuel when used in
engine. Good ignition quality means short delay angle at
given speed , compression ration, air inlet and jacket
temperature.
Viscosity
- Diesel fuel is injected into the combustion chamber. High
viscosity fuel is not finely atomized and requires more injection
pressure. The injection pressure and the degree of atomisation
of the fuel depend on diesel viscosity.

Chapter 4. Fuels
Sulphur Content
- The pressure of the sulphur in the diesel fuel reduces the self
ignition temperature of the fuel. The injected fuel starts
burning at a lower temperature in the combustion chamber.
On the other hand high sulphur increases wear due to acidic
corrosion and deposition of carbon on piston rings.
Volatility
- Diesel fuel must be volatile at the cylinder temperature. If
volatility of fuel is less, it burns only partially and leave carbon
particles. These carbon particles in the cylinder cause cylinder
wearand can chock the injector orifice.

Chapter 4. Fuels
Cleanliness
- The fuel should be free from water and sediments. These can
damage the injection unit( Fuel pump and Fuel Injector)
Ignition Lag
- A fuel particle takes a certain time to ignite after injection into
the combustion chamber. The time interval is called ignition
lag. Lesser the time of ignition lag , better quality of fuel.

Chapter 4. Fuels
CI or Diesel fuel Rating:
The ignition lag of diesel fuel can result in sudden and rapid
ignition of accumulated fuel in the combustion chamber. This
causes knock in CI Engine . The ignition quality of diesel is
measured by cetane number.
Cetane number- is the percentage of cetane over the mixture
of cetane and methyl naphthalene. For example if the cetane
number of diesel fuel is assigned to be 85 that means the
mixture has 85% cetane and 15% methyl naphthalene.

Chapter 4. Fuels
Methods of fuel Rating for CI Engines:
1. Aniline Point
2. Diesel Index
3. Triptane number
1. Aniline Point- This is the lowest temperature at which
mixture of equal parts of a fuel and aniline will form a clear
solution. The aniline point in Degree celsius is correlated to
with cetane number.

Chapter 4. Fuels
2.Diesel Index - It is also considered to be good criteria of
Suitability of a fuel use in diesel engine.
Diesel Index = Aniline point (F) x API gravity
100
3. Triptane Number- Trimethyl Butane is used as nonn knocking
reference fuel and triptane scale is prepared. Triptane
number 65.5 is equal to 100 cetane number.

Chapter 4. Fuels
Dopes or Additives for CI Engine Fuels:
Cetane number of diesel fuel can be improved by mixing some
additives into the fuel. They decrease the ignition lag and
maximum pressure of the cycle and increase the cetane
number.
Most Common Additives for Diesel Fuel are:
1. Ethyl Nitrate
2. Isoamyl Nitrate
3. Methyl cetane
4. Butyl Peroxide
5. Acetone peroxide

Chapter 4. Fuels
Diesel OIL
- Diesel oil is widely used as fuel for CI engines because of low
cost and Higher Thermal efficiency. The cost of diesel is less
than that of gasoline as it is obtained by fractional distillation
of crude petroleum at lower temperatures. The production
cost of of diesel fuel is less.
Alternative Fuels
- There are rapid depletion of petroleum fuels ( Petrol , Diesel
oil) creating shortage and escalation in their cost. There is
intensive search for alternative fuels. Alcohols have been found
to be main fuels which can substitute the petroleum fuels.
Methly alcohol can be produced by gasification of coal

Chapter 4. Fuels
Or lignite and also municipal wastes. Ethyl alcohol can be
produced by fermentation of carbohydrates such as
sugarcane, corn and potatoes. Brazil, Cuba and Philippines
are using alcohol as motor fuel for a long period.
Alcohols are being used as follows:
1. Pure alcohol
2. Alcohol gasoline blends for SI Engines
3. Alcohol Diesel Blends for CI Engines

