Internal Combustion VS External Combustion Engines

A combustion engine is an engine which generates mechanical power by combustion of a fuel. Either they can burn internally or externally.

According to it's combustion process they can be classified as-

• Internal Combustion or I-C Engine
• External Combustion or E-C Engine

1. Internal Combustion or I-C Engine-  An internal combustion engine is a heat engine where the combustion of a fuel occurs with an oxidizer (usually air) in a Combustion chamber that is an integral part of the engine. All modern type of engine are of this type. There are many advantages of this type of engine. The first commercially successful internal combustion engine was created by Etienne Lenoir around 1859. Fig shows the illustration of this type of engine-

Fig. Internal Combustion Engine

Advantages of internal combustion engine-

1. An internal combustion engine is compact and lighter.
2. An internal combustion engine is quite safe to use.
3. An internal combustion engine can be started immediately.
4. An internal combustion engine has higher efficiency than external combustion engine.
5. High power to weight ratio 
6. Emissions are minimized by advanced combustion control, design and aftertreatment.
7. It is possible to raise the efficiency to relatively high levels by minor means.
8. An internal combustion engine has higher efficiency.

2. External Combustion or E-C Engine- An external combustion engine is a heat engine where a working fluid, contained internally, is heated by combustion in an external source, through the engine wall or a heat exchanger. In this type of engines ignition of fuel (such as coal) are taken outside from the cylinder, then the fluid by expanding acting on the mechanism of the engine, produces motion and usable work. These type of engines are no longer used due to their many drawbacks. Example of this type of engine is steam engines. Fig shows the illustration of this type of engine-

Fig. An External Combustion Engine( Steam Engine)

Fig. External Combustion Engine

 As shown in fig the water is ignite externally, which produce steam, thus providing motion to the  piston.

Disadvantages of external combustion engine-

1. An external combustion engine is huge and heavy.
2. An external combustion engine does not start at once.
3. An external combustion engine is unsafe to use.
4. An external combustion engine has low efficiency.