The fourth stage of the compression ignition process is Burning on the expansion stroke.

Stages of Combustion in Compression Ignition Engine:

1. Ignition Delay Period
2. Period of Uncontrolled Combustion
3. Period of Controlled Combustion
4. Burning on the Expansion Stroke

The fourth stage of combustion in a compression ignition engine is called afterburning.

It begins when the maximum temperature of the cycle is reached and lasts until the end of heat release. A soot-burning reaction occurs during this stage. The following factors affect the course of the fourth stage.

1. The phenomenon of fuel falling on cool surfaces of the cylinder space causes the extension of the duration of this stage.
2. Supercharging the engine leads to a prolongation of the period of combustion of fuel, due to the longer fuel injection time and the deterioration of the spread of the fuel in the combustion chamber.
3. The spraying process is in the final stage of combustion. The large maximum diameter of the fuel droplets results in extended fuel injection, which means that the afterburning time of the combustible mixture is longer. This deteriorates the use of thermal energy resulting from combustion, which affects the operation and reliability of the engine by depositing carbon combustion deposits and coking the fuel atomizers.
4. Turbulent charge fluctuation contributes to improving the mixing of fuel and air.