Chapter 5 Combustion
Air Fuel ratio
-The chemically correct air fuel ratio by mass for an
internal combustion engine can be calculated from
the analysis by mass of the fuel used .
For example if petrol approximates to hexane C6H14.
the air fuel ratio giving “chemically correct”
combustion can be estimated as follows:
2( C6H14) + 19O2 = 12(CO2) +14(H2O)
(2x86)+ ( 19x32)=(12X44) + (14x18) : Chemical BalanceO2
required per kg of fuel= (19 x 32)/ (2 x 86)= 3.52 kg

Combustion in SI Engines
The main conditions for combustion of fuel in SI
Engines are:
1. Presence of a combustible ( mixture of fuel and
air) supplied by carburettor.
2. Some means of initiating combustion by a spark
plug.
3. Stabilization and propagation of flame in the
combustion chamber.

Detonation (Knocking):
- Auto ignition of unburned gases due to favorable conditions
before the flame front reaches it.
Effects of Detonation:
1. Noise and Roughness
2. Mechanical Damage
3. Carbon Deposits

4. Increase in Heat transfer
5. Decrease in Power output and efficiency
6. Pre ignition
Pre ignition:
- Ignition of charge by some hot surface within the engine
can result in extremely large losses in efficiency if this
ignition occurs earlier than normal spark plug discharge.
Effect of pre Ignition:
1. Pre ignition results in excessive heating of piston heads and
there can be local melting of piston.
2. Pre ignition causes low power and efficiency.

SI COMBUSTION CHAMBER DESIGN:
The engine with good combustion chamber design should
ensure the following:
1. High Power Output- this can be achieved with high
compression ratio, minimum of excess air , optimum
turbulence and high volumetric efficiency.
2. High Thermal Efficiency- depends upon high compression
ratio.
3. Smooth operation- There should be absence of detonation
and moderate pressure rise.

Main Designs of Combustion Chamber:
1. T head combustion Chamber
2. L head combustion Chamber
3. I head combustion Chamber
4. F head combustion Chamber
5. Hemispherical Combustion Chamber

1. T head combustion Chamber

2. L head combustion Chamber

3. I head combustion Chamber

4. F head combustion Chamber

5. Hemispherical combustion Chamber

CI COMBUSTION CHAMBER DESIGN:
The Design requirements of combustion chamber for CI
Engines are as Follows:
1. During the delay period, the fuel air contact should be
limited or shorten the delay period.
2. Provide high turbulence after combustion starts or achieve
early termination of combustion.

1.DIRECT INJECTON (DI) OR OPEN CHAMBER DESIGN:

DIRECT INJECTON OR OPEN CHAMBER DESIGN:
1. Semi quiescent or Low Swirl Open Chamber

2. Medium Swirl Open Chamber

3. High Swirl Open Chamber

INDIRECT INJECTON OR DIVIDED COMBUSTION
CHAMBER DESIGN:

CHAMBER DESIGN:
1. Swirl or Turbulent Chamber

CHAMBER DESIGN:
2. Pre combustion Chamber

CHAMBER DESIGN:
3. Air and Energy Cells Chamber

Sample Problems 1:

Sample Problems 2:

Sample Problems 3:

Sample Problems 4:

Chapter 6
6.1 Valve timing
A valve timing diagram is a graphical representation of
the exact moments , in the sequence of operations at which
two valves (inlet and exhaust valves) opens and close as well
as firing of fuels. It is generally expressed in terms of angular
positions of crankshafts.

Chapter 6
6.1a Theoretical Valve Timing for Four Stroke

Chapter 6
6.1b Theoretical Valve timing for Two Stroke

Chapter 6
6.1c Valve timing for Four Stroke SI Engine

Chapter 6
6.1d Valve timing for Four Stroke CI Engine

Chapter 6
6.1e Valve timing for Two Stroke SI Engine

Chapter 6
6.1f Valve timing for Two Stroke CI Engine

Chapter 7 Fueling System of SI and
CI Engine
7.1 Carburettor:
Carburation – is the process of vaporization of liquid
hydrocarbon fuels. Fuels such as Petrol, benzol and alcohol
vaporize slightly at atmospheric conditions. The engine
suction is sufficient to vaporize these fuels and no preheating
is required. The device used for vaporizing these fuels is
called Carburettor.
Functions of carburretor:
1. Maintain a small reserve of petrol under a constant head.
2. Vaporize the petrol by means of engine suction , atomize it
and produce a homogeneneous air fuel mixture.

