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Diesel engine

The operating principle of the Diesel engineRudolph Diesel patented 1893on February 23.

THE Diesel engine only takes in air, and it takes in a lot of aircompresses and the dispenser injects into the heated air in the combustion chamber the fuel.

Diesel engines were able to make progress in freight transport because their specific consumption is lower compared to gasoline engines. This is due to structural features: the larger

(17..20:1) compression ratio results in better thermodynamic efficiency.

However, it is the most polluting engine.

Diesel engine operation, diesel injection is indicated by the red arrow

  • Suction

    • intake of clean air

  • Compression

    • compressing air, causing it to heat up

  • Blasting and working

    • the compressed, heated air ignites the injected fuel

    • then pushes the piston down

  • Exhaust

    • exit of the combustion product


The diesel engine only takes in clean air and compresses it. Due to the high pressure, the air heats up. Into this hot air, the metering pump injects diesel oil, which ignites at a high temperature without a separate ignition device (spark plug).

The torque of diesel engines depends on the amount of fuel injected, but it is limited by the amount of air taken in.

The amount of air taken in can be increased by using a turbocharger, which fills the cylinder with up to 2.5 times as much air, and the torque and performance will also be 2.5 times higher. Of course, this overloads the engine, so it is much more powerful compared to the aspirated version


Diesel burns more slowly and imperfectly than gasoline, so its speed is much lower than that of an Otto engine with a similar displacement.k.

The first experimental engines ran on vegetable oil, later the idea of petroleum and the possibility of using "diesel oil" produced as waste from gasoline production.

However, it also has serious environmental effects:

  • the high soot emissions caused by the incomplete combustion of high-carbon fuel

  • high nitrogen oxide emissions are caused by locally high temperatures (hydrogen is separated from the carbon chain first), as a result of which nitrogen and oxygen in the air react with each other to create NOx molecules

  • according to some, diesel oil contains more than 20 components (mineral, synthetic, combustion improver, lubricity enhancer, etc.) during their combustion and through the reaction of the combustion products with each other, many solid particles are formed, a significant part of which are carcinogenic!

A complex flue gas treatment system is used to reduce environmental impacts:

  • with EGR (exhaust gas recirculation)

  • DPF (Diesel Particulate Filter, Diesel particulate filter)

    • The huge flaw in this is that they are mostly not replaced, but ​ are burned during the journey, causing significant environmental pollution

  • AdBlue system SCR (SCR - Selective Catalytic Reduction, selective catalytic reduction

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