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Reciprocating Engines

Reciprocating engines

, (I) Intake camshaft, (S) Spark plug, (V) Valves, (P) Piston, (R) Connecting rod, (C) Crankshaft, (W) Water jacket for coolant flow.]] A reciprocating engine, also often known as a piston engine, is an engine that utilizes one or more pistons in order to convert pressure into a rotating motion. The reciprocating engine was introduced with the now obsolete steam engine, but today the most common form of reciprocating engines is the internal combustion engine using the burning of gasoline, diesel fuel, oil or natural gas to provide pressure. There may be one or more pistons. Each piston is located inside a cylinder, into which a fuel and air mixture is introduced, and then ignited. The now hot gases expand, pushing the piston away. The linear movement of the piston is converted to a circular movement via a connecting rod and a crankshaft. The more cylinders a piston engine has, the more power it is capable of producing, so it is common for such engines to be classified by the number and alignment of cylinders. Single- and two-cylinder engines are common in smaller vehicles such as motorcycles; automobiles, locomotives, and ships may have a dozen cylinders or more. These engines are known collectively as internal-combustion engines, although internal-combustion engines do not necessarily contain pistons. Though not often used today, steam is another power source for reciprocating engines, in the steam engine. In these cases high pressure steam is used to drive the piston. In most applications of steam power, the piston engine has been replaced by the more efficient turbine, with pistons being used in cars owing to their requirement for a high level of torque.

Poppet valve

A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide. In most applications a pressure differential helps to seal the valve and in some applications also open it. Presta and Schrader valves used on tires are examples of poppet valves. The Presta valve has no spring and relies on a pressure differential for opening and closing while being inflated. Poppet valves are used in many industrial process from controlling the flow of rocket fuel to controlling the flow of milk.

Internal combustion engine

Poppet valves are used in most piston engines to open and close the intake and exhaust ports. The valve is usually a flat disk of metal with a long rod known as the valve stem out one end. The stem is used to push down on the valve and open it, with a spring generally used to close it when the stem is not being pushed on. Desmodromic valves are closed by positive mechanical action instead of by a spring, and are used in some high speed motorcycle and auto racing engines, eliminating 'valve float' at high RPM. For certain applications the valve stem and disk are made of different steel alloys, or the valve stems may be hollow and filled with sodium to improve heat transport and transfer. The engine normally operates the valves by pushing on the stems with cams and cam followers. The shape and position of the cam determines the valve lift and when and how quickly (or slowly) the valve is opened. The cams are normally placed on a fixed camshaft which is then geared to the crankshaft, running at half crankshaft speed in a four-stroke engine. On high performance engines e.g. used in Ferrari cars, the camshaft is moveable and the cams have a varying height, so by axially moving the camshaft in relation with the engine RPM, also the valve lift varies. See variable valve timing. In very early engine designs the valves were 'upside down' in the block, parallel to the cylinders - the so called L-head engine because of the shape of the cylinder and combustion space, also called 'flathead engine' as the top of the cylinder head is flat. Although this design makes for simplified and cheap construction, it has two major drawbacks; the tortuous path followed by the intake charge effectively prevents speeds greater than 2,000-2,500 RPM, and the travels of the exhaust through the block lead to excessive overheating under sustained heavy load. This design therefore evolved into 'Intake Over Exhaust', IOE or F-head, where the intake valve was in the block and the exhaust valve was in the head; later both valves moved to the head. In most such designs the camshaft remained relatively near the crankshaft, and the valves were operated through pushrods and rocker arms. This led to significant energy losses in the engine, but was simpler, especially in a V engine where one camshaft can actuate the valves for both cylinder banks; for this reason, pushrod engine designs persisted longer in these configurations than others. More modern designs have the camshaft on top of the cylinder head, pushing directly on the valve stem (again through cam followers), a system known as overhead camshaft; if there is just one camshaft, this is a single overhead cam or SOHC engine. Often there are two camshafts, one for the intake and one for exhaust valves, creating the dual overhead cam, or DOHC. The camshaft is driven by the crankshaft - through gears, a chain or in modern engines with a rubber belt. In the early days of engine building, the poppet valve was a major problem. Metallurgy was not what it is today, the rapid opening and closing of the valves against the cylinder heads led to rapid wear. They would need to be re-ground every two years or so, in an expensive and time consuming process known as a valve job. Adding tetra-ethyl lead to the petrol reduced this problem to some degree as the lead would coat the valve seats, hardening the metal. Valve seats made of improved alloys such as stellite have generally made this problem disappear completely and making leaded fuel unnecessary. The poppet valve was also used in a limited fashion in steam engines, particularly steam locomotives. Most steam locomotives used slide valves or piston valves, but these designs, although mechanically simpler and very rugged, were significantly less efficient than the poppet valve. A number of designs of locomotive poppet valve system were tried, the most popular being the Italian Caprotti valve gear, the British Caprotti valve gear (an improvement of the Italian one), the German Lentz rotary-cam valve gear, and two American versions by Franklin, their oscillating-cam valve gear and rotary-cam valve gear. They were used with some success, but they were less ruggedly reliable than traditional valve gear and did not see widespread adoption.