CI Engine
7.1 Carburettor:
3. Supply the required quantity of air and fuel vapour at correct
mixture strength according to the varying requirements of
the engine at all speeds and loads of the engine.

CI Engine
7.1 Carburettor:
3. Supply the required quantity of air and fuel vapour at correct
mixture strenght according to the varying requirements of
the engine at all speeds and loads of the engine.

CI Engine
7.1 Carburettor:
The Simple caburettor has the following Parts:
1. Float Chamber
2. Venturi
3. Nozzle with metering orifice
4. Throttle Valve
1. Float Chamber- The fuel is pumped or flows by gravity into
float chamber . When the fuel reaches the proper height in
the chamber , the float rises sufficiently to cut off flow. The
level of fuel is kept constant in the fuel chamber.

CI Engine
7.1 Carburettor:
2. Venturi -The fuel flows out the float chamber through
metering orifice into nozzle which opens into the venturi
throat . The pressure drop produced in the venturi throat by
the air flows is used directly to control the rate of fuel flow
through fuel orifice. The vaccum produced at the venturi
throat due to air flow is called carburretor depression.
3. Nozzle with metering orifice- The carburettor depression
causes a pressure difference across the metering orifice .
The fuel is sprayed into the air stream and carried to the
engine cylinder. The fuel vaporize due to low pressure
produced by the venturi.

CI Engine
7.1 Carburettor:
4. Throttle- It serves as a damper at the inlet of the engine and
control the speed and the power of the engine . It regulates the
amount of air flowing to the engine and chectks the quantity of
fuel. The amount of mixture is regulated to control the power
and the speed of the engine. The mixture quality is also
affected as the throttle opening affects the carburettor
depression.

CI Engine
7.1 Carburettor:

CI Engine
7.2 Fuel Injection System- The fuel injection system is the
heart of the engine which has to supply, meter , inject and
atomise the fuel. The engine performance depends upon the
accurate and reliable functioning of the system which is
manufactured with fine tolerance and hence is very costly.
Diesel does not vaporise by engine suction. Therefore,
carburation is not possible in diesel engines Only air is drawn
into the cylinder during suction stroke and compressed to very
high pressure. This raises the air temperature sufficient for auto
ignition of fuel.

CI Engine
The temperature of compressed air is higher than the ignition
temperature of the fuel. The fuel is injected into the engine
cylinder almost towards the end of the compression stroke. For
proper atomization, dispersion and penetration of fuel spray
required for proper mixing of fuel and air and combustion, the
oil is injected at a high pressure of 100-150 bar .

CI Engine
Fuel Injection Requirements
The fuel injection system must ensure the following
requirements:
1. The unit must meter and deliver the correct quantity of fuel
at the precise instant required for a wider range of speeds
and loads of the engine.
2. The beginning and end of injection must be sharp.
3. The injection fuel must be properly atomised.
4. The fuel must be properly sprayed to ensure uniform
distribution and penetration into the space of combustion
chamber.

CI Engine
Fuel Injection Requirements
In order to meet the above requirements, the fuel injection
system must have the following functional elements.
1. Pumping
2. Metering and metering control
3. Distribution
4. Timing Control
5. Mixing

CI Engine
Types of Injection Systems
Basically there are two types of fuel injection system:
1. Air injection System
2. Solid Injection System
1. Air injection system – air and fuel are supplied in the fuel
valve where they are mixed and supplied to the engine
cylinder. The fuel metered and pumped to the fuel valve by a
fuel pumped driven by camshaft. The fuel valve is opened by
means of mechanical linkage operated by the camshaft which
controls the timing of the fuel injection.

