Introduction
In general sense, the term Internal Combustion Engine refers to an engine in which the process of combustion is sporadic. In such an engine combustion of fuel especially fossil fuels (mainly petroleum) takes place in the combustion chamber, which is an integral part of the engine. In this process of internal combustion, expansion of high temperature and pressure takes place, which in turn applies force to certain parts of the engines (such as pistons, turbine blades etc.) that allows movement. In simple terms Internal Combustion Engine is used for converting chemical energy into mechanical energy.
History
Evidence says that there were several Internal Combustion Engines present before the advent of the 19th century but their development was hindered until the production of petroleum began in the mid 1850s. It was towards the mid of the 19th century that various engineering advances and developments led to their pervasive usage and adoption. However, Étienne Lenoir was the first to have developed a commercially efficacious Internal Combustion Engine.
Applications
In current times, the Internal Combustion Engines are used in all forms of machinery that requires mobile propulsion, as it provides high power-to-weight ratios along with outstanding fuel energy density. Its general usage includes automobiles, boats, aircrafts, rockets etc.
Types
Depending on the layouts and the type of engines, Internal Combustion Engines can be classified as follows;
- Reciprocating:
- Two-stroke engine
- Four-stroke engine (Otto cycle)
- Six-stroke engine
- Diesel engine
- Atkinson cycle
- Miller cycle
Gyratory
- Wankel engine
Incessant combustion
- Gas turbine
- Jet engine
Functioning
The common usage of Internal Combustion Engines could be easily explained through its workings in a 4-stroke engine, which are as follows:
- Intake / Suction Stroke – This stroke is the first step that an Internal Combustion engine takes. As the name specifies, in this stroke the piston of the engines moves downward thereby creating a vacuum in the upper part of the cylinder leading the inlet valve to open up. As a result of this the vaporized fuel mixture is sucked into the combustion chamber.
- Compression Stroke – In this step, both the valves are closed and the piston moves upward creating compression on the mixture.
- Power Stroke – Just before the piston reaches top dead center, the spark plugs ignite the fuel mixture, which leads to its combustion in the presence of air (oxidizer) thereby generating a great amount of heat, steam and carbon dioxide along with other chemicals at very high temperature. This whole process basically generates power that is transmitted to the crankshaft mechanism.
- Exhaust Stroke – In this step the piston again starts moving downwards, which opens the exhaust valve so that exhaust gases can easily escape. At the end of this stroke the exhaust valve is closed and the inlet valve gets opened. Hence the whole process keeps on repeating itself starting from Step-1.
However it should be noted that here, Oxygen has been mentioned as an ideal oxidizer for the combustion of vaporized fuel mixture due to the fact that it could be found in plenty and doesn’t require being stored in the vehicle. But there are other oxidizers too, which do the same work but they are either more power generating and less energy efficient or vice-versa.