Connecting rod

In a reciprocating piston engine, the connecting rod or con rod connects the piston to the crank or crankshaft. __TOC__

Internal combustion engines

In modern automotive internal combustion engines, the connecting rods are most usually made of steel for production engines, but can be made of aluminium (for lightness and the ability to absorb high impact at the expense of durability) or titanium (for a combination of strength and lightness at the expense of affordability) for high performance engines, or of cast iron for applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the con rod and the piston can change as the rod moves up and down and rotates around the crankshaft. The small end attaches to the piston pin or wrist pin, which is currently most often press fit into the con rod but can swivel in the piston, a "floating wrist pin" design. The big end connects to the bearing journal on the crank throw, running on replaceable bearing shells accessible via the con rod bolts which hold the bearing "cap" onto the big end; typically there is a pinhole bored through the bearing and the big end of the con rod so that pressurized lubricating motor oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings. The con rod is under tremendous stress from the reciprocating load represented by the piston, actually stretching and relaxing with every rotation, and the load increases rapidly with increasing engine speed. Failure of a connecting rod is one of the most common causes of catastrophic engine failure in cars, frequently putting the broken rod through the side of the crankcase and thereby rendering the engine irreparable; it can result from overheating, a physical defect in the rod, lubrication failure in a bearing due to faulty maintenance, or from failure of the rod bolts from a defect, improper tightening, or re-use of already used (stressed) bolts where not recommended. Luckily, despite their frequent occurrence on televised competitive automobile events, such failures are quite rare on production cars during normal daily driving. When building a high performance engine, great attention is paid to the con rods, eliminating stress risers by such techniques as grinding the edges of the rod to a smooth radius, shotpeening to relieve internal stress, balancing all con rod/piston assemblies to the same weight and Magnafluxing to reveal otherwise invisible small cracks which would cause the rod to fail under stress. In addition, great care is taken to torque the con rod bolts to the exact value specified; often these bolts must be replaced rather than reused. The big end of the rod is fabricated as a unit and cut or cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end "caps" are not interchangeable between con rods, and when rebuilding an engine, care must be taken to ensure that the caps of the different con rods are not mixed up. Both the con rod and its bearing cap are usually embossed with the corresponding position number in the engine block. A more recent manufacturing technique, used in the Ford 4.6 liter engine and the Chrysler 2.0 liter engine for instance, is to forge the rod as a single piece from powdered metal, which allows more precise control of size and weight with less machining and less excess mass to be machined off for balancing. The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal. This ensures that upon reassembly, the cap will be perfectly positioned with respect to the rod, compared to the minor misalignments which can occur if the mating surfaces are both flat. A major source of engine wear is the sideways force exerted on the piston through the con rod by the crankshaft, which typically wears the cylinder into an oval cross-section rather than circular, making it impossible for piston rings to correctly seal against the cylinder walls. Geometrically, it can be seen that longer con rods will reduce the amount of this sideways force, and therefore lead to longer engine life. However, for a given engine block, the sum of the length of the con rod plus the piston stroke is a fixed number, determined by the fixed distance between the crankshaft axis and the top of the cylinder block where the cylinder head fastens; thus, for a given cylinder block longer stroke, giving greater engine displacement and power, requires a shorter connecting rod (or a piston with smaller compression height), resulting in accelerated cylinder wear.

Steam engines

In a steam locomotive, the crank pins are often mounted directly on one or more pairs of driving wheels, and the axle of these wheels serves as the crankshaft. The connecting rods, also called the main rods, run between the crank pins and crosshead bearings, where they connect to the piston rods. See also steam locomotive nomenclature. Category:engine technology Category:Steam locomotives

Engine

An engine is something that produces some effect from a given input. The origin of engineering was the working of engines. There is an overlap in English between two meanings of the word "engineer": 'those who operate engines' and 'those who design and construct new items'.

Usage of the term

In original usage, an engine was any sort of mechanical device. The term "gin" in cotton gin is a short form of this usage. Practically every device from the industrial revolution was referred to as an engine, and this is where the steam engine gained its name. This form of the term has recently come into use once again in computer science, where terms like search engine, "3-D graphics rendering engine" and "text-to-speech engine" are common. The earliest mechanical computing device was called the difference engine; Military devices such as catapults are referred to as siege engines. In more recent usage, the term is typically used to describe devices that perform mechanical work, follow-ons to the original steam engine. In most cases the work is supplied by exerting a torque, which is used to operate other machinery, generate electricity, pump water or compress gas. In the context of propulsion systems, an air breathing engine is one that uses atmospheric air to oxidise the fuel carried, rather than carrying an oxidiser, as in a rocket. Theoretically, this should result in a better specific impulse than for rocket engines.

History of engines

Antiquity

While chemical and electrical engines of enormous power dominate the modern world, engines themselves are not new. Engines using human power, animal power, water power, wind power and even steam power date back to antiquity. Human power was focused by the use of simple engines, such as the capstan, windlass or treadmill, and with ropes, pulleys, and block and tackle arrangements, this power was transmitted and multiplied. These were commonly used in cranes and aboard ships during Ancient Greece, and in mines, water pumps and siege engines in Ancient Rome. Early oared warships used human power augmented by the simple engine of the lever -- the oar itself. The writers of those times, including Vitruvius, Frontinus and Pliny the Elder, treat these engines as commonplace, so their invention may be far more ancient. By the 1st century AD, various breeds of cattle and horses were used in mills, using machines similar to those powered by humans in earlier times. According to Strabo, a water powered mill was built in Kaberia in the kingdom of Mithridates in the 1st century BC. Use of water wheels in mills slowly spread through Europe over the next few centuries. Some were quite complex, with aqueducts, dams, and sluices to maintain and channel the water, and systems of gears, or toothed-wheels made of wood with metal, used to regulate the speed of rotation. In a poem by Ausonius in the 4th century, he mentions a stone-cutting saw powered by water. Hero of Alexandria demonstrated both wind and steam powered machines in the 1st century, although it's not known if these were put to any practical use until much later. In the broadest sense of the term, internal combustion engines can be said to have been invented in China, with the invention of fireworks during the Song dynasty, with some sources putting this invention a thousand years earlier still. Monumental structures of Ancient Egypt, it has been purported, might have been constructed with engines, especially in the transport and/or raising of some 15 to over 100 ton stone blocks. Electrical devices have been purported to have been discovered in digs in Iraq and Egypt and on ancient Egyptian walls and writings.

