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Diesel Engines

Diesel engines

The diesel engine is a type of internal combustion engine; more specifically, it is a compression ignition engine, in which the fuel is ignited by being suddenly exposed to the high temperature and pressure of a compressed gas containing oxygen (usually atmospheric air), rather than a separate source of ignition energy (such as a spark plug), as is the case in the gasoline engine. This is known as the diesel cycle, after German engineer Rudolf Diesel, who invented it in 1892 and received the patent on February 23, 1893 (1893-02-23). Diesel intended the engine to use a variety of fuels including coal dust. He demonstrated it in the 1900 Exposition Universelle (World's Fair) using peanut oil (see biodiesel).

How diesel engines work

When a gas is compressed, its temperature rises (see the combined gas law); a diesel engine uses this property to ignite the fuel. Air is drawn into the cylinder of a diesel engine and compressed by the rising piston at a much higher compression ratio than for a spark-ignition engine, up to 25:1. The air temperature reaches 700–900 °C, or 1300–1650 °F. At the top of the piston stroke, diesel fuel is injected into the combustion chamber at high pressure, through an atomising nozzle, mixing with the hot, high-pressure air. The resulting mixture ignites and burns very rapidly. This contained explosion causes the gas in the chamber to heat up rapidly, which increases its pressure, which in turn forces the piston downwards. The connecting rod transmits this motion to the crankshaft, which is forced to turn, delivering rotary power at the output end of the crankshaft. Scavenging (pushing the exhausted gas-charge out of the cylinder, and drawing in a fresh draught of air) of the engine is done either by ports or valves. To fully realize the capabilities of a diesel engine, use of a turbocharger to compress the intake air is necessary; use of an aftercooler/intercooler to cool the intake air after compression by the turbocharger further increases efficiency. In very cold weather, diesel fuel thickens and increases in viscosity and forms wax crystals or a gel. This can make it difficult for the fuel injector to get fuel into the cylinder in an effective manner, making cold weather starts difficult at times, though recent advances in diesel fuel technology have made these difficulties rare. A commonly applied advance is to electrically heat the fuel filter and fuel lines. Other engines utilize small electric heaters called glow plugs inside the cylinder to warm the cylinders prior to starting. A small number use resistive grid heaters in the intake manifold to warm the inlet air until the engine reaches operating temperature. Engine block heaters (electric resistive heaters in the engine block) plugged into the utility grid are often used when an engine is shut down for extended periods (more than an hour) in cold weather to reduce startup time and engine wear. A vital component of any diesel engine system is the governor, which limits the speed of the engine by controlling the rate of fuel delivery. Older governors were driven by a gear system from the engine (and thus supplied fuel only linearly with engine speed). Modern electronically-controlled engines achieve this through the electronic control module (ECM) or electronic control unit (ECU) - the engine-mounted "computer". The ECM/ECU receives an engine speed signal from a sensor and then using its algorithms and look-up calibration tables stored in the ECM/ECU, it controls the amount of fuel and its timing (the "start of injection") through electric or hydraulic actuators to maintain engine speed. Controlling the timing of the start of injection of fuel into the pistons is key to minimising their emissions and maximising the fuel economy (efficiency) or the engine. The exact timing of starting this fuel injection into the cylinder is controlled electronically in most of today's modern engines. The timing is usually measured in units of crank angles before Top Dead Center (TDC) that the piston is at. For example, if the ECM/ECU initiates fuel injection when the piston is 10 degrees before TDC, the start of injection or "timing" is said to be 10 deg BTDC. The optimal timing will depend on both the engine design as well as its speed and load. Advancing (injecting when the piston is further away from TDC) the start of injection results in higher in-cylinder pressure and higher efficiency but also results in higher Nitrous Oxide (NOx) emissions. At the other extreme, very retarded start of injection or timing causes incomplete combustion. This results in higher Particulate Matter (PM) emissions and higher smoke.

Fuel injection in diesel engines

Early diesels often employed indirect injection in order to use simple, flat-top pistons, and made the positioning of the early, bulky diesel injectors easier, but all modern diesel engines employ some form of direct injection, coupled with more complicated bowl-in-piston designs. Modern engines also use a very highly pressurised fuel supply line, which replaces the older, noisier, and mechanically more complicated combined pump and selector valve assembly (see below).

Indirect Injection

An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a prechamber, where combustion begins and then spreads into the main combustion chamber. The prechamber is carefully designed to ensure adequate mixing of the atomized fuel with the compression-heated air. This has the effect of slowing the rate of combustion, which tends to reduce audible noise. It also softens the shock of combustion and produces lower stresses on the engine components. The addition of a prechamber, however, increases heat loss to the cooling system and thereby lowers engine efficiency.

Direct injection

Modern diesel engines make use of one of the following direct injection methods:

Common rail direct injection

The common rail system on its prototype was already developed in late sixties with Mr. Hiber in Switzerland. After that, Ganser of the Swiss Federal Institute of Technology focusing on his research the common rail technology was advanced. In mid nineties, Dr. Shohei Itoh and Masahiko Miyaki, Japanese automotive parts manufacturer Denso Corporation, developed the Common Rail Fuel System for Heavy Duty Vehicles and finally turned into its first practical use on their ECD-U2 common Rail system, which was mounted on the HINO RAISING RANGER truck and sold for general use in 1995. Later in 1997 the German automotive parts manufacturer Robert Bosch GmbH extended its use for passenger car. Today the common rail system is responsible for a revolution in diesel engine technology. Delphi Automotive Systems of the US also make common-rail systems. Different car makers refer to their common rail engines by different names, e.g. DaimlerChrysler's CDI, Ford Motor Company's TDCi (most of these engines are manufactured by PSA), Fiat Group's (Fiat, Alfa Romeo and Lancia) JTD, Renault's DCi, GM/Opel's CDTi (most of these engines are manufactured by Fiat, other by Isuzu), PSA Peugeot Citroen's HDI, Toyota's D-4D, and so on. In older diesel engines, a distributor-type injection pump, regulated by the engine, supplies bursts of fuel to injectors which are simply nozzles through which the diesel is sprayed into the engine's combustion chamber. As the fuel is at low pressure and there cannot be precise control of fuel delivery, the spray is relatively coarse and the combustion process is relatively crude and inefficient. In common rail systems, the distributor injection pump is eliminated. Instead an extremely high pressure pump stores a reservoir of fuel at high pressure - up to 1,800 bar (180 MPa) - in a "common rail", basically a tube which in turn branches off to computer-controlled injector valves, each of which contains a precision-machined nozzle and a plunger driven by a solenoid. Driven by a computer (which also controls the amount of fuel to the pump), the valves, rather than pump timing, control the precise moment when the fuel injection into the cylinder occurs and also allow the pressure at which the fuel is injected into the cylinders to be increased. As a result, the fuel that is injected atomises easily and burns cleanly, reducing exhaust emissions and increasing efficiency. In addition, the engine's Electronic Control Unit (ECU) can inject a small amount of diesel just before the main injection event ("pilot" injection) that reduces noise and vibration, as well as optimises injection timing and quantity for variations in fuel quality, cold starting, and so on. Most European automakers have common rail diesels in their model lineups, even for commercial vehicles. Some Japanese manufacturers, such as Toyota, Nissan and recently Honda, have also developed common rail diesel engines.

