PETROL ENGINE VS

DIESEL ENGINE1

THE BASICS A four-stroke engine:

Is an internal combustion engineConverts gasoline into motion Is the most common car engine type Is relatively efficient Is relatively inexpensive

PETROL ENGINE

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A petrol engine is an internal combustion engine with spark-ignition, designed to run on petrol (gasoline) and similar volatile fuels.

 It was invented in 1876 in Germany by German inventor Nikolaus August Otto.

 The process differs from a diesel engine in the method of mixing the fuel and air, and in using spark plugs to initiate the combustion process. 

INTRODUCTION

Four Stroke CycleIntakeCompression PowerExhaust

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Intake StrokeIntake valve opens.Piston moves down,

½ turn of crankshaft.A vacuum is created

in the cylinder.Atmospheric

pressure pushes the air/fuel mixture into the cylinder.

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Compression StrokeValves close.Piston moves up,

½ turn of crankshaft.

Air/fuel mixture is compressed.

Fuel starts to vaporize and heat begins to build.

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Power StrokeValves remain

closed.Spark plug fires

igniting fuel mixture.

Piston moves down, ½ turn of crankshaft.

Heat is converted to mechanical energy.

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Exhaust StrokeExhaust valve

opens.Piston move up,

crankshaft makes ½ turn.

Exhaust gases are pushed out polluting the atmosphere.

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INTRODUCTION Invented by Rudolf Diesel

The diesel engine (also known as a  compression-ignition engine) is an internal combustion engine.

 in which ignition of the fuel that has been injected into the combustion chamber by injector.

It has the highest thermal efficiency due to its very high compression ratio.

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Intake Stroke:•Piston moves from TDC to BDC creating vacuum in the cylinder

•Intake valve opens allowing only air to enter the cylinder and exhaust valve remains closed

Compression Stroke

•Both valves stay closed

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

•Compressing the air to this extent increases the temperature inside the cylinder to above 1000 degree F.

Power Stroke

•Both valves stay closed•When the piston is at the end of compression stroke(TDC) the injector sprays a mist of diesel fuel into the cylinder. •When hot air mixes with diesel fuel an explosion takes place in the cylinder.

•Expanding gases push the piston from TDC to BDC

Exhaust Stroke

•Piston moves from BDC to TDC

•Exhaust valve opens and the exhaust gases escape

•Intake valve remains closed

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The only difference between diesel engine and a four-strokegasoline engine is:

•No sparkplug on Diesel engine.

•Has a higher compression ratio. (14:1 to 25:1)

•Better fuel mileage.

ADVANTAGES1. Diesels are more efficient. Most gasoline

engines convert about 30 percent of their fuel energy into actual power. A traditional diesel converts about 45 percent. And advanced diesels can hit about 50 percent.

2. Diesels are more reliable. Because they don’t need high-voltage ignition systems, diesel engines never fail for lack of a spark. They also don’t emit radio frequency emissions that can interfere with a vehicle’s other electronic systems.

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3. Diesels run cooler. Because they are more efficient, diesel engines release less waste heat while in operation.

4. Diesels last longer. Diesel engine parts are generally stronger than gas engine components, and diesel fuel has superior lubricating properties. As a result, diesel engines tend to last twice as long as gas-powered ones.

5. Diesel fuel is safer. Diesel fuel doesn’t release fumes like gasoline does. It’s more difficult to burn and won’t explode like its lighter counterpart.

6. Diesels are more easily turbo-charged. Put under sufficient pressure, gasoline engines will spontaneously detonate. By contrast, the amount of super- or turbo-charging pressures diesel engines can endure are limited only by the strength of the engines themselves.

7. Diesels produce minimal carbon monoxide. This makes diesel generators useful in mines and submarines, environments in which gasoline engine exhaust would prove deadly.

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1. Diesel engines, because they have much higher compression ratios (20:1 for a typical diesel vs. 8:1 for a typical gasoline engine), as compare to gasoline engine.

2. Diesel engines also more expensive.

3. Diesel engines, because of the weight and compression ratio, tend to have lower maximum RPM ranges than gasoline engines .

DISADVANTAGES

4. This makes diesel engines high torque rather than high horsepower, and that tends to make diesel cars slow in terms of acceleration.

5. Diesel engines must be fuel injected, and in the past fuel injection was expensive and less reliable

6. Diesel engines tend to produce more smoke and "smell funny".

7. Diesel engines are harder to start in cold weather, and if they contain glow plugs, diesel engines can require you to wait before starting the engine so the glow plugs can heat up.

8. Diesel engines are much noisier and tend to

vibrate.

9. Diesel fuel is less readily available than gasoline

APPLICATIONPassenger cars- Diesel engines have long been popular in bigger

cars and have been used in smaller cars

Other transport uses- Larger transport applications (trucks, buses, etc.)

also benefit from the Diesel's reliability and high torque output.

Non Transport Uses-generators, irrigation pumps, corn grinders