Internal combustion engine - Wikipedia, the free encyclopediaPage 1 of 8 Internal combustion engine From Wikipedia, the free encyclopedia The internal combustion engine is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and -pressure gases produced by combustion applies direct force to some component of the engine, such as pistons, turbine blades, or a nozzle. This force moves the component over a distance, generating useful mechanical energy.[1][2][3][4] 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.[1][2][3][4] The internal combustion engine (or ICE) is 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 some kind of boiler. A large number of different designs for ICEs have been developed and built, with a variety of different strengths and weaknesses. Powered by an energy-dense fuel (which is very frequently gasoline, a liquid derived from fossil fuels). While there have been and still are many stationary applications, the real strength of internal combustion engines is in mobile applications and they dominate as a power supply for cars, aircraft, and boats. Animated two stroke engine in operation Contents ■ ■ ■ ■ 1 Applications 2 History 3 Nomenclature 4 Types of internal combustion engine ■ 4.1 Engine configurations ■ 4.1.1 Operation ■ 4.1.2 Combustion ■ 4.1.3 Two stroke configuration ■ 4.1.4 Wankel ■ 4.1.5 Gas turbines ■ 4.1.6 Jet engine ■ 4.2 Engine cycle ■ 4.2.1 Two-stroke ■ 4.2.2 Four-stroke ■ 4.2.3 Diesel cycle ■ 4.2.4 Five-stroke ■ 4.2.5 Six-stroke ■ 4.2.6 Brayton cycle ■ 4.2.7 Obsolete ■ 4.3 Fuels and oxidizers ■ 4.3.1 Fuels ■ 4.3.2 Hydrogen ■ 4.3.3 Oxidizers ■ 5 Engine starting ■ 6 Measures of engine performance ■ 6.1 Energy efficiency ■ 6.2 Measures of fuel/propellant efficiency ■ 7 Air and noise pollution ■ 7.1 Air pollution ■ 7.2 Noise pollution ■ 7.3 Idling ■ ■ ■ ■ 8 See also 9 References 10 Further reading 11 External links An automobile engine partly opened and colored to show components. Applications Internal combustion engines are most commonly used for mobile propulsion in vehicles and portable machinery. In mobile equipment, internal combustion is advantageous since it can provide high power-to-weight ratios together with excellent fuel energy density. Generally using fossil fuel (mainly petroleum), these engines have appeared in transport in almost all vehicles (automobiles, trucks, motorcycles, boats, and in a wide variety of aircraft and locomotives). Where very high power-to-weight ratios are required, internal combustion engines appear in the form of gas turbines. These applications include jet aircraft, helicopters, large ships and electric generators. History Main article: History of the internal combustion engine http://en.wikipedia.org/wiki/Internal_combustion_engine 11/1/2011 electric motors are not referred to as "Engines".8 bar (1. gasoline and petroleum gas. hot tube and flame methods were used. or by the cooling system employed. Power stroke: When the piston reaches the minimum volume position. Exhaust stroke: In the end of the power stroke. ramjet. The inlet valve opens as a result of piston movement. typically with oxygen from the air (though it is possible to inject nitrous oxide in order to do more of the same thing and gain a power boost). Gasoline engines take in a mixture of air and gasoline and compress it to not more than 12. as well as by the compression and other factors. the layout of the engine. as well as from so-called producer gas made from other convenient biomass. 4. During this stroke. Liquid and gaseous biofuels. the piston starts its movement in the minimum volume position. 3. Recently.Wikipedia. Exhaust All internal combustion engines depend on the combustion of a chemical fuel. 2. "mover") is any machine that produces mechanical power. jet engines do all steps simultaneously at different parts of the engines. This battery is recharged during operation using an electricity-generating device such as an alternator or generator driven by the engine. and the vaporized fuel mixture enters the combustion chamber. "ability") meant any piece of machinery—a sense that persists in expressions such as siege engine.[5] Gasoline Ignition Process Gasoline engine ignition systems generally rely on a combination of a lead-acid battery and an induction coil to provide a high-voltage electric spark to ignite the air-fuel mix in the engine's cylinders. can also be used. then use a spark plug to ignite the mixture when it is compressed by the piston head in each cylinder. Four stroke engines require two revolutions. http://en. combustion engines are often referred to as "motors. etc. Intake 2. and the rarer use of propane. The open exhaust valve allows the exhaust gases to escape the cylinder. turbofan. as well as the production of steam and carbon dioxide and other chemicals at very high temperature. Rocket. Intake stroke: The first stroke of the internal combustion engine is also known as the suction stroke because the piston moves to the maximum volume position (downward direction in the cylinder). most internal combustion engines that are designed for gasoline use can run on natural gas or liquefied petroleum gases without major modifications. Engines with appropriate modifications can also run on hydrogen gas.org/wiki/Internal_combustion_engine 11/1/2011 . The most common modern fuels are made up of hydrocarbons and are derived mostly from fossil fuels (petroleum). temperature and the density of the fuel mixture increases. the inlet valve opens. ingenium. or charcoal gas. Compression stroke: In this stroke. the spark plug ignites the fuel mixture and burns.) Operation As their name implies. either by spark ignition (SI) or compression ignition (CI). the exhaust valve closes. and the sequence repeats in the next cycle. the word. Traditionally.wikipedia. source of energy.28 MPa). Engine configurations Internal combustion engines can be classified by their configuration. via Old French. the use of the engine.Internal