What Is an Internal Combustion 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 working fluid flow circuit.
In an internal combustion engine the expansion of the high-temperature and high-pressure gases produced by combustion apply direct force to some component of the engine. The force is applied typically to pistons, turbine blades, rotor or a nozzle. This force moves the component over a distance, transforming chemical energy into useful mechanical energy.
The first commercially successful internal combustion engine was created by Étienne Lenoir around 1859 and the first modern internal combustion engine was created in 1876 by Nikolaus Otto.
In 1885, two Germans, Gottlieb Daimler and Karl Benz, designed an engine that burned a petroleum fuel and used the resulting power to generate motion. This was the internal combustion engine, a power source that eventually replaced the steam engine as a method for running vehicles. The internal combustion engine is used for many other devices, too. This engine flies airplanes, run boats, and many other devices too.
The term internal combustion engine usually refers to an engine in which combustion is intermittent, such as the more familiar four-stroke and two-stroke piston engines, along with variants, such as the six-stroke piston engine and the Wankel rotary engine.
A second class of internal combustion engines use continuous combustion: gas turbines, jet engines and most rocket engines, each of which are internal combustion engines on the same principle as previously described. Firearms are also a form of internal combustion engine.
Internal combustion engines are quite different from external combustion engines, such as steam or Stirling engines, in which the energy is delivered to a working fluid not consisting of, mixed with, or contaminated by combustion products.
Working fluids can be air, hot water, pressurized water or even liquid sodium, heated in a boiler. Internal combustion engines are usually powered by energy-dense fuels such as gasoline or diesel, liquids derived from fossil fuels. While there are many stationary applications, most internal combustion engines are used in mobile applications and are the dominant power supply for vehicles such as cars, aircraft, and boats.
Typically an internal combustion engine is fed with fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel or fuel oil. There’s a growing usage of renewable fuels like biodiesel for compression ignition engines and bioethanol or methanol for spark ignition engines. Hydrogen is sometimes used, and can be made from either fossil fuels or renewable energy.