Modern

English inventor Sir Samuel Morland allegedly used gunpowder to drive water pumps in the 17th century. For more conventional, reciprocating internal combustion engines the fundamental theory for two-stroke engines was established by Sadi Carnot, France, 1824, whilst the American Samuel Morey received a patent on April 1, 1826. Automotive production down the ages has required a wide range of energy-conversion systems. These include electric, steam, solar, turbine, rotary, and different types of piston-type internal combustion engines. The gasoline internal combustion engine, operating on a four-stroke Otto cycle, has traditionally been the most successful for automobiles, while diesel engines are widely used for trucks and buses. However, in the twenty first century the diesel engine has been increasing in popularity with automobile owners. This is partially due to the improvement of engine control systems (computers) and forced induction (turbos and superchargers), giving modern diesel engines the same power charachteristics as gasoline engines. This is especially evident with the popularity of diesel engines in Europe. The internal combustion engine was originally selected for the automobile due to its flexibility over a wide range of speeds. Also, the power developed for a given weight engine was reasonable; it could be produced by economical mass-production methods; and it used a readily available, moderately priced fuel--gasoline. In today’s world, there has been a growing emphasis on the pollution producing features of automotive power systems. This has created new interest in alternate power sources and internal-combustion engine refinements that were not economically feasible in prior years. Although a few limited-production battery-powered electric vehicles have appeared from time to time, they have not proved to be competitive owing to costs and operating characteristics. However, the gasoline engine, with its new emission-control devices to improve emission performance, has not yet been challenged significantly. The first half of the twentieth century saw a trend to increase engine power, particularly in the American models. Design changes incorporated all known methods of raising engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the speed at which power is generated. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements. In passenger cars, V-8 layouts were adopted for all piston displacements greater than 250 cubic inches (4 litres). Smaller cars brought about a return a to smaller engines, the four- and six-cylinder designs rated as low as 80 horsepower (60 kW), compared with the standard-size V-8 of large cylinder bore and relatively short piston stroke with power ratings in the range from 250 to 350 hp (190 to 260 kW). The automobile motor from Europe had a bigger range, varying from 1to12 cylinders with corresponding differences in overall size, weight, piston displacement, and cylinder bores. Four cylinders and power ratings from 19 to 120 hp (14 to 90 kW) was followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead camshafts were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and '80s saw an increased interest in improved fuel economy which brought in a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency. Air-breathing engines include:
- Internal combustion engine
- Jet engine
- Ramjet
- Scramjet
- Pulse detonation engine
- Pulse jet engine
- Liquid air cycle engine

References

- J. G. Landels, Engineering in the Ancient World, ISBN 0520041275

External links

- [http://auto.howstuffworks.com/engine.htm How stuff works : Cars Engines]
- [http://www.keveney.com/Engines.html Engines working. Animation]
- Category:Mechanical engineering ja:エンジン

Piston

In general, a piston is a sliding plug that fits closely inside the bore of a cylinder. Its purpose is either to change the volume enclosed by the cylinder, or to exert a force on a fluid inside the cylinder.

Internal combustion engine

Most pistons fitted in a cylinder have piston rings. Usually there are two spring-compression rings that act as a seal between the piston and the cylinder wall, and one or more oil control rings below the compression rings. The head of the piston can be flat, bulged or otherwise shaped. Pistons can be forged or cast. A special type of cast piston is the hypereutectic piston. The piston is an important component of a piston engine and of hydraulic pneumatic systems. In an Otto or Diesel engine, the head of the piston forms one wall of an expansion chamber inside the cylinder. The opposite wall, called the cylinder head, contains inlet and exhaust valves for gases. As the piston moves inside the cylinder, it transforms the energy from the expansion of a burning gas (usually a mixture of petrol or diesel and air) into mechanical power (in the form of a reciprocating linear motion). From there the power is conveyed through a connecting rod to a crankshaft, which transforms it into a rotary motion, which usually drives a gearbox through a clutch.

External combustion engine

A steam engine is another type of piston engine. In most steam engines, the pistons are double acting: steam is alternately admitted to either end of the cylinder, so that every piston stroke produces power. .

External links

- [http://www.grantpistonrings.com/ Grant Piston Rings], manufacturer of piston rings
- [http://www.perfectcircleindia.com/aboutus.html Perfect Circle], manufacturer of piston rings
- [http://www.wellfar.com.cn/index.html Wellfar], another manufacturer
- [http://www.usa.kolbenschmidt-pierburg.com/kp_divkarlschmidtunisia.html Kolbenschmidt Pierburg], manufacturer of pistons
- [http://www.mahle.com Mahle], manufacturer of pistons Category:engine technology ja:ピストン

Pressure

:For the psychological or political context, see Peer pressure. Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. Mathematically: :

p = F/A\,

where p is the pressure, F is the normal force, and A is the area. Pressure is transmitted to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point. It is a fundamental parameter in thermodynamics and it is conjugate to volume. A closely related quantity is the stress tensor σ which relates the vector force F to the vector area A via :

\mathbf=\mathbf

This tensor may be divided up into a scalar part (pressure) and a traceless tensor part shear. The shear tensor gives the force in directions parallel to the surface, usually due to viscous or frictional forces. The stress tensor is sometimes called the pressure tensor, but in the following, the term "pressure" will refer only to the scalar pressure. shear

Example

As an example of varying pressures, a finger can be pressed against a wall without making any lasting impression; however, the same finger pushing a thumbtack can easily damage the wall. Although the force applied to the surface is the same, the thumbtack applies more pressure because the point concentrates that force into a smaller area. Pressure is transmitted to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point. Unlike stress, pressure is defined as a scalar quantity. The gradient of pressure is force density. In the human body, baroreceptors monitor blood pressure.

Relative or gauge pressure

For gases, pressure is sometimes measured, not as an absolute pressure, but relative to atmospheric pressure; such measurements are sometimes called gauge pressure. An example of this is the air pressure in a car tire, which might be said to be "220 kPa," but is actually 220 kPa above atmospheric pressure. Since atmospheric pressure at sea level is about 100 kPa, the absolute pressure in the tire is therefore about 320 kPa. In technical work, this is written "a gauge pressure of 220 kPa." Where space is limited, such as on gauges, name plates, graph labels, and table headings, the use of a modifier in parentheses, such as "kPa (gauge)" or "kPa (absolute)," is permitted. In non-SI technical work, a gauge pressure is sometimes written as "32 psig," though the other methods explained above that avoid attaching characters to the unit of pressure are preferred [http://physics.nist.gov/Pubs/SP811/sec07.html#7.4 ¹].