combustion engine . "Engine" (from Latin. The combustion process typically results in the production of a great quantity of heat. Combustion Two-stroke engine Four-stroke engine Six-stroke engine Diesel engine Atkinson cycle Miller cycle A 1906 gasoline engine Four-stroke cycle (or Otto cycle) 1. A "motor" (from Latin motor.) Types of internal combustion engine Engines can be classified in many different ways: By the engine cycle used. During the compression process. The fuel produces power that is transmitted to the crank shaft mechanism. Except for the fuel delivery components. the free encyclopedia Page 2 of 8 Nomenclature At one time. the exhaust valve opens." (An electric engine refers to a locomotive operated by electricity. experiments have been made with using powdered solid fuels. such as the magnesium injection cycle. Large diesels can run with air mixed with gases and a pilot diesel fuel ignition injection. such as ethanol and biodiesel (a form of diesel fuel that is produced from crops that yield triglycerides such as soybean oil). wood gas. four-stroke internal combustion engines have four basic steps that repeat with every two revolutions of the engine: (1) Intake stroke (2) Compression stroke (3) Power stroke and (4) Exhaust stroke 1. Common layouts of engines are: Reciprocating: ■ ■ ■ ■ ■ ■ Rotary: ■ Wankel engine Continuous combustion: ■ Gas turbine ■ Jet engine (including turbojet. Power 4. The inlet valve closes at the end of this stroke. Compression 3. however. Fossil fuels include diesel fuel. Before the invention of reliable electrical methods. the temperature reached is determined by the chemical make up of the fuel and oxidisers (see stoichiometry). both valves are closed and the piston starts its movement to the minimum volume position (upward direction in the cylinder) and compresses the fuel mixture. Many engines overlap these steps in time. Experimental engines with laser ignition have been built. pressure. Internal combustion engines require ignition of the mixture. At the end of this stroke. a combustion chamber. Aircraft engines can also adopt a radial configuration which allows more effective cooling. This is also why diesel and HCCI engines are more susceptible to cold-starting issues. like in the four stroke engine. Wankel Main article: Wankel engine The Wankel engine (rotary engine) does not have piston strokes. or turbocharging) to scavenge the cylinders. Most diesels also have a battery and charging system. This type of engine is most notably used in the current Mazda RX-8. The most common method in spark-ignition two-strokes is to use the downward motion of the piston to pressurize fresh charge in the crankcase. The advantage of having one power stroke for every 360° of crankshaft rotation (compared to 720° in a 4 stroke motor) is balanced by the less complete intake and exhaust and the shorter effective compression and power strokes. due to higher pressures and heat. Two-stroke engines are widely used in snowmobiles. which is then blown through the cylinder through ports in the cylinder walls.Wikipedia. however. at the expense of less power at other speeds. Also the thermal efficiency is improved because of lack of cylinder heads. Jet engine Main article: Jet engine Jet engines take a large volume of hot gas from a combustion process (typically a gas turbine. one can achieve uniflow scavenging.Internal combustion engine . and continues to be used for marine engines.wikipedia. an example of this type of motor is the Wartsila-Sulzer turbocharged two-stroke diesel as used in large container ships. over a narrow range of engine speeds. turning fuel on and off (which can also be done via a switch or mechanical apparatus). The shaft turns three times for each rotation of the rotor around the lobe and once for each orbital revolution around the eccentric shaft. It may be possible for a two stroke to produce more power than an equivalent four stroke. Common cylinder configurations include the straight or inline configuration. both for propulsion and for auxiliary generators. nevertheless. These used three crankshafts to serve three banks of double-ended cylinders arranged in an equilateral triangle with the crankshafts at the corners. typically around 1. efficient over a wide range of revolution numbers. Multiple crankshaft configurations do not necessarily need a cylinder head at all because they can instead have a piston at each end of the cylinder called an opposed piston design. Most new engines rely on electrical and electronic engine control units (ECU) that also adjust the combustion process to increase efficiency and reduce emissions. Fuel injection is essential for a modern two-stroke engine in order to meet ever more stringent emission standards. using at either end of a single bank of cylinders with two crankshafts. chain saws. so may be thought of as a "four-phase" engine. It is the most efficient and powerful internal combustion engine in the world with over 50% thermal efficiency. lawnmowers.[6][7][8][9] For comparison. a small quantity of diesel fuel is sprayed into the cylinder via a fuel injector that allows the fuel to instantly ignite. The Wankel cycle. one down) for every power stroke. As the jet accelerates through the nozzle. It was also used in singlebank locomotive engines. this engine provides three power 'strokes' per revolution per rotor giving it a greater power-to-weight ratio than piston engines. While it is true that three power strokes typically occur per rotor revolution due to the 3:1 revolution ratio of the rotor to the eccentric shaft.5 times that of a typical four-stroke engine. Research continues into improving many aspects of two-stroke motors including direct fuel injection. rely solely on heat and pressure created by the engine in its compression process for ignition. although they will run just as well in cold weather once started. the free encyclopedia Diesel Ignition Process Page 3 of 8 Diesel engines and