Unit direct injection

This also injects fuel directly into the cylinder of the engine. However, in this system the injector and the pump are combined into one unit positioned over each cylinder. Each cylinder thus has its own pump, feeding its own injector, which prevents pressure fluctuations and allows more consistent injection to be achieved. This type of injection system, also developed by Bosch, is used by Volkswagen AG in cars, and most major diesel engine manufactures, in large commercial engines (Cat, Cummins, Detroit Diesel). With recent advancements, the pump pressure has been raised to 2,050 bar (205 MPa), allowing injection parameters similar to common rail systems.

Types of diesel engines

There are two classes of diesel engines: two-stroke and four-stroke. Most diesels generally use the four-stroke cycle, with some larger diesels operating on the two-stroke cycle. Normally, banks of cylinders are used in multiples of two, although any number of cylinders can be used as long as the load on the crankshaft is counterbalanced to prevent excessive vibration. The inline-6 is the most prolific in medium- to heavy-duty engines, though the V8 and straight-4 are also common.

Advantages and disadvantages versus spark-ignition engines

Diesel engines are more efficient than gasoline/petrol engines of the same power (by approx. 15%), resulting in lower fuel consumption. Naturally aspirated diesel engines are more massive than gasoline/petrol engines of the same power for two reasons; the first is that it takes a larger capacity diesel engine than a gasoline engine to produce the same power. This is essentially because the diesel cannot operate as quickly - the "rev limit" is lower - because getting the fuel-air mixture into a diesel engine is more difficult than a gasoline engine [http://www.perkins.com/perkins/cda/articleDisplay/1,4094,7___32_____7_10020408,00.html]. The second reason is that a diesel engine must be stronger to withstand the higher combustion pressures needed for ignition. Yet it is this same build quality that has allowed some enthusiasts to acquire significant power increases with turbocharged engines through fairly simple and inexpensive modifications. A gasoline engine of similar size cannot put out a comparable power increase without extensive alterations because the stock components would not be able to withstand the higher stresses placed upon them. Since a diesel engine is already built to withstand higher levels of stress, it makes an ideal candidate for performance tuning with little expense. However it should be said that any modification that raises the amount of fuel and air put through a diesel engine will increase its operating temperature which will reduce its life and service interval requirements. In addition, sending additional fuel to the cylinders will wash away lubricating oil faster. These things are issues with newer, lighter, "high performance" diesel engines which aren't "overbuilt" to the degree of older engines and are being pushed to provide greater power in smaller engines. The addition of a turbocharger or supercharger to the engine (see turbodiesel) greatly assists in increasing fuel economy and power output. Boost pressures can be higher on diesels than gasoline engines, and the higher compression ratio allows a diesel engine to be more efficient than a comparable spark ignition engine, although the calorific value of the fuel is slightly lower at 45.3 megajoules per kilogram to gasoline at 45.8 MJ/kg. The increased fuel economy of the diesel over the petrol engine means that the diesel produces less carbon dioxide (CO₂) per unit distance. The recent development of biofuel alternatives to fossil fuels has unleashed the ability to produce a net-sum of zero emissions of CO₂, as it is re-absorbed into plants and then comes full circle, being used to produce the fuel. Diesel engines can produce black soot from their exhaust. This consists of unburned carbon compounds. Modern diesel engines catch the soot in a particle filter, which when saturated is automatically regenerated by burning the particles. Other problems associated with the exhaust gases (nitrogen oxide, sulfurous fumes) can be mitigated with further investment and equipment. The lack of an electrical ignition system greatly improves the reliability. The high durability of a diesel engine is also due to its overbuilt nature (see above) as well as the diesel's combustion cycle, which creates less-violent changes in pressure when compared to a spark-ignition engine, a benefit that is magnified by the lower rotating speeds in diesels. Unfortunately, due to the greater compression force required and the increased weight of the stronger components, starting a diesel engine is a harder task. More torque is required to push the engine through compression. Either an electrical starter or an air start system is used to start the engine turning. On large engines, pre-lubrication and slow turning of an engine, as well as heating, are required to minimize the possibility of damaging the engine during initial start-up and running. Some smaller military diesels can be started with an explosive cartridge that provides the extra power required to get the machine turning. In the past, Caterpillar and John Deere used a small gasoline "pony" motor in their tractors to start the primary diesel motor. The pony motor heated the diesel to aid in ignition and utilized a small clutch and transmission to actually spin up the diesel engine. Even more unusual was an International Harvester design in which the diesel motor had its own carburetor and ignition system, and started on gasoline. Once warmed up, the operator moved two levers to switch the motor to diesel operation, and work could begin. These engines had very complex cylinder heads (with their own gasoline combustion chambers) and in general were vulnerable to expensive damage if special care was not taken (especially in letting the engine cool before turning it off).

Automobile racing

Although the weight and lower output of a diesel engine tend to keep them away from automotive racing applications, there are many diesels being raced in classes that call for them, mainly in truck racing, as well in types of racing where these drawbacks are less severe, such as land speed record racing. [http://www.cumminsracing.com/ Diesel engined dragsters] even exist, despite the diesel's drawbacks being central to performance in this sport. In 1952, [http://www.cummins.com/eu/pages/en/whoweare/cumminshistory.cfm Cummins Diesel] won the pole at the Indianapolis 500 race with a supercharged 3 liter diesel car, relying on torque and fuel efficiency to overcome weight and low peak power, and led most of the race until the badly situated air intake of the car swallowed enough debris from the track to disable the car.

