BIRLA INSTITUTE OF BIRLA INSTITUTE OF TECHNOLOGY TECHNOLOGY ((PATNA CAMPUS)PATNA CAMPUS)

DEPARTEMENT OF MECHANCAL DEPARTEMENT OF MECHANCAL ENGINEERINGENGINEERING

PRESENTED BY:- SHIVAM KUMAR (BE/15250/13) PRAVEEN KUMAR

(BE/15251/13) ABINASH PANDA

(BE/5271/13)

Introduction :Introduction : =

• Heat engine : It can be defined as any engine that converts thermal energy to mechanical work output. Examples of heat engines include: steam engine, diesel engine, and gasoline (petrol) engine.

• On the basis of how thermal energy is being delivered to working fluid of the heat engine, heat engine can be classified as an internal combustion engine and external combustion engine.

Types of EngineTypes of Engine

Internal Engine

Petrol Engine Diesel Engine

External Engine

Steam Engine Turbines

External Combustion External Combustion EngineEngine• In an External

combustion engine, combustion takes place inside the cylinder.

• -Steam engine is an

example of external combustion engine, where the working fluid is steam.

IC EnginesIC Engines• In an Internal

combustion engine, combustion takes place within the cylinder.

• Petrol engine is an example of internal combustion engine, where the working fluid is a mixture of air and fuel .

Internal combustion engines may be classified as : Internal combustion engines may be classified as : – Spark Ignition engines.Spark Ignition engines.– Compression Ignition engines.Compression Ignition engines.

• Spark ignition engine (SI engine): Spark ignition engine (SI engine): An engine in which An engine in which the combustion process in each cycle is started by use the combustion process in each cycle is started by use of an external spark.of an external spark.

• Compression ignition engine (CI engine): Compression ignition engine (CI engine): An engine in An engine in which the combustion process starts when the air-fuel which the combustion process starts when the air-fuel mixture self ignites due to high temperature in the mixture self ignites due to high temperature in the combustion chamber caused by high compression.combustion chamber caused by high compression.

– Spark ignition and Compression Ignition engine Spark ignition and Compression Ignition engine operate on either a four stroke cycle or a two operate on either a four stroke cycle or a two stroke cycle.stroke cycle.

• Four stroke cycle Four stroke cycle : It has four piston strokes : It has four piston strokes over two revolutions for each cycle.over two revolutions for each cycle.

• Two stroke cycle Two stroke cycle : It has two piston strokes : It has two piston strokes over one revolution for each cycle.over one revolution for each cycle.

SI Engine & CI Engine have two types:-

Figure2: Engine components

Engine components :-

Internal combustion Engine Internal combustion Engine ComponentsComponents:-:-

1. Block : Body of the engine containing cylinders, made of cast iron or aluminium.

2. Cylinder2. Cylinder

C

A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels.

3. Head 3. Head :: The piece The piece which closes the end which closes the end

of the cylinders, of the cylinders, usually containing usually containing

part of the clearance part of the clearance volume of the volume of the combustion combustion chamber.chamber.

4. Connecting Rod4. Connecting Rod

In a reciprocating piston engine , the connecting rod or conrod connects the piston to the crank or crankshaft.

5. Piston5. Piston

Piston

The piston of an internal combustion

engine is acted upon by the pressure of the expanding combustion gases in the combustion chamber space at the top of the cylinder.

6. Piston rings6. Piston rings

A piston ring is a metal rings that fit into circumferential grooves around the piston and form a sliding surface against the cylinder walls.

7. Crankshaftt:: Rotating shaft Rotating shaft through which through which engine work engine work output is output is supplied to supplied to external external systemssystems..

8. Camshaft 8. Camshaft :: Rotating shaft used Rotating shaft used to push open valves to push open valves at the proper time in at the proper time in

the engine cycle, the engine cycle, either directly or either directly or

through mechanical through mechanical or hydraulic linkage or hydraulic linkage (push rods, rocker (push rods, rocker

arms, tappets) .arms, tappets) .

9. Intake manifold9. Intake manifold: : Piping system which Piping system which

deliver incoming air to deliver incoming air to the cylinders, usually the cylinders, usually made of cast metal, made of cast metal, plastic, or composite plastic, or composite material . In most SI material . In most SI

engines, fuel is added engines, fuel is added to the air in the intake to the air in the intake manifold system either manifold system either

by fuel injectors or by fuel injectors or with a carburetor.with a carburetor.

10. Exhaust 10. Exhaust manifold manifold :: Piping Piping

system which system which carries exhaust carries exhaust

gases away from gases away from the engine the engine

cylinders, usually cylinders, usually made of cast ironmade of cast iron

11. Spark plug 11. Spark plug : : Electrical device Electrical device used to initiate used to initiate

combustion in an combustion in an SI engine by SI engine by creating high creating high

voltage discharge voltage discharge across an across an

electrode gapelectrode gap

12. Flywheel 12. Flywheel : : Rotating mass Rotating mass

with a large with a large moment of inertia moment of inertia connected to the connected to the crank shaft of the crank shaft of the

engine.engine.The purpose of The purpose of

the flywheel is to the flywheel is to store energy store energy ..

13. Fuel 13. Fuel injector injector :: A A pressurized pressurized

nozzle that sprays nozzle that sprays fuel into the fuel into the

incoming air (SI incoming air (SI engines )or into engines )or into the cylinder (CI the cylinder (CI

engines).engines).

14. Combustion chamber14. Combustion chamber: : The end The end of the cylinder between the head and the of the cylinder between the head and the piston face where combustion occurs . piston face where combustion occurs .