HCCI (Homogeneous charge compression ignition) engines. U. power to volume ratio). HCCI type engines will take in both air and fuel but continue to rely on an unaided auto-combustion process. the earlier RX-7.and outlets are positioned at opposed ends of the cylinder. Modern designs (Sarich and Paggio) use air-assisted fuel injection which avoids this loss.org/wiki/Internal_combustion_engine 11/1/2011 . crankcase-scavenged two-stroke engines have been less fuel-efficient than other types of engines when the fuel is mixed with the air prior to scavenging allowing some of it to escape out of the exhaust port. They use forced induction (similar to supercharging. and are more efficient than comparably sized four-stroke engines. Light duty diesel engines with indirect injection in automobiles and light trucks employ glowplugs that pre-heat the combustion chamber just before starting to reduce no-start conditions in cold weather. used in some locomotives and large ships. About ⅔ of the heated air combined with the products of combustion is expanded in a turbine resulting in work output which is used to drive the compressor. Two-stroke engines have the advantage of an increased specific power ratio (i. In terms of power per cm³. More unusual configurations such as the H. and shortly before peak compression. Since there are no dedicated intake or exhaust strokes. It operates with the same separation of phases as the four-stroke engine with the phases taking place in separate locations in the engine. the most efficient small four-stroke motors are around 43% thermal efficiency (SAE 900648). The rest (about ⅓) is available as useful work output. amongst other things. this creates thrust and in turn does useful work. The initial results have produced motors that are much cleaner burning than their traditional counterparts. Because here gas in. they are also generally less efficient and more polluting than their four-stroke counterparts. The largest internal combustion engines in the world are two-stroke diesels. but rocket forms of jet propulsion often use solid or liquid propellants. and ramjet forms also lack the gas turbine) and feed it through a nozzle which accelerates the jet to high speed. and many motorcycles. a two-stroke engine produces comparable power to an equivalent four-stroke engine. Gas turbines Main article: gas turbine A gas turbine is a rotary machine similar in principle to a steam turbine and it consists of three main components: a compressor. and other models. the more compact V configuration. string trimmers. and the wider but smoother flat or boxer configuration. Diesel engines will take in air only. Two stroke configuration Main article: Two-stroke engine Engines based on the two-stroke cycle use two strokes (one up. jet skis. and W have also been used. outboard motors. and most remarkably in the Napier Deltic diesel engines. The air after being compressed in the compressor is heated by burning fuel in it. Small displacement. this system is secondary and is added by manufacturers as a luxury for the ease of starting. The compression level that occurs is usually twice or more than a gasoline engine. size is an advantage for efficiency due to the increase in the ratio of volume to surface area. which is. and for running auxiliary electrical components and accessories. X. Spark-ignition two-strokes are small and light for their power output and mechanically very simple. Engine cycle Two-stroke Main article: Two-stroke cycle http://en. and a turbine. In thermodynamic terms it follows the Otto engine cycle.e. alternative methods must be used to scavenge the cylinders. This design was used in the Junkers Jumo 205 diesel aircraft engine. mopeds. only one power stroke per shaft revolution actually occurs. Wikipedia. Some form of pressure is needed.[10] They are used in cars. the bottom is the compression stroke Split-cycle engines separate the four strokes of intake. based on the above advantages and disadvantages. ■ The piston motion creates a vacuum that sucks the fuel/air mixture from the carburetor and pushes it from the crankcase (adjacent chamber) to the combustion chamber. and 4th stroke the piston is relying on power and the momentum generated by the other pistons. Combustion stroke: Fuel combusts and piston is pushed downwards. The cycle is repeated. ■ The sides of the piston act like the valves. the fuel/air intake port. Previous split-cycle engines have had two major problems . the 2-stroke engines are supposed to operate in vehicles where the weight of the engine is required to be small. a four-cylinder engine would be less powerful than a six or eight cylinder engine. In this cycle. resulting in a simpler. When the piston is at bottom dead center the burnt gases escape from the exhaust port. ■ Crankshaft: A shaft which converts the reciprocating motion of the piston into a rotary motion. but more environmentally damaging system. fuel mixture starts to flow to the combustion chamber and the second process of fuel compression starts. covering and uncovering the intake and exhaust ports drilled into the side of the cylinder wall.org/wiki/Internal_combustion_engine 11/1/2011 . Compression stroke: Fuel-air mix is compressed and ignited. receives back the liberated energy. In this engine the intake and exhaust strokes are eliminated and ports are used instead of valves. the petrol is mixed with lubricant oil. http://en. Intake stroke: Air and vaporized fuel are drawn in. larger boats. the 2-stroke engines have a shorter life. • Sometimes part of the fuel leaks to the exhaust with the exhaust gases. as the excess oils do not burn and are left as a residue. This is achieved by exhausting and recharging the cylinder simultaneously. They are generally quieter. some motorcycles. Intake and exhaust ports: An intake port allows the fresh fuel-air mixture to enter the combustion chamber and an exhaust port discharges the products of combustion. Exhaust stroke: Exhaust