DIESEL ENGINE: Classification, Characteristics & Applications.


Diesel engine date back to the last of the 19th century.

As the propulsion and land transportation of Dr Rudolf Diesel began both, on the road and on the railroad, is the subject of intensive development today, and is possible.

The diesel engine is the most efficient liquid fuel combustion engine up to date.

The war greatly boosted the development of high-speed diesel engines with its remarkably high specific output in order to expand its application to vehicles.

The 1st generation road transport engine was undoubtedly a positive ignition type, but the development of diesel engines based on the principle of compression or compression ignition continued shortly after a slight delay, and that was used in the mid-1930s.

The high-speed naturally aspirated diesel engine is firmly established as the most efficient drive unit for trucks and buses.

As the use of turbochargers increased, it began to replace the highly inefficient steam engine of railroad locomotives, and the imminent war led to the development of a highly charged diesel engine as a new aircraft engine.


It gave an important impetus , especially in Germany.

All major industrials have developed their own set of diesel engines.

The largest market penetration has undoubtedly occurred in the area of ​​heavy road, where it is dominant today, at least in Europe.

Especially in this region, it is and development for various forms of turbocharger has progressed rapidly in the last 20 years, and much of and current R & D efforts are concentrated.

However, the ongoing process of performance improvements is available for all applications, from the largest low speed marine 2-stroke engines to medium speed fixed engines to small single cylinder engines for remote operation.


The main feature of diesel engines is, the principle of self-ignition.

Adoption of a special type of fuel adjustment.

Instead of relying on to generate sparks at a given point in time towards the end of, the compression process produces a completely gaseous fuel-air mixture premixed at a stoichiometric ratio.

Like the properly named category of igniting Spark engine (SI), the engine operates on compression ignition (CI) with a non-uniform filling of previously compressed air and a finely divided spray of liquid fuel.

The latter is injected into the engine cylinder towards the end of compression, and after a suitably intensive mixed with air, the self-ignition property of fuel causes combustion from small nuclei already in cylinder.

These are distributed quickly, ensuring complete combustion of all injected fuel.

Air-fuel ratios usually far exceed stoichiometry.

The mixing process is important for the operation of the diesel engine and has received a lot of attention.

Which is reflected in a wide variety of combustion systems which may conveniently be grouped in two broad categories,


Fuel is injected directly into the combustion chamber formed in the cylinder itself.

That is, it is injected between the non-stationary piston crown of the corresponding shape and the stationary cylinder head.

The fuel injection valve is also mounted on its single or multiple spray orifices or nozzles.


Used in the diesel engine where fuel is injected into a pre chamber that communicates with cylinder through a narrow passage.

Rapid movement of air from the top dead center (TDC) of the ignition stroke facilitates very high movement of air in the pre chamber, which is Especially promotes rapid fuel and air mixing.


Compression ignition:

Due to almost adiabatic compression, fuel ignites without a spark plug or other ignition device.

Formation of air-fuel mixture in the combustion chamber:

Air and fuel are mixed in the combustion chamber, not the intake manifold.

Torque adjustment only by the quality of the air-fuel mixture:

Instead of squeezing the air-fuel mixture, the torque generated is always adjusted only by the injected fuel mass, mixed with as much air as possible.

Non-uniform air / fuel mixture:

Non-uniform distribution of air and fuel in the combustion chamber.

Diffuse Flame:

During combustion, oxygen must first diffuse into the flame, rather than mixing oxygen and fuel before combustion.

This creates a premixed flame.

High ignition capacity fuel:

Since diesel engines rely only on compression ignition, high ignition capacity (cetane number) fuels are ideal for proper engine operation and have high knock resistance (octane number) (Gasoline, etc.) is not ideal for diesel engine.


High performance motor.

Diesel engine combustion is caused by compression, not sparks, so the engine is ruggedly built and does not fail frequently.

Impressive fuel efficiency.

Clear safety benefits.

Increased torque.

Clean the burning fuel.


High duty engine.

Diesel engine combustion is caused by compression, not sparks, so the engine is ruggedly built and does not fail frequently.

Impressive fuel efficiency.

Clear safety benefits.

Increased torque.

Cleans the burning fuel.


Diesel engines are commonly used in mechanical engines, generators, and mobile drives.

Widely used in locomotives, construction machinery, automobiles, and countless industrial applications.

Power generation for primary or standby emergency power is the main application of today’s diesel generators.

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