Understanding diesel engine

The diesel engine is one of the most effective and powerful engines when compared to that of a gasoline engine. Though it is the continuation of a gasoline engine. This article will give an understanding of diesel engines which includes, their definition, efficiency, history, working, and types. See some articles on automobile engines below!

diesel engine


Diesel engine

The diesel engine is an internal combustion engine in which the ignition of fuel is caused by the rising temperature of the air in the cylinder due to the mechanical compression called “adiabatic compression”. Let me explain in detail for more clarification…

Unlike spark-ignition engines such as gasoline engines (petrol engines) that use a spark plug to ignite the air-fuel mixture. It totally differs from diesel engines. Diesel engines work by compressing only air in the cylinder, which increases to an elevated temperature (hot air), and atomizes the diesel fuel injected into the combustion chamber, causing the ignition spontaneously. These engines work with a heterogeneous air-fuel mixture. That is, the injected fuel into the air before combustion dispersed unevenly. The torque a diesel engine produces is controlled by manipulating the air-fuel ratio (λ); instead of throttling the intake air, the diesel engine relies on altering the amount of fuel that is injected, and the air-fuel ratio is usually high.

Diagram of diesel engine:


The diesel engine is also known as a compression-ignition or CI engine, named after the founder Rudolf Diesel. Rudolf Diesel was a student of Polytctechnikum in Munich, where he attended the lectures of Carl von Linden. Carl examined a steam engine and said steam engines are capable of converting just 6-10% of the heat energy into work, but the Carnot cycle has the ability to convert much more heat energy into work by means of isothermal change in condition.

These ideas built momentum on Diesel for creating a highly efficient engine that could work on the Carnot cycle. He was also exposed to a fire piston, a traditional fire starter using rapid adiabatic compression principles which Linde had acquired from Southeast Asia. After several years of working on his ideas, Diesel published them in 1893 in the essay Theory and Construction of a Rational Heat Motor.

The diesel engine exists as the engine with the highest thermal efficiency either with the internal or external combustion engine. This occurs due to the very high expansion ratio and inherent lean burn which enables heat dissipation by the excess air. A small efficiency loss is also avoided compared with non-direct-injection gasoline engines since unburned fuel is not present during valve overlap and therefore no fuel goes directly from the intake/injection to the exhaust.

The diesel engine has become highly replaceable for stationary steam engines because of its high efficiency. Diesel engines may be designed as either two-stroke or four-stroke cycles.

Diesel engine diagram

Diesel engines have been applicable since the 1910s in ships and Submarines, locomotives, trucks, heavy equipment, electricity generation plants, etc. In the 1930s, it began to be used in a few automobiles, which became widespread on larger on-road and off-road vehicles since the 1979s, which was accounted based on the newly registered diesel cars. The world’s largest diesel engines put in service are 14-cylinder, two-stroke watercraft diesel engines; they produce a peak power of almost 100 MW each.

Watch the video below to learn the workings of a diesel engine:

Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can reach effective efficiencies of up to 55%.

The main development purpose for future diesel engines is described as improvements in exhaust emissions, reduction of fuel consumption, and increase in lifespan. Diesel engine, especially for commercial vehicles is expected to remain the most important vehicle powerplant until the mid-2030s. However, the advancement of life and technology makes the introduction of electric engines considered an effective one.

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