is driven out. However. combustion and exhaust into two separate but paired cylinders. In case of diesel: Air is compressed. and transfers it to the crankshaft. Piston: A cylindrical component making an up and down movement in the cylinder. and the it is not used continuously for long periods of time. where combustion and exhaust occur. During the 1st. Due to the expansion of the gases the piston moves downwards covering the intake port and causes the fuel-air mixture inside the crank chamber to be compressed. The steps involved here are: 1. therefore the processes of fuel injection and exhausting are synchronized to avoid that concern. The design carefully considers the point that the fuel-air mixture should not mix with the exhaust. Four-stroke Main article: Four-stroke cycle Engines based on the four-stroke ("Otto cycle") have one power stroke for every four strokes (up-down-up-down) and employ spark plug ignition. • High power to weight ratio Disadvantages: • The lack of lubrication system that protects the engine parts from wear. 3. Compression stroke: Fuel vapor and air are compressed and ignited. to rest in an adjacent fuel chamber. Combustion chamber: A portion above the cylinder in which the combustion of the fuel-air mixture takes place. The compressed air is then transferred through a crossover passage from the compression cylinder into the second cylinder. Operation: When the piston moves from bottom dead center (BDC) to top dead center (TDC) the fresh air and fuel mixture enters the crank chamber through the intake port. Intake and exhaust occur at bottom dead center. most notably the Atkinson and Miller cycles. either crankcase compression or supercharging. the engine executes one cycle—the 4-stroke executes one cycle per two crankshafts revolutions. 3. fuel is injected and selfignited. In that case. • 2-stroke engines do not consume fuel efficiently. It should be noted that the piston has three functions in its operation: ■ The piston acts as the combustion chamber with the cylinder and compresses the air/fuel mixture. ignition takes place at the top of the stroke. 4. and many light aircraft. Accordingly. Advantages: • It has no valves or camshaft mechanism. As the piston proceeds downward another port is opened. Idealised Pressure/volume diagram of the Otto cycle showing combustion heat input Qp and waste exhaust output Qo. ■ ■ ■ ■ There are a number of variations of these cycles. The major components of a two stroke spark ignition engine are the: Cylinder: A cylindrical vessel in which a piston makes an up and down motion. more efficient. The steps involved here are: 1.wikipedia. The diesel cycle is somewhat different. 2. Two Stroke Spark Ignition (SI) engine: Page 4 of 8 Idealised P/V diagram for two stroke Otto cycle In a two stroke SI engine a cycle is completed in two strokes of a piston or one complete revolution (360º) of a crankshaft. Ignition: With the help of a spark plug. Power stroke: Piston is pushed downward by the hot exhaust gases. ■ Spark plug: An ignition-source located at the cylinder head that is used to initiate the combustion process. • Less weight and easier to manufacture. the free encyclopedia This system manages to pack one power stroke into every two strokes of the piston (up-down).poor breathing (volumetric efficiency) and low thermal efficiency. hence simplifying its mechanism and construction • For one complete revolution of the crankshaft. The fresh charge is deflected upwards by a hump provided on the top of the piston and removes the exhaust gases from the combustion chamber. and larger than their two-stroke counterparts. The mixture enters due to the pressure difference between the crank chamber and the outer atmosphere while simultaneously the fuel-air mixture above the piston is compressed. ■ Connecting rod: A rod which connects the piston with the crankshaft. where it was mixed. the power stroke is the top curved line. • 2-stroke engines produce lots of pollution. 2. new designs are being introduced that seek to address these problems. When the piston moves further down and the cylinder doesn't have anymore gases. A split-cycle engine is really an air compressor on one side with a combustion chamber on the other. 2nd. compression.Internal combustion engine . At the time the transfer port is uncovered the compressed charge from the crank chamber enters into the combustion chamber through the transfer port. In conclusion. and during combustion the volume varies little ("constant volume"). Again the piston moves from bottom dead center to top dead center and the fuel-air mixture is compressed when the both the exhaust port and transfer ports are covered. Combustion occurs rapidly. The first cylinder is used for intake and compression. Air/fuel/oil mixtures come from the carburetor. and a turbine. In the diesel cycle. Brayton cycle Fuels and oxidizers Engines are often classified by the fuel (or propellant) used. combustion. EHV. This engine corresponds to a 2003 US patent by Gerhard Schmitz. P-v Diagram for the Ideal Diesel cycle. Otto cycle is exactly the same one that was described for the four-stroke engine. firing every three crankshaft revolutions.Wikipedia. and this extra energy is tapped by the turbine which in turn powers the compressor closing the cycle and powering the shaft. The air after being compressed in the compressor is heated by burning fuel in it. diesel fuel is injected directly into the cylinder so that combustion occurs at constant pressure. ■ Gasoline can be made from carbon (coal) using the Fischer-Tropsch process http://en. Six-stroke First invented in 1883. and an improved SFC. ■ Jet fuel (aviation fuel) ■ Residual fuel ■ Coal: ■ Most methanol is made from coal. and a 1975 patent (# P0433850 ) by Carlos Ubierna-Laciana ( www. the six-stroke engine has seen renewed interest over the last 20 or so years.org/wiki/Internal_combustion_engine 11/1/2011 . rather than needing a separate ignition system. the