CI Engine
Types of Injection Systems
A multi stage compressor supplies air at 60-70 bar to
the fuel valve. When the fuel valve is opened, the blast air
sweeps fuel and well atomized fuel spray is sent to the
combustion chamber. This system gives very good
atomization and dispersion of fuel. However, additional
multi-stage compressor and mechanical linkage increase the
engine weight, lowers mechanical efficiency and is often
source of trouble. This method is particularly unsuitable for
portable engines.
- The fuel is supplied to the cylinder directly by an injector

CI Engine
Types of Injection Systems :
- The fuel is supplied to the cylinder directly by an injector. This
may also called airless mechanical or hydraulic injection
system. A fuel pump is used to supply high pressure fuel to
an injector which injects a fine spray of fuel to the
compressed air in the combustion chamber.

CI Engine
Fuel Injector:

CI Engine
Fuel Pump:

CI Engine
7.2 Individual Pump System:
In the individual pumps system each cylinder of the engine
is provided with individual injection valve, high pressure
pump and metering device run by the crankshaft of the
engine. The high pressure pump plunger is actuated by a cam
and produces fuel pressure that is necessary to open the
injection valve at the correct time. The amount of fuel
injected depends upon the effective stroke of the engine.

CI Engine
7.2 Individual Pump System:

CI Engine
7.2 Rotary Distributing Pump System:
The fuel supply is delivered to a rotating distributor at the
correct time and then the distributor supplies fuel to the
injector of individual cylinders. Pump has to make as many
injection strokes per cycle as the number of cylinders. The
distributor merely selects the cylinder to receive the fuel.

CI Engine
7.3 Eletronic Fueling Injection System
7.3a Gasoline Injection System:
Modern Carburettors , though highly develop , have certain drawback
discussed below:
1. Non uniform of distribution of mixture in multi-cylinder engines due to
unequal lengths of induction passages.
2. Loss of volumetric efficiency due to resistance of mixture flow.
3. There are chances of backfire and fuel ignition outside the carburetor .
4. Surging of fuel in tilted carburettor especially in aircraft.
5. The carburettor performance deteriorates due to wearing of its parts.

CI Engine
Modern Carburettors , though highly develop , have certain drawback
discussed below:
6. Freezing of Mixtures at low temperatures.
A petrol injection system can be used to overcome the above limitations of
carburation. Two types of Petrol injection systems are :
1. Continuous Injection System
2. Timed Injection System

CI Engine
1. Continuous Injection System- Fuel is sprayed continuously
into air supply system at low pressure the amount of fuel is
controlled by air throttle opening . No timing device is used.
It has certain advantages :
a. Ensures uniform mixture strength supply to all cylinders.
b. Promotes efficient atomization of fuel.
c. Higher volumetric efficiency due to evaporative cooling of
compressed charge.
d. System requires only one fuel injection pump and one
injector.

CI Engine
2. Timed Injection System
The fuel is injected only during induction stroke over limited
period . The system is similar to injection system used in high
speed engines.
a. Multiple plunger jack pump system – The system consist of
a pump with separate plunger for each cylinder. The nozzle
pressure is 100 to 300 bar.
b. Low pressure single pump distribution system – The supply
pressure is only 3.5 to 7 bar. The system consist of single
plunger or gear pump which supplies fuel to rotating
distributor.

CI Engine
Some Advantages of Petrol Injection:
1. Increased of efficiency , power and torque outputs.
2. Better distribution of mixture to each cylinder.
3. Lower specific fuel consumption.
4. Freedom from flowbacks .
5. Better starting and acceleration.

CI Engine
Disadvantages of Petrol Injection:
1. Higher initial cost due to large number of precise and
complicated components.
2. Complex design and maintenance problems.
3. More Noise.
4. High weight and bulk of system than that of a carburretor.

CI Engine
7.3a Sample of Electronic Control Injection System:
Disadvantages of Petrol Injection:
1. Higher initial cost due to large number of precise and
complicated components.
2. Complex design and maintenance problems.
3. More Noise.
4. High weight and bulk of system than that of a carburretor.

