Internal Combustion engine

Aniinternalicombustionienginei(ICE) 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-pressureigases producediby combustion apply direct force to some component of the engine. The force is applied typicallyito 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.

The term internal combustioniengine 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 pistoniengine 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. ICEs are usually powered by energy-dense fuels such as gasoline or diesel, liquids derived from fossil fuels. While there are many stationary applications, most ICEs are used in mobile applications and are the dominant power supply for vehicles such as cars, aircraft, and boats.

Typically an ICE 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.

Reciprocating piston engines are by far the most common power source for land and water vehicles, including automobiles, motorcycles, ships and to a lesser extent, locomotives (some are electrical but most use Diesel engines). Rotary engines of the Wankel design are used in some automobiles, aircraft and motorcycles.

ICEs drive some of the large electric generators that power electrical grids. They are found in the form of combustion turbines in combined cycle power plants with a typical electrical output in the range of 100 MW to 1 GW. The high temperature exhaust is used to boil and superheat water to run a steam turbine. Thus, the efficiency is higher because more energy is extracted from the fuel than what could be extracted by the combustion turbine alone. In combined cycle power plants efficiencies in the range of 50% to 60% are typical. In a smaller scale Diesel generators are used for backup power and for providing electrical power to areas not connected to an electric grid.

Small engines (usually 2‐stroke gasoline engines) are a common power source for lawnmowers, string trimmers, chain saws, leafblowers, pressure washers, snowmobiles, jet skis, outboard motors, mopeds, and motorcycles

Where very high power-to-weight ratios are required, internal combustion engines appear in the form of combustion turbines or Wankel engines. Powered aircraft typically uses an ICE which may be a reciprocating engine. Airplanes can instead use jet engines and helicopters can instead employ turboshafts; both of which are types of turbines. In addition to providing propulsion, airliners may employ a separate ICE as an auxiliary power unit. Wankel engines are fitted to many unmanned aerial vehicles.

The Abbé Hautefeuille described in 1678, an engine for raising water, in which the motive power was obtained by burning gunpowder in a cylinder and cooling the remaining gases with water. The idea was similar to that expressed in the early forms of the steam engine, but Hautefeuille does not appear to have preformed any actual experiments. The same idea was suggested by Huygens in 1680, but experiments made by him and later by Denis Papinwere not attended by success and were abandoned, though they are interesting as representing the first actual attempts at the building of internal-combustion engines.

A long period of inaction followed. The discovery of the distillation of gas from coal and the demonstration, by Murdock in 1792, of the application of coal gas for lighting purposes roused new interest in the subject. The introduction of the steam engine for commercial purposes about this time was also a powerful incentive, though for many decades the steam engine was too firmly intrenched and fitted the existing conditions too well to afford much opportunity for competition. About 1791 John Barber explained in a patent how a wheel with vanes could be driven by the released pressure of an orifice close to the vanes. In the century and a quarter that have elapsed since that day, no economical gas turbine has been constructed.

The first internal-combustion engine, according to our modern ideas, was that of Robert Street, patented in England in 1794. In this the bottom of a cylinder was heated by fire and a small quantity of tar or turpentine was projected into the hot part of the cylinder, forming a vapor. The rising of the piston sucked in a quantity of air to form the explosion mixture and also flame for ignition. The cycle was that which was used later by Lenoir in the first commercially successful engine. About 1800 Phillippe Lebon patented in France an engine using compressed air, compressed gas and electricity for ignition. Some authorities believe that his early death retarded the development of the internal-combustion engine half a century, as all of the features mentioned are necessary to the highly efficient engines of today, though they did not come into use for three-quarters of a century after his death.

The next engine to attain any considerable prominence was that of Samuel Brown, who secured several patents in England about 1825. His engine did not represent an advance, since the old ideas of Huygens were employed instead of the advanced ideas of Street. The success of the atmospheric steam engines was probably responsible for this. Brown's engine consisted of a number of large chambers, in which the hot gases produced by flame were cooled by the injection of water, thus forming a partial vacuum. The working pistons, in cylinders adjacent to the large chambers, were operated by atmospheric pressure, all pistons being connected to the same crankshaft, as shown in Fig. 1. Since the burning did not occur in the working cylinder, the engine can scarcely be called an internal-combustion engine in the accepted sense of the term. The inventor appears to have been a man of considerable force, and a number of his engines were built for pumping and for driving carriages and boats. In 1833, W. L. Wright patented in England, the engine illustrated in Fig. 2. The gas and air were supplied by separate pumps to a working cylinder. The charge was contained in the spherical bulbs near the ends of the cylinder, ignition occurring while the piston was at the end of the stroke. The engine was double acting, water jacketed, with poppet exhaust valves and a fly-ball governor. It represented a great advance in design and was probably built, though no records of its performance are known to exist.

