In mechanical engineering internal combustion engines are basically of two types:
A) Spark ignition (SI) or Petrol engine
B) Compression ignition (CI) or diesel engine
A) Spark ignition (SI) or Petrol engine
1) spark-ignition engine is sometimes known as a petrol engine.
2) Petrol engines are spark-ignited internal combustion engines.
3) They use fuels that are reasonably volatile, like petrol.
4) In these engines, fuel and air are often combined after compression.
5) Petrol engines operate via the Otto cycle, which entails two isochoric and two isentropic processes.
6) Internal combustion engines use two completely distinct mechanical technologies for ignition: spark and compression. Compression ignition (CI) engines and the petrol engine(SI) engines; both operate similarly and sometimes on the same operational principles.
Note: Diesel is utilised as a fuel in compression ignition (CI) engines while petrol or gasoline is used in spark ignition (SI) engines. Diesel engines are heavy and operate at lower speeds, whereas petrol engines are light and operate at faster speeds.
B) Compression ignition (CI) or diesel engine
1) A compression-ignition engine (CI engine), often known as a diesel engine named after Rudolf Diesel, is an internal combustion engine in which the fuel is ignited by use of the heated air in the cylinder brought about by mechanical compression.
2) Because CI engines have a higher compression ratio than SI engines do, more work is done with each expansion stroke, increasing their thermodynamic efficiency.
3) CI engine works on diesel cycle.
4) Compared to petrol engines (20%), diesel engine has a fairly high efficiency (35–40%) Because of its high compression ratio of about 18.
5) Diesel engines are more difficult to start than petrol engines of comparable design and displacement because of the higher compression ratio and the added weight of the stronger components.
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