Dieseling in spark-ignition engines

A gasoline (spark ignition) engine can sometimes act as a compression ignition engine under abnormal circumstances, a phenomenon typically described as "pinging" or "pinking" (during normal running) or "dieseling" (when the engine continues to run after the electrical ignition system is shut off). This is usually caused by hot carbon deposits within the combustion chamber that act as would a "glow plug" within a diesel or model aircraft engine. Excessive heat can also be caused by improper ignition timing and/or fuel/air ratio which in turn overheats the exposed portions of the spark plug within the combustion chamber.

Fuel and fluid characteristics

Diesel engines can operate on a variety of different fuels, depending on configuration, though the eponymous diesel fuel derived from crude oil is most common. Good-quality diesel fuel can be synthesised from vegetable oil and alcohol. Biodiesel is growing in popularity since it can frequently be used in unmodified engines, though production remains limited. Petroleum-derived diesel is often called "petrodiesel" if there is need to distinguish the source of the fuel. The engines can work with thicker, heavier oil, or oil with higher viscosity, as long as it is heated to ease pumping and injection. These fuels are cheaper than clean, refined diesel oil, although they are dirtier. The biofuels straight vegetable oil (SVO) and waste vegetable oil (WVO) can fall into this category. Moving beyond that, use of low-grade fuels can lead to serious maintenance problems. Most diesel engines that power ships like supertankers are built so that the engine can safely use low grade fuels. Ethanol is also used in some cases, since it has a high octane rating which means it can be highly compressed before spontaneously igniting. One way this is used is in E95 fuel which actually contains 5% gasoline along with 95% ethanol. Normal diesel fuel is more difficult to ignite than gasoline because of its higher flash point, but once burning, a diesel fire can be extremely fierce.

Diesel applications

The vast majority of modern heavy road vehicles (trucks), ships, large-scale portable power generators, most farm and mining vehicles, and many long-distance locomotives have diesel engines. However, in the U.S. they are not as popular in passenger vehicles as they are in Europe as they are perceived as being heavier, noisier, of having performance characteristics which makes them slower to accelerate, and of being more expensive than petrol vehicles. In addition, before the mandatory reduction of sulphur in on-road diesel fuel to 15 parts per million, which will start at 15 Oct 2006 (2006-10-15) in the U.S. (1 June 2006 (2006-06-01) in Canada), diesel fuel used in North America has higher sulphur content than the fuel used in Europe, effectively limiting diesel use to industrial vehicles. 2006-06-01 In Europe, where tax rates in many countries make diesel fuel much cheaper than petrol, diesel vehicles are very popular and newer designs have significantly narrowed differences between petrol and diesel vehicles in the areas mentioned. One anecdote tells of Formula One driver Jenson Button, who was arrested while driving a diesel-powered BMW coupe at 230 km/h (about 140 mph) in France, where he was too young to have a petrol-engined car hired to him. Button dryly observed in subsequent interviews that he had actually done BMW a public relations service, as nobody had believed a diesel could be driven that fast. The BMW diesel lab in Steyr, Austria is led by Ferenc Anisits and is considered to be a leader in development of automotive diesel engines. Similarly, Mercedes Benz had a successful run of diesel-powered passenger cars in the late 1970s and 1980s. After a hiatus in the 1990s with relatively few diesel cars in its lineup, Mercedes Benz has revived diesel cars in its newer ranges with an emphasis on high performance versus the older models' lack thereof. ;High-Speed :High-speed (approximately 1200 rpm and greater) engines are used to power lorries (trucks), buses, tractors, cars, yachts, compressors, pumps and small generators. ;Medium-Speed :Large electrical generators are driven by medium speed engines, (approximately 300 to 1200 rpm) optimised to run at a set speed and provide a rapid response to load changes. ;Low-Speed : The largest diesel engines are used to power ships. These monstrous engines have power outputs over 80,000 kW, turn at about 60 to 100 rpm, and are up to 15 m tall. They often run on cheap low-grade fuel, which require extra heat treatment in the ship for tanking and before injection due to their low volatility. Companies such as Burmeister & Wain and Wärtsilä (e.g., Sulzer Diesels) design such large low speed engines. They are unusually narrow and tall due to the addition of a crosshead bearing. Today (2005), the Wärtsilä-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world, with cylinder bores of 960 mm (37.8 in) and stroke of 2500 mm (98.4 in), producing up to 80,080 kW (107,389 hp) in the 14-cylinder configuration. The zeppelins Graf Zeppelin II and Hindenburg were propelled by reversible diesel engines. The direction of operation was changed by shifting gears on the camshaft. From full power forward, the engines could be brought to a stop, changed over, and brought to full power in reverse in less than 60 seconds. This was done before reversible pitch propellers for aircraft had been perfected. A few airplanes have been built that use diesel engines, such as the Junkers-powered Blohm & Voss Ha 139 of the late 1930s. This is quite rare because of the high importance of power-weight ratios in aeronautical applications, and the development of kerosene-powered jet engines and the closely-related turboprop engines. However, this may change in the near future. The newer automotive diesels have power-weight ratios comparable to the ancient spark-ignition designs common in general aviation aircraft, and have better fuel efficiency. Their use of electronic ignition, fuel injection, and sophisticated engine management systems also makes them far easier to operate than mass-produced spark-ignition aircraft engines, most of which still use carburetors. Combined with Europe's very favourable tax treatment of diesel fuel compared to petrol, these factors have led to considerable interest in diesel-powered small general aviation planes, and several manufacturers have recently begun selling diesel engines for this purpose. The Diamond Twin Star is currently one of the very few general aviation aircraft manufactured with diesel engines. It can be twice as efficient as a comparable twin aircraft due to the diesel engines made by Thielert. Another major advantage for aviation users is that diesel engines can be fuelled with jet fuel, which is produced in a much greater quantity than avgas. See aircraft engine. Also, some motorcycles have been built using diesel engines.

