Diesel engine

Diesel engines work by compressing only air, or air plus residual combustion gases from the exhaust (known as exhaust gas recirculation, "EGR"). Air is inducted into the chamber during the intake stroke, and compressed during the compression stroke. This increases the air temperature inside the cylinder so that atomised diesel fuel injected into the combustion chamber ignites. With the fuel being injected into the air just before combustion, the dispersion of the fuel is uneven; this is called a heterogeneous air-fuel mixture. The torque a diesel engine produces is controlled by manipulating the air-fuel ratio (λ); instead of throttling the intake air, the diesel engine relies on altering the amount of fuel that is injected, and the air-fuel ratio is usually high.

The diesel engine has the highest thermal efficiency (engine efficiency) of any practical internal or external combustion engine due to its very high expansion ratio and inherent lean burn which enables heat dissipation by the excess air. A small efficiency loss is also avoided compared with non-direct-injection gasoline engines since unburned fuel is not present during valve overlap and therefore no fuel goes directly from the intake/injection to the exhaust. Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can reach effective efficiencies of up to 55%.^[1] The combined cycle gas turbine (Brayton and Rankin cycle) is a combustion engine that is more efficient than a diesel engine, but it is, due to its mass and dimensions, unsuited for vehicles, watercraft, or aircraft. The world's largest diesel engines put in service are 14-cylinder, two-stroke marine diesel engines; they produce a peak power of almost 100 MW each.^[2]

Diesel engines may be designed with either two-stroke or four-stroke combustion cycles. They were originally used as a more efficient replacement for stationary steam engines. Since the 1910s, they have been used in submarines and ships. Use in locomotives, buses, trucks, heavy equipment, agricultural equipment and electricity generation plants followed later. In the 1930s, they slowly began to be used in a few automobiles. Since the 1970s energy crisis, demand for higher fuel efficiency has resulted in most major automakers, at some point, offering diesel-powered models, even in very small cars.^[3][4] According to Konrad Reif (2012), the EU average for diesel cars at the time accounted for half of newly registered cars.^[5] However, air pollution emissions are harder to control in diesel engines than in gasoline engines, so the use of diesel auto engines in the U.S. is now largely relegated to larger on-road and off-road vehicles.^[6][7]

Though aviation has traditionally avoided diesel engines, aircraft diesel engines have become increasingly available in the 21st century. Since the late 1990s, for various reasons – including the diesel's normal advantages over gasoline engines, but also for recent issues peculiar to aviation – development and production of diesel engines for aircraft has surged, with over 5,000 such engines delivered worldwide between 2002 and 2018, particularly for light airplanes and unmanned aerial vehicles.^[8][9]

Discover more about Introduction related topics

Cylinder (engine)

Cylinder (engine)

In a reciprocating engine, the cylinder is the space in which a piston travels.

Engine efficiency

Engine efficiency

Engine efficiency of thermal engines is the relationship between the total energy contained in the fuel, and the amount of energy used to perform useful work. There are two classifications of thermal engines-Internal combustion and External combustion engines.

Expansion ratio

Expansion ratio

The expansion ratio of a liquefied and cryogenic substance is the volume of a given amount of that substance in liquid form compared to the volume of the same amount of substance in gaseous form, at room temperature and normal atmospheric pressure.

Air–fuel ratio

Air–fuel ratio

Air–fuel ratio (AFR) is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process. The combustion may take place in a controlled manner such as in an internal combustion engine or industrial furnace, or may result in an explosion.

Combined cycle power plant

Combined cycle power plant

A combined cycle power plant is an assembly of heat engines that work in tandem from the same source of heat, converting it into mechanical energy. On land, when used to make electricity the most common type is called a combined cycle gas turbine (CCGT) plant. The same principle is also used for marine propulsion, where it is called a combined gas and steam (COGAS) plant. Combining two or more thermodynamic cycles improves overall efficiency, which reduces fuel costs.

Aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or the dynamic lift of an airfoil, or, in a few cases, the downward thrust from jet engines. Common examples of aircraft include airplanes, helicopters, airships, gliders, paramotors, and hot air balloons.

Steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be transformed, by a connecting rod and crank, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle. In general usage, the term steam engine can refer to either complete steam plants, such as railway steam locomotives and portable engines, or may refer to the piston or turbine machinery alone, as in the beam engine and stationary steam engine.

Submarine

Submarine

A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as boats rather than ships irrespective of their size.

Heavy equipment

Heavy equipment

Heavy equipment or heavy machinery or Earthmover refers to heavy-duty vehicles specially designed to execute construction tasks, most frequently involving earthwork operations or other large construction tasks. Heavy equipment usually comprises five equipment systems: the implement, traction, structure, power train, and control/information.

1970s energy crisis

1970s energy crisis

The 1970s energy crisis occurred when the Western world, particularly the United States, Canada, Western Europe, Australia, and New Zealand, faced substantial petroleum shortages as well as elevated prices. The two worst crises of this period were the 1973 oil crisis and the 1979 energy crisis, when, respectively, the Yom Kippur War and the Iranian Revolution triggered interruptions in Middle Eastern oil exports.

European Union

European Union

The European Union (EU) is a supranational political and economic union of 27 member states that are located primarily in Europe. The union has a total area of 4,233,255.3 km2 (1,634,469.0 sq mi) and an estimated total population of nearly 447 million. The EU has often been described as a sui generis political entity combining the characteristics of both a federation and a confederation.

Air pollution

Air pollution

Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. It is also the contamination of indoor or outdoor surrounding either by chemical activities, physical or biological agents that alters the natural features of the atmosphere. There are many different types of air pollutants, such as gases, particulates, and biological molecules. Air pollution can cause diseases, allergies, and even death to humans; it can also cause harm to other living organisms such as animals and food crops, and may damage the natural environment or built environment. Air pollution can be caused by both human activities and natural phenomena.

Diesel's idea

Rudolf Diesel's 1893 patent on a rational heat motor

Diesel's second prototype. It is a modification of the first experimental engine. On 17 February 1894, this engine ran under its own power for the first time.^[10]

Effective efficiency 16.6%
Fuel consumption 519 g·kW⁻¹·h⁻¹

First fully functional diesel engine, designed by Imanuel Lauster, built from scratch, and finished by October 1896.^[11][12][13]

Rated power 13.1 kW
Effective efficiency 26.2%
Fuel consumption 324 g·kW⁻¹·h⁻¹.

In 1878, Rudolf Diesel, who was a student at the "Polytechnikum" in Munich, attended the lectures of Carl von Linde. Linde explained that steam engines are capable of converting just 6–10% of the heat energy into work, but that the Carnot cycle allows conversion of much more of the heat energy into work by means of isothermal change in condition. According to Diesel, this ignited the idea of creating a highly efficient engine that could work on the Carnot cycle.^[14] Diesel was also introduced to a fire piston, a traditional fire starter using rapid adiabatic compression principles which Linde had acquired from Southeast Asia.^[15] After several years of working on his ideas, Diesel published them in 1893 in the essay Theory and Construction of a Rational Heat Motor.^[14]

Diesel was heavily criticised for his essay, but only few found the mistake that he made;^[16] his rational heat motor was supposed to utilise a constant temperature cycle (with isothermal compression) that would require a much higher level of compression than that needed for compression ignition. Diesel's idea was to compress the air so tightly that the temperature of the air would exceed that of combustion. However, such an engine could never perform any usable work.^[17][18][19] In his 1892 US patent (granted in 1895) #542846, Diesel describes the compression required for his cycle:

pure atmospheric air is compressed, according to curve 1 2, to such a degree that, before ignition or combustion takes place, the highest pressure of the diagram and the highest temperature are obtained-that is to say, the temperature at which the subsequent combustion has to take place, not the burning or igniting point. To make this more clear, let it be assumed that the subsequent combustion shall take place at a temperature of 700°. Then in that case the initial pressure must be sixty-four atmospheres, or for 800° centigrade the pressure must be ninety atmospheres, and so on. Into the air thus compressed is then gradually introduced from the exterior finely divided fuel, which ignites on introduction, since the air is at a temperature far above the igniting-point of the fuel. The characteristic features of the cycle according to my present invention are therefore, increase of pressure and temperature up to the maximum, not by combustion, but prior to combustion by mechanical compression of air, and there upon the subsequent performance of work without increase of pressure and temperature by gradual combustion during a prescribed part of the stroke determined by the cut-oil.^[20]

By June 1893, Diesel had realised his original cycle would not work and he adopted the constant pressure cycle.^[21] Diesel describes the cycle in his 1895 patent application. Notice that there is no longer a mention of compression temperatures exceeding the temperature of combustion. Now it is simply stated that the compression must be sufficient to trigger ignition.

1. In an internal-combustion engine, the combination of a cylinder and piston constructed and arranged to compress air to a degree producing a temperature above the igniting-point of the fuel, a supply for compressed air or gas; a fuel-supply; a distributing-valve for fuel, a passage from the air supply to the cylinder in communication with the fuel-distributing valve, an inlet to the cylinder in communication with the air-supply and with the fuel-valve, and a cut-oil, substantially as described.^[22][23][24]

In 1892, Diesel received patents in Germany, Switzerland, the United Kingdom and the United States for "Method of and Apparatus for Converting Heat into Work".^[25] In 1894 and 1895, he filed patents and addenda in various countries for his engine; the first patents were issued in Spain (No. 16,654),^[26] France (No. 243,531) and Belgium (No. 113,139) in December 1894, and in Germany (No. 86,633) in 1895 and the United States (No. 608,845) in 1898.^[27]

Diesel was attacked and criticised over a time period of several years. Critics claimed that Diesel never invented a new motor and that the invention of the diesel engine is fraud. Otto Köhler and Emil Capitaine [de] were two of the most prominent critics of Diesel's time.^[28] Köhler had published an essay in 1887, in which he describes an engine similar to the engine Diesel describes in his 1893 essay. Köhler figured that such an engine could not perform any work.^[19][29] Emil Capitaine had built a petroleum engine with glow-tube ignition in the early 1890s;^[30] he claimed against his own better judgement that his glow-tube ignition engine worked the same way Diesel's engine did. His claims were unfounded and he lost a patent lawsuit against Diesel.^[31] Other engines, such as the Akroyd engine and the Brayton engine, also use an operating cycle that is different from the diesel engine cycle.^[29][32] Friedrich Sass says that the diesel engine is Diesel's "very own work" and that any "Diesel myth" is "falsification of history".^[33]

The first diesel engine

Diesel sought out firms and factories that would build his engine. With the help of Moritz Schröter and Max Gutermuth [de],^[34] he succeeded in convincing both Krupp in Essen and the Maschinenfabrik Augsburg.^[35] Contracts were signed in April 1893,^[36] and in early summer 1893, Diesel's first prototype engine was built in Augsburg. On 10 August 1893, the first ignition took place, the fuel used was petrol. In winter 1893/1894, Diesel redesigned the existing engine, and by 18 January 1894, his mechanics had converted it into the second prototype.^[37] During January that year, an air-blast injection system was added to the engine's cylinder head and tested.^[38] Friedrich Sass argues that, it can be presumed that Diesel copied the concept of air-blast injection from George B. Brayton,^[32] albeit that Diesel substantially improved the system.^[39] On 17 February 1894, the redesigned engine ran for 88 revolutions – one minute;^[10] with this news, Maschinenfabrik Augsburg's stock rose by 30%, indicative of the tremendous anticipated demands for a more efficient engine.^[40] On 26 June 1895, the engine achieved an effective efficiency of 16.6% and had a fuel consumption of 519 g·kW⁻¹·h⁻¹. ^[41] However, despite proving the concept, the engine caused problems,^[42] and Diesel could not achieve any substantial progress.^[43] Therefore, Krupp considered rescinding the contract they had made with Diesel.^[44] Diesel was forced to improve the design of his engine and rushed to construct a third prototype engine. Between 8 November and 20 December 1895, the second prototype had successfully covered over 111 hours on the test bench. In the January 1896 report, this was considered a success.^[45]

