A combustion engine is a device that converts chemical energy (in the form of fuel) to useful mechanical energy. Combustion engines can be broadly classified into two types. They are:
- External Combustion Engine (EC Engine)
- Internal Combustion Engine (IC Engine)
External Combustion Engine (EC Engine):
In an external combustion engine, fuel is burnt externally (in a heat exchanger) to produce heat. This heat is used for inducing useful mechanical motion in the cylinder of the engine.
A very good example of external combustion engine is steam engine.
Internal Combustion Engine (IC Engine):
Here, the fuel is burnt inside the cylinder of the engine. Chemical energy of the fuel is converted to thermal energy and thermal energy is converted to mechanical energy, which moves the piston up and down inside the cylinder. Power from the piston is transmitted to the crankshaft which is ultimately transmitted to the wheels via a transmission system.