Current and future developments

Already, many common rail and unit injection systems employ new injectors using stacked piezoelectric crystals in lieu of a solenoid, which gives finer control of the injection event. Variable geometry turbochargers have flexible vanes, which move and let more fuel into the engine depending on load. This technology increases both performance and fuel economy A technique called accelerometer pilot control (APC) uses a sensor called an accelerometer to provide feedback on the engine's level of noise and vibration and thus instruct the ECU to inject the minimum amount of fuel that will produce quiet combustion and still provide the required power (especially while idling.) The next generation of common rail diesels are expected to use variable injection geometry, which allows the amount of fuel injected to be varied over a wider range, and variable valve timing similar to that on gasoline engines. At least in the US, diesels will slowly face displacement by tougher emissions regulations. Other methods to achieve even more efficient combustion, such as HCCI (homogeneous charge compression ignition), are being studied.

Modern diesel facts

(Source: Robert Bosch GmbH) Fuel passes through the injector jets at speeds of nearly 1500 miles per hour (2400 km/h) – as fast as the top speed of a jet plane. Fuel is injected into the combustion chamber in less than 1.5 milliseconds (one and a half thousandths of a second) – about as long as a camera flash. The smallest quantity of fuel injected is one cubic millimetre – about the same volume as the head of a pin. The largest injection quantity at the moment for automobile diesel engines is around 70 cubic millimetres. If the camshaft of a six-cylinder engine is turning at 4500 rpm, the injection system has to control and deliver 225 injection cycles per second. On a demonstration drive, a Volkswagen 1-liter diesel-powered car used only 0.89 liters of fuel in covering 100 kilometers – making it probably the most fuel-efficient car in the world. Bosch’s high-pressure fuel injection system was one of the main factors behind the prototype’s extremely low fuel consumption. Production record-breakers in fuel economy include the Volkswagen Lupo 3L TDI and the Audi A2 3L 1.2 TDI with standard consumption figures of 3 liters of fuel per 100 kilometers. Their high-pressure diesel injection systems are also supplied by Bosch. In 2001, nearly 36% of newly registered cars in Western Europe had diesel engines. Austria leads the league table of registrations of diesel-powered cars with 66%, followed by Belgium with 63% and Luxembourg with 58%. Germany, with 34.6% in 2001, was in the middle of the league table. By way of comparison: in 1996, diesel-powered cars made up only 15% of the new car registrations in Germany. In 1998, for the very first time in the history of the legendary 24-hour race at the Nürburgring, a diesel-powered car was the overall winner – the BMW works team 320d, fitted with modern high-pressure diesel injection technology from Bosch.

External links

-
- [http://auto.howstuffworks.com/diesel.htm/ HowStuffWorks Article]
- [http://www.bath.ac.uk/~ccsshb/12cyl/ The Most Powerful Diesel Engine in the World]
- [http://www.cumminsracing.com Cummins Racing, home of the world's fastest diesel dragster...]
- [http://www.thedieselstop.com The Diesel Stop - Information on the Power Stroke Diesel]
- [http://www.northtexaspowerstrokes.com North Texas Power Stroke Association - Ford/International Power Stroke Diesel Enthusiasts]
- [http://www.rolls-royce.com/marine/product/diesel/default.jsp Rolls-Royce corporate website - diesel engines]
- [http://www.tdiclub.com TDIClub.com - TDI Enthusiasts]
- [http://www.turbodieselregister.com Turbodiesel Register - Dodge/Cummins Turbodiesel Enthusiasts]
- [http://www.volvo.com/volvopenta/global/en-gb Volvo Penta - manufacturer of marine and industrial diesel engines]
- [http://www.best-generator.com/ Best Engine - Manufacturer of Diesel Engine]
- [http://www.centurion-engines.com Centurion Engines - aeronautical applications]
- [http://www.wartsila.com/ Wärtsilä - manufacturer of diesel power plants]
- [http://www.cat.com/cda/layout?m=37532&x=7 Caterpillar - manufacturer of Caterpiller (Cat) diesel engines as well as construction equipment]
- [http://www.cummins.com Cummins - manufacturer of Cummins diesel engines]
- [http://www.detroitdiesel.com Detroit Diesel - manufacturer of diesel engines]
- [http://www.internationaldelivers.com/ -International/Navistar- manufacturer of International and Ford PowerStroke diesel engines, as well as heavy duty trucks]
- [http://www.perkins.com Perkins - manufacturer of diesel engines]
- [http://www.deutz.de Deutz - manufacturer of esoteric diesel engines]
- [http://www.deere.com John Deere - manufacturer of diesel engines and farm and construction equipment]
- [http://www.yanmar.com Yanmar - manufacturer of diesel engines, specilzing in those for marine use]
- [http://www.komatsu.com/kdl Komatsu Diesel - manufacturer of diesel engines]
- http://www.sisudiesel.com/ - Sisu Diesel
- [http://wagoneers.com/ wagoneers.com - see Mercedes Diesels and DIESELS] Category:Piston engines ko:디젤 엔진 ja:ディーゼルエンジン

Internal combustion engine

The internal combustion engine is a heat engine in which combustion occurs in a confined space called a combustion chamber. Combustion of a fuel creates high temperature/pressure gases, which are permitted to expand. The expanding gases are used to directly move a piston, turbine blades, rotor(s), or the engine itself thus doing useful work. Internal combustion engines can be powered by any fuel that can be combined with an "oxidizer" in the chamber. By way of contrast, an external combustion engine such as a steam engine does work when the combustion process heats a separate working fluid, such as water or steam, which then in turn does work. Jet engines, most rockets and many gas turbines are strictly classed as internal combustion engines, but the term internal combustion engine is also used to refer specifically to reciprocating engines, Wankel engines and similar designs in which combustion is intermittent. Today, in some published discussions, internal combustion engine is abbreviated to the acronym ICE.

History

Wankel engine English inventor Sir Samuel Morland used gunpowder to drive water pumps in the 17th century. For more conventional, reciprocating internal combustion engines the fundamental theory for two-stroke engines was established by Sadi Carnot in France in 1824, whilst the American Samuel Morey received a patent on April 1, 1826 for a "Gas Or Vapor Engine". The Italians Eugenio Barsanti and Felice Matteucci patented the first working, efficient version of an internal combustion engine in 1854 in London (pt. Num. 1072). Despite these and other attempts, it wasn't until 1859 that the Frenchman Étienne Lenoir (1822 - 1900) designed an engine that ran on a mixture of explosive gas and air. In 1860, Jean Joseph Etienne Lenoir produced a gas-fired internal combustion engine not dissimilar in appearance to a steam beam engine. This closelly resembled a horizontal double acting steam engine, with cylinders, pistons, connecting-rods and fly wheel in which the gas essentially took the place of the steam. In 1870 in Vienna Siegfried Marcus put the first mobile gasoline engine on a handcart. Nikolaus Otto working with Gottlieb Daimler and Wilhelm Maybach in the 1870's developed the four-stroke cycle (Otto cycle) engine.