In February 1896, Diesel considered supercharging the third prototype.^[46] Imanuel Lauster, who was ordered to draw the third prototype "Motor 250/400", had finished the drawings by 30 April 1896. During summer that year the engine was built, it was completed on 6 October 1896.^[47] Tests were conducted until early 1897.^[48] First public tests began on 1 February 1897.^[49] Moritz Schröter's test on 17 February 1897 was the main test of Diesel's engine. The engine was rated 13.1 kW with a specific fuel consumption of 324 g·kW⁻¹·h⁻¹,^[50] resulting in an effective efficiency of 26.2%.^[51][52] By 1898, Diesel had become a millionaire.^[53]

Timeline

1890s

• 1893: Rudolf Diesel's essay titled Theory and Construction of a Rational Heat Motor appears.^[54][55]
• 1893: February 21, Diesel and the Maschinenfabrik Augsburg sign a contract that allows Diesel to build a prototype engine.^[56]
• 1893: February 23, Diesel obtains a patent (RP 67207) titled "Arbeitsverfahren und Ausführungsart für Verbrennungsmaschinen" (Working Methods and Techniques for Internal Combustion Engines).
• 1893: April 10, Diesel and Krupp sign a contract that allows Diesel to build a prototype engine.^[56]
• 1893: April 24, both Krupp and the Maschinenfabrik Augsburg decide to collaborate and build just a single prototype in Augsburg.^[56][36]
• 1893: July, the first prototype is completed.^[57]
• 1893: August 10, Diesel injects fuel (petrol) for the first time, resulting in combustion, destroying the indicator.^[58]
• 1893: November 30, Diesel applies for a patent (RP 82168) for a modified combustion process. He obtains it on 12 July 1895.^[59][60][61]
• 1894: January 18, after the first prototype had been modified to become the second prototype, testing with the second prototype begins.^[37]
• 1894: February 17, The second prototype runs for the first time.^[10]
• 1895: March 30, Diesel applies for a patent (RP 86633) for a starting process with compressed air.^[62]
• 1895: June 26, the second prototype passes brake testing for the first time.^[41]
• 1895: Diesel applies for a second patent US Patent # 608845^[63]
• 1895: November 8 – December 20, a series of tests with the second prototype is conducted. In total, 111 operating hours are recorded.^[45]
• 1896: April 30, Imanuel Lauster completes the third and final prototype's drawings.^[47]
• 1896: October 6, the third and final prototype engine is completed.^[11]
• 1897: February 1, Diesel's prototype engine is running and finally ready for efficiency testing and production.^[49]
• 1897: October 9, Adolphus Busch licenses rights to the diesel engine for the US and Canada.^[53][64]
• 1897: 29 October, Rudolf Diesel obtains a patent (DRP 95680) on supercharging the diesel engine.^[46]
• 1898: February 1, the Diesel Motoren-Fabrik Actien-Gesellschaft is registered.^[65]
• 1898: March, the first commercial diesel engine, rated 2×30 PS (2×22 kW), is installed in the Kempten plant of the Vereinigte Zündholzfabriken A.G.^[66][67]
• 1898: September 17, the Allgemeine Gesellschaft für Dieselmotoren A.-G. is founded.^[68]
• 1899: The first two-stroke diesel engine, invented by Hugo Güldner, is built.^[52]

1900s

An MAN DM trunk piston diesel engine built in 1906. The MAN DM series is considered to be one of the first commercially successful diesel engines.^[69]

• 1901: Imanuel Lauster designs the first trunk piston diesel engine (DM 70).^[69]
• 1901: By 1901, MAN had produced 77 diesel engine cylinders for commercial use.^[70]
• 1903: Two first diesel-powered ships are launched, both for river and canal operations: The Vandal naphtha tanker and the Sarmat.^[71]
• 1904: The French launch the first diesel submarine, the Aigrette.^[72]
• 1905: January 14: Diesel applies for a patent on unit injection (L20510I/46a).^[73]
• 1905: The first diesel engine turbochargers and intercoolers are manufactured by Büchi.^[74]
• 1906: The Diesel Motoren-Fabrik Actien-Gesellschaft is dissolved.^[28]
• 1908: Diesel's patents expire.^[75]
• 1908: The first lorry (truck) with a diesel engine appears.^[76]
• 1909: March 14, Prosper L'Orange applies for a patent on precombustion chamber injection.^[77] He later builds the first diesel engine with this system.^[78][79]

1910s

• 1910: MAN starts making two-stroke diesel engines.^[80]
• 1910: November 26, James McKechnie applies for a patent on unit injection.^[81] Unlike Diesel, he managed to successfully build working unit injectors.^[73][82]
• 1911: November 27, the Allgemeine Gesellschaft für Dieselmotoren A.-G. is dissolved.^[65]
• 1911: The Germania shipyard in Kiel builds 850 PS (625 kW) diesel engines for German submarines. These engines are installed in 1914.^[83]
• 1912: MAN builds the first double-acting piston two-stroke diesel engine.^[84]
• 1912: The first locomotive with a diesel engine is used on the Swiss Winterthur-Romanshorn railroad.^[85]
• 1912: The Selandia is the first ocean-going ship with diesel engines.^[86]
• 1913: NELSECO diesels are installed on commercial ships and US Navy submarines.^[87]
• 1913: September 29, Rudolf Diesel dies mysteriously when crossing the English Channel on the SS Dresden.^[88]
• 1914: MAN builds 900 PS (662 kW) two-stroke engines for Dutch submarines.^[89]
• 1919: Prosper L'Orange obtains a patent on a Precombustion chamber insert incorporating a needle injection nozzle.^[90][91][79] First diesel engine from Cummins.^[92][93]

1920s

Fairbanks Morse model 32

• 1923: At the Königsberg DLG exhibition, the first agricultural tractor with a diesel engine, the prototype Benz-Sendling S6, is presented.^[94]
• 1923: December 15, the first lorry with a direct-injected diesel engine is tested by MAN. The same year, Benz builds a lorry with a pre-combustion chamber injected diesel engine.^[95]
• 1923: The first two-stroke diesel engine with counterflow scavenging appears.^[96]
• 1924: Fairbanks-Morse introduces the two-stroke Y-VA (later renamed to Model 32).^[97]
• 1925: Sendling starts mass-producing a diesel-powered agricultural tractor.^[98]
• 1927: Bosch introduces the first inline injection pump for motor vehicle diesel engines.^[99]
• 1929: The first passenger car with a diesel engine appears. Its engine is an Otto engine modified to use the diesel principle and Bosch's injection pump. Several other diesel car prototypes follow.^[100]

1930s

• 1933: Junkers Motorenwerke in Germany start production of the most successful mass-produced aviation diesel engine of all time, the Jumo 205. By the outbreak of World War II, over 900 examples are produced. Its rated take-off power is 645 kW.^[101]
• 1933: General Motors uses its new roots-blown, unit-injected two-stroke Winton 201A diesel engine to power its automotive assembly exhibit at the Chicago World's Fair (A Century of Progress).^[102] The engine is offered in several versions ranging from 600–900 hp (447–671 kW).^[103]
• 1934: The Budd Company builds the first diesel–electric passenger train in the US, the Pioneer Zephyr 9900, using a Winton engine.^[102]
• 1935: The Citroën Rosalie is fitted with an early swirl chamber injected diesel engine for testing purposes.^[104] Daimler-Benz starts manufacturing the Mercedes-Benz OM 138, the first mass-produced diesel engine for passenger cars, and one of the few marketable passenger car diesel engines of its time. It is rated 45 PS (33 kW).^[105]
• 1936: March 4, the airship LZ 129 Hindenburg, the biggest aircraft ever made, takes off for the first time. It is powered by four V16 Daimler-Benz LOF 6 diesel engines, rated 1,200 PS (883 kW) each.^[106]
• 1936: Manufacture of the first mass-produced passenger car with a diesel engine (Mercedes-Benz 260 D) begins.^[100]
• 1937: Konstantin Fyodorovich Chelpan develops the V-2 diesel engine, later used in the Soviet T-34 tanks, widely regarded as the best tank chassis of World War II.^[107]
• 1938: General Motors forms the GM Diesel Division, later to become Detroit Diesel, and introduces the Series 71 inline high-speed medium-horsepower two-stroke engine, suitable for road vehicles and marine use.^[108]

1940s

• 1946: Clessie Cummins obtains a patent on a fuel feeding and injection apparatus for oil-burning engines that incorporates separate components for generating injection pressure and injection timing.^[109]
• 1946: Klöckner-Humboldt-Deutz (KHD) introduces an air-cooled mass-production diesel engine to the market.^[110]

1950s

Piston of an MAN M-System centre sphere combustion chamber type diesel engine (4 VD 14,5/12-1 SRW)

• 1950s: KHD becomes the air-cooled diesel engine global market leader.^[111]
• 1951: J. Siegfried Meurer obtains a patent on the M-System, a design that incorporates a central sphere combustion chamber in the piston (DBP 865683).^[112]
• 1953: First mass-produced swirl chamber injected passenger car diesel engine (Borgward/Fiat).^[81]
• 1954: Daimler-Benz introduces the Mercedes-Benz OM 312 A, a 4.6 litre straight-6 series-production industrial diesel engine with a turbocharger, rated 115 PS (85 kW). It proves to be unreliable.^[113]
• 1954: Volvo produces a small batch series of 200 units of a turbocharged version of the TD 96 engine. This 9.6 litre engine is rated 136 kW.^[114]
• 1955: Turbocharging for MAN two-stroke marine diesel engines becomes standard.^[96]
• 1959: The Peugeot 403 becomes the first mass-produced passenger sedan/saloon manufactured outside West Germany to be offered with a diesel engine option.^[115]

1960s

Mercedes-Benz OM 352, one of the first direct injected Mercedes-Benz diesel engines. It was introduced in 1963, but mass production only started in summer 1964.^[116]

• 1964: Summer, Daimler-Benz switches from precombustion chamber injection to helix-controlled direct injection.^[117][112]
• 1962–65: A diesel compression braking system, eventually to be manufactured by the Jacobs Manufacturing Company and nicknamed the "Jake Brake", is invented and patented by Clessie Cummins.^[118]

1970s

• 1972: KHD introduces the AD-System, Allstoff-Direkteinspritzung, (anyfuel direct-injection), for its diesel engines. AD-diesels can operate on virtually any kind of liquid fuel, but they are fitted with an auxiliary spark plug that fires if the ignition quality of the fuel is too low.^[119]
• 1976: Development of the common rail injection begins at the ETH Zürich.^[120]
• 1976: The Volkswagen Golf becomes the first compact passenger sedan/saloon to be offered with a diesel engine option.^[121][122]
• 1978: Daimler-Benz produces the first passenger car diesel engine with a turbocharger (Mercedes-Benz OM 617).^[123]
• 1979: First prototype of a low-speed two-stroke crosshead engine with common rail injection.^[124]

