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Diesel cycle
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Idealised compression-ignition engine.
Compression-ignition engine: adiabatic compression, constant-pressure combustion, adiabatic expansion, constant-volume exhaust. Higher compression ratios give higher efficiency than petrol.
Diesel engines reach about 40%.
Air only compressed, fuel injected later.
In more detail
The Diesel cycle models a diesel engine, which compresses air until it ignites fuel, with heating at constant pressure. It typically has higher compression ratios than petrol engines.
Real-world uses
- Trucks and ships often use diesel engines for their efficiency.
- Diesel engines use the high temperature from compression to ignite fuel.
- Diesel engines in trucks and ships use the Diesel cycle, which compresses air so hot that fuel ignites without a spark.
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Frequently asked questions
How does a diesel engine ignite fuel?
The compressed air becomes hot enough that injected fuel ignites without a spark.
Why is diesel more efficient?
It uses higher compression ratios, which increase the efficiency of the cycle.
How does a Diesel engine differ from a petrol engine?
It compresses air alone to a higher pressure and ignites the fuel by heat, rather than using a spark plug.
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