The diesel engine (also known as compression-ignition or CI engine ), named Rudolf Diesel, is an internal combustion engine in which a fuel ignition injected into the combustion chamber caused by an increase in air temperature in the cylinder due to mechanical compression (adiabatic compression). Diesel engines work only by compressing air. This increases the air temperature inside the cylinder so high that the sprayed diesel fuel injected into the combustion chamber lights up spontaneously. This is in contrast to the spark-ignition engines such as gasoline engines (gasoline engines) or gas engines (using gas fuel as opposed to gasoline), which uses spark plugs to ignite the fuel-air mixture. In diesel engines, sparkplugs (burning fuel cell preilepers) can be used to help get started in cold weather, or when the machine uses a lower compression ratio, or both. Original diesel engines operate at a gradual "constant pressure" cycle of burning and do not produce audible beats.
Diesel engines have the highest thermal efficiency (engine efficiency) of any internal or external combustion engine practically because of the very high expansion ratio and the inherent burns that allow heat dissipation by excess air. A small efficiency loss is also avoided compared to a two-stroke non-direct-injection gasoline engine because unburned fuel is not present in the overlap of the valve and therefore no direct fuel from the intake/injection to the exhaust. Low speed diesel engines (such as those used in ships and other applications where overall machine weight is relatively insignificant) can have thermal efficiencies that exceed 50%.
Diesel engines can be designed as a two-step or four-step cycle. They were originally used as a more efficient substitute for stationary steam engines. Since the 1910s they have been used in submarines and ships. Use in locomotives, trucks, heavy equipment and power plants followed later. In the 1930s, they slowly began to be used in some cars. Since the 1970s, the use of diesel engines in larger on-road and off-road vehicles in the US has increased. According to the British Society of Motor Manufacturing and Traders, the average EU for diesel cars accounts for 50% of total sales, including 70% in France and 38% in the UK.
The world's largest diesel engine, which began operating in 2006, is the WÃÆ'¤rtsilÃts¤-Sulzer RTA96-C Common Rail, which produces peak power output of 84.42 MW (113,210 hp) at 102 rpm.
Video Diesel engine
History
The definition of "Diesel" engine for many people has become a machine that uses compression ignition. For some it may be a machine that uses heavy fuel oil. For others machines that do not use ignition plugs. However the original cycle proposed by Rudolf Diesel in 1892 was a constant temperature cycle (cycle based on Carnot theory) which would require much higher compression than was necessary for compression ignition. The idea of ​​Diesel is to compress the air so strong that the air temperature will exceed the burning. In 1892, US patent (granted in 1895) # 542846 Diesel describes the compression required for its cycle:
- "pure atmospheric air is compressed, in accordance with curve 1 2, such that, before ignition or combustion occurs, the highest diagram and highest temperature pressure is obtained - that is, the temperature at which the next combustion must occur, not the point burning or triggering. To make this clearer, suppose that the next combustion should occur at a temperature of 700 °. Then in that case the initial pressure should be sixty-four atmospheres, or for 800 ° celsius pressure should be ninety atmospheres, and so on. the compressed air is then gradually introduced from exterior-separated fuel, which ignites on the introduction, since the air is at a temperature well above the fuel point. The characteristic feature of the cycle according to my present invention is the increase in pressure and temperature to a maximum, not with combustion, but before combustion by my compressed air in the air, and there after the work performance next without increasing pressure and temperature with incremental combustion during the determined portion of the stroke determined by cut-oil ".
In the following years Diesel realized his initial cycle would not work and he adopted a constant pressure cycle. Diesel describes the cycle in its patent application in 1895. Note that there is no mention of compression temperatures beyond combustion temperatures. Now all that mentioned is compression must be high enough for ignition.
- "1. In an internal combustion engine, the combination of cylinders and pistons is built and regulated to compress air to degrees that produce temperatures above the fuel point, supply for compressed air or gas, fuel supply, distribution valves for fuel, the channel from the air supply to the cylinder in communication with the fuel distribution valve, the inlet to the cylinder in communication with the air supply and with the fuel valve, and the cutting oil, substantially as described. "See US patent # 608845 submitted 1895/awarded 1898
History shows that the invention of the Diesel engine is not solely based on the idea of ​​one person, but is the culmination of many different ideas developed over time.
In 1806, Claude and NicÃÆ'Â © phore NiÃÆ'Â © pce (brother) developed the first known internal combustion engine and first fuel injection system. The PyrÃÆ' Â © olophore fuel system uses an air burst provided by a bellows to spray Lycopodium (a highly combustible fuel made of broad moss). Then coal dust is mixed with resin into fuel. Finally in 1816 they experimented with alcohol and white oil oil (a fuel similar to kerosene). They found that kerosene type fuels can be vaporized smoothly by passing it through a device of a kind of reed, which makes the fuel extremely combustible.
In 1874, George Brayton developed and patented 2 strokes, a constant pressure oil-fueled engine "The Ready Motor". This machine uses a scalable pump to supply fuel to the injection device where it is vaporized by air and burned when it enters the cylinder. These are some of the first practical internal combustion engines to supply motive power. Brayton machines are installed in several ships, train cars, 2 submarines and buses. Early Diesel engines use the same cycle.