Chapter 8 Ignition System
Engine Requirements

Ignition System of Petrol Engine

Coil Ignition System

Magneto Ignition System

Chapter 9 Emission Control
System

Exhaust Gasses
 Carbon monoxide emission are exhaust emission that
is the result of partially burned fuel.
 A high carbon monoxide emission can be caused by a:
 Restricted or dirty air cleaner.
 Advance ignition timing.
 Clogged fuel injectors.

Exhaust Gasses
 Oxides of nitrogen, (NOx) are emission produced by
extreme heat.
 Air consist of approximately 79% nitrogen and 21%
oxygen
 When combustion chamber temperature reaches 2500
degrees F or 1370 degrees C nitrogen and oxygen
combine to produce oxide of nitrogen (NOx)

Exhaust Gasses
 Decrease valve overlap, is used to decrease exhaust
emission. A larger valve overlap increases power but
dilutes incoming fuel mixture and requires a richer air
fuel mixture at lower engine speed therefore
increasing HC and CO emissions.

252
Hydrocarbons
Hydrocarbon emissions result from the presence of unburned fuel in the
engine exhaust.
However, some of the exhaust hydrocarbons are not found in the fuel, but are
hydrocarbons derived from the fuel whose structure was altered do to
chemical reaction that did not go to completion. For example: acetaldehyde,
formaldehyde, 1,3 butadiene, and benzene all classified as toxic emissions.
About 9% of the fuel supplied to the engine is not burned during the normal
combustion phase of the expansion stroke.
Only 2% ends up in the exhaust the rest is consumed during the other
three strokes.
As a consequence hydrocarbon emissions cause a decrease in the thermal
efficiency, as well as being an air pollutant.

253
Hydrocarbon Emission Sources
Crevices – these are narrow regions in the combustion chamber into which
the flame cannot propagate because it is smaller than the quenching distance.
Crevices are located around the piston, head gasket, spark plug and valve
seats and represent about 1 to 2% of the clearance volume.
The crevice around the piston is by far the largest, during compression the fuel
air mixture is forced into the crevice (density higher than cylinder gas since gas
is cooler near walls) and released during expansion.
Crevice
Piston ring

254
Oil layers - Since the piston ring is not 100% effective in preventing oil
migration into the cylinder above the piston, oil layers exist within the
combustion chamber. This oil layer traps fuel and releases it later during
expansion.
Deposits – With continued use carbon deposits build up on the valves, cylinder
and piston head. These deposits are porous with pore sizes smaller than the
quenching distance so trapped fuel cannot burn. The fuel is released later
during expansion.
Liquid fuel – For some fuel injection systems there is a possibility that liquid
fuel is introduced into the cylinder past an open intake valve. The less volatile
fuel constituents may not vaporize (especially during engine warm-up) and be
absorbed by the crevices or carbon deposits.
Flame quenching – It has been shown that the flame does not burn completely
to the internal surfaces, the flame extinguishes at a small but finite distance
from the wall. Most of this gas eventually diffuses into the burned gas during
expansion stroke.
Hydrocarbon Emission Sources

255
Hydrocarbon Exhaust Process
When the exhaust valve opens the large rush of gas escaping the cylinder
drags with it some of the hydrocarbons released from the crevices, oil layer
and deposits.
During the exhaust stroke the piston rolls the hydrocarbons distributed along the
walls into a large vortex that ultimately becomes large enough that a portion of
it is exhausted.
Blowdown Exhaust
Stroke

256
Particulates
A high concentration of particulate matter (PM) is manifested as visible
smoke in the exhaust gases.
Particulates are any substance other than water that can be collected by
filtering the exhaust, classified as:
1) solid carbon material or soot
2) condensed hydrocarbons and their partial oxidation products
Diesel particulates consist of solid carbon (soot) at exhaust gas temperatures
below 500oC HC compounds become absorbed on the surface.
In a properly adjusted SI engines soot is not usually a problem
Particulate can arise if leaded fuel or overly rich fuel-air mixture are used.
burning crankcase oil will also produce smoke especially during engine warm
up where the HC condense in the exhaust gas.