fuel-air mixture fired. and a Connecticut (USA) based company. that performs the double expansion of exhaust gas from the other cylinders.Internal combustion engine . Diesel cycle Main article: Diesel cycle Most truck and automotive diesel engines use a cycle reminiscent of a four-stroke cycle. having two outer cylinders. Firing ATDC can be accomplished by using high-pressure air in the transfer passage to create sonic flow and high turbulence in the power cylinder. This variation is called the diesel cycle. constant volume. The Beare Head and "piston charger" engines operate as opposed-piston engines. rather than with the Otto cycle. Gas turbine cycle engines employ a continuous combustion system where compression. compression. Brayton cycle Main article: Brayton cycle A gas turbine is a rotary machine somewhat similar in principle to a steam turbine and it consists of three main components: a compressor. 1-2: Intake: suction stroke 2-3: Isentropic Compression stroke 3-4: Heat addition stroke 4-5: Exhaust stroke (Isentropic expansion) 5-2: Heat rejection The distance between points 1-2 is the stroke of the engine. larger in diameter. but with a compression heating ignition system. By dividing V2/V1. in 1879. Notably. The concept of double expansion was developed early in the history of ICE by Otto himself. by Francisco Jimeno-Cataneo. The systems capture the wasted heat of the four-stroke Otto cycle with an injection of air or water. and was developed apparently also by Honda of Japan for a Quad engine.wikipedia. The Scuderi design requires the use of outwardly opening valves that enable the piston to move very close to the cylinder head without the interference of the valves. in the remainder of the down-stroke. a combustion chamber. The efficiency is taken to be: ________________________________________ Five-stroke The British company ILMOR presented a prototype of 5-Stroke double expansion engine. as the piston moves. Otto cycle: Otto cycle is the typical cycle for most of the cars internal combustion engines. that work using gasoline as a fuel.oepm. The cycle follows the numbers 1-4 in clockwise direction. The first part of the piston downstroke drew in a fuel-air mixture. Obsolete The very first internal combustion engines did not compress the mixture. and expansion occur simultaneously at different places in the engine—giving continuous power. Four kinds of six-stroke use a regular piston in a regular cylinder (Griffin six-stroke. that didn't give the expected results. ■ Compressed natural gas. working as usual. Bajulaz six-stroke. British term: petrol) ■ Petroleum diesel. the free encyclopedia Page 5 of 8 The Scuderi Engine addresses the breathing problem by reducing the clearance between the piston and the cylinder head through various turbo charging techniques. Scuderi addresses the low thermal efficiency via firing ATDC. then the inlet valve closed and. this heats and expands the air. the combustion takes place at constant pressure. built in 1906 some engines and cars with this principle. firing every two revolutions rather more like a regular four-stroke. with an increased efficiency in the gas energy use. PV diagram for Otto cycle On the PV-diagram. This engine has a similar precedent in a Spanish 1942 patent (# P0156621 ). Velozeta six-stroke and Crower six-stroke). two pistons in a single cylinder. we get: where r is called the compression ratio of the engine. These attempts at imitating the principle of a steam engine were very inefficient. ■ Autogas (liquified petroleum gas). The exhaust valve opened for the piston upstroke. ignition and exhaust. plus a central one.es ). fuels used include: ■ Petroleum: ■ Petroleum spirit (North American term: gasoline. Fuels Nowadays. It consists of the same four major steps: Intake. Gasoline engines are used in most other road vehicles including most cars. There are also engines that run on hydrogen. and more powerful at lower speeds than gasoline engines. biodiesel. some automobiles (increasingly so for their increased fuel efficiency over gasoline engines). is its storage. ■ Compressed air has been commonly used in torpedoes. ■ Bioethanol and Biomethanol (wood alcohol) and other biofuels (see Flexible-fuel vehicle). the free encyclopedia ■ Diesel fuel can be made from carbon using the Fischer-Tropsch process ■ Biofuels and vegoils: ■ Peanut oil and other vegoils. noisier. which varies between engines. ■ Nitrous oxide has been used—with extra gasoline—in tactical aircraft and in specially equipped cars to allow short bursts of added power from engines that otherwise run on gasoline and air. increasing the power-to-weight and power to volume ratios. Any heat that isn't translated into work is normally considered a waste product and is removed from the engine either by an air or liquid cooling system. overall pressure ratio for jet engines and gas turbines Energy efficiency Once ignited and burnt. ■ Nitromethane is added to some racing and model fuels to increase power and control combustion.Wikipedia. wood gas. It is also used in the Burt Rutan rocket spacecraft. ships. relative to carbon fuels. often to increase power output or to allow operation under water or in space. and light aircraft. railway locomotives. but have not been found to be practical. ■ Biofuels: ■ Biobutanol (replaces gasoline). the energy density of hydrogen is considerably higher than that of electric batteries. gasoline engines are also often colloquially referred to as. motorcycles. Unless that electricity is produced from a renewable source—and is not required for other purposes— hydrogen does not solve any energy crisis. liquefied petroleum gas (LPG). Note that in Europe. Although there are multiple ways of producing free hydrogen. Diesel engines are generally heavier. Engine starting Main article: Starter motor One-cylinder gasoline engine (ca. In many situations the disadvantage of hydrogen. but has other issues such as the high price of the sodium