Applications

Internal combustion engines are most commonly used for mobile propulsion systems. In mobile scenarios internal combustion is advantageous, since it can provide high power to weight ratios together with excellent fuel energy-density. These engines have appeared in almost all cars, motorbikes, many boats, and in a wide variety of aircraft and locomotives. Where very high power is required, such as jet aircraft, helicopters and large ships, they appear mostly in the form of gas turbines. They are also used for electric generators and by industry. For low power mobile and many non-mobile applications an electric motor is a competitive alternative. In the future, electric motors may also become competitive for most mobile applications. However, the high cost and weight and poor energy density of batteries and lack of affordable onboard electric generators such as fuel cells has largely restricted their use to specialist applications.

Operation

All internal combustion engines depend on the exothermic chemical process of combustion: the reaction of a fuel, typically with air, although other oxidisers such as nitrous oxide may be employed. Also see stoichiometry. The most common fuels in use today are made up of hydrocarbons and are derived from petroleum. These include the fuels known as diesel, gasoline and liquified petroleum gas. Most internal combustion engines designed for gasoline can run on natural gas or liquified petroleum gases without modifications except for the fuel delivery components. Liquid and gaseous biofuels of adequate formulation can also be used. Some have theorized that in the future hydrogen might replace such fuels. Furthermore, with the introduction of hydrogen fuel cell technology, the use of internal combustion engines may be phased out. The advantage of hydrogen is that its combustion produces only water. This is unlike the combustion of hydrocarbons, which also produces carbon dioxide, a major cause of global warming, as well as carbon monoxide, resulting from incomplete combustion. The big disadvantage of hydrogen in many situations its storage. Liquid hydrogen has extremely low density- 14 times lower than water and requires extensive insulation, whilst gaseous hydrogen requires very heavy tankage. While hydrogen is light and therefore has a higher specific energy, the volumetric efficiency is still roughly five times lower than petrol. This is why hydrogen must be compressed if there is to be a useful amount of stored energy. All internal combustion engines must have a means of ignition to promote combustion. Most engines use either an electrical or a compression heating ignition system. Electrical ignition systems generally rely on a lead-acid battery and an induction coil to provide a high voltage electrical spark to ignite the air-fuel mix in the engine's cylinders. This battery can be recharged during operation using an alternator driven by the engine. Compression heating ignition systems (Diesel engines and HCCI engines) rely on the heat created in the air by compression in the engine's cylinders to ignite the fuel. Once successfully ignited and burnt, the combustion products (hot gases) have more available energy than the original compressed fuel/air mixture (which had higher chemical energy). The available energy is manifested as high temperature and pressure which can be translated into work by the engine. In a reciprocating engine, the high pressure product gases inside the cylinders drive the engine's pistons. Once the available energy has been removed 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 - TDC). The piston can then proceed to the next phase of its cycle (which varies between engines). Any heat not translated into work is a waste product and is removed from the engine either by an air or liquid cooling system.

Parts

heat The parts of an engine vary depending on the engine's type. For a four-stroke engine, key parts of the engine include the crankshaft (purple), one or more camshafts (red and blue) and valves. For a two-stroke engine, there may simply be an exhaust outlet and fuel inlet instead of a valve system. In both types of engines, there are one or more cylinders (grey and green) and for each cylinder there is a spark plug (darker-grey), a piston (yellow) and a crank (purple). A single sweep of the cylinder by the piston in an upward or downward motion is known as a stroke and the downward stroke that occurs directly after the air-fuel mix in the cylinder is ignited is known as a power stroke. A Wankel engine has a triangular rotor that orbits in an epitroichoidal (figure 8 shape) chamber around an eccentric shaft. The four phases of operation (intake, compression, power, exhaust) take place in separate locations, instead of one single location as in a reciprocating engine. A Bourke Engine uses a pair of pistons integrated to a scotch yoke that transmits reciprocating force through a specially designed bearing assembly to turn a crank mechanism. Intake, compression, power, and exhaust all occur in each stroke of this yoke.

Classification

There is a wide range of internal combustion engines corresponding to their many varied applications. Likewise there is a wide range of ways to classify internal-combustion engines, some of which are listed below. Although the terms sometimes cause confusion, there is no real difference between an "engine" and a "motor." At one time, the word "engine" (from Latin, via Old French, ingenium, "ability") meant any piece of machinery. A "motor" (from Latin motor, "mover") is any machine that produces mechanical power. Traditionally, electric motors are not referred to as "engines," but combusion engines are often referred to as "motors."

Principles of operation

electric motor Reciprocating:
- Two-stroke engine
- Four-stroke engine
- Bourke Engine Rotary:
- Demonstrated:
- Wankel engine
- Proposed:
- orbital engine
- quasiturbine Continuous combustion:
- gas turbine
- jet engine
- rocket engine

Engine cycle

Engines based on the two-stroke cycle use two strokes (one up, one down) for every power stroke, relying on the action of the bottom of the piston within the crankcase to help move the fuel-air mixture, and are used where small size and weight are important, such as snowmobiles, lawnmowers, mopeds, outboard motors and some motorcycles. Gasoline two-stroke engines are generally louder, less efficient, more polluting, and smaller than their four-stroke counterparts, although large two-stroke diesel engines are not subject to these complaints and are used in many applications, for instance some locomotives built by EMD. Engines based on the four-stroke cycle or Otto cycle have one power stroke for every four strokes (up-down-up-down) and are used in cars, larger boats and many light aircraft. They are generally quieter, more efficient and larger than their two-stroke counterparts. There are a number of variations of these cycles, most notably the Atkinson and Miller cycles. Most truck and automotive Diesel engines use a four-stroke cycle, but with a compression heating ignition system it is possible to talk separately about a diesel cycle. The Wankel engine operates with the same separation of phases as the four-stroke engine (but with no piston strokes, would more properly be called a four-phase engine), since the phases occur in separate locations in the engine; however like a two-stroke piston engine, it provides one power 'stroke' per revolution per rotor, giving it similar space and weight efficiency. The Bourke cycle's combustion phase more closely approximates constant volume combustion than either four stroke or two stroke cycles do. It also uses less moving parts, hence needs to overcome less friction than the other two reciprocating types have to. In addition, its greater expansion ratio also means more of the heat from its combustion phase is utilized than is used by either four stroke or two stroke cycles.

