Conversion of heat energy into mechanical work is termed as a heat engine.
Heat engines are classified into two main classes they are.
- Internal combustion engines (I.C. ENGINES)
- External combustion engines (E.C. ENGINES)
Internal combustion engine:
Internal combustion engines, combustion takes place outside the engine.
The internal combustion engines are generally used for driving petrol, diesel, and oil engines.
External combustion engine:
Combustion takes place outside the engine. The External combustion engines are generally used for driving petrol, diesel, and oil engines.
According to cycle operation internal combustion engines are classified two types they are.
- Two strokes engines
- Four strokes engines
The main part of diesel engine is Fuel injector. The main parts of petrol engine is Spark plug and carburetor.
The volume contained in cylinder above the top of the piston, when the piston is at top dead center, is called clearance volume.
The volume swept through by the piston in moving between bottom dead center and top dead center.
The ratio of total cylinder volume to clearance volume.
- Compression ratio in petrol engine is 5:1 to 9 :1
- Compression ratio in diesel engine is 11:1 to 22:1
Piston speed: Average speed of the piston is called piston speed.
Piston speed = 2 L N
The ratio is area of the actual indicator diagram to the theoretical one is called diagram factor.