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Ravi Kumar K

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Introduction.A Heat Engine a thermal prime mover which converts

the chemical energy into heat energy by combustion offuel and utilizes this energy to perform usefulmechanical work.

Broadly classified into two categories

1. Internal combustion Engine

2. External combustion Engine

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Classification of IC Engine

The important way of Classification of IC engine are1. According to Type of Fuel used

-Petrol Engine -Diesel Engine

-Gas Engine - Bi-fuel Engine

2. According to Number of Strokes

-4 stroke Engine -2 Stroke Engine

3. According to Method of Ignition- Spark ignition Engine (SI) - Compression Ignition Engine(CI)

4.According to Cycle of Combustion

- Otto Cycle -Diesel -Dual Combustion

5.According to number of Cylinder

- Single Cylinder - Multi Cylinder6. According arrangement of Cylinder

-Vertical Horizontal Inline Radial V-Engine

7.According to their Use

- Stationary Automobile Marine Locomotive Air craft

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Parts of IC Engine

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IC Engine Terminologies Bore Top Dead Centre(TDC) Bottom Dead Centre(BDC) Stroke

Clearance volume(Vc) Swept Volume/Stroke Volume/Piston Displacement(Vs) Compression Ratio(Rc)

Ratio of total cylinder volume to clearance volume.Rc = (Vs+Vc)/Vc

Piston Speed =2LN.

Where L = Stroke length in mN= Piston speed in RPM.

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4 Stroke Engines.

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Based on fuel used 4-Stroke engines are classified as

- 4 Stroke petrol Engine

- 4 Stroke Diesel Engine.

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4 Stroke Petrol EngineWorking principle of Petrol engine is based on Otto

cycle hence it is also called Otto cycle engine.

4 Diff Strokes1 Suction stroke

2 Compression Stroke

3 Power Stroke

4 Exhaust Stroke

It is Also Called as Spark Ignition Engine.

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Diesel Engine Diesel engine is similar to that of a 4 stroke petrol

Engine except fuel injector is fitted in place of sparkplug.

Only air enters into cylinder during suction stroke.Air alone is compressed during the compressed stroke.

Fuel(diesel) is injected at the end of compressionstroke & ignited when it comes in contact with

compressed air . Hence it is called Compression ignition engine.

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Sl.No Description Petrol Engine (SI) Diesel Engine

1 Cycle of operation Works on Otto Cycle Works on Diesel Cycle

2 Fuel Used Petrol/Gasoline Diesel

3 Admission of Charge Air+Petrol Carburettor is used to Supply Only air enters and fuel injector is used

4 Ignition of fuel By means of spark plug

Hence called SI Engines

Fuel ignited when it comes in contact with

compressed air & hence called CI Engines

5 Compression Ratio Varies from 6:1 to 10:1 Compression ratio ranges from 16:1 to 22:1

6 Power Power developed is lower as compression ratio is lower Power developed is Higher as compression ratio is

Higher

7 Thermal Efficiency Low due to Lower Compression ration Higher due to Higher Compression ration

8 Fuel Consumption More Less

9 Weight Light in weight &occupies less space Heavier& also require more space

10 Speed Run at high speed due to light wt Runs at low/Med speed due to heavy load

11 Starting of Engine Can be easily started in cold weather Difficult to start in cold weather

12 Running /Operation Cost Less initial Cost but high running cost due cost of petrol is

more

High Initial cost but Less running cost

13 Uses Used in light vehicles such as cars, Motorcycles etc Used in Heavy Vehicles such as busses Trucks and

Heavy machineries

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