Fuel and oxidiser types

Fuels used include gasoline (aka petrol), Liquified Petroleum Gas, Vapourized Petroleum Gas, Compressed Natural Gas, hydrogen, diesel fuel, JP18 (jet fuel), landfill gas, biodiesel, peanut oil, ethanol, methanol (methyl or wood alcohol). Engines that use gases for fuel are called gas engines and those that use liquid hydrocarbons are called oil engines. However, gasoline engines are often called gas engines for short. The only limitations are that the fuel must be easily transportable through the fuel system to the combustion chamber, and that the fuel release sufficient energy in the form of heat upon combustion to make use of the engine practical. The oxidiser is typically air, but can be pure oxygen, nitrous oxide or hydrogen peroxide. Other chemicals such as chlorine or fluorine have seen experimental use; but mostly are impractical. Diesel engines are generally heavier, noisier and more powerful at lower speeds than gasoline engines. They are also more fuel-efficient in most circumstances and are used in heavy road-vehicles, some automobiles (increasingly more so for their increased fuel-efficiency over gasoline engines), ships and some locomotives and light aircraft. Gasoline engines are used in most other road-vehicles including most cars, motorcycles and mopeds. Note that in Europe, sophisticated diesel-engined cars are far more prevalent, representing around 40% of the market. Both gasoline and diesel engines produce significant emissions. There are also engines that run on hydrogen, methanol, ethanol, liquefied petroleum gas (LPG) and biodiesel. Paraffin and Tractor vaporising oil (TVO) engines are no longer seen. Tractor vaporising oil

Cylinders

Internal combustion engines can contain any number of cylinders with numbers between one and twelve being common, though as many as 28 have been used. Having more cylinders in a engine yields two potential benefits: First. the engine can have a larger displacement with smaller individual reciprocating masses (that is, the mass of each piston can be less) thus making a smoother running engine (since the engine tends to vibrate as a result of the pistons moving up and down). Second, with a greater displacement and more pistons, more fuel can be combusted and there can be more combustion events (that is, more power strokes) in a given period of time, meaning that such an engine can generate more torque than a similar engine with fewer cylinders. The down side to having more pistons is that, over all, the engine will tend to weigh more and tend to generate more internal friction as the greater number of pistons rub against the inside of their cylinders. This tends to decrease fuel efficiency and rob the engine of some of its power. For high performance gasoline engines using current materials and technology (such as the engines found in modern automobiles), there seems to be a break point around 10 or 12 cylinders, after which addition of cylinders becomes an overall detriment to performance and efficiency, although exceptions such as the W-16 engine from Volkswagen exist.
- Most car engines have four to eight cylinders, with some high performance cars having ten, twelve, or even sixteen, and some very small cars and trucks having two or three. In previous years some quite large cars, such as the DKW and Saab 92, had two cylinder, two stroke engines.
- Radial aircraft engines, now obsolete, had from five to 28 cylinders. A row contains an odd number of cylinders, so an even number indicates a two- or four-row engine.
- Motor cycles commonly have from one to four cylinders, with a few high performance models having six.
- Snowmobiles usually have two cylinders. Some larger (not necessarily high-performance, but also touring machines) have four.
- Small appliances such as chainsaws and domestic lawn mowers most commonly have one cylinder, although two-cylinder chainsaws exist.

Ignition system

Internal combustion engines can be classified by their ignition system. Today most engines use an electrical or compression heating system for ignition. However outside flame and hot-tube systems have been used historically. Nikola Tesla gained one of the first patents on the mechanical ignition system with , "Electrical Igniter for Gas Engines", on 16 August 1898.

Fuel systems

Often for simpler reciprocating engines a carburetor is used to supply fuel into the cylinder. However, exact control of the correct amount of fuel supplied to the engine is impossible. Larger gasoline engines such as used in cars have mostly moved to Fuel injection systems. LPG engines use a mix of Fuel injection systems and closed loop carburetors. Diesel engines always use fuel injection. Other internal combustion engines like Jet engines use burners, and rocket engines use various different ideas including impinging jets, gas/liquid shear, preburners and many other ideas.

Engine configuration

Internal combustion engines can be classified by their configuration which affects their physical size and smoothness (with smoother engines producing less vibration). Common configurations include the straight or inline configuration, the more compact V configuration and the wider but smoother flat or boxer configuration. Aircraft engines can also adopt a radial configuration which allows more effective cooling. More unusual configurations, such as "H", "U", "X", or "W" have also been used. Multiple-crankshaft configurations do not necessarily need a cylinder head at all, but can instead have a piston at each end of the cylinder, called an opposed piston design. This design was used in the Junkers Jumo 205 diesel aircraft engine, using two crankshafts, one at either end of a single bank of cylinders, and most remarkably in the Napier Deltic diesel engines, which used three crankshafts to serve three banks of double-ended cylinders arranged in an equilateral triangle with the crankshafts at the corners. It was also used in single-bank locomotive engines, and continues to be used for marine engines, both for propulsion and for auxiliary generators. The Gnome Rotary engine, used in several early aircraft, had a stationary crankshaft and a bank of radially arranged cylinders rotating around it.

Engine capacity

An engine's capacity is the displacement or swept volume by the pistons of the engine. It is generally measured in litres or cubic inches for larger engines and cubic centimetres (abbreviated to cc's) for smaller engines. Engines with greater capacities are usually more powerful and provide greater torque at lower rpms but also consume more fuel. Apart from designing an engine with more cylinders, there are two ways to increase an engine's capacity. The first is to lengthen the stroke and the second is to increase the piston's diameter. In either case, it may be necessary to make further adjustments to the fuel intake of the engine to ensure optimal performance. An engine's quoted capacity can be more a matter of marketing than of engineering. The Morris Minor 1000, the Morris 1100, and the Austin-Healey Sprite Mark II all had engines of the same stroke and bore according to their specifications, and were from the same maker. However the engine capacities were quoted as 1000cc, 1100cc and 1098cc respectively in the sales literature and on the vehicle badges.