Throughout the 1880s, Brayton kept trying to improve his engine. In 1887, Brayton developed and patented a 4-step direct injection oil machine (US Patent # 432,114 from 1890, application filed in 1887) Fuel system uses variable quantity pumps and injection type high-pressure liquid fuel spray. The liquid is forced through a spring-loaded spring type (injector) valve that causes the fuel to be split into tiny droplets (vaporized). The time injection occurs at or near the peak of stroke compression. A platinum igniter or ignitor provides a source of ignition. Brayton describes this discovery as follows: "I have found that heavy oils can be mechanically transformed into finely divided conditions within the cylinder ignition section, or in a communicating firing space." Another passage reads "I have for the first time, as far as my knowledge is expanding, the speed regulated by controlling differently direct discharge of liquid fuel into the combustion chamber or cylinder into finely divided conditions is very advantageous for immediate combustion". This may be the first machine to use a sleek burning system to adjust the speed/output of the engine. In this way, the machine is powered on each power attack and the speed/output is controlled only by the amount of fuel injected.
In 1890, Brayton developed and patented a 4-stroke air blast oil engine (US Pat. # 432,260) The fuel system transmits a variable amount of fuel that evaporates to the center of the cylinder under pressure at or near the top of the compression. The ignition source is a flame made of platinum wire. The variable quantity injection pump provides fuel to the injector where it is mixed with air as it enters the cylinder. Small crank compressors provide air sources. This machine also uses a slim combustion system.
Brayton died in 1893, but will be credited with the invention of the Brayton cycle of constant pressure.
In 1885, the British inventor Herbert Akroyd Stuart began investigating the possibility of using paraffin oil (very similar to modern solar) to the engine, which unlike gasoline would be difficult to evaporate in the carburetor because of its insufficient volatility to allow this..
Hotbob machine, first made in 1886 and built from 1891 by Richard Hornsby and Sons, uses a low pressure fuel injection system. The Hornsby-Akroyd oil machine uses a comparatively low compression ratio, so the temperature of the compressed air in the combustion chamber at the end of the compression step is not high enough to start combustion. Combustion takes place in a separate combustion chamber, "vaporizer" or "hot ball" mounted on the cylinder head, where fuel is sprayed. Self-ignition occurs from the contact between the air-fuel mixture and the hot vaporizer wall. As the engine load increases, so does the temperature of the bulb, causing the ignition period to advance; to ward off pre-ignition, water dripping into the air intake.
In 1892, Akroyd Stuart patented a water-jacketed vaporizer to allow an improved compression ratio but mainly to reduce automatic ignition problems at higher loads and compression ratios. That same year, Thomas Henry Barton at Hornsbys built a high-compression version that served for experimental purposes, where the vaporizer was replaced with a cylinder head, therefore not dependent on preheated air, but by combustion through higher compression ratios. It runs for six hours - the first automatic ignition is produced by compression alone, but the claim is not proven by any source and since then until 1907 the hotbulb machine should be filled with fuel in the intake step, although apart from the air, such a machine would be vulnerable against failure, poor performance or extreme damage due to pre-ignition.
Herbert Akroyd Stuart was a pioneer in developing heat-assisted compression ignition retained from burning in a bulb, Rudolf Diesel, however, then credited with a true compression ignition engine relying solely on heat compression and no other form of heat retained. Higher compression and thermal efficiency along with fuel injection time and fuel evaporation through the injection system and not by the heated surface is what distinguishes Solar patents from 3,500 kilopascals (508 psi).
In 1892, Diesel received patents in Germany, Switzerland, the United Kingdom, and the United States for "Methods and Tools to Turn Heat into Jobs". In 1893, he described the "slow-burning machine" that first compressed the air so as to raise the temperature above the fuel point, then gradually introducing the fuel while allowing the mixture to expand "against sufficient resistance to prevent significant temperature rise and pressure" then cutting fuel and "developing without heat transfer". In 1894 and 1895, he filed patents and addenda in different countries for his Diesel engine; the first patents issued in Spain (No. 16,654), 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) 1898. He operated his first successful machine in 1897.
The diesel internal combustion engine differs from the Otto cycle of gasoline powered by using highly compressed hot air to ignite the fuel rather than using spark plug ( ignition compression rather than ignition spark plug ).
In a true diesel engine, only air is initially put into the combustion chamber. Air is then compressed with a compression ratio usually between 15: 1 and 23: 1. This high compression causes the air temperature to rise. At about the top of the compression step, the fuel is injected directly into the compressed air in the combustion chamber. This may be a void (usually toroidal) at the top of the piston or pre-chamber depending on the engine design. Fuel injectors ensure that the fuel is broken down into small droplets, and that the fuel is distributed evenly. The heat from the compressed air evaporates the fuel from the surface of the droplets. The vapor is then turned on by heat from compressed air in the combustion chamber, the droplets continue to evaporate from its surface and burn, smaller, until all the fuel in the droplets has burned. Burning takes place at a very constant pressure during the initial part of the power movement. Initial vaporization causes delays before ignition and unique diesel-tapping sounds when the steam reaches the ignition temperature and causes a sudden increase of pressure above the piston (not shown on the P-V indicator diagram). When the combustion is complete, the combustion gases expands when the piston falls further; High pressure in the cylinder pushes the piston down, supplying power to the crankshaft.
As well as a high level of compression allowing combustion to take place without a separate ignition system, the high compression ratio greatly improves engine efficiency. Increase the compression ratio in a spark-ignition engine in which fuel and air are mixed before entering the cylinder is limited by the need to prevent pre-ignition damage. Because only the air is compressed in a diesel engine, and the fuel is not inserted into the cylinder until just before the top dead center (TDC), premature detonation is not a problem and the compression ratio is much higher.
The p-V diagram is a simple and ideal representation of the events involved in the Diesel engine cycle, set to illustrate the similarities to the Carnot cycle. Starting from 1, the piston is at the bottom down center and both valves are closed at the beginning of the compression step; cylinder containing air at atmospheric pressure. Between 1 and 2 air is compressed adiabatically - ie without heat transfer to or from the environment - by the rise of the piston. (This is