The size of combustion chamber The size of combustion chamber continuously changes from minimum continuously changes from minimum

volume when the piston is at TDC to a volume when the piston is at TDC to a maximum volume when the piston at maximum volume when the piston at

BDCBDC

Four Stock SI Engine & CI Four Stock SI Engine & CI Engine Engine :-:-

1. SI Engine:- It this engine, cycle of operation is completed in four stocks of the piston or two strokes of crankshaft . Each stroke consists of 180 degree of crankshaft rotation. Four strokes are follows:- A) Suction stroke.B) Compression stroke.C) Expansion stroke.D) Exhaust stroke.

1. Suction stroke:-1. Suction stroke:- In suction stroke fuel-In suction stroke fuel-air mixture enters in the cylindair mixture enters in the cylinderer

2. Compression Stroke:-2. Compression Stroke:-compression ratio of petrol engine is 6-10compression ratio of petrol engine is 6-10

3. Power or Expansion 3. Power or Expansion strokestroke:-:-

Exhaust stroke:- Exhaust stroke:-

2. CI Engine:- 2. CI Engine:- The diesel engine was first patented in 1892 by Rudolph Diesel. Like SI Engine, CI Engine complete cycle in 4 stroke. Four stokes are:- 1. intake or suction stroke:-The intake valve opens, and fresh air (containing no fuel), is drawn into the cylinder.

2. Compression stroke:- 2. Compression stroke:-

•Both valves stay closed

•Piston moves from BDC to TDC, compressing air to 22:1

increases the temperature inside the cylinder to above 1000 degree F.

•Compressing the air to this extent

3. Power stroke:-3. Power stroke:-

•When the piston is at the end of compression stroke(TDC) the injector sprays a mist of diesel fuel into the cylinder.

•Both valves stay closed

•When hot air mixes with diesel fuel an explosion takes place in the cylinder.

•Expanding gases push the piston from TDC to BDC

4. Exhaust Stroke4. Exhaust Stroke

•Piston moves from BDC to TDC

•Exhaust valve opens and the exhaust gases escape

•Intake valve remains closed

2- Stroke Engine2- Stroke EngineAs the name itself implies, all the processes in the two stroke cycle engine are completed in two strokes.

In the two stroke engine there is a two opening called ports are provided in place of valve of four stroke engines.

One port known as a inlet port and another port is known as a exhaust port.

Working of the two stroke Working of the two stroke petrol enginepetrol engine

•At the beginning of the first stroke piston Is at the TDC. Piston moves from TDC to BDC

First stroke:-

•Another A/F/O mixture is sucked into crankcase while First one is compressed in cylinder

Intake/ compression StrokeIntake/ compression Stroke

Fig. B

Piston uncovers transfer port During first stroke

Fig. A

Beginning of the first stroke

Second stroke Second stroke :- :- Power/Exhaust Power/Exhaust StrokeStroke

•In this stroke piston moves from BDC to TDC.

•Exhaust port is uncovered and exhaust starts leaving.

Fig. C.Transfer port covered

Fig. D.Compression commenced

•Because it is light, can be used at any Because it is light, can be used at any angle, operates at high RPM Weed eatersangle, operates at high RPM Weed eatersChain sawsChain sawsBoatsBoatsSnowmobilesSnowmobilesDirt bikesDirt bikes

Good uses of two stroke Good uses of two stroke enginesengines

11/2001 40

Usually don’t use 2 strokes Usually don’t use 2 strokes in :-in :-

Because of pollution, efficiency, lack of low RPM power, and convenience of not mixing oil– Cars– Trucks– Road bikes– Lawn mowers– Generators

Difference between 4 Difference between 4 stroke & 2 strokestroke & 2 stroke

Principle 4 stroke 2 stroke

1.Stroke per cycle2.Crank rotation per cycle3.Power stroke per cycle4.Power5.Fly wheel6.Sizeof engine7.Admission of charge8.Valves9.Crankcase10.Direction of rotation the crankshaft11.Lubricant oil consumption12.Thermal efficiency13.Mechanical efficiency14.uses

Four piston strokeTwo crank rotationHalf of speed of crankshaftIn every alternate revolutionHeavy flywheelHeavier , larger and more space Directly into cylinderInlet and exhaust valves It is not hermetically sealedIn one directionLessHigherLowCars, tractors, buses

Only two piston strokeOnly one crank rotationEqual to speed of crankshaftIn every revolutionLighter flywheelLighter , more compact and less spaceFirst admitted into crankcase, then transfer to engineIn place of valves, ports are thereHermetically sealedIn both directionsMore LessHighMopeds, scooter, motor, cycle

Gasoline vs. Diesel EngineGasoline vs. Diesel Engine

Wartsila-Sulzer RTA96-C is the largest IC engine, but the Space Shuttle Solid Rocket Boosters are the most powerful (≈ 42 million horsepower (32 hp/lb); not shaft power but kinetic energy of exhaust stream)

Most powerful shaft-power engine: Siemens SGT5-8000H stationary gas turbine (340 MW = 456,000 HP) (0.52 hp/lb) used for electrical power generation

Most powerful internal Most powerful internal combustion enginecombustion engine

Safety PrecautionsSafety Precautions

NoiseFuel FlammabilityMaintenanceWater Issues

• http://www.small-engines.com/4cycleth.html• http://en.wikipedia.org/wiki/Engine_displacement• http://en.wikipedia.org/wiki/Stroke_(engine) • http://en.wikipedia.org/wiki/Internal_combustion_engine• http://www.howstuffworks.com/diesel-two-stroke.htm• http://www.mustangmonthly.com/techarticles/97278_how_engines_work/

index.html

• http://www.kruse-ltc.com/Otto/otto_cycle.phphttp://www.kruse-ltc.com/Diesel/diesel_cycle.php

• http://www.answers.com/topic/internal-combustion-enginehttp://www.britannica.com/EBchecked/topic/162716/diesel-engine

ReferencesReferences::

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