Engine pollution

Generally internal combustion engines, particularly reciprocating internal combustion engines, produce moderately high pollution levels, due to incomplete combustion of carbonaceous fuel, leading to carbon monoxide and some soot along with oxides of nitrogen & sulphur and some unburnt hydrocarbons depending on the operating conditions and the fuel/air ratio. Diesel engines produce a wide range of pollutants including aerosols of many small particles that are believed to penetrate deeply into human lungs.
- Many fuels contain sulfur leading to sulfur oxides (SOx) in the exhaust, promoting acid rain.
- The high temperature of combustion creates greater proportions of nitrogen oxides (NOx), demonstrated to be hazardous to both plant and animal health.
- Net carbon dioxide production is not a necessary feature of engines, but since most engines are run from fossil fuels this usually occurs. If engines are run from biomass, then no net carbon dioxide is produced as the growing plants absorb as much, or more carbon dioxide while growing.
- Hydrogen engines only produce water, in theory.

Bibliography

- Singer, Charles Joseph; Raper, Richard, A history of technology : The Internal Combustion Engine, edited by Charles Singer ... [et al.], Clarendon Press, 1954-1978. pp.157-176[http://proxy.bib.uottawa.ca:2398/cgi/t/text/pageviewer-idx?c=acls&cc=acls&idno=heb02191.0005.001&q1=bicycle&frm=frameset&seq=5]

External links

- [http://www.keveney.com/Engines.html Animated Engines] - explains a variety of types
- [http://auto.howstuffworks.com/engine3.htm How Internal Combustion Works] - with animation Category:Energy conversion Category:Engines ja:内燃機関

Compression ignition engine

How diesel engines work

Fuel injection in diesel engines

Indirect Injection

Direct injection

Modern diesel engines make use of one of the following direct injection methods:

Common rail direct injection

Unit direct injection

Types of diesel engines

Advantages and disadvantages versus spark-ignition engines

Automobile racing

Dieseling in spark-ignition engines

Fuel and fluid characteristics

Diesel applications

Current and future developments

Modern diesel facts

External links

Ignition

Ignition occurs when the heat produced by a reaction becomes sufficient to sustain the reaction, whether it be a fire, an explosion, or nuclear fusion. By analogy, the sudden change from a cold gas to a hot plasma in a plasma source is also called ignition.
- In chemistry it refers to heating a material to the point that it spontaneously combusts.
- In nuclear fusion it refers to the conditions under which a plasma can be maintained by fusion reactions without external energy input. See Fusion energy gain factor.
- An ignition system is a method for activating and controlling the combustion of fuel in an internal combustion engine. For a car, it is initiated by turning the car's key in a lock to start the engine.
- In semiconductor processing, ignition is the process of starting up a plasma generator. In DC plasma systems, this involves a transition from voltaic arcing to sustained and delocalized plasma generation. RF and microwave systems must produce sufficient power at the proper frequency to generate usable plasma, which generally requires some adjustment of the equipment.
- Ignition (song) was a hip hop song by R. Kelly.
- Ignition (game) is a humorous racing game for PC published in 1997 by UDS (Unique Development Studios).
- Ignition Entertainment is a computer video games company founded in 2002 which is currently focusing on games for the Nintendo DS and Sony PSP

Gas

:For other meanings see gas (disambiguation). ---- A gas is one of the four main phases of matter (after solid and liquid, and followed by plasma), that subsequently appear as a solid material is subjected to increasingly higher temperatures. Thus, as energy in the form of heat is added, a solid (e.g. ice) will first melt to become a liquid (e.g. water), which will then boil or evaporate to become a gas (e.g. water vapor). In some circumstances, a solid (e.g. "dry ice") can directly turn into a gas: this is called sublimation. If the gas is further heated, its atoms or molecules can become (wholly or partially) ionized, turning the gas into a plasma.

Properties of a gas

#All collisions are perfectly elastic #The gas fills the entire container #The molecules have negligible volume In the gas phase, the atoms or molecules constituting the matter basically move independently, with no forces keeping them together or pushing them apart. Their only interactions are rare and random collisions. The particles move in random directions, at high speeds, whose range is dependent on the temperature and defined by the Maxwell-Boltzmann distribution. Therefore, the gas phase is a completely disordered state. Following the second law of thermodynamics, gas particles will immediately diffuse to homogeneously fill any shape or volume of space that is made available to them. The thermodynamic state of a gas is characterized by its volume, its temperature, which is determined by the average velocity or kinetic energy of the molecules, and its pressure, which is determined by the average velocity and density or number of molecules. These variables are related by the fundamental gas laws, which state that the pressure in an ideal gas is proportional to its temperature and number of molecules, but inversely proportional to its volume. Like liquids and plasmas, gases are fluids: they have the ability to flow and do not tend to return to their former configuration after deformation, although they do have viscosity. Unlike liquids, however, unconstrained gases do not occupy a fixed volume, but expand to fill whatever space they occupy. The kinetic energy per molecule in a gas is the second greatest of the states of matter (after plasma). Because of this high kinetic energy, gas atoms and molecules tend to bounce off of any containing surface and off one another, the more powerfully as the kinetic energy is increased. A common misconception is that the collisions of the molecules with each other is essential to explain gas pressure, but in fact their random velocities are sufficient to define that quantity. Mutual collisions are important only for establishing the Maxwell-Boltzmann distribution. Gas particles are normally well separated, as opposed to liquid particles, which are in contact. A material particle (say a dust mote) in a gas moves in Brownian Motion. Since it is at the limit of (or beyond) current technology to observe individual gas particles (atoms or molecules), only theoretical calculations give suggestions as to how they move, but their motion is different from Brownian Motion. The reason is that Brownian Motion involves a smooth drag due to the frictional force of many gas molecules, punctuated by violent collisions of an individual (or several) gas molecule(s) with the particle. The particle (generally consisting of millions or billions of atoms) thus moves in a jagged course, yet not so jagged as we would expect to find if we could examine an individual gas molecule.

Etymology

The word "gas" was apparently coined in the early 17th century by the Belgian chemist Jan Baptist van Helmont, as a re-spelling of his pronunciation of the Greek word chaos.