Scalar nature of pressure

In static gas, the gas as a whole does not appear to move, the individual molecules of the gas, which we cannot see, are in constant random motion. Because we are dealing with an extremely large number of molecules and because the motion of the individual molecules is random in every direction, we do not detect any motion. If we enclose the gas within a container, we detect a pressure in the gas from the molecules colliding with the walls of our container. We can put the walls of our container anywhere inside the gas, and the force per unit area (the pressure) is the same. We can shrink the size of our "container" down to an infinitely small point, and the pressure has a single value at that point. Therefore, pressure is a scalar quantity, not a vector quantity. It has a magnitude but no direction associated with it. Pressure acts in all directions at a point inside a gas. At the surface of a gas, the pressure force acts perpendicular to the surface.

Hydrostatic pressure

Hydrostatic pressure is the pressure due to the weight of a fluid. :p = ρgh where ρ (rho) is density of the fluid, g is acceleration due to gravity, and h is height of the fluid above the point being measured. See also Pascal's law.

Stagnation pressure

Stagnation pressure is the pressure a fluid exerts when it is forced to stop moving. Consequently, although a fluid moving at higher speed will have a lower static pressure, it may have a higher stagnation pressure when forced to a standstill. Static pressure and stagnation pressure are related by the Mach number of the fluid. In addition, there can be differences in pressure due to differences in the elevation (height) of the fluid. See Bernoulli's equation. The pressure of a moving fluid can be measured using a Pitot probe, or one of its variations such as a Kiel probe or Cobra probe, connected to a manometer. Depending on where the inlet holes are located on the probe, it can measure static pressure or stagnation pressure.

Units

The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N·m^-2 or kg·m^-1·s^-2). This special name for the unit was added in 1971; before that, pressure in SI was expressed in units such as N/m². Non-SI measures (still in use in some parts of the world) include the pound-force per square inch (psi) and the bar. The cgs unit of pressure is the barye (ba). It is equal to 1 dyn·cm^-2. Pressure is still sometimes expressed in kgf/cm² or grams-force/cm² (sometimes as kg/cm² and g/cm² without properly identifying the force units). But using the names kilogram, gram, kilogram-force, or gram-force (or their symbols) as a unit of force is expressly forbidden in SI; the unit of force in SI is the newton (N). The technical atmosphere (symbol: at) is 1 kgf/cm². Some meteorologists prefer the hectopascal (hPa) for atmospheric air pressure, which is equivalent to the older unit millibar (mbar). Similar pressures are given in kilopascals (kPa) in practically all other fields, where the hecto prefix is hardly ever used. In Canadian weather reports, the normal unit is kPa. The obsolete unit inch of mercury (inHg) is still sometimes used in the United States. Blood pressure is still measured in millimetres of mercury in most of the world, and lung pressures in centimeters of water are still common. These obsolete manometric units of pressure are based on the pressure exerted by the weight of some "standard" fluid under some "standard" gravity. They are effectively attempts to define a unit for expressing the readings of a manometer. When millimetres or inches of mercury are used today, they have precise definitions that can be expressed in terms of SI units. The water-based units depend on the density of water, a measured, rather than defined, quantity. The standard atmosphere (atm) is an established constant. It is approximately equal to typical air pressure at earth mean sea level and is defined as follows. :standard atmosphere = 101325 Pa = 101.325 kPa = 1013.25 hPa. A rule of thumb commonly used by scuba divers is that one atmosphere is approximately equal to the pressure exerted by ten metres of water. Non-SI units presently or formerly in use include the following.
- atmosphere.
- manometric units:
- centimetre, inch, and millimetre of mercury (Torr).
- millimetre, centimetre, metre, inch, and foot of water.
- imperial units:
- kip, ton-force (short), ton-force (long), pound-force, ounce-force, and poundal per square inch.
- pound-force, ton-force (short), and ton-force (long) per square foot.
- non-SI metric units:
- bar, millibar.
- kilogram-force, or kilopond, per square centimetre (technical atmosphere).
- gram-force and tonne-force (metric ton-force) per square centimetre.
- barye (dyne per square centimetre).
- kilogram-force and tonne-force per square metre.
- sthene per square metre (pieze).

External links

- [http://calc.skyrocket.de/en/ Online unit converter] - conversion of many different units.
- [http://avc.comm.nsdlib.org/cgi-bin/wiki_grade_interface.pl?An_Exercise_In_Air_Pressure An exercise in air pressure]
- [http://www.grc.nasa.gov/WWW/K-12/airplane/pressure.html Pressure being a scalar quantity] Category:Diving Category:Meteorology Category:Physical quantity Category:Thermodynamics ko:압력 ms:Tekanan ja:圧力

Internal combustion engine

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

History

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

Applications

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

Operation

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

Parts

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

Classification

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

Principles of operation

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

Engine cycle

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

Fuel and oxidiser types

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

Cylinders

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

Ignition system

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

Fuel systems

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

Engine configuration

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

Engine capacity

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

Engine pollution

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

Bibliography

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

External links

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

Gasoline

:Petrol (petroleum spirit) redirects here. For the seabird, see petrel, spelled with an 'e'. Gasoline is a petroleum-derived liquid mixture consisting primarily of hydrocarbons, used as fuel in internal combustion engines. Many Commonwealth countries use the term petrol (abbreviated from petroleum spirit), or more rarely, motor spirit. The term gasoline is commonly used in North America, and within the oil industry generally, even within companies that are not American. The word is commonly shortened in colloquial usage to "gas" (see other meanings). The term mogas, short for motor gasoline, for use in cars is used to distinguish it from avgas, aviation gasoline used in (light) aircraft. This should be distinguished in usage from genuinely gaseous fuels used in internal combustion engines such as LPG.