borohydride which is the raw material. and that the fuel releases sufficient energy in the form of heat upon combustion to make practical use of the engine. The 'Hydrogen on Demand' process (see direct borohydride fuel cell) creates hydrogen as it is needed. Even when liquefied. Engines that use gases for fuel are called gas engines and those that use liquid hydrocarbons are called oil engines. "gas engines" ("petrol engines" in the UK). Hydrogen Main article: Hydrogen internal combustion engine vehicle Hydrogen could eventually replace conventional fossil fuels in traditional internal combustion engines.Internal combustion engine .org/wiki/Internal_combustion_engine 11/1/2011 . Alternatively fuel cell technology may come to deliver its promise and the use of the internal combustion engines could even be phased out. thrust specific fuel consumption for jet engines) power to weight ratio thrust to weight ratio Torque curves (for shaft engines) thrust lapse (jet engines) Compression ratio for piston engines. However. Paraffin and tractor vaporizing oil (TVO) engines are no longer seen. those methods require converting combustible molecules into hydrogen or consuming electric energy. the highpressure gases inside the cylinders drive the engine's pistons. Liquid hydrogen has extremely low density (14 times lower than water) and requires extensive insulation—whilst gaseous hydrogen requires heavy tankage. the remaining hot gases are vented (often by opening a valve or exposing the exhaust outlet) and this allows the piston to return to its previous position (top dead center. ■ Compressed oxygen. Rockets very often use liquid oxygen. ethanol. the combustion products—hot gases—have more available thermal energy than the original compressed fuel-air mixture (which had higher chemical energy). The piston can then proceed to the next phase of its cycle. Many different systems have been used in the past but modern engines are usually started by an electric motor in the small and medium sizes or by compressed air in the large sizes. hydrogen has a higher specific energy but the volumetric energetic storage is still roughly five times lower than petrol. ■ Hydrogen peroxide power was under development for German World War II submarines and may have been used in some nonnuclear submarines and was used on some rocket engines (notably Black Arrow and Me-163 rocket plane) ■ Other chemicals such as chlorine or fluorine have been used experimentally. They are also more fuel-efficient in most circumstances and are used in heavy road vehicles.wikipedia. making it a serious contender as an energy carrier to replace fossil fuels. and mopeds. was used in the Japanese Type 93 torpedo. Measures of engine performance Engine types vary greatly in a number of different ways: ■ ■ ■ ■ ■ ■ energy efficiency fuel/propellant consumption (brake specific fuel consumption for shaft engines. Once the available energy has been removed. ■ Biodiesel (replaces petrodiesel). In a reciprocating engine. the oxidizer is typically atmospheric oxygen which has the advantage of not being stored within the vehicle. http://en. as well as some compressed air. however. Some submarines are designed to carry pure oxygen. There are other materials that are used for special purposes. methanol. or TDC). & charcoal gas. 1910) An internal combustion engine is not usually self-starting so an auxiliary machine is required to start it. The main limitations on fuels are that it must be easily transportable through the fuel system to the combustion chamber. The available energy is manifested as high temperature and pressure that can be translated into work by the engine. ■ Biogas ■ Hydrogen (mainly spacecraft rocket engines) Page 6 of 8 Even fluidized metal powders and explosives have seen some use. sophisticated diesel-engined cars have taken over about 40% of the market since the 1990s. Oxidizers Since air is plentiful at the surface of the earth. 1808)[14] introduced the concept of a "stationary idling offence". a small amount of fuel will be present after combustion. such as specific impulse and effective exhaust velocity. Only a few local authorities have implemented the regulations. hence greater thermodynamic efficiency.3-butadiene.a two stroke engine Dynamometer Electric vehicle Engine test stand .[13] There are many inventions aimed at increasing the efficiency of IC engines. Carbon fuels contain sulfur and impurities that eventually lead to producing sulfur monoxides (SO) and sulfur dioxide (SO2) in the exhaust which promotes acid rain. It reduces the efficiency and increases knocking. Further chemicals released are benzene and 1. however. In addition. practical engines are always compromised by trade-offs between different properties such as efficiency. such as formaldehyde or acetaldehyde. sometimes causing the engine to stall. one of them being Oxford City Council. as do aircraft flights due to jet noise. termed its power band. there is no way of proving they are safe at any level so the experts set standards where the risk to health is. Automobile and truck traffic operating on highways and street systems produce noise. Idling Internal combustion engines continue to consume fuel and emit pollutants when idling so it is desirable to keep periods of idling to a minimum. up to 70%. so carbon monoxide (CO) is also produced.wikipedia.3-butadiene that are also particularly harmful. and ozone). For the other three: benzene. so one tends to be lower where the other is higher. a real engine runs best at a specific load. This is not emitted directly but made in the air by the action of sunlight on other pollutants to form "ground level ozone". due to incomplete combustion of carbonaceous fuel. but tends to encourage the oxygen and nitrogen in the air to combine to produce nitrogen oxides (NOx) that has been demonstrated to be hazardous to both plant and animal health. The volume of hydrocarbon assumes a standard energy content. Air and