IC Engine Classification based on Combustion Process
IC Engines may be classified based on the state of air-fuel mixture present at the time of ignition in the engine cycle, the type of ignition employed and the nature of combustion process subsequent to ignition of the air-fuel mixture.
- Physical State of Mixture
- Homogeneous Charge
- Premixed outside( conventional gasoline and gas engines with fuel inducted in the intake manifold)
- Premixed in-cylinder: In- cylinder direct injection and port fuel injection
- Heterogeneous Charge
- Ignition Type
- Positive source of Ignition e.g., spark ignition
- Compression ignition
- Mode of Combustion
- Flame propagation
- Spray combustion
This course primarily deals with combustion generated engine emissions and approaches the subject from the point of fundamentals of engine combustion processes. The engines are therefore, categorized based on the mode of ignition employed viz., ‘Spark Ignition (SI) Engines’ and ‘Compression Ignition (CI) Engines’.
Method of ignition has been adopted as the main criterion of classification as in the conventional type IC engines it governs
- Fuel type
- Mixture preparation methods
- Progression of combustion process
- Combustion chamber design
- Engine load control, and
- Operating and emission characteristics
More advanced and newer combustion systems are dealt as special variations of the IC engines. For example the direct injection stratified charge (DISC) engine is taken as a special variant of SI engine. The homogeneous charge compression ignition engines are being developed around the conventional SI and CI engines and are discussed accordingly.
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