Chemical analysis and production

Gasoline is produced in oil refineries. These days, material that is simply separated from crude oil via distillation, called natural gasoline, will not meet the required specifications (in particular octane rating; see below) for modern engines, but these streams will form part of the blend. The bulk of a typical gasoline consists of hydrocarbons with between 5 and 12 carbon atoms per molecule. The various refinery streams that are blended together to make gasoline all have different characteristics. Some important streams are:
- Reformate, produced in a catalytic reformer with a high octane and high aromatics content, and very low olefins (alkenes).
- Cat Cracked Gasoline or Cat Cracked Naphtha, produced from a catalytic cracker, with a moderate octane, high olefins (alkene) content, and moderate aromatics level. Here, "cat" is short for "catalyst".
- Hydrocrackate (Heavy, Mid, and Light), produced from a hydrocracker, with medium to low octane and moderate aromatic levels.
- Natural Gasoline (has very many names), directly from crude oil with low octane, low aromatics (depending on the crude oil), some naphthenes (cycloalkanes) and zero olefins (alkenes).
- Alkylate, produced in an alkylation unit, with a high octane and which is pure paraffin (alkane), mainly branched chains.
- Isomerate (various names) which is made by isomerising Natural Gasoline to increase its octane rating and is very low in aromatics and benzene content. (The terms used here are not always the correct chemical terms. Typically they are old fashioned, but they are the terms normally used in the oil industry. The exact terminology for these streams varies by oil company and by country.) Overall a typical gasoline is predominantly a mixture of paraffins (alkanes), naphthenes (cycloalkanes), aromatics and olefins (alkenes). The exact ratios can depend on
- the oil refinery that makes the gasoline, as not all refineries have the same set of processing units.
- the crude oil used by the refinery on a particular day.
- the grade of gasoline, in particular the octane. These days, gasoline in many countries has tight limits on aromatics in general, benzene in particular, and olefins (alkene) content. This is increasing the demand for high octane pure paraffin (alkane) components, such as alkylate, and is forcing refineries to add processing units to reduce the benzene content. Gasoline can also contain some other organic compounds: such as organic ethers, (deliberately added) plus small levels of contaminants, in particular sulfur compounds such as disulfides and thiophenes. Some contaminants, in particular mercaptans and hydrogen sulfide must be removed because they cause corrosion in engines.

Volatility

Gasoline is more volatile than diesel or kerosene, not only because of the base constituents, but because of the additives that are put into it. The final control of volatility is often via blending of butane. The desired volatility depends on the ambient temperature: In hotter climates, gasoline components of higher molecular weight and thus lower volatility are used. In Australia the volatility limit changes every month and differs for each main distribution center, but most countries simply have a summer, winter and perhaps intermediate limit. The maximum volatility of gasoline in many countries has been reduced in recent years to reduce the fugitive emissions during refueling. Volatility standards may be relaxed (allowing more gasoline components into the atmosphere) during emergency anticipated gasoline shortages. For example, on 31 August 2005 in response to Hurricane Katrina, the United States activated an early switch to "winter gasoline" which has a volatility limit exceeding the usual summertime standard. As mandated by EPA administrator Stephen L. Johnson, this "fuel waiver" was made effective through 15 September 2005 [http://www.epa.gov/katrina/activities.html#aug31johnson]. Though relaxed volatility standards negatively impact ozone and other air quality criteria, higher volatility gasoline (which contains less additives than gasoline whose volatility has been artificially lowered) essentially increases a nation's gasoline supply.

Octane rating

The most important characteristic of gasoline is its octane rating, which is a measure of how resistant gasoline is to premature detonation (knocking). It is measured relative to a mixture of 2,2,4-trimethylpentane (an isomer of octane) and n-heptane. An 87-octane gasoline has the same knock resistance as a mixture of 87% isooctane and 13% n-heptane. The octane rating system was developed by the chemist Russell Marker.

Dangers

Many of the non-aliphatic hydrocarbons naturally present in gasoline (especially aromatic ones like benzene), as well as many anti-knocking additives, are carcinogenic. Because of this, any large-scale or ongoing leaks of gasoline pose a threat to the public's health and the environment, should the gasoline reach a public supply of drinking water. The chief risks of such leaks come not from vehicles, but from gasoline delivery truck accidents and leaks from storage tanks. Because of this risk, most (underground) storage tanks now have extensive measures in place to detect and prevent any such leaks, such as sacrificial anodes. Gasoline is rather volatile (meaning it readily evaporates), requiring that storage tanks on land and in vehicles be properly sealed. But the high volatility also means that it will easily ignite in cold weather conditions, unlike diesel for example. However, certain measures must be in place to allow appropriate venting to ensure the level of pressure is similar on the inside and outside. Gasoline also reacts dangerously with certain common chemicals; for example, gasoline and crystal Drāno (sodium hydroxide) react together in a spontaneous combustion. Gasoline is also one of the sources of pollutant gases. Even gasoline which does not contain lead or sulfur compounds produces carbon dioxide, nitrogen oxides, and carbon monoxide in the exhaust of the engine which is running on it. Through misuse as an inhalant, gasoline also contributes to damage to health. "Petrol sniffing" is a common way of obtaining a high for many people and has become epidemic in many poorer communities such as with Indigenous Australians. In response, Opal fuel has been developed by the BP Kwinana Refinery in Australia, and contains only 5% aromatics (unlike the usual 25%) which inhibits the effects of inhalation.