noise pollution Air pollution Internal combustion engines such as reciprocating internal combustion engines produce air pollution emissions. depending on the operating conditions and the fuel-air ratio. Sometimes economy also plays a role in not only the cost of manufacturing the engine itself. The thermodynamic limits assume that the engine is operating under ideal conditions: a frictionless world. sulphur dioxide. most engines retain an average efficiency of about 18%-20%. Rocket engines create the most intense noise. shall be guilty of an offence and be liable on summary conviction to a fine not exceeding level 3 on the standard scale". The main derivatives of the process are carbon dioxide CO2. which is the number of pounds of propellant that is needed to generate impulses that measure a pound force-hour. In general. carbon monoxide. or hydrocarbons not initially present in the fuel mixture. require him to stop the running of the engine of that vehicle" and a "person who fails to comply . exhaust emissions. All metals and alloys eventually melt or decompose. In metric units. some of which can react to form oxygenates. unlike the "ozone layer" in the high atmosphere. but also manufacturing and distributing the fuel. Real world applications introduce complexities that reduce efficiency.Internal combustion engine . otherwise the fuel would burn more completely in excess air. which.. particularly supersonic-capable aircraft. the power output varies drastically with airspeed and a less variable measure is used: thrust specific fuel consumption (TSFC). Even when aided with turbochargers and stock efficiency aids. Not all of the fuel will be completely consumed by the combustion process. or noise. quenching is commonly observed in diesel (compression ignition) engines that run on natural gas. weight. In the UK (but applying only to England). Increasing the engine's efficiency brings better fuel economy but only if the fuel cost per energy content is the same. "exceedingly small". For the pollutants described above (nitrogen oxides. power. Most steel engines have a thermodynamic limit of 37%. Many bus companies now instruct drivers to switch off the engine when the bus is waiting at a terminus. The effects of inhaling particulate matter have been studied in humans and animals and include asthma.[11][12] Rocket engine efficiencies are better still. Higher thermal stability allows for greater temperature difference between the lower and upper operating temperatures. This means that a driver can be ordered "by an authorised person .information about how to check an internal combustion engine External Combustion Engine 11/1/2011 http://en. upon production of evidence of his authorisation.Wikipedia. ideal gases. and not all of the fuel burns up completely. One final element in exhaust pollution is ozone (O3). Noise pollution Significant contributions to noise pollution are made by internal combustion engines.org/wiki/Internal_combustion_engine . because they operate at very high temperatures and pressures and can have very high expansion ratios. is regarded as a bad thing if the levels are too high. and there is significant researching into ceramic materials that can be made with greater thermal stability and desirable structural properties. and particulates. because it is designed for the higher loads required for rapid acceleration. there are accepted levels that are set by legislation to which no harmful effects are observed — even in sensitive population groups. Engine fuel economy is usually measured in the units of miles per gallon (or fuel consumption in liters per 100 kilometers) for automobiles. and as such their theoretical efficiency can be calculated by idealized thermodynamic cycles. For example. but typically other equivalent measures are traditionally used.. whose efficiency is determined by the difference between the lower and upper operating temperatures of the engine. fuel consumption is measured by calculating the brake specific fuel consumption which measures the mass flow rate of fuel consumption divided by the power produced. perfect insulators. For internal combustion engines in the form of jet engines. The upper operating temperature of a terrestrial engine is limited by the thermal stability of the materials used to construct it. heat. Measures of fuel/propellant efficiency For stationary and shaft engines including propeller engines. When running at lower speeds. For rockets. TSFC can be used. some additional products of the combustion process that include nitrogen oxides and sulfur and some uncombusted hydrocarbons. The primary causes of this is the need to operate near the stoichiometric ratio for gasoline engines in order to achieve combustion and the resulting "quench" of the flame by the relatively cool cylinder walls. and premature death. 1. response. The efficiency of a theoretical cycle cannot exceed that of the Carnot cycle.. lung cancer. and operation for infinite time. Ozone is broken down by nitrogen oxides.. factors such as wind resistance reduce overall system efficiency. There are. The engine in a car cruising on a highway is usually operating significantly below its ideal load. the number of grams of propellant needed to generate an impulse that measures one kilonewton-second. the free encyclopedia Page 7 of 8 Internal combustion engines are primarily heat engines. cardiovascular issues. water and some soot — also called particulate matter (PM).[15] See also ■ ■ ■ ■ ■ ■ ■ ■ Adiabatic flame temperature Air-fuel ratio Component parts of internal combustion engines Crude oil engine . Increasing the amount of air in the engine reduces the amount of the first two pollutants. the Road Traffic (Vehicle Emissions) (Fixed Penalty) Regulations 2002 (Statutory Instrument 2002 No. infoplease. 2010-07-16.britannica.Animation of the components and built-up of a 4-cylinder engine youtube (http://www.mhi. http://en. Nakano. Retrieved 2010-08-28.com/display_article/152601/6/ARTCL/none/none/1/New-Benchmarks-for-Steam-Turbine-Efficiency/.co.com/watch?v=2QB7XPMeLnA) . 