257
Catalytic Converter
All catalytic converters are built in a honeycomb or pellet geometry to expose
the exhaust gases to a large surface made of one or more noble metals:
platinum, palladium and rhodium.
Rhodium used to remove NO and platinum used to remove HC and CO.
Lead and sulfur in the exhaust gas severely inhibit the operation of a catalytic
converter (poison).

Catalytic Converters
 There are a few different types catalytic
converters.
 Monolithic Converter
 Two way converter
 Three way converter
 Dual bed converter

 Monolithic converter uses a ceramic
honey-comb catalytic
 Small ceramic beads converter are
referred to as a pellet type catalytic
converter

 Two way catalytic converters only
convert HC and CO
 With a two way converter NOx is not
converted
 Two way converter are coated with
platinum only
 Two way converter are sometime referred
to as oxidation converters

 Three way catalytic converters can
convert all three exhaust gasses
 HC
 CO
 NOx

 A three way catalytic converter is usually
plated with rhodium and platinum
 Three way converter are also called
reduction converters.

 Dual bed catalytic converter is an
oxidation and reduction converter built into
one unit.
Mixing Chamber
CO,
HC
and
NOx
CO2 and H20

 Dual bed catalytic converters must be at
an operating temperature of 130 degrees
F
 When the engine is cold additional air is
forced into the exhaust manifold to aid in
the burning and reduction of HC and CO

 On a warn engine air is forced into the converter
to aid in burning exhaust gasses.
 As exhaust gasses flows iinto the front part of
the converter HC,CO and NOx is reduced.
 As exhaust flow into the mixing chamber
additional air is added to continue the burning
process.
 Exhaust gasses is the passed into the rear part
of the converter to reduce HC,CO2 and NOx
ever more.

270
Effect of Temperature
The temperature at which the converter becomes 50% efficient is referred to
as the light-off temperature.
The converter is not very effective during the warm up period of the engine

271
Catalytic Converter for Diesels
For Diesel engines catalytic converters are used to control HC and CO, but
reduction of NO emissions is poor because the engine runs lean in order to
avoid excess smoke.
The NO is controlled by retarding the fuel injection from 20o to 5o before TC in
order to reduce the peak combustion temperature.
This has a slight negative impact, increases the fuel consumption by about 15%.

Chapter 10 Lubrication system of
Internal Combustion Engine

Chapter 11 Cooling system of
Internal Combustion Engine

Chapter 12 Turbocharging and
Supercharging
Introduction

Supercharging
Supercharging

Supercharging
Uses of Supercharged Engines

Supercharging
Factors which Increase the Power Output by
Supercharging:
1.
2.

Supercharging
Factors which Increase the Power Output by
Supercharging:
3.

Supercharging
Methods of Supercharging:
1. Mechanical Supercharging
2. Turbocharging
3. Pressure Wave Supercharging
1. Mechanical Supercharging

Supercharging
2. Turbocharging

Supercharging
3. Pressure Wave Supercharging

Supercharging
Thermodynamics Cycle of Supercharging

Supercharging
Supercharging of SI Engine

Supercharging
Supercharging of CI Engine

Supercharging
Effects of Supercharging
1. Power Output

Supercharging
2. Fuel Consumption

Supercharging
3. Mechanical Efficiency
4. Volumetric Efficiency

Chapter 13 Two Stroke Engine
1. Crankcase Scavenged Engine

2. Separately Scavenged Engine

Scavenging Process

1.Return- flow Scavenging

A. Cross flow (Fig. a)

B. MAN- Loop (Fig. b)

C. Schnuerle-Loop (Fig. c)

D. Curtiss-Loop (Fig. d)

2. Uniflow Scavenging

A. Port and Poppet Valve Scavenging

B. Port Scavenging with opposed piston

Advantages of Two Stroke Engines

Disadvantages of Two Stroke Engines

Chapter 14 Reciprocating
Compressors
Introduction:

Compressors (Single Stage)

Compressors ( Single Stage)

Compressors ( Multi Stage)

Chapter 14 Reciprocating Compressors ( Multi
Stage)

Chapter 14 Reciprocating Compressors (Multi
Stage)

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