Energy content

Gasoline contains about 45 megajoules per kilogram (MJ/kg)
Volumetric energy density of some fuels compared to gasoline: A high octane fuel such as LPG has a lower energy content than lower octane gasoline, resulting in an overall lower power output at the regular compression ratio an engine ran at on gasoline. However, with an engine tuned to the use of LPG (ie. via higher compression ratios such as 12:1 instead of 8:1), this lower power output can be overcome. This is because higher-octane fuels allow for a higher compression ratio - this means less space in a cylinder on its combustion stroke, hence a higher cylinder temperature, less wasted hydrocarbons (therefore less pollution and wasted energy), and therefore higher power levels coupled with less pollution overall because of the greater efficiency. Note that the main reason for the lower energy content (per litre) of LPG in comparison to gasoline is that is has a lower density. Energy content per kilogram is higher than for gasoline (higher hydrogen to carbon ratio). In lay terms, we burn mass, not volume! As an interesting side note different countries have some variation in what RON is standard for gasoline, or petrol. In the UK, ordinary premium unleaded petrol is always 95 RON whereas super unleaded is usually 97-98 RON. In the US, octane ratings in fuels can vary between 87 AKI (92 RON) for regular, through 90 (95) for mid-grade (European Premium), up to 93/94 for premium unleaded or E10 (Super in Europe)

Additives

Lead

The mixture known as gasoline when used in high compression internal combustion engines, has a tendency to explode early ( pre-ignition pre-detonation) causing a disturbing "engine knocking" (also called "pinging") noise. Early research into this effect was led by A.H. Gibson and Harry Ricardo in England and Thomas Midgley and Thomas Boyd in the United States. The discovery that lead additives modified this behavior led to the widespread adoption of the practice in the 1920s and hence more powerful higher compression engines. The most popular additive was tetra-ethyl lead. However, with the recognition of the environmental damage caused by the lead, and the incompatibility of lead with catalytic converters, this practice began to wane in the 1980s. Most countries are phasing out leaded fuel; different additives have replaced the lead compounds. The most popular additives include aromatic hydrocarbons, ethers and alcohol (usually ethanol or methanol). In the U.S., where lead has been blended with gasoline, primarily to boost octane levels, since the early 1920s, standards to phase out leaded gasoline were first implemented in 1973. In 1995, leaded fuel accounted for only 0.6 % of total gasoline sales and less than 2,000 tons of lead per year. Effective January 1, 1996, the Clean Air Act banned the sale of the small amount of leaded fuel that was still available in some parts of the country for use in on-road vehicles. (Fuel containing lead may continue to be sold for off-road uses, including aircraft, racing cars, farm equipment, and marine engines.) The ban on leaded gasoline was presumed to lower levels of lead in people's bloodstream and led to thousands of tons of lead being removed from the air. A side effect of the lead additives was protection of the valve seats from erosion. Many classic car's engines have needed modification to use lead-free fuels since leaded fuels became unavailable. Gasoline, as delivered at the pump, also contains additives to reduce internal engine carbon buildups, improve combustion, and to allow easier starting in cold climates.

MMT

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used for many years in Canada and recently in Australia to boost octane. It also helps old cars designed for leaded fuel run on unleaded fuel without need for additives to prevent valve problems. There are currently ongoing debates as to whether or not MMT is harmful to the environment and toxic to humans.

Oxygenate blending

Oxygenate blending adds oxygen to the fuel in oxygen-bearing compounds such as MTBE, ethanol and ETBE, and so reduces the amount of carbon monoxide and unburned fuel in the exhaust gas, thus reducing smog. In many areas throughout the US oxygenate blending is mandatory. For example, in Southern California, fuel must contain 2% oxygen by weight. The resulting fuel is often known as reformulated gasoline (RFG) or oxygenated gasoline. MTBE use is being phased out due to issues with contamination of ground water. In some places it is already banned. Ethanol and to a lesser extent the ethanol derived ETBE are a common replacements. Especially ethanol derived from biomatter such as corn, sugar cane or grain is frequent, this will often be referred to as bio-ethanol. An ethanol-gasoline mix of 10% ethanol mixed with gasoline is called gasohol. An ethanol-gasoline mix of 85% ethanol mixed with gasoline is called E85. The most extensive use of ethanol takes place in Brazil, where the ethanol is derived from sugarcane. Over 3,400 million US gallons (13,000,000 m³) of ethanol mostly produced from corn was produced in the United States in 2004 for fuel use, and E85 is fast becoming available in many of the United States. The use of bioethanol, either directly or indirectly by conversion of such ethanol to bio-ETBE, is encouraged by the European Union Biofuels Directive.

History

bioethanol).]]

Pharmaceutical

Before internal combustion engines were invented in the mid-1800s, gasoline was sold in small bottles as a treatment against lice and their eggs. In those early times, the word "Petrol" was a trade name. This treatment method is no longer common, due to the inherent fire hazard and risk of dermatitis and that gasoline is a carcinogen where continued contact might develop cancerous growths. The word petrol may be derived from Old French pétrole, meaning petroleum: see Etymology. Petrol is also abused as a psychoactive inhalant.

Etymology

The word "gasolene" was coined in 1865 from the word gas and the chemical suffix -ine/-ene. The modern spelling was first used in 1871. The shortened form "gas" was first recorded in American English in 1905.[http://www.etymonline.com/index.php?search=gasoline] Although, Gasoline originally referred to any liquid offered for sale, sold or used as the fuel for a gasoline-powered engine, but does not include diesel fuel or liquefied gas. Methanol racing fuel would have been classed as a type of gasoline.[http://www.window.state.tx.us/taxinfo/audit/motorfue/glossary.htm] The word "petrol" was first used in reference to the refined substance as early as 1892 (it previously referred to unrefined petroleum), and was registered as a trade name by English wholesaler Carless, Capel & Leonard. [http://www.etymonline.com/index.php?search=petrol] [http://www.chrysler-restorers-sa.org.au/crcmag154.pdf] Bertha Benz got petrol for her famous drive from Mannheim to Pforzheim and back from chemists' shops. In Germany petrol is called Benzin but this is not related to her name but to the chemical Benzine. Benzine