2010-11.. ^ "CFX aids design of world’s most efficient steam turbine" (http://www. ^ "Improving IC Engine Efficiency" (http://courses. pp. 5. 2008-07-11.oxford. additional terms may apply.ansys.com/ce6/sci/A0825332.1. 195.manbw.com/ce6/sci/A0825332. ^ a b "Internal combustion engine" (http://www.technologyreview.edu/autolab/Projects/index. 8. SAE.grc.about. ^ a b "Columbia encyclopedia: Internal combustion engine" (http://inventors. 1999 External links ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Animated Engines (http://www.pdf) (PDF). [et al. Raper.. ■ Text is available under the Creative Commons Attribution-ShareAlike License.html) . ^ Takaishi. Mb-soft.1.pennnet.com/assets/testimonials/siemens.com/gi/dynamic/offsite. 2011. 15.explains a variety of types Intro to Car Engines (http://www.mhi.pdf.com.html?series=19) retrieved May 9.6. ^ "Ideal Otto Cycle" (http://www. 2.htm) .htm) .popularmechanics. Katsuhiko (March 2008). Retrieved 2010-08-28.6.gov.com/news/2011-04-laser-revolution-internal-combustion. ^ a b "Private Tutor" (http://www. ^ Laser sparks revolution in internal combustion engines (http://www.com.uottawa.edu.]. Richard.com/console/?avi=7660291) Next generation engine technologies (http://www.70.html) . Answers.99.gov/WWW/K-12/airplane/otto. www.html.gov. "Approach to High Efficiency Diesel and Gas Engines" (https://www.70/si/si2002/20021808.htm#13) .about.bartleby.Cut-away images and a good overview of the internal combustion engine Walter E. 13.gov. http://www.edu/me341/oct22v2. Wikipedia® is a registered trademark of the Wikimedia Foundation. Courses. 3.99.infoplease. 1997 Further reading ■ Singer.nasa.0005. Akira.jp/technology/review/pdf/e451/e451021. 4..pennnet.mit. ^ "Fees & Charges" (http://www. Horst O. http://195.pdf) .gov/WWW/K-12/airplane/otto. Grc.com/engines/TwoStrokeLowSpeedPropMEEngines. and Fuels Engine Combustion Network (http://www. 2010-08-24. Ryouji.uk/Direct/2_Item%205.html) . Retrieved 2010-08-28.html. Pepei.Internal combustion engine .edu/me341/oct22v2. Tatsuo.com/EBchecked/topic/290504/internal-combustion-engine) .htm?site=http://www..umich. Sakaguchi.html) .html) .com/display_article/152601/6/ARTCL/none/none/1/New-Benchmarks-for-SteamTurbine-Efficiency/) . http://www.com.gov.html. MAN Diesel. 12.grc.edu/professional/short-programs/courses/internal_combustion_engines. Efficiency.pdf.ca:2398/cgi/t/text/pagevieweridx?c=acls&cc=acls&idno=heb02191.com.com/65/in/intern-co.jp/technology/review/pdf/e451/e451021.com/automotive/new_cars/4261289.99.answers.70/si/si2002/20021808.Animation of the internal moving parts of a 4-cylinder engine Hypervideo showing construction and operation of a four cylinder internal combustion engine courtesy of Ford Motor Company (http://www.com/public2/engine. Infoplease.answers.Research at The University of Michigan youtube (http://www. http://courses. Retrieved 2010-08-28.com/topic/internalcombustion-engine?cat=technology.com. Ph.htm#13. ^ "The Road Traffic (Vehicle Emissions) (Fixed Penalty) (England) Regulations 2002" (http://195.washington. http://inventors. ^ "New Benchmarks for Steam Turbine Efficiency .pdf.autoeducation.org/w/index. Retrieved 2010-08-28. Charles Joseph.uk/Direct/2_Item%205.britannica.physorg."The Romance of Engines".co.asp?model=S80ME-C7. 10. See Terms of use for details.001&q1=bicycle&frm=frameset&seq=5) . http://www. Clarendon Press.bib. Retrieved 2010-08-28.oxford. A History of Technology: The Internal Combustion Engine (http://proxy. Retrieved 2010-08-28.about.bartleby. Inventors. http://www.html.uk.ansys.com.wikipedia.engin.com/rm_preview/engine_intro.Present & Future Internal Combustion Engines: Performance. 9. Accessed April 2011 6. Lay Auto Lab (http://me. Inc. Retrieved 2010 -08-28.htm.nasa. The Middle Ages of the Internal combustion Engine. 2009-05-09. 7.com/gi/dynamic/offsite.php?title=Internal_combustion_engine&oldid=457901193" Categories: Internal combustion engine ■ This page was last modified on 29 October 2011 at 00:29. Britannica.howstuffworks. ^ Rocket propulsion elements 7th edition-George Sutton. 1954-1978.washington.html) .com) . 157 –176 ■ Hardenberg.nasa. Automakers Show Interest in an Unusual Engine Design (http://www. Mitsubishi Heavy Industries Technical Review 45 (1).pdf) (PDF).com/assets/testimonials/siemens. April 20. 2009 MIT Overview (http://web. http://mb-soft. http://www. the free encyclopedia ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Fossil fuels Gas turbine Heat pump Deglazing (engine mechanics) Diesel engine Forced induction Indirect injection Magnesium injection cycle Direct injection Turbocharger Dieselisation Gasoline direct injection Hybrid vehicle Jet engine Petrofuel Piston engine Reciprocating engine Variable displacement Page 8 of 8 References 1. ^ "Physics In an Automotive Engine" (http://mb-soft.oxford.animatedengines.pennnet. Society of Automotive Engineers (SAE).com/energy/27124/page1/?a=f) How Car Engines Work (http://www.youtube. Retrieved 2010-08-28.youtube. http://pepei.wikipedia. edited by Charles Singer .asterpix. Retrieved 2011-02-04.D.Open forum for international collaboration among experimental and computational researchers in engine combustion.com/watch?v=W2eILCrW53M&NR) .com.. http://www. Emissions.html) Physorg.com/engine1. Retrieved 2010-08-28. Oscar Biblarz pg 37-38 14.sandia. ■ Takashi Suzuki.gov/ecn) . ^ Low Speed Engines (http://www.com/topic/internal-combustion-engine?cat=technology) .com/EBchecked/topic/290504/internal-combustion-engine. a non-profit organization.Power Engineering" (http://pepei.Wikipedia. Retrieved 2011-0204.1.html) .com/public2/engine. https://www. 11. ^ a b Encyclopædia Britannica.htm?site=http://www.washington. Numata.com/65/in/intern-co.org/wiki/Internal_combustion_engine 11/1/2011 . "Encyclopedia Britannica: Internal Combustion engines" (http://www.htm) Retrieved from "http://en.