1980s

BMW E28 524td, the first mass-produced passenger car with an electronically controlled injection pump

• 1981/82: Uniflow scavenging for two-stroke marine diesel engines becomes standard.^[125]
• 1985: December, road testing of a common rail injection system for lorries using a modified 6VD 12,5/12 GRF-E engine in an IFA W50 takes place.^[126]
• 1986: The BMW E28 524td is the world's first passenger car equipped with an electronically controlled injection pump (developed by Bosch).^[81][127]
• 1987: Daimler-Benz introduces the electronically controlled injection pump for lorry diesel engines.^[81]
• 1988: The Fiat Croma becomes the first mass-produced passenger car in the world to have a direct injected diesel engine.^[81]
• 1989: The Audi 100 is the first passenger car in the world with a turbocharged, direct injected, and electronically controlled diesel engine.^[81]

1990s

• 1992: 1 July, the Euro 1 emission standard comes into effect.^[128]
• 1993: First passenger car diesel engine with four valves per cylinder, the Mercedes-Benz OM 604.^[123]
• 1994: Unit injector system by Bosch for lorry diesel engines.^[129]
• 1996: First diesel engine with direct injection and four valves per cylinder, used in the Opel Vectra.^[130][81]
• 1996: First radial piston distributor injection pump by Bosch.^[129]
• 1997: First mass-produced common rail diesel engine for a passenger car, the Fiat 1.9 JTD.^[81][123]
• 1998: BMW wins the 24 Hours Nürburgring race with a modified BMW E36. The car, called 320d, is powered by a 2-litre, straight-four diesel engine with direct injection and a helix-controlled distributor injection pump (Bosch VP 44), producing 180 kW. The fuel consumption is 23 L/100 km, only half the fuel consumption of a similar Otto-powered car.^[131]
• 1998: Volkswagen introduces the VW EA188 Pumpe-Düse engine (1.9 TDI), with Bosch-developed electronically controlled unit injectors.^[123]
• 1999: Daimler-Chrysler presents the first common rail three-cylinder diesel engine used in a passenger car (the Smart City Coupé).^[81]

2000s

Audi R10 TDI, 2006 24 Hours of Le Mans winner.

• 2000: Peugeot introduces the diesel particulate filter for passenger cars.^[81][123]
• 2002: Piezoelectric injector technology by Siemens.^[132]
• 2003: Piezoelectric injector technology by Bosch,^[133] and Delphi.^[134]
• 2004: BMW introduces dual-stage turbocharging with the BMW M57 engine.^[123]
• 2006: The world's most powerful diesel engine, the Wärtsilä RT-flex96C, is produced. It is rated 80,080 kW.^[135]
• 2006: Audi R10 TDI, equipped with a 5.5-litre V12-TDI engine, rated 476 kW, wins the 2006 24 Hours of Le Mans.^[81]
• 2006: Daimler-Chrysler launches the first series-production passenger car engine with selective catalytic reduction exhaust gas treatment, the Mercedes-Benz OM 642. It is fully complying with the Tier2Bin8 emission standard.^[123]
• 2008: Volkswagen introduces the LNT catalyst for passenger car diesel engines with the VW 2.0 TDI engine.^[123]
• 2008: Volkswagen starts series production of the biggest passenger car diesel engine, the Audi 6-litre V12 TDI.^[123]
• 2008: Subaru introduces the first horizontally opposed diesel engine to be fitted to a passenger car. It is a 2-litre common rail engine, rated 110 kW.^[136]

2010s

• 2010: Mitsubishi developed and started mass production of its 4N13 1.8 L DOHC I4, the world's first passenger car diesel engine that features a variable valve timing system.^[127]
• 2012: BMW introduces dual-stage turbocharging with three turbochargers for the BMW N57 engine.^[123]
• 2015: Common rail systems working with pressures of 2,500 bar launched.^[81]
• 2015: In the Volkswagen emissions scandal, the US EPA issued a notice of violation of the Clean Air Act to Volkswagen Group after it was found that Volkswagen had intentionally programmed turbocharged direct injection (TDI) diesel engines to activate certain emissions controls only during laboratory emissions testing.^{[137][138][139][140]}

Discover more about History related topics

Rudolf Diesel

Rudolf Diesel

Rudolf Christian Karl Diesel was a German inventor and mechanical engineer who is famous for having invented the diesel engine, which burns diesel fuel; both are named after him.

Munich

Munich

Munich is the capital and most populous city of the German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the third-largest city in Germany, after Berlin and Hamburg, and thus the largest which does not constitute its own state, as well as the 11th-largest city in the European Union. The city's metropolitan region is home to 6 million people. Straddling the banks of the River Isar north of the Bavarian Alps, Munich is the seat of the Bavarian administrative region of Upper Bavaria, while being the most densely populated municipality in Germany with 4,500 people per km2. Munich is the second-largest city in the Bavarian dialect area, after the Austrian capital of Vienna.

Carl von Linde

Carl von Linde

Carl Paul Gottfried von Linde was a German scientist, engineer, and businessman. He discovered a refrigeration cycle and invented the first industrial-scale air separation and gas liquefaction processes, which led to the first reliable and efficient compressed-ammonia refrigerator in 1876. These breakthroughs laid the backbone for the 1913 Nobel Prize in Physics that was awarded to Heike Kamerlingh Onnes. Linde was a member of scientific and engineering associations, including being on the board of trustees of the Physikalisch-Technische Reichsanstalt and the Bavarian Academy of Sciences and Humanities. Linde was also the founder of what is now known as Linde plc but formerly known (variously) as the Linde division of Union Carbide, Linde, Linde Air Products, Praxair, and others. Linde is the world's largest producer of industrial gases and ushered in the creation of the global supply chain for industrial gases. He was knighted in 1897 as Ritter von Linde.

Carnot cycle

Carnot cycle

A Carnot cycle is an ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. By Carnot's theorem, it provides an upper limit on the efficiency of any classical thermodynamic engine during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference through the application of work to the system.

Fire piston

Fire piston

A fire piston, sometimes called a fire syringe or a slam rod fire starter, is a device of ancient Southeast Asian origin which is used to kindle fire. It uses the principle of the heating of a gas by rapid and adiabatic compression to ignite a piece of tinder, which is then used to set light to kindling.

Fire making

Fire making

Fire making, fire lighting or fire craft is the process of artificially starting a fire. It requires completing the fire triangle, usually by heating tinder above its autoignition temperature.

Southeast Asia

Southeast Asia

Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland China, east of the Indian subcontinent, and north-west of mainland Australia which is part of Oceania. Southeast Asia is bordered to the north by East Asia, to the west by South Asia and the Bay of Bengal, to the east by Oceania and the Pacific Ocean, and to the south by Australia and the Indian Ocean. Apart from the British Indian Ocean Territory and two out of 26 atolls of Maldives in South Asia, Maritime Southeast Asia is the only other subregion of Asia that lies partly within the Southern Hemisphere. Mainland Southeast Asia is completely in the Northern Hemisphere. Timor-Leste and the southern portion of Indonesia are the only parts in Southeast Asia that are south of the Equator.

German Empire

German Empire

The German Empire, also referred to as Imperial Germany, the Second Reich, or simply Germany, was the period of the German Reich from the unification of Germany in 1871 until the November Revolution in 1918, when the German Reich changed its form of government from a monarchy to a republic.

Spain

Spain

Spain, or the Kingdom of Spain, is a country primarily located in southwestern Europe with parts of territory in the Atlantic Ocean and across the Mediterranean Sea. The largest part of Spain is situated on the Iberian Peninsula; its territory also includes the Canary Islands in the Atlantic Ocean, the Balearic Islands in the Mediterranean Sea, and the autonomous cities of Ceuta and Melilla in Africa. The country's mainland is bordered to the south by Gibraltar; to the south and east by the Mediterranean Sea; to the north by France, Andorra and the Bay of Biscay; and to the west by Portugal and the Atlantic Ocean. With an area of 505,990 km2 (195,360 sq mi), Spain is the second-largest country in the European Union (EU) and, with a population exceeding 47.4 million, the fourth-most populous EU member state. Spain's capital and largest city is Madrid; other major urban areas include Barcelona, Valencia, Seville, Zaragoza, Málaga, Murcia, Palma de Mallorca, Las Palmas de Gran Canaria, and Bilbao.

France

France

France, officially the French Republic, is a country located primarily in Western Europe. It also includes overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans, giving it one of the largest discontiguous exclusive economic zones in the world. Its metropolitan area extends from the Rhine to the Atlantic Ocean and from the Mediterranean Sea to the English Channel and the North Sea; overseas territories include French Guiana in South America, Saint Pierre and Miquelon in the North Atlantic, the French West Indies, and many islands in Oceania and the Indian Ocean. Its eighteen integral regions span a combined area of 643,801 km2 (248,573 sq mi) and had a total population of over 68 million as of January 2023. France is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre; other major urban areas include Marseille, Lyon, Toulouse, Lille, Bordeaux, and Nice.

Belgium

Belgium

Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to the southwest, and the North Sea to the northwest. It covers an area of 30,528 km2 (11,787 sq mi) and has a population of more than 11.5 million, making it the 22nd most densely populated country in the world and the 6th most densely populated country in Europe, with a density of 376/km2 (970/sq mi). Belgium is part of an area known as the Low Countries, historically a somewhat larger region than the Benelux group of states, as it also included parts of northern France. The capital and largest city is Brussels; other major cities are Antwerp, Ghent, Charleroi, Liège, Bruges, Namur, and Leuven.

Germany

Germany

Germany, officially the Federal Republic of Germany, is a country in Central Europe. It is the second-most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between the Baltic and North seas to the north, and the Alps to the south; it covers an area of 357,022 square kilometres (137,847 sq mi), with a population of over 84 million within its 16 constituent states. Germany borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, and France, Luxembourg, Belgium, and the Netherlands to the west. The nation's capital and most populous city is Berlin and its main financial centre is Frankfurt; the largest urban area is the Ruhr.

Overview

The characteristics of a diesel engine are^[141]

• Use of compression ignition, instead of an ignition apparatus such as a spark plug.
• Internal mixture formation. In diesel engines, the mixture of air and fuel is only formed inside the combustion chamber.
• Quality torque control. The amount of torque a diesel engine produces is not controlled by throttling the intake air (unlike a traditional spark-ignition petrol engine, where the airflow is reduced in order to regulate the torque output), instead, the volume of air entering the engine is maximised at all times, and the torque output is regulated solely by controlling the amount of injected fuel.
• High air-fuel ratio. Diesel engines run at global air-fuel ratios significantly leaner than the stoichiometric ratio.
• Diffusion flame: At combustion, oxygen first has to diffuse into the flame, rather than having oxygen and fuel already mixed before combustion, which would result in a premixed flame.
• Heterogeneous air-fuel mixture: In diesel engines, there is no even dispersion of fuel and air inside the cylinder. That is because the combustion process begins at the end of the injection phase, before a homogeneous mixture of air and fuel can be formed.
• Preference for the fuel to have a high ignition performance (Cetane number), rather than a high knocking resistance (octane rating) that is preferred for petrol engines.

Thermodynamic cycle

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Diesel engine model, left side

Diesel engine model, right side

The diesel internal combustion engine differs from the gasoline powered Otto cycle by using highly compressed hot air to ignite the fuel rather than using a spark plug (compression ignition rather than spark ignition).