World War II and octane

One interesting historical issue involving octane rating took place during WWII. Germany received nearly all its oil from Romania, and set up huge distilling plants in Germany to produce gasoline from coal. In the US the oil was not "as good" and the oil industry had to invest heavily in various expensive boosting systems. This turned out to have benefits. The US industry started delivering fuels of ever-increasing octane ratings by adding more of the boosting agents and the infrastructure was in place for post war octane agents additive industry. Good crude oil was no longer a factor during wartime and by war's end, American aviation fuel was commonly 130 to 150 octane. This high octane could easily be used in existing engines to deliver much more power by increasing the compression delivered by the superchargers. The Germans, relying entirely on "good" gasoline, had no such industry, and instead had to rely on ever-larger engines to deliver more power. However, German aviation engines were of the direct fuel injection type and could use methanol-water injection and nitrous oxide injection, which gave 50% more engine power for five minutes of dogfight. This could be done only five times or after 40 hours run-time and then the engine would have to be rebuilt. Most German aero engines used 87 octane fuel (called B4), while some high-powered engines used 100 octane (C2/C3) fuel. This historical "issue" is based on a very common misapprehension about wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being always greater. So, for example, a common British aviation fuel of the later part of the war was 100/125. The misapprehension that German fuels have a lower octane number (and thus a poorer quality) arises because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number for their fuels. Standard German high-grade aviation fuel used in the later part of the war (given the designation C3) had lean/rich octane numbers of 100/130. The Germans would list this as a 100 octane fuel while the Allies would list it as 130 octane. After the war the US Navy sent a Technical Mission to Germany to interview German petrochemists and examine German fuel quality. Their report entitled "Technical Report 145-45 Manufacture of Aviation Gasoline in Germany" chemically analyzed the different fuels and concluded that "Toward the end of the war the quality of fuel being used by the German fighter planes was quite similar to that being used by the Allies".

Current use

The United States uses 360 million US liquid gallons (1.36 billion litres) of gasoline each day. Western countries have among the highest usage rates per head, while eastern developing nations as China typically have the highest usage per square mile/kilometer. Some countries, e.g. in Europe, impose heavy fuel taxes on fuels such as gasoline, leading to greater efficiency and economy in car design.

Stability

When gasoline is let sit for a certain period of time, gums and varnishes may build up and precipitate in the gasoline, causing "stale fuel." This will cause gums to build up in the cylinders and also the fuel lines, making it harder to start the engine. Gums and varnishes should be removed by a professional to extend engine life. Motor gasoline may be stored up to 60 days in an UL approved container. If it is to be stored for a longer period of time, a fuel stabilizer may be used. This will extend the life of the fuel to about 1-2 years, and keep it fresh for the next uses. Fuel stabilizer is commonly used for small engines such as lawnmower and tractor engines to promote quicker and more reliable starting.

External links

Information:
- [http://www.faqs.org/faqs/autos/gasoline-faq Gasoline FAQ]
- [http://zfacts.com/p/35.html Graph of inflation-corrected historic prices, 1970-2005. Highest in 1981]
- [http://www.fact-sheets.com/cars/high_octane_gas/ High Octane Gasoline - Fact Sheet]
- [http://www.sefsc.noaa.gov/HTMLdocs/Gasoline.htm Gasoline MSDS (material safety data sheet)] includes composition, flash point, handling precautions, etc.
- [http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm FTC: The Low-Down on High Octane Gasoline]
- An [http://www.gasresources.net/Introduction.htm introduction to the modern petroleum science], and to the Russian-Ukrainian theory of deep, abiotic petroleum origins.
- [http://www.straightdope.com/columns/041008.html What's the difference between premium and regular gas?] (from The Straight Dope)
- [http://www.epa.gov/otaq/regs/fuels/additive/mmt_cmts.htm MMT-US EPA] Data
- [http://tonto.eia.doe.gov/oog/info/gdu/gasdiesel.asp EIA - Gasoline and Diesel Fuel Update]
- [http://www.gtz.de/en/themen/umwelt-infrastruktur/transport/10285.htm International Fuel Prices 2005] with diesel and gasoline prices of 172 countries
- [http://www.petrolgauge.com PetrolGauge] UK & Ireland Interactive Petrol/Diesel Price Wiki
- [http://www.petrolprices.com Petrol Prices] Prices at 10,000 UK petrol stations updated daily. Other
- [http://www.gasresources.net/DisposalBioClaims.htm Dismissal of the Claims of a Biological Connection for Natural Petroleum.]
- [http://www.stanford.edu/~bmoses/knock.html All About Engine Knock (and Other Mysteries of Internal Combustion)] Good paper on why knocks happen...
- [http://journeytoforever.org/biofuel_library/ethanol_motherearth/me2.html#table Durability of various plastics: Alcohols vs. Gasoline] What plastics store gasoline the best. Images
- "[http://www.archive.org/movies/details-db.php?collection=prelinger&collectionid=19334&from=collectionSpotlight Down the Gasoline Trail]" Handy Jam Organization, 1935 (Cartoon) category:engine technology Category:Petroleum products ja:ガソリン

Diesel

:This article is about the fuel. For other uses see diesel (disambiguation) Diesel or Diesel fuel is a specific fractional distillate of fuel oil (mostly petroleum) that is used as fuel in a diesel engine invented by German engineer Rudolf Diesel. The term typically refers to fuel that has been processed from petroleum, but increasingly, alternatives such as biodiesel or biomass to liquid (BTL) or gas to liquid (GTL) diesel that are not derived from petroleum are being developed.