Energy

Energy is a measure of being able to do work. This is a fundamental concept pertaining to the ability for action. In physics, it is a quantity that every physical system possesses. This quantity is not absolute but relative to a state of the system known as its reference state or reference level. The energy of a physical system is defined as the amount of mechanical work that the system can produce if it changes its state to its reference state; for example if a liter of water cools down to 0°C or if a car hits a tree and decelerates from 120 km/h to 0 km/h. Energy of an object can be in several forms, potential—due to the position of the object relative to other objects; kinetic—energy because of its motion; chemical—due to chemical bonds between atoms that make up the substance; electrical—due to its charge; thermal—due to its heat; and nuclear—due to the instability of the nuclei of its atoms. In the case where the "object" is an electromagnetic wave or light, then radiant energy can also be defined. One form of energy can be readily transformed into another; for instance, a battery converts chemical energy into electrical energy, which can be converted into thermal energy. Similarly, potential energy is converted into kinetic energy of moving water and turbine in a dam, which in turn transforms into electric energy by generator. The law of conservation of energy states that in a closed system the total amount of energy, corresponding to the sum of a system's constituent energy components, remains constant. This law follows from translational symmetry of time (that is, independence of any physical process on the moment it started). Some works (thus some forms of energy) are not easily measured by the unaided observer. The term 'energy' is also used in a spiritual or non-scientific way that cannot be quantified, to make certain prepositions look like they are more plausible, by imitating the scientific terminology. Usually this has something to do with mystical and/or healing type references such as acupuncture and reiki.

Forms of Energy

Below is a list of different energy forms. Lotka (1956, p. 5) asked an interesting question about what defines an energy form. :"We are equipped with two separate and distinct senses, the one responding to electromagnetic waves ranging from about 4×10^-4 to 8×10^-4 mm., light waves; the other to somewhat longer waves otherwise of the same character, heat waves. Accordingly we have two separate terms in our language light and heat, to denote two phenomena which, objectively considered, are not separated by any line of division, but merge into one another by gradual transition. Here the question might be raised whether an electromagnetic wave of a length of 9×10^-4 mm. is a light wave or a heat wave." That is to ask, if all forms of energy are defined in terms of infinitesimal increments of the wave spectrum, what makes one form of energy different to another?
- Kinetic energy: the energy of moving objects
- Thermal energy: the energy associated with heat
- Sound energy: the energy of compression waves
- Electrical energy: the energy of moving charged particles
- Potential Energy: the energy that an object has due to position; also known as stored energy
- Chemical energy: the stored energy of chemical substances
- Nuclear energy: the stored energy of the atomic nucleus
- Radiant energy: the energy of electromagnetic waves, including light

Units

SI

The SI unit for both energy and work is the joule (J), named in honour of James Prescott Joule and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton-metre and, in terms of SI base units:

1\ \mathrm = 1\ \mathrm \left( \frac \right ) ^ 2 = 1\ \frac

An energy unit that is used in particle physics is the electronvolt (eV). One eV is equivalent to 1.60217653×10⁻¹⁹ J. In spectroscopy the unit cm^-1 = 0.0001239 eV is used to represent energy since energy is inversely proportional to wavelength from the equation

E = h \nu = h c/\lambda

. (Note that torque, which is typically expressed in newton-metres, has the same dimension and this is not a simple coincidence: a torque of 1 newton-metre applied on 1 radian requires exactly 1 newton-metre=joule of energy.)

Other units of energy

In cgs units, one erg is 1 g cm² s⁻², equal to 1.0×10⁻⁷ J. Another obsolete metric unit is the litre-atmosphere (101.325 J). The imperial/US units for both energy and work include the foot-pound force (1.3558 J), the British thermal unit (Btu) which has various values in the region of 1055 J, and the horsepower-hour (2.6845 MJ). The energy unit used for everyday electricity, particularly for utility bills, is the kilowatt-hour (kW h), and one kW h is equivalent to 3.6×10⁶ J (3600 kJ or 3.6 MJ; the metric units usually are self-consistent, and this particular one may seem arbitrary; it's not, the metric measurement for time is the second, and there are 3,600 seconds in an hour -- in other words, 1 kW second = 1 kJ, but the kW h is a more convenient unit for everyday use). The calorie is mainly used in nutrition and equals the amount of heat necessary to raise the temperature of one kilogram of water by 1 degree Celsius, at a pressure of 1 atm. This amount of heat depends somewhat on the initial temperature of the water, which results in various different units sharing the name of "calorie" but having slightly different energy values. It is equal to 4.1868 kJ. The calories used for food energy in nutrition are the large calories based on the kilogram rather than the gram, often identified as food calories. These are sometimes called kilocalories with that calorie being the small calorie based on the gram, and as a result the prefixes are generally avoided for the large calories (i.e., 1 kcal is 4.184 kJ, never 4.184 MJ, even if "calories" are also used for the other, larger unit in the same document or the same nutrition label). Food calories are sometimes noted as Calories (1000 calories) or simply abbreviated Cal with the capital C, but that convention is more often found in chemistry or physics textbooks—which do not use these large calories—than it is in real-world applications by those who do use these calories. (This convention is also, of course, useless when the word calorie appears in a location where it would ordinarily be capitalized, as at the beginning of a sentence or in the first column of a nutrition label as a substitute fo

Diesel engines

How diesel engines work

Fuel injection in diesel engines

Indirect Injection

Direct injection

Common rail direct injection

Unit direct injection

Types of diesel engines

Advantages and disadvantages versus spark-ignition engines

Automobile racing

Dieseling in spark-ignition engines

Fuel and fluid characteristics

Diesel applications

Current and future developments

Modern diesel facts

See also

External links

Internal combustion engine

History

Applications

Operation

Parts

Classification

Principles of operation

Engine cycle

Fuel and oxidiser types

Cylinders

Ignition system

Fuel systems

Engine configuration

Engine capacity

Engine pollution

Bibliography

External links

Compression ignition engine

How diesel engines work

Fuel injection in diesel engines

Indirect Injection

Direct injection

Common rail direct injection

Unit direct injection

Types of diesel engines

Advantages and disadvantages versus spark-ignition engines

Automobile racing

Dieseling in spark-ignition engines

Fuel and fluid characteristics

Diesel applications

Current and future developments

Modern diesel facts

See also

External links

Ignition

Gas

Properties of a gas

Etymology

See also

Energy

Forms of Energy

Units

SI

Other units of energy