In the diesel engine, only air is initially introduced into the combustion chamber. The air is then compressed with a compression ratio typically between 15:1 and 23:1. This high compression causes the temperature of the air to rise. At about the top of the compression stroke, fuel is injected directly into the compressed air in the combustion chamber. This may be into a (typically toroidal) void in the top of the piston or a pre-chamber depending upon the design of the engine. The fuel injector ensures that the fuel is broken down into small droplets, and that the fuel is distributed evenly. The heat of the compressed air vaporises fuel from the surface of the droplets. The vapour is then ignited by the heat from the compressed air in the combustion chamber, the droplets continue to vaporise from their surfaces and burn, getting smaller, until all the fuel in the droplets has been burnt. Combustion occurs at a substantially constant pressure during the initial part of the power stroke. The start of vaporisation causes a delay before ignition and the characteristic diesel knocking sound as the vapour reaches ignition temperature and causes an abrupt increase in pressure above the piston (not shown on the P-V indicator diagram). When combustion is complete the combustion gases expand as the piston descends further; the high pressure in the cylinder drives the piston downward, supplying power to the crankshaft.

As well as the high level of compression allowing combustion to take place without a separate ignition system, a high compression ratio greatly increases the engine's efficiency. Increasing the compression ratio in a spark-ignition engine where fuel and air are mixed before entry to the cylinder is limited by the need to prevent pre-ignition, which would cause engine damage. Since only air is compressed in a diesel engine, and fuel is not introduced into the cylinder until shortly before top dead centre (TDC), premature detonation is not a problem and compression ratios are much higher.

pV diagram for the ideal diesel cycle (which follows the numbers 1–4 in clockwise direction). The horizontal axis is the cylinder volume. In the diesel cycle the combustion occurs at almost constant pressure. On this diagram the work that is generated for each cycle corresponds to the area within the loop.

The pressure–volume diagram (pV) diagram is a simplified and idealised representation of the events involved in a diesel engine cycle, arranged to illustrate the similarity with a Carnot cycle. Starting at 1, the piston is at bottom dead centre and both valves are closed at the start of the compression stroke; the cylinder contains air at atmospheric pressure. Between 1 and 2 the air is compressed adiabatically – that is without heat transfer to or from the environment – by the rising piston. (This is only approximately true since there will be some heat exchange with the cylinder walls.) During this compression, the volume is reduced, the pressure and temperature both rise. At or slightly before 2 (TDC) fuel is injected and burns in the compressed hot air. Chemical energy is released and this constitutes an injection of thermal energy (heat) into the compressed gas. Combustion and heating occur between 2 and 3. In this interval the pressure remains constant since the piston descends, and the volume increases; the temperature rises as a consequence of the energy of combustion. At 3 fuel injection and combustion are complete, and the cylinder contains gas at a higher temperature than at 2. Between 3 and 4 this hot gas expands, again approximately adiabatically. Work is done on the system to which the engine is connected. During this expansion phase the volume of the gas rises, and its temperature and pressure both fall. At 4 the exhaust valve opens, and the pressure falls abruptly to atmospheric (approximately). This is unresisted expansion and no useful work is done by it. Ideally the adiabatic expansion should continue, extending the line 3–4 to the right until the pressure falls to that of the surrounding air, but the loss of efficiency caused by this unresisted expansion is justified by the practical difficulties involved in recovering it (the engine would have to be much larger). After the opening of the exhaust valve, the exhaust stroke follows, but this (and the following induction stroke) are not shown on the diagram. If shown, they would be represented by a low-pressure loop at the bottom of the diagram. At 1 it is assumed that the exhaust and induction strokes have been completed, and the cylinder is again filled with air. The piston-cylinder system absorbs energy between 1 and 2 – this is the work needed to compress the air in the cylinder, and is provided by mechanical kinetic energy stored in the flywheel of the engine. Work output is done by the piston-cylinder combination between 2 and 4. The difference between these two increments of work is the indicated work output per cycle, and is represented by the area enclosed by the pV loop. The adiabatic expansion is in a higher pressure range than that of the compression because the gas in the cylinder is hotter during expansion than during compression. It is for this reason that the loop has a finite area, and the net output of work during a cycle is positive.^[142]

Efficiency

The fuel efficiency of diesel engines is better than most other types of combustion engines,^[143][144] due to their high compression ratio, high air–fuel equivalence ratio (λ),^[145] and the lack of intake air restrictions (i.e. throttle valves). Theoretically, the highest possible efficiency for a diesel engine is 75%.^[146] However, in practice the efficiency is much lower, with efficiencies of up to 43% for passenger car engines,^[147] up to 45% for large truck and bus engines, and up to 55% for large two-stroke marine engines.^[1][148] The average efficiency over a motor vehicle driving cycle is lower than the diesel engine's peak efficiency (for example, a 37% average efficiency for an engine with a peak efficiency of 44%).^[149] That is because the fuel efficiency of a diesel engine drops at lower loads, however, it does not drop quite as fast as the Otto (spark ignition) engine's.^[150]

Emissions

Diesel engines are combustion engines and, therefore, emit combustion products in their exhaust gas. Due to incomplete combustion,^[151] diesel engine exhaust gases include carbon monoxide, hydrocarbons, particulate matter, and nitrogen oxides pollutants. About 90 per cent of the pollutants can be removed from the exhaust gas using exhaust gas treatment technology.^[152][153] Road vehicle diesel engines have no sulfur dioxide emissions, because motor vehicle diesel fuel has been sulfur-free since 2003.^[154] Helmut Tschöke argues that particulate matter emitted from motor vehicles has negative impacts on human health.^[155]

The particulate matter in diesel exhaust emissions is sometimes classified as a carcinogen or "probable carcinogen" and is known to increase the risk of heart and respiratory diseases.^[156]

Electrical system

In principle, a diesel engine does not require any sort of electrical system. However, most modern diesel engines are equipped with an electrical fuel pump, and an electronic engine control unit.

However, there is no high-voltage electrical ignition system present in a diesel engine. This eliminates a source of radio frequency emissions (which can interfere with navigation and communication equipment), which is why only diesel-powered vehicles are allowed in some parts of the American National Radio Quiet Zone.^[157]

Torque control

To control the torque output at any given time (i.e. when the driver of a car adjusts the accelerator pedal), a governor adjusts the amount of fuel injected into the engine. Mechanical governors have been used in the past, however electronic governors are more common on modern engines. Mechanical governors are usually driven by the engine's accessory belt or a gear-drive system^[158][159] and use a combination of springs and weights to control fuel delivery relative to both load and speed.^[158] Electronically-governed engines use an electronic control unit (ECU) or electronic control module (ECM) to control the fuel delivery. The ECM/ECU uses various sensors (such as engine speed signal, intake manifold pressure and fuel temperature) to determine the amount of fuel injected into the engine.

Due to the amount of air being constant (for a given RPM) while the amount of fuel varies, very high ("lean") air-fuel ratios are used in situations where minimal torque output is required. This differs from a petrol engine, where a throttle is used to also reduce the amount of intake air as part of regulating the engine's torque output. Controlling the timing of the start of injection of fuel into the cylinder is similar to controlling the ignition timing in a petrol engine. It is therefore a key factor in controlling the power output, fuel consumption and exhaust emissions.

Discover more about Operating principle related topics

Spark-ignition engine

Spark-ignition engine

A spark-ignition engine is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug. This is in contrast to compression-ignition engines, typically diesel engines, where the heat generated from compression together with the injection of fuel is enough to initiate the combustion process, without needing any external spark.

Diffusion flame

Diffusion flame

In combustion, a diffusion flame is a flame in which the oxidizer and fuel are separated before burning. Contrary to its name, a diffusion flame involves both diffusion and convection processes. The name diffusion flame was first suggested by S.P. Burke and T.E.W. Schumann in 1928, to differentiate from premixed flame where fuel and oxidizer are premixed prior to burning. The diffusion flame is also referred to as nonpremixed flame. The burning rate is however still limited by the rate of diffusion. Diffusion flames tend to burn slower and to produce more soot than premixed flames because there may not be sufficient oxidizer for the reaction to go to completion, although there are some exceptions to the rule. The soot typically produced in a diffusion flame becomes incandescent from the heat of the flame and lends the flame its readily identifiable orange-yellow color. Diffusion flames tend to have a less-localized flame front than premixed flames.

Premixed flame

Premixed flame

A premixed flame is a flame formed under certain conditions during the combustion of a premixed charge of fuel and oxidiser. Since the fuel and oxidiser—the key chemical reactants of combustion—are available throughout a homogeneous stoichiometric premixed charge, the combustion process once initiated sustains itself by way of its own heat release. The majority of the chemical transformation in such a combustion process occurs primarily in a thin interfacial region which separates the unburned and the burned gases. The premixed flame interface propagates through the mixture until the entire charge is depleted. The propagation speed of a premixed flame is known as the flame speed which depends on the convection-diffusion-reaction balance within the flame, i.e. on its inner chemical structure. The premixed flame is characterised as laminar or turbulent depending on the velocity distribution in the unburned pre-mixture.

Cetane number

Cetane number

Cetane number is an indicator of the combustion speed of diesel fuel and compression needed for ignition. It plays a similar role for diesel as octane rating does for gasoline. The CN is an important factor in determining the quality of diesel fuel, but not the only one; other measurements of diesel fuel's quality include energy content, density, lubricity, cold-flow properties and sulphur content.

Octane rating

Octane rating

An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates gasoline's capability against compression.

Diesel cycle

Diesel cycle

The Diesel cycle is a combustion process of a reciprocating internal combustion engine. In it, fuel is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is then injected. This is in contrast to igniting the fuel-air mixture with a spark plug as in the Otto cycle (four-stroke/petrol) engine. Diesel engines are used in aircraft, automobiles, power generation, diesel–electric locomotives, and both surface ships and submarines.

Otto cycle

Otto cycle

An Otto cycle is an idealized thermodynamic cycle that describes the functioning of a typical spark ignition piston engine. It is the thermodynamic cycle most commonly found in automobile engines.

Compression ratio

Compression ratio

The compression ratio is the ratio between the volume of the cylinder and combustion chamber in an internal combustion engine at their maximum and minimum values.

Pressure–volume diagram

Pressure–volume diagram

A pressure–volume diagram is used to describe corresponding changes in volume and pressure in a system. They are commonly used in thermodynamics, cardiovascular physiology, and respiratory physiology.

Carnot cycle

Carnot cycle

A Carnot cycle is an ideal thermodynamic cycle proposed by French physicist Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. By Carnot's theorem, it provides an upper limit on the efficiency of any classical thermodynamic engine during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference through the application of work to the system.

Cylinder (engine)

Cylinder (engine)

In a reciprocating engine, the cylinder is the space in which a piston travels.

Fuel efficiency

Fuel efficiency

Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is often illustrated as a continuous energy profile. Non-transportation applications, such as industry, benefit from increased fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process.

There are several different ways of categorising diesel engines, as outlined in the following sections.

RPM operating range

Günter Mau categorises diesel engines by their rotational speeds into three groups:^[160]

• High-speed engines (> 1,000 rpm),
• Medium-speed engines (300–1,000 rpm), and
• Slow-speed engines (

High-speed diesel engines

High-speed engines are used to power trucks (lorries), buses, tractors, cars, yachts, compressors, pumps and small electrical generators.^[161] As of 2018, most high-speed engines have direct injection. Many modern engines, particularly in on-highway applications, have common rail direct injection.^[162] On bigger ships, high-speed diesel engines are often used for powering electric generators.^[163] The highest power output of high-speed diesel engines is approximately 5 MW.^[164]

Medium-speed diesel engines

Stationary 12 cylinder turbo-diesel engine coupled to a generator set for auxiliary power

Medium-speed engines are used in large electrical generators, railway diesel locomotives, ship propulsion and mechanical drive applications such as large compressors or pumps. Medium speed diesel engines operate on either diesel fuel or heavy fuel oil by direct injection in the same manner as low-speed engines. Usually, they are four-stroke engines with trunk pistons;^[165] a notable exception being the EMD 567, 645, and 710 engines, which are all two-stroke.^[166]

The power output of medium-speed diesel engines can be as high as 21,870 kW,^[167] with the effective efficiency being around 47-48% (1982).^[168] Most larger medium-speed engines are started with compressed air direct on pistons, using an air distributor, as opposed to a pneumatic starting motor acting on the flywheel, which tends to be used for smaller engines.^[169]

Medium-speed engines intended for marine applications are usually used to power (ro-ro) ferries, passenger ships or small freight ships. Using medium-speed engines reduces the cost of smaller ships and increases their transport capacity. In addition to that, a single ship can use two smaller engines instead of one big engine, which increases the ship's safety.^[165]

Low-speed diesel engines

The MAN B&W 5S50MC, a two-stroke, low-speed, inline five-cylinder marine diesel engine onboard a 29,000 tonne chemical carrier

Low-speed diesel engines are usually very large in size and mostly used to power ships. There are two different types of low-speed engines that are commonly used: Two-stroke engines with a crosshead, and four-stroke engines with a regular trunk-piston. Two-stroke engines have a limited rotational frequency and their charge exchange is more difficult, which means that they are usually bigger than four-stroke engines and used to directly power a ship's propeller.

Four-stroke engines on ships are usually used to power an electric generator. An electric motor powers the propeller.^[160] Both types are usually very undersquare, meaning the bore is smaller than the stroke.^[170] Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) often have an effective efficiency of up to 55%.^[1] Like medium-speed engines, low-speed engines are started with compressed air, and they use heavy oil as their primary fuel.^[169]

Combustion cycle

Schematic of a two-stroke diesel engine with a roots blower

Detroit Diesel timing

Four-stroke engines use the combustion cycle described earlier. Most smaller diesels, for vehicular use, for instance, typically use the four-stroke cycle. This is due to several factors, such as the two-stroke design's narrow powerband which is not particularly suitable for automotive use and the necessity for complicated and expensive built-in lubrication systems and scavenging measures.^[171] The cost effectiveness (and proportion of added weight) of these technologies has less of an impact on larger, more expensive engines, while engines intended for shipping or stationary use can be run at a single speed for long periods.^[171]

Two-stroke engines use a combustion cycle which is completed in two strokes instead of four strokes. Filling the cylinder with air and compressing it takes place in one stroke, and the power and exhaust strokes are combined. The compression in a two-stroke diesel engine is similar to the compression that takes place in a four-stroke diesel engine: As the piston passes through bottom centre and starts upward, compression commences, culminating in fuel injection and ignition. Instead of a full set of valves, two-stroke diesel engines have simple intake ports, and exhaust ports (or exhaust valves). When the piston approaches bottom dead centre, both the intake and the exhaust ports are "open", which means that there is atmospheric pressure inside the cylinder. Therefore, some sort of pump is required to blow the air into the cylinder and the combustion gasses into the exhaust. This process is called scavenging. The pressure required is approximately 10-30 kPa.^[172]

Due to the lack of discrete exhaust and intake strokes, all two-stroke diesel engines use a scavenge blower or some form of compressor to charge the cylinders with air and assist in scavenging.^[172] Roots-type superchargers were used for ship engines until the mid-1950s, however since 1955 they have been widely replaced by turbochargers.^[173] Usually, a two-stroke ship diesel engine has a single-stage turbocharger with a turbine that has an axial inflow and a radial outflow.^[174]

Scavenging in two-stroke engines

In general, there are three types of scavenging possible:

• Uniflow scavenging
• Crossflow scavenging
• Reverse flow scavenging

Crossflow scavenging is incomplete and limits the stroke, yet some manufacturers used it.^[175] Reverse flow scavenging is a very simple way of scavenging, and it was popular amongst manufacturers until the early 1980s. Uniflow scavenging is more complicated to make but allows the highest fuel efficiency; since the early 1980s, manufacturers such as MAN and Sulzer have switched to this system.^[125] It is standard for modern marine two-stroke diesel engines.^[2]

Fuel used

So-called dual-fuel diesel engines or gas diesel engines burn two different types of fuel simultaneously, for instance, a gaseous fuel and diesel engine fuel. The diesel engine fuel auto-ignites due to compression ignition, and then ignites the gaseous fuel. Such engines do not require any type of spark ignition and operate similar to regular diesel engines.^[176][177]

Discover more about Classification related topics

Bus

Bus

A bus is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for charter purposes, or through private ownership. Although the average bus carries between 30 and 100 passengers, some buses have a capacity of up to 300 passengers. The most common type is the single-deck rigid bus, with double-decker and articulated buses carrying larger loads, and midibuses and minibuses carrying smaller loads. Coaches are used for longer-distance services. Many types of buses, such as city transit buses and inter-city coaches, charge a fare. Other types, such as elementary or secondary school buses or shuttle buses within a post-secondary education campus, are free. In many jurisdictions, bus drivers require a special large vehicle licence above and beyond a regular driving licence.

Tractor

Tractor

A tractor is an engineering vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery such as that used in agriculture, mining or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially tillage, and now many more. Agricultural implements may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.

Pump

Pump

A pump is a device that moves fluids, or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy.

Common rail

Common rail

Common rail direct fuel injection is a direct fuel injection system built around a high-pressure fuel rail feeding solenoid valves, as opposed to a low-pressure fuel pump feeding unit injectors. High-pressure injection delivers power and fuel consumption benefits over earlier lower pressure fuel injection, by injecting fuel as a larger number of smaller droplets, giving a much higher ratio of surface area to volume. This provides improved vaporization from the surface of the fuel droplets, and so more efficient combining of atmospheric oxygen with vaporized fuel delivering more complete combustion.

Diesel locomotive

Diesel locomotive

A diesel locomotive is a type of railway locomotive in which the prime mover is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving wheels.

EMD 567

EMD 567

The EMD 567 is a line of large medium-speed diesel engines built by General Motors' Electro-Motive Division. This engine, which succeeded Winton's 201A, was used in EMD's locomotives from 1938 until its replacement in 1966 by the EMD 645. It has a bore of 8+1⁄2 in (216 mm), a stroke of 10 in (254 mm) and a displacement of 567 cu in (9.29 L) per cylinder. Like the Winton 201A, the EMD 645 and the EMD 710, the EMD 567 is a two-stroke engine.

EMD 645

EMD 645

The EMD 645 is a family of diesel engines that was designed and manufactured by the Electro-Motive Division of General Motors. While the 645 series was intended primarily for locomotive, marine and stationary engine use, one 16-cylinder version powered the 33-19 "Titan" prototype haul truck designed by GM's Terex division.

EMD 710

EMD 710

The EMD 710 is a line of diesel engines built by Electro-Motive Diesel. The 710 series replaced the earlier EMD 645 series when the 645F series proved to be unreliable in the early 1980s 50-series locomotives which featured a maximum engine speed of 950 rpm. The EMD 710 is a relatively large medium-speed two-stroke diesel engine that has 710 cubic inches displacement per cylinder, and a maximum engine speed of 900 rpm.

Roll-on/roll-off

Roll-on/roll-off

Roll-on/roll-off ships are cargo ships designed to carry wheeled cargo, such as cars, motorcycles, trucks, semi-trailer trucks, buses, trailers, and railroad cars, that are driven on and off the ship on their own wheels or using a platform vehicle, such as a self-propelled modular transporter. This is in contrast to lift-on/lift-off (LoLo) vessels, which use a crane to load and unload cargo.

Straight-five engine

Straight-five engine

The straight-five engine is a piston engine with five cylinders mounted in a straight line along the crankshaft.

Ship

Ship

A ship is a large watercraft that travels the world's oceans and other sufficiently deep waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally distinguished from boats, based on size, shape, load capacity and purpose. Ships have supported exploration, trade, warfare, migration, colonization, and science. After the 15th century, new crops that had come from and to the Americas via the European seafarers significantly contributed to world population growth. Ship transport is responsible for the largest portion of world commerce.

Four-stroke engine

Four-stroke engine

A four-stroke engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft. A stroke refers to the full travel of the piston along the cylinder, in either direction. The four separate strokes are termed:Intake: Also known as induction or suction. This stroke of the piston begins at top dead center (T.D.C.) and ends at bottom dead center (B.D.C.). In this stroke the intake valve must be in the open position while the piston pulls an air-fuel mixture into the cylinder by producing a partial vacuum in the cylinder through its downward motion. Compression: This stroke begins at B.D.C, or just at the end of the suction stroke, and ends at T.D.C. In this stroke the piston compresses the air-fuel mixture in preparation for ignition during the power stroke (below). Both the intake and exhaust valves are closed during this stage. Combustion: Also known as power or ignition. This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. the compressed air-fuel mixture is ignited by a spark plug or by heat generated by high compression, forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft. Exhaust: Also known as outlet. During the exhaust stroke, the piston, once again, returns from B.D.C. to T.D.C. while the exhaust valve is open. This action expels the spent air-fuel mixture through the exhaust port.

The fuel is injected at high pressure into either the combustion chamber, the "swirl chamber" or the "pre-chamber"^[141] (unlike older petrol engines where the fuel is added in the inlet manifold or carburetor). Engines where the fuel is injected into the main combustion chamber are called "direct injection" (DI) engines, while those which use a swirl chamber or pre-chamber are called "indirect injection" (IDI) engines.^[178]

Direct injection

Different types of piston bowls

Most direct injection diesel engines have a combustion cup in the top of the piston where the fuel is sprayed. Many different methods of injection can be used. Usually, an engine with helix-controlled mechanic direct injection has either an inline or a distributor injection pump.^[158] For each engine cylinder, the corresponding plunger in the fuel pump measures out the correct amount of fuel and determines the timing of each injection. These engines use injectors that are very precise spring-loaded valves that open and close at a specific fuel pressure. Separate high-pressure fuel lines connect the fuel pump with each cylinder. Fuel volume for each single combustion is controlled by a slanted groove in the plunger which rotates only a few degrees releasing the pressure and is controlled by a mechanical governor, consisting of weights rotating at engine speed constrained by springs and a lever. The injectors are held open by the fuel pressure. On high-speed engines the plunger pumps are together in one unit.^[179] The length of fuel lines from the pump to each injector is normally the same for each cylinder in order to obtain the same pressure delay. Direct injected diesel engines usually use orifice-type fuel injectors.^[180]

Electronic control of the fuel injection transformed the direct injection engine by allowing much greater control over the combustion.^[181]

Common rail

Common rail (CR) direct injection systems do not have the fuel metering, pressure-raising and delivery functions in a single unit, as in the case of a Bosch distributor-type pump, for example. A high-pressure pump supplies the CR. The requirements of each cylinder injector are supplied from this common high pressure reservoir of fuel. An Electronic Diesel Control (EDC) controls both rail pressure and injections depending on engine operating conditions. The injectors of older CR systems have solenoid-driven plungers for lifting the injection needle, whilst newer CR injectors use plungers driven by piezoelectric actuators that have fewer moving mass and therefore allow even more injections in a very short period of time.^[182] Early common rail system were controlled by mechanical means.

The injection pressure of modern CR systems ranges from 140 MPa to 270 MPa.^[183]

Indirect injection

Ricardo Comet indirect injection chamber

An indirect diesel injection system (IDI) engine delivers fuel into a small chamber called a swirl chamber, precombustion chamber, pre chamber or ante-chamber, which is connected to the cylinder by a narrow air passage. Generally the goal of the pre chamber is to create increased turbulence for better air / fuel mixing. This system also allows for a smoother, quieter running engine, and because fuel mixing is assisted by turbulence, injector pressures can be lower. Most IDI systems use a single orifice injector. The pre-chamber has the disadvantage of lowering efficiency due to increased heat loss to the engine's cooling system, restricting the combustion burn, thus reducing the efficiency by 5–10%. IDI engines are also more difficult to start and usually require the use of glow plugs. IDI engines may be cheaper to build but generally require a higher compression ratio than the DI counterpart. IDI also makes it easier to produce smooth, quieter running engines with a simple mechanical injection system since exact injection timing is not as critical. Most modern automotive engines are DI which have the benefits of greater efficiency and easier starting; however, IDI engines can still be found in the many ATV and small diesel applications.^[184] Indirect injected diesel engines use pintle-type fuel injectors.^[180]

Air-blast injection

Typical early 20th century air-blast injected diesel engine, rated at 59 kW.

Early diesel engines injected fuel with the assistance of compressed air, which atomised the fuel and forced it into the engine through a nozzle (a similar principle to an aerosol spray). The nozzle opening was closed by a pin valve actuated by the camshaft. Although the engine was also required to drive an air compressor used for air-blast injection, the efficiency was nonetheless better than other combustion engines of the time.^[52] However the system was heavy and it was slow to react to changing torque demands, making it unsuitable for road vehicles.^[185]

Unit injectors

A unit injector system, also known as "Pumpe-Düse" (pump-nozzle in German) combines the injector and fuel pump into a single component, which is positioned above each cylinder. This eliminates the high-pressure fuel lines and achieves a more consistent injection. Under full load, the injection pressure can reach up to 220 MPa.^[186] Unit injectors are operated by a cam and the quantity of fuel injected is controlled either mechanically (by a rack or lever) or electronically.

Due to increased performance requirementss, unit injectors have been largely replaced by common-rail injection systems.^[162]

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Combustion chamber

Combustion chamber

A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.

Inlet manifold

Inlet manifold

In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders. The word manifold comes from the Old English word manigfeald and refers to the multiplying of one (pipe) into many.

Carburetor

Carburetor

A carburetor is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Venturi tube in the main metering circuit, though various other components are also used to provide extra fuel or air in specific circumstances.

Fuel injection

Fuel injection

Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines.

Groove (engineering)

Groove (engineering)

In manufacturing or mechanical engineering a groove is a long and narrow indentation built into a material, generally for the purpose of allowing another material or part to move within the groove and be guided by it. Examples include:A canal cut in a hard material, usually metal. This canal can be round, oval or an arc in order to receive another component such as a boss, a tongue or a gasket. It can also be on the circumference of a dowel, a bolt, an axle or on the outside or inside of a tube or pipe etc. This canal may receive a circlip, an o-ring, or a gasket. A depression on the entire circumference of a cast or machined wheel, a pulley or sheave. This depression may receive a cable, a rope or a belt. A longitudinal channel formed in a hot rolled rail profile such as a grooved rail. This groove is for the flange on a train wheel.

Common rail

Common rail

Common rail direct fuel injection is a direct fuel injection system built around a high-pressure fuel rail feeding solenoid valves, as opposed to a low-pressure fuel pump feeding unit injectors. High-pressure injection delivers power and fuel consumption benefits over earlier lower pressure fuel injection, by injecting fuel as a larger number of smaller droplets, giving a much higher ratio of surface area to volume. This provides improved vaporization from the surface of the fuel droplets, and so more efficient combining of atmospheric oxygen with vaporized fuel delivering more complete combustion.

Indirect injection

Indirect injection

Indirect injection in an internal combustion engine is fuel injection where fuel is not directly injected into the combustion chamber.

Injector

Injector

An injector is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is entrained in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic pump with no moving parts except a valve to control inlet flow. A steam injector is a typical application of the principle used to deliver cold water to a boiler against its own pressure, using its own live or exhaust steam, replacing any mechanical pump. When first developed, its operation was intriguing because it seemed paradoxical, almost like perpetual motion, but it was later explained using thermodynamics. Other types of injector may use other pressurised motive fluids such as air.

Air-blast injection

Air-blast injection

Air-blast injection is a historical direct injection system for Diesel engines. Unlike modern designs, air-blast injected Diesel engines do not have an injection pump. A simple low-pressure fuel-feed-pump is used instead to supply the injection nozzle with fuel. At injection, a blast of compressed air presses the fuel into the combustion chamber, hence the name air-blast injection. The compressed air comes from compressed-air tanks which feed the injection nozzle. A large crankshaft-driven compressor is used to re-fill these tanks; the size of the compressor and the low rotational frequency of the engine's crankshaft means that air-blast injected Diesel engines are huge in size and mass, this, combined with the problem that air-blast injection does not allow for quick load alteration makes it only suitable for stationary applications and watercraft. Before the invention of precombustion chamber injection, air-blast injection was the only way a properly working internal air fuel mixture system could be built, required for a Diesel engine. During the 1920s, air-blast injection was rendered obsolete by superior injection system designs that allowed much smaller but more powerful engines. Rudolf Diesel was granted a patent on air-blast injection in November 1893.

Needle valve

Needle valve

A needle valve is a type of valve with a small port and a threaded, needle-shaped plunger. It allows precise regulation of flow, although it is generally only capable of relatively low flow rates.

Camshaft

Camshaft

A camshaft is a shaft that contains a row of pointed cams, in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines, mechanically controlled ignition systems and early electric motor speed controllers.

Cam

Cam

A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an eccentric disc or other shape that produces a smooth reciprocating motion in the follower, which is a lever making contact with the cam. A cam timer is similar, and were widely used for electric machine control before the advent of inexpensive electronics, microcontrollers, integrated circuits, programmable logic controllers and digital control.

Mass

The average diesel engine has a poorer power-to-mass ratio than an equivalent petrol engine. The lower engine speeds (RPM) of typical diesel engines results in a lower power output.^[187] Also, the mass of a diesel engine is typically higher, since the higher operating pressure inside the combustion chamber increases the internal forces, which requires stronger (and therefore heavier) parts to withstand these forces.^[188]

Noise ("diesel clatter")

The distinctive noise of a diesel engine, particularly at idling speeds, is sometimes called "diesel clatter". This noise is largely caused by the sudden ignition of the diesel fuel when injected into the combustion chamber, which causes a pressure wave that sounds like knocking.

Engine designers can reduce diesel clatter through: indirect injection; pilot or pre-injection;^[189] injection timing; injection rate; compression ratio; turbo boost; and exhaust gas recirculation (EGR).^[190] Common rail diesel injection systems permit multiple injection events as an aid to noise reduction. Through measures such as these, diesel clatter noise is greatly reduced in modern engines. Diesel fuels with a higher cetane rating are more likely to ignite and hence reduce diesel clatter.^[191]

Cold weather starting

In warmer climates, diesel engines do not require any starting aid (aside from the starter motor). However, many diesel engines include some form of preheating for the combustion chamber, to assist starting in cold conditions. Engines with a displacement of less than 1 litre per cylinder usually have glowplugs, whilst larger heavy-duty engines have flame-start systems.^[192] The minimum starting temperature that allows starting without pre-heating is 40 °C for precombustion chamber engines, 20 °C for swirl chamber engines, and 0 °C for direct injected engines.

In the past, a wider variety of cold-start methods were used. Some engines, such as Detroit Diesel engines used a system to introduce small amounts of ether into the inlet manifold to start combustion.^[193] Instead of glowplugs, some diesel engines are equipped with starting aid systems that change valve timing. The simplest way this can be done is with a decompression lever. Activating the decompression lever locks the outlet valves in a slight down position, resulting in the engine not having any compression and thus allowing for turning the crankshaft over with significantly less resistance. When the crankshaft reaches a higher speed, flipping the decompression lever back into its normal position will abruptly re-activate the outlet valves, resulting in compression − the flywheel's mass moment of inertia then starts the engine.^[194] Other diesel engines, such as the precombustion chamber engine XII Jv 170/240 made by Ganz & Co., have a valve timing changing system that is operated by adjusting the inlet valve camshaft, moving it into a slight "late" position. This will make the inlet valves open with a delay, forcing the inlet air to heat up when entering the combustion chamber.^[195]

Supercharging & turbocharging

1980s BMW M21 passenger car turbo-diesel engine

Forced induction, especially turbocharging is commonly used on diesel engines because it greatly increases efficiency, and torque output.^[196] Diesel engines are well suited for forced induction setups due to their operating principle which is characterised by wide ignition limits^[141] and the absence of fuel during the compression stroke. Therefore, knocking, pre-ignition or detonation cannot occur, and a lean mixture caused by excess supercharging air inside the combustion chamber does not negatively affect combustion.^[197]

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Power (physics)

Power (physics)

In physics, power is the amount of energy transferred or converted per unit time. In the International System of Units, the unit of power is the watt, equal to one joule per second. In older works, power is sometimes called activity. Power is a scalar quantity.

MWM AKD 112 Z

MWM AKD 112 Z

The MWM AKD 112 Z is an air-cooled two-cylinder inline diesel engine produced by MWM from 1955 – 1960. One, three and four cylinder variants of the same engine family were also produced by MWM.

Exhaust gas recirculation

Exhaust gas recirculation

In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. The exhaust gas displaces atmospheric air and reduces O2 in the combustion chamber. Reducing the amount of oxygen reduces the amount of fuel that can burn in the cylinder thereby reducing peak in-cylinder temperatures. The actual amount of recirculated exhaust gas varies with the engine operating parameters.

Starter (engine)

Starter (engine)

A starter is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. The starter can also be another internal-combustion engine in the case, for instance, of very large engines, or diesel engines in agricultural or excavation applications.

Flame-start system

Flame-start system

The flame-start system is a cold start aid for starting diesel engines at low ambient temperatures. It reduces the white smoke emission after the engine is started. In addition, it reduces the strain on the starter motor and batteries by shortening the start-up time.

Detroit Diesel

Detroit Diesel

Detroit Diesel Corporation (DDC) is an American diesel engine manufacturer headquartered in Detroit, Michigan. It is a subsidiary of Daimler Truck North America, which is itself a wholly owned subsidiary of the multinational Daimler Truck AG. The company manufactures heavy-duty engines and chassis components for the on-highway and vocational commercial truck markets. Detroit Diesel has built more than 5 million engines since 1938, more than 1 million of which are still in operation worldwide. Detroit Diesel's product line includes engines, axles, transmissions, and a Virtual Technician service.

Diethyl ether

Diethyl ether

Diethyl ether, or simply ether, is an organic compound in the ether class with the formula (CH3CH2)2O or (C2H5)2O, sometimes abbreviated as Et2O, where Et stands for monovalent ethyl group CH3CH2 which is often written as C2H5. It is a colourless, highly volatile, sweet-smelling, extremely flammable liquid. It is commonly used as a solvent in laboratories and as a starting fluid for some engines. It was formerly used as a general anesthetic, until non-flammable drugs were developed, such as halothane. It has been used as a recreational drug to cause intoxication.

BMW M21

BMW M21

The BMW M21 is a straight-six diesel engine developed by the Bavarian engine manufacturer BMW. It has swirl chamber injection and is based on the M20 petrol engine and was produced for BMW by the Upper Austrian Steyr engine plant from 1983 to 1991. It was succeeded by the M51.

Turbo-diesel

Turbo-diesel

The term turbo-diesel, also written as turbodiesel and turbo diesel, refers to any diesel engine equipped with a turbocharger. As with other engine types, turbocharging a diesel engine can significantly increase its efficiency and power output, especially when used in combination with an intercooler.

Forced induction

Forced induction

In an internal combustion engine, forced induction is where turbocharging or supercharging is used to increase the density of the intake air. Engines without forced induction are classified as naturally aspirated.

Diesel engines can combust a huge variety of fuels, including several fuel oils that have advantages over fuels such as petrol. These advantages include:

• • Low fuel costs, as fuel oils are relatively cheap
  • Good lubrication properties
  • High energy density
  • Low risk of catching fire, as they do not form a flammable vapour
  • Biodiesel is an easily synthesised, non-petroleum-based fuel (through transesterification) which can run directly in many diesel engines, while gasoline engines either need adaptation to run synthetic fuels or else use them as an additive to gasoline (e.g., ethanol added to gasohol).

In diesel engines, a mechanical injector system atomizes the fuel directly into the combustion chamber (as opposed to a Venturi jet in a carburetor, or a fuel injector in a manifold injection system atomizing fuel into the intake manifold or intake runners as in a petrol engine). Because only air is inducted into the cylinder in a diesel engine, the compression ratio can be much higher as there is no risk of pre-ignition provided the injection process is accurately timed.^[197] This means that cylinder temperatures are much higher in a diesel engine than a petrol engine, allowing less volatile fuels to be used.

The MAN 630's M-System diesel engine is a petrol engine (designed to run on NATO F 46/F 50 petrol), but it also runs on jet fuel, (NATO F 40/F 44), kerosene, (NATO F 58), and diesel engine fuel (NATO F 54/F 75)

Therefore, diesel engines can operate on a huge variety of different fuels. In general, fuel for diesel engines should have a proper viscosity, so that the injection pump can pump the fuel to the injection nozzles without causing damage to itself or corrosion of the fuel line. At injection, the fuel should form a good fuel spray, and it should not have a coking effect upon the injection nozzles. To ensure proper engine starting and smooth operation, the fuel should be willing to ignite and hence not cause a high ignition delay, (this means that the fuel should have a high cetane number). Diesel fuel should also have a high lower heating value.^[198]

Inline mechanical injector pumps generally tolerate poor-quality or bio-fuels better than distributor-type pumps. Also, indirect injection engines generally run more satisfactorily on fuels with a high ignition delay (for instance, petrol) than direct injection engines.^[199] This is partly because an indirect injection engine has a much greater 'swirl' effect, improving vaporisation and combustion of fuel, and because (in the case of vegetable oil-type fuels) lipid depositions can condense on the cylinder walls of a direct-injection engine if combustion temperatures are too low (such as starting the engine from cold). Direct-injected engines with an MAN centre sphere combustion chamber rely on fuel condensing on the combustion chamber walls. The fuel starts vaporising only after ignition sets in, and it burns relatively smoothly. Therefore, such engines also tolerate fuels with poor ignition delay characteristics, and, in general, they can operate on petrol rated 86 RON.^[200]

Fuel types

In his 1893 work Theory and Construction of a Rational Heat Motor, Rudolf Diesel considers using coal dust as fuel for the diesel engine. However, Diesel just considered using coal dust (as well as liquid fuels and gas); his actual engine was designed to operate on petroleum, which was soon replaced with regular petrol and kerosene for further testing purposes, as petroleum proved to be too viscous.^[201] In addition to kerosene and petrol, Diesel's engine could also operate on ligroin.^[202]

Before diesel engine fuel was standardised, fuels such as petrol, kerosene, gas oil, vegetable oil and mineral oil, as well as mixtures of these fuels, were used.^[203] Typical fuels specifically intended to be used for diesel engines were petroleum distillates and coal-tar distillates such as the following; these fuels have specific lower heating values of:

• Diesel oil: 10,200 kcal·kg⁻¹ (42.7 MJ·kg⁻¹) up to 10,250 kcal·kg⁻¹ (42.9 MJ·kg⁻¹)
• Heating oil: 10,000 kcal·kg⁻¹ (41.8 MJ·kg⁻¹) up to 10,200 kcal·kg⁻¹ (42.7 MJ·kg⁻¹)
• Coal-tar creosote: 9,150 kcal·kg⁻¹ (38.3 MJ·kg⁻¹) up to 9,250 kcal·kg⁻¹ (38.7 MJ·kg⁻¹)
• Kerosene: up to 10,400 kcal·kg⁻¹ (43.5 MJ·kg⁻¹)

Source:^[204]

The first diesel fuel standards were the DIN 51601, VTL 9140-001, and NATO F 54, which appeared after World War II.^[203] The modern European EN 590 diesel fuel standard was established in May 1993; the modern version of the NATO F 54 standard is mostly identical with it. The DIN 51628 biodiesel standard was rendered obsolete by the 2009 version of the EN 590; FAME biodiesel conforms to the EN 14214 standard. Watercraft diesel engines usually operate on diesel engine fuel that conforms to the ISO 8217 standard (Bunker C). Also, some diesel engines can operate on gasses (such as LNG).^[205]

Modern diesel fuel properties

Gelling

DIN 51601 diesel fuel was prone to waxing or gelling in cold weather; both are terms for the solidification of diesel oil into a partially crystalline state. The crystals build up in the fuel system (especially in fuel filters), eventually starving the engine of fuel and causing it to stop running.^[207] Low-output electric heaters in fuel tanks and around fuel lines were used to solve this problem. Also, most engines have a spill return system, by which any excess fuel from the injector pump and injectors is returned to the fuel tank. Once the engine has warmed, returning warm fuel prevents waxing in the tank. Before direct injection diesel engines, some manufacturers, such as BMW, recommended mixing up to 30% petrol in with the diesel by fuelling diesel cars with petrol to prevent the fuel from gelling when the temperatures dropped below −15 °C.^[208]

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Diesel fuel

Diesel fuel

Diesel fuel, also called diesel oil or historically heavy oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and then injection of fuel. Therefore, diesel fuel needs good compression ignition characteristics.

Biodiesel

Biodiesel

Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil with an alcohol, producing a methyl, ethyl or propyl ester by the process of transesterification.

Synthetic fuel

Synthetic fuel

Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.

Ethanol

Ethanol

Ethanol is an organic compound. It is an alcohol with the chemical formula C2H6O. Its formula can also be written as CH3−CH2−OH or C2H5OH. Ethanol is a volatile, flammable, colorless liquid with a characteristic wine-like odor and pungent taste. It is a psychoactive recreational drug, and the active ingredient in alcoholic drinks.

Fuel injection

Fuel injection

Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines.

M-System

M-System

The MAN M-System, also referred to as M-Process and M combustion process, is a direct injection system for Diesel engines. In M-System engines, the fuel is injected onto the walls of the combustion chamber that is solely located inside the piston, and shaped like a sphere. The M-System was rendered obsolete by modern fuel injection systems for Diesel engines. Due to its particularities, the M-System was only used for stationary applications and commercial vehicle engines, passenger car engines with this design have never been made. The letter M is an abbreviation for the German word Mittenkugelverfahren, meaning centre sphere combustion process.

Injection pump

Injection pump

An Injection Pump is the device that pumps fuel into the cylinders of a diesel engine. Traditionally, the injection pump was driven indirectly from the crankshaft by gears, chains or a toothed belt that also drives the camshaft. It rotates at half crankshaft speed in a conventional four-stroke diesel engine. Its timing is such that the fuel is injected only very slightly before top dead centre of that cylinder's compression stroke. It is also common for the pump belt on gasoline engines to be driven directly from the camshaft. In some systems injection pressures can be as high as 620 bar.

Cetane number

Cetane number

Cetane number is an indicator of the combustion speed of diesel fuel and compression needed for ignition. It plays a similar role for diesel as octane rating does for gasoline. The CN is an important factor in determining the quality of diesel fuel, but not the only one; other measurements of diesel fuel's quality include energy content, density, lubricity, cold-flow properties and sulphur content.

Lipid

Lipid

Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology.

Theory and Construction of a Rational Heat Motor

Theory and Construction of a Rational Heat Motor

Theory and Construction of a Rational Heat Motor is an essay written by German engineer Rudolf Diesel. It was composed in 1892, and first published by Springer in 1893. A translation into English followed in 1894. One thousand copies of the German first edition were printed. In this essay, Rudolf Diesel describes his idea of an internal combustion engine based on the Carnot cycle, transforming heat energy into kinetic energy using high pressure, with a thermal efficiency of up to 73%, outperforming any steam engine of the time.

Coal dust

Coal dust

Coal dust is a fine powdered form of which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal. It is a form of fugitive dust.

Petroleum

Petroleum

Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that consist of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, mostly zooplankton and algae, are buried underneath sedimentary rock and subjected to both prolonged heat and pressure.

Fuel flammability

Diesel fuel is less flammable than petrol, because its flash point is 55 °C,^[207][209] leading to a lower risk of fire caused by fuel in a vehicle equipped with a diesel engine.

Diesel fuel can create an explosive air/vapour mix under the right conditions. However, compared with petrol, it is less prone due to its lower vapour pressure, which is an indication of evaporation rate. The Material Safety Data Sheet^[210] for ultra-low sulfur diesel fuel indicates a vapour explosion hazard for diesel fuel indoors, outdoors, or in sewers.

Cancer

Diesel exhaust has been classified as an IARC Group 1 carcinogen. It causes lung cancer and is associated with an increased risk for bladder cancer.^[211]

Engine runaway (uncontrollable overspeeding)

See diesel engine runaway.

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Vapor pressure

Vapor pressure

Vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system. The equilibrium vapor pressure is an indication of a liquid's thermodynamic tendency to evaporate. It relates to the balance of particles escaping from the liquid in equilibrium with those in a coexisting vapor phase. A substance with a high vapor pressure at normal temperatures is often referred to as volatile. The pressure exhibited by vapor present above a liquid surface is known as vapor pressure. As the temperature of a liquid increases, the attractive interactions between liquid molecules become less significant in comparison to the entropy of those molecules in the gas phase, increasing the vapor pressure. Thus, liquids with strong intermolecular interactions are likely to have smaller vapor pressures, with the reverse true for weaker interactions.

Diesel exhaust

Diesel exhaust

Diesel exhaust is the gaseous exhaust produced by a diesel type of internal combustion engine, plus any contained particulates. Its composition may vary with the fuel type or rate of consumption, or speed of engine operation, and whether the engine is in an on-road vehicle, farm vehicle, locomotive, marine vessel, or stationary generator or other application.

Lung cancer

Lung cancer

Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. Lung cancers are caused by genetic damage to the DNA of cells in the airways, often exacerbated by cigarette smoking, or inhaling damaging chemicals. Damaged airway cells sometimes gain the ability to proliferate unchecked, causing the growth of a tumor. Without treatment, lung tumors can spread throughout the lung, damaging lung function. Eventually lung tumors metastasize, spreading to distant parts of the body, and causing varying disease. Lung cancers are classified based on the cells they originate from. Around 15% are small-cell lung cancers, while the remaining 85% are adenocarcinomas, squamous-cell carcinomas, and large-cell carcinomas.

Bladder cancer

Bladder cancer

Bladder cancer is any of several types of cancer arising from the tissues of the urinary bladder. Symptoms include blood in the urine, pain with urination, and low back pain. It is caused when epithelial cells that line the bladder become malignant.

Diesel engine runaway

Diesel engine runaway

Diesel engine runaway is a rare condition affecting diesel engines, in which the engine draws extra fuel from an unintended source and overspeeds at higher and higher RPM, producing up to ten times the engine's rated output until destroyed by mechanical failure or bearing seizure due to a lack of lubrication. Hot-bulb engines and jet engines can also run away via the same process.

The characteristics of diesel have different advantages for different applications.

Passenger cars

Diesel engines have long been popular in bigger cars and have been used in smaller cars such as superminis in Europe since the 1980s. They were popular in larger cars earlier, as the weight and cost penalties were less noticeable.^[212] Smooth operation as well as high low-end torque are deemed important for passenger cars and small commercial vehicles. The introduction of electronically controlled fuel injection significantly improved the smooth torque generation, and starting in the early 1990s, car manufacturers began offering their high-end luxury vehicles with diesel engines. Passenger car diesel engines usually have between three and twelve cylinders, and a displacement ranging from 0.8 to 6.0 litres. Modern powerplants are usually turbocharged and have direct injection.^[161]

Diesel engines do not suffer from intake-air throttling, resulting in very low fuel consumption especially at low partial load^[213] (for instance: driving at city speeds). One fifth of all passenger cars worldwide have diesel engines, with many of them being in Europe, where approximately 47% of all passenger cars are diesel-powered.^[214] Daimler-Benz in conjunction with Robert Bosch GmbH produced diesel-powered passenger cars starting in 1936.^[81] The popularity of diesel-powered passenger cars in markets such as India, South Korea and Japan is increasing (as of 2018).^[215]

Commercial vehicles and lorries

In 1893, Rudolf Diesel suggested that the diesel engine could possibly power "wagons" (lorries).^[217] The first lorries with diesel engines were brought to market in 1924.^[81]

Modern diesel engines for lorries have to be both extremely reliable and very fuel efficient. Common-rail direct injection, turbocharging and four valves per cylinder are standard. Displacements range from 4.5 to 15.5 litres, with power-to-mass ratios of 2.5–3.5 kg·kW⁻¹ for heavy duty and 2.0–3.0 kg·kW⁻¹ for medium duty engines. V6 and V8 engines used to be common, due to the relatively low engine mass the V configuration provides. Recently, the V configuration has been abandoned in favour of straight engines. These engines are usually straight-6 for heavy and medium duties and straight-4 for medium duty. Their undersquare design causes lower overall piston speeds which results in increased lifespan of up to 1,200,000 kilometres (750,000 mi).^[218] Compared with 1970s diesel engines, the expected lifespan of modern lorry diesel engines has more than doubled.^[216]

Railroad rolling stock

Diesel engines for locomotives are built for continuous operation between refuelings and may need to be designed to use poor quality fuel in some circumstances.^[219] Some locomotives use two-stroke diesel engines.^[220] Diesel engines have replaced steam engines on all non-electrified railroads in the world. The first diesel locomotives appeared in 1913,^[81] and diesel multiple units soon after. Nearly all modern diesel locomotives are more correctly known as diesel–electric locomotives because they use an electric transmission: the diesel engine drives an electric generator which powers electric traction motors.^[221] While electric locomotives have replaced the diesel locomotive for passenger services in many areas diesel traction is widely used for cargo-hauling freight trains and on tracks where electrification is not economically viable.

In the 1940s, road vehicle diesel engines with power outputs of 150–200 metric horsepower (110–150 kW; 150–200 hp) were considered reasonable for DMUs. Commonly, regular truck powerplants were used. The height of these engines had to be less than 1 metre (3 ft 3 in) to allow underfloor installation. Usually, the engine was mated with a pneumatically operated mechanical gearbox, due to the low size, mass, and production costs of this design. Some DMUs used hydraulic torque converters instead. Diesel–electric transmission was not suitable for such small engines.^[222] In the 1930s, the Deutsche Reichsbahn standardised its first DMU engine. It was a 30.3 litres (1,850 cu in), 12-cylinder boxer unit, producing 275 metric horsepower (202 kW; 271 hp). Several German manufacturers produced engines according to this standard.^[223]

Watercraft

One of the eight-cylinder 3200 I.H.P. Harland and Wolff – Burmeister & Wain diesel engines installed in the motorship Glenapp. This was the highest powered diesel engine yet (1920) installed in a ship. Note man standing lower right for size comparison.

The requirements for marine diesel engines vary, depending on the application. For military use and medium-size boats, medium-speed four-stroke diesel engines are most suitable. These engines usually have up to 24 cylinders and come with power outputs in the one-digit Megawatt region.^[219] Small boats may use lorry diesel engines. Large ships use extremely efficient, low-speed two-stroke diesel engines. They can reach efficiencies of up to 55%. Unlike most regular diesel engines, two-stroke watercraft engines use highly viscous fuel oil.^[1] Submarines are usually diesel–electric.^[221]

The first diesel engines for ships were made by A. B. Diesels Motorer Stockholm in 1903. These engines were three-cylinder units of 120 PS (88 kW) and four-cylinder units of 180 PS (132 kW) and used for Russian ships. In World War I, especially submarine diesel engine development advanced quickly. By the end of the War, double acting piston two-stroke engines with up to 12,200 PS (9 MW) had been made for marine use.^[224]

Aviation

Early

Diesel engines had been used in aircraft before World War II, for instance, in the rigid airship LZ 129 Hindenburg, which was powered by four Daimler-Benz DB 602 diesel engines,^[225] or in several Junkers aircraft, which had Jumo 205 engines installed.^[101]

In 1929, in the United States, the Packard Motor Company developed America's first aircraft diesel engine, the Packard DR-980 -- an air-cooled, 9-cylinder radial engine. They installed it in various aircraft of the era -- some of which were used in record-breaking distance or endurance flights,^{[226][227][228][229]} and in the first successful demonstration of ground-to-air radiophone communications (voice radio having been previously unintelligible in aircraft equipped with spark-ignition engines, due to electromagnetic interference).^[227][228] Additional advantages cited, at the time, included a lower risk of post-crash fire, and superior performance at high altitudes.^[227]

On March 6, 1930, the engine received an Approved Type Certificate -- first ever for an aircraft diesel engine -- from the U.S. Department of Commerce.^[230] However, noxious exhaust fumes, cold-start and vibration problems, engine structural failures, the death of its developer, and the industrial economic contraction of the Great Depression, combined to kill the program.^[227]

Modern

From then, until the late 1970s, there had not been many applications of the diesel engine in aircraft. In 1978, Piper Cherokee co-designer Karl H. Bergey argued that “the likelihood of a general aviation diesel in the near future is remote.”^[231]

However, with the 1970s energy crisis and environmental movement, and resulting pressures for greater fuel economy, reduced carbon and lead in the atmosphere, and other issues, there was a resurgence of interest in diesel engines for aircraft. High-compression piston aircraft engines that run on aviation gasoline ("avgas") generally require the addition of toxic Tetraethyl lead to avgas, to avoid engine pre-ignition and detonation; but diesel engines do not require leaded fuel. Also, biodiesel can, theoretically, provide a net reduction in atmospheric carbon compared to avgas. For these reasons, the general aviation community has begun to fear the possible banning or discontinuance of leaded avgas.^{[8][232][233][234]}

Additionally, avgas is a specialty fuel in very low (and declining) demand, compared to other fuels, and its makers are susceptible to costly aviation-crash lawsuits, reducing refiners' interest in producing it. Outside the United States, avgas has already become increasingly difficult to find at airports (and generally), than less-expensive, diesel-compatible fuels like Jet-A and other jet fuels.^{[8][232][233][234]}

By the late 1990s / early 2000s, diesel engines were beginning to appear in light aircraft. Most notably, Frank Thielert and his Austrian engine enterprise, began developing diesel engines to replace the 100 horsepower (75 kW) - 350 horsepower (260 kW) gasoline/piston engines in common light aircraft use.^[235] First successful application of the Theilerts to production aircraft was in the Diamond DA42 Twin Star light twin, which exhibited exceptional fuel efficiency surpassing anything in its class,^[8][9][236] and its single-seat predecessor, the Diamond DA40 Diamond Star.^[8][9][235]

In subsequent years, several other companies have developed aircraft diesel engines, or have begun to^[235] -- most notably Continental Aerospace Technologies which, by 2018, was reporting it had sold over 5,000 such engines worldwide.^[8][9][237]

The United States' Federal Aviation Administration has reported that "by 2007, various jet-fueled piston aircraft had logged well over 600,000 hours of service".^[235] In early 2019, AOPA reported that a diesel engine model for general aviation aircraft is “approaching the finish line.”^[238] By late 2022, Continental was reporting that its "Jet-A" fueled engines had exceeded "2,000... in operation today," with over "9 million hours," and were being "specified by major OEMs" for Cessna, Piper, Diamond, Mooney, Tecnam, Glasair and Robin aircraft.^[237]

In recent years (2016), diesel engines have also found use in unmanned aircraft (UAV), due to their reliability, durability, and low fuel consumption.^{[239][240][241]}

Non-road diesel engines

Air-cooled diesel engine of a 1959 Porsche 218

Non-road diesel engines are commonly used for construction equipment and agricultural machinery. Fuel efficiency, reliability and ease of maintenance are very important for such engines, whilst high power output and quiet operation are negligible. Therefore, mechanically controlled fuel injection and air-cooling are still very common. The common power outputs of non-road diesel engines vary a lot, with the smallest units starting at 3 kW, and the most powerful engines being heavy duty lorry engines.^[219]

Stationary diesel engines

Three English Electric 7SRL diesel-alternator sets being installed at the Saateni Power Station, Zanzibar 1955

Stationary diesel engines are commonly used for electricity generation, but also for powering refrigerator compressors, or other types of compressors or pumps. Usually, these engines either run continuously with partial load, or intermittently with full load. Stationary diesel engines powering electric generators that put out an alternating current, usually operate with alternating load, but fixed rotational frequency. This is due to the mains' fixed frequency of either 50 Hz (Europe), or 60 Hz (United States). The engine's crankshaft rotational frequency is chosen so that the mains' frequency is a multiple of it. For practical reasons, this results in crankshaft rotational frequencies of either 25 Hz (1500 per minute) or 30 Hz (1800 per minute).^[242]

Discover more about Applications related topics

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Power-to-weight ratio

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Electric locomotive

Electric locomotive

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Freight train

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Deutsche Reichsbahn

Deutsche Reichsbahn

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Myanmar

Myanmar

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LZ 129 Hindenburg

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Daimler-Benz DB 602

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