Petroleum diesel

gas to liquid Diesel is produced from petroleum, and is sometimes called petrodiesel (or, less seriously, dinodiesel) when there is a need to distinguish it from diesel obtained from other sources. As a hydrocarbon mixture, it is obtained in the fractional distillation of crude oil between 250 °C and 350 °C at atmospheric pressure. Petro Diesel is considered to be a fuel oil and is about 18% heavier than gasoline. Diesel typically weighs about 7.1 pounds (lb) per US gallon (gal.) (850 grams per liter (g/l)), whereas gasoline weighs about 6.0 lb per US gal. (720 g/l), or about 15% less. When burnt diesel typically releases about 147,000 British thermal units (BTU) per US gal. (40.9 megajoules (MJ) per liter), whereas gasoline releases 125,000 BTUs per US gal. (34.8 MJ/l), also about 15% less. Diesel is generally simpler to refine than gasoline and often costs less (although price fluctuations often mean that the inverse is true; for example, the cost of diesel traditionally rises during colder months as demand for heating oil, which is refined much the same way, rises). Diesel fuel, however, often contains higher quantities of sulfur. In Europe, emission standards and preferential taxation have both forced oil refineries to dramatically reduce the level of sulfur in diesel fuels. In contrast, the United States has long had "dirtier" diesel, although more stringent emission standards have been adopted with the transition to ultra-low sulfur diesel (ULSD) occurring in 2006 (see also diesel exhaust). US diesel fuel typically also has a lower cetane number (a measure of ignition quality) than European diesel, resulting in worse cold weather performance and some increase in emissions. High levels of sulfur in diesel are harmful for the environment. It prevents the use of catalytic diesel particulate filters to control diesel particulate emissions, as well as more advanced technologies, such as nitrogen oxide (NOx) adsorbers (still under development), to reduce emissions. However, lowering sulfur also reduces the lubricity of the fuel, meaning that additives must be put into the fuel to help lubricate engines. Biodiesel is an effective lubricity additive. Diesel contains approximately 18% more energy per unit of volume than gasoline, which, along with the greater efficiency of diesel engines, contributes to fuel economy (distance traveled per volume of fuel consumed). In the maritime field various grades of diesel fuel are used.

Chemical composition

Petroleum derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes).

Synthetic diesel

Wood, straw, corn, garbage, and sewage-sludge may be dried and gasified. After purification the so called Fischer Tropsch process is used to produce synthetic diesel. Other attempts use enzymatic processes and are also economic in case of high oil prices. Synthetic diesel may also be produced out of natural gas in the GTL process. Such synthetic diesel has 30% less particulate emissions than conventional diesel (US- California) .

Biodiesel

Biodiesel can be obtained from vegetable oil and animal fats (bio-lipids, using transesterification). Biodiesel is a non-fossil fuel alternative to petrodiesel. It can also be mixed with petrodiesel in any amount in modern engines, though it is a strong solvent and can cause problems in some cases. There have been reports that a diesel-biodiesel mix results in lower emissions than either can achieve alone. A small percentage of biodiesel can be used as an additive in low-sulfur formulations of diesel to increase the lubricating ability that is lost when the sulfur is removed. Chemically, biodiesel consists of alkyl (usually methyl) esters instead of the alkanes and aromatic hydrocarbons of petroleum derived diesel. However, biodiesel has combustion properties very similar to regular diesel, including combustion energy and cetane ratings.

Uses

Diesel fuel is very similar to heating oil which used in central heating. In both Europe and the United States, taxes on diesel fuel are higher than on heating oil, and in those areas, heating oil is marked with dye and trace chemicals to prevent and detect tax fraud. Similarly, "untaxed" diesel is available in the United States, which is available for use primarily in agricultural applications such as for tractor fuel. This untaxed diesel is also dyed red for identification purposes, and should a person be found to be using this untaxed diesel fuel for a typically taxed purpose (such as "over-the-road", or driving use), the user can be fined $10,000 USD on the spot. Also, in the United Kingdom and Ireland it is known as red diesel, and is also used by agricultural vehicles. The term DERV (short for "diesel engined road vehicle") is also used in the UK as a synonym for diesel fuel. Diesel is used in diesel engines, a type of internal combustion engine. Rudolf Diesel originally designed the diesel engine to use coal dust as a fuel, but oil proved more effective. Diesel engines are used in cars, trucks, motorcycles, boats and locomotives. Packard diesel motors were used in aircraft as early as 1927, and Charles Lindbergh flew a Stinson SM1B with a Packard Diesel in 1928. A Packard diesel motor designed by L.M. Woolson was fitted to a Stinson X7654, and in 1929 it was flown 1000 km non-stop from Detroit to Langley, Virginia (near Washington, D.C.). In 1931, Walter Lees and Fredrick Brossy set the nonstop flight record flying a Bellanca powered by a Packard Diesel for 84h 32m. The very first diesel-engine automobile trip was completed on January 6, 1930. The trip was from Indianapolis to New York City - a distance of nearly 800 miles (1300 km). This feat helped to prove the usefulness of the internal combustion engine. The following year Dave Evans drove his Cummins Diesel Special to a nonstop finish in the Indianapolis 500, the first time a car had completed the race without a pit stop. That car and a later Cummins Diesel Special are on display at the Indianapolis Motor Speedway Hall of Fame Museum. Westport claims to have invented a process called Westport-Cycle with comparable efficiency using natural gas and petrodiesel.

Notes

# Agency for Toxic Substances and Disease Registry (ATSDR). 1995. [http://www.atsdr.cdc.gov/toxprofiles/tp75-c3.pdf Toxicological profile for fuel oils]. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service # # # #

External links

- [http://www.straightdope.com/mailbag/mdieselvsgas.html Can I use diesel fuel instead of regular gas?] (from The Straight Dope)
- [http://www.dieselnet.com/standards/fuels/us.html DieselNet.com: US Diesel Fuel]
- [http://www.greencarcongress.com/2005/07/opel_offers_par.html Opel announces particulate filter] Category:Petroleum products category:engine technology Category:Solvents Category:German loanwords ko:경유 ja:軽油

Cylinder (engine)

A cylinder in an internal combustion engine or external combustion engine is the space within which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or 'block'. A cylinder block is typically cast from aluminum or cast iron before precision features are machined into it. The cylinders may then be lined with 'sleeves' of some harder metal, or given a wear-resistant coating such as