In 1838 William Barnett patented in England an engine which was an advance upon preceding types in that country. It compressed the gas and air separately, igniting the mixture when the piston was at the end of its stroke. The third engine described by this inventor is shown in Fig. 3, and is interesting because it embodies several features of the modern two-cycle engine. In the figure the piston is supposed to be moving upward, compressing a mixture of gas and air. Ignition occurs when the piston has reached its highest position, and the piston driven down, expansion occurring until the piston passes the exhaust port at the middle of the cylinder. During the latter half of the stroke the pumps are forcing gas and air into space below the piston, The compression being completed by the working piston and an explosion occurring when the piston reaches its lowest position. One of the interesting features of this engine was the use of spongy platinum for ignition, though Barnett also devised an exceedingly ingenious igniting cock of burning gas jets.

The well known hot-tube method of ignition, which later became popular and has only in comparatively recent times been supplanted by electric ignition, was patented in America by Drake, and later, in 1855, by Newton, in England. The engine of Barsanti-Matteucci Engine, patented in 1857, is interesting because it illustrates a type of machine that was the first to achieve a real commercial success, though that good fortune din not happen to its Italian inventors. It is illustrated in Fig. 4. Gas and air were exploded under the piston, which was driven upward, finally coming to a rest when all of the work of the explosion had been done. The piston, descending under the pressure of atmosphere, did the work. Lenoir, of France, patented in 1860, the first engine to attain considerable use. In general, it resembled a double-acting steam engine, with a slide valve for the admission and another for the exhaust. This engine was well advertised and attained considerable use, though its economy was not very good. It was deemed of sufficient merit, however, to secure awards from the Exposition of London in 1862, of Paris in 1867, and Vienna in 1873. The improvement on the Lenoir engine by Hugon brought its inventor some prominence, but its success was short lived, as the new Otto-Langen free-piston engine, which was exhibited at the Paris Exposition in 1867, Carried all before it and held command of the market for many years, during which time a large number were built.

The Lenoir engine admitted gas and air for part of the stroke, after which the explosion occurred and then an expansion. An indicator card for this engine is shown in Fig. 5. All of these engines, it will be noted, were non-compression engines. In 1860, Beau de Rochas stated the conditions required for the efficiency of an internal-combustion engine as follows:

1) The greatest volume of the cylinder having a given surface of periphery.

2) Highest possible velocity of motion.

3) Greatest possible expansion.

4) Greatest possible pressure at commencement of the expansion.

Beau de Rochas also described the four strokes, which makes the cycle of what is known as the four-cycle engine.

To the American the most interesting part of the development of internal-combustion engines is that played by Brayton about 1872 to 1874. This engine is shown in Fig. 5. The Brayton engine was to some extent the precursor of the present Diesel engine. The mixture of gas and air burned at constant pressure and gave a card resembling somewhat that of the steam engine. This engine was manufactured for a while, but was not able to compete with the Otto-Langen free-piston engine in economy. It was adapted for both gas and petroleum.

The well-known Otto engine was invented by Dr. Nicholas Otto, of Germany, and was patented in this country in 1877. It follows the cycle that has been described by Beau de Rochas , now known as the four-cycle, or sometimes as the Otto cycle. The engine was first known as the Otto-Silent, to distinguish it from the free-piston engine, which was rather noisy. It immediately established the internal-combustion engine on a firm footing, and the engines of the four-cycle type sold today show merely minor improvements. The sliding valve on 1876 has been replaced by poppet valves, and the flame ignition has been replaced by the electric spark. Otherwise, the Otto cycle of 1876 has persisted and at this time thousands of them are being manufactured.

The development of the Diesel engine for oil began about 1894. As has been stated, this engine is similar to the Brayton. Air is compressed to about 500 pounds pressure and oil is sprayed into this highly compressed air. It burns spontaneously at nearly constant pressure, which is followed by a long expansion. The extremely high temperature of the air previous to the injection of the fuel, and the high temperature maintained during this injection, together with the long expansion, give the engine the highest efficiency of any thermal motor. The development of the Diesel engine has been so recent that it is not necessary to elaborate upon it. At this time, it is being manufactured in all of the European countries and in America, and there is a tendency on the part of many of the American manufacturers who are bringing out new engines to adopt the features of the Diesel. The gas turbine is as yet in the experimental stage. A number have been built and are of course, extremely interesting. The success of the steam turbine has encouraged many to believe that the gas turbine will achieve similar success. Nothing of recent development can be said to encourage this view. The difficulties in the way of successful gas turbines are very great, and while some turbines have been designed and run, none of them has shown an efficiency at all comparable to that of ordinary four-cycle engines.