An Internal Combustion engine (IC) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber. Based on type of ignition there are two types of engines Compression Ignition (CI) and Spark Ignition.
Marine diesel engines are Compression Ignition engines (CI) which use heavy fuel oil or diesel oil. Unlike a Spark Ignition system where a spark is used to ignite the fuel, a Compression Ignition system uses heat from compression to ignite the fuel in the combustion chamber.
Marine Diesel Engines are Compression Ignition Engines so we shall discuss about CI engines only
Classification of Compression Ignition Engines
Classifications can be done under various categories,
> 2 stroke (Main propulsion Engine) and 4 stroke ( Auxiliary Engines for Power generation)
> Fuel used
> Naturally Aspirated or Supercharged:
> Single or double acting
> Trunk type or Cross head type
> Single or Multi cylinder
> Low, Medium, and High Speed etc.
Working
CI engine is an internal combustion engine in which ignition of the fuel takes place with the help of hot compressed air. In this type of engine the air is sucked during suction stroke and then this air is compressed during compression stroke. At the end of the compression stroke, fuel is injected into the cylinder and it gets ignited from the heat of compressed air and the burning process begins.