Editing Diesel engine (section)

==Introduction==
Diesel engines work by compressing only air, or air combined with 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 air temperature inside the [[Cylinder (engine)|cylinder]] so that atomised diesel fuel injected into the combustion chamber ignites. The torque a diesel engine produces is controlled by manipulating the [[Air–fuel ratio#Air–fuel equivalence ratio (λ)|air-fuel ratio (λ)]]; instead of throttling the intake air, the diesel engine relies on altering the amount of fuel that is injected, and thus the air-fuel ratio is usually high.

The diesel engine has the highest [[thermal efficiency]] ''(see [[engine efficiency]])'' of any practical [[internal combustion|internal]] or [[external combustion]] engine due to its very high [[expansion ratio]] and inherent [[Air–fuel ratio|lean]] burn, which enables heat dissipation by excess air. A small efficiency loss is also avoided compared with non-direct-injection gasoline engines, as 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%.<ref name="Reif_2014_13" /> The [[combined cycle power plant|combined cycle gas turbine]] (Brayton and Rankine cycle) is a combustion engine that is more efficient than a diesel engine, but due to its mass and dimensions, is unsuitable for many vehicles, including [[watercraft]] and some [[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&nbsp;MW each.<ref name="Grote_2018_P93" />

Diesel engines may be designed with either [[two-stroke engine|two-stroke]] or [[four-stroke]] [[#Combustion cycle|combustion cycles]]. They were originally used as a more efficient replacement for stationary [[steam engine]]s. Since the 1910s, they have been used in [[submarine]]s 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 some [[automobile]]s. 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.<ref name="time_forgot_2021_04_13_autoweek_com">{{citation | last = Ramey | first = Jay | url = https://www.autoweek.com/car-life/classic-cars/g36106078/diesel-cars-time-forgot/ | archive-url = https://web.archive.org/web/20221206053344/https://www.autoweek.com/car-life/classic-cars/g36106078/diesel-cars-time-forgot/ | archive-date = 2022-12-06 | title = 10 Diesel Cars That Time Forgot | date = April 13, 2021 | work = [[Autoweek]] | publisher = Hearst Autos, Inc. }}</ref><ref name="critical_evaluation_2013_springeropen_com">[https://enveurope.springeropen.com/articles/10.1186/2190-4715-25-15 "Critical evaluation of the European diesel car boom - global comparison, environmental effects and various national strategies,"] 2013, ''Environmental Sciences Europe,'' volume&nbsp;25, Article&nbsp;number:&nbsp;15, retrieved December 5, 2022</ref> According to Konrad Reif (2012), the [[European Union|EU]] average for diesel cars at the time accounted for half of newly registered cars.<ref name="Reif_2012_286" /> However, [[air pollution]] and overall emissions are more difficult to control in diesel engines compared to gasoline engines, so the use of diesel engines in the US is now largely relegated to larger on-road and [[off-road vehicle]]s.<ref name="every_new_diesel_2021_03_06_caranddriver_com">Huffman, John Pearley: [https://www.caranddriver.com/features/g20980996/diesel-car-truck-suv/ "Every New 2021 Diesel for Sale in the U.S. Today,"] March 6, 2021, ''[[Car and Driver]],'' retrieved December 5, 2022</ref><ref name="the_15_best_2021_04_23_usnews_com">Gorzelany, Jim: [https://cars.usnews.com/cars-trucks/advice/best-diesel-cars?slide=18 "The Best 15 Best Diesel Vehicles of 2021,"] April 23, 2021, ''[[U.S. News]],'' retrieved December 5, 2022</ref>

Though aviation has traditionally avoided using diesel engines, aircraft diesel engines have become increasingly available in the 21st century. Since the late 1990s, for various reasons—including diesel's inherent 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 aircraft|light airplanes]] and [[unmanned aerial vehicles]].<ref name="inside_2018_08_01_flyingmag_com">[https://www.flyingmag.com/inside-aviation-diesel-revolution/ "Inside the Diesel Revolution,"] August 1, 2018, ''[[Flying (magazine)|Flying]],''  retrieved December 5, 2022</ref><ref name="diamond_2020_12_30_avweb_com">O'Connor, Kate: [https://www.avweb.com/aviation-news/diamond-rolls-out-500th-da40-ng/ "Diamond Rolls Out 500th DA40 NG,"] December 30, 2020 Updated: December 31, 2020, ''[[Avweb]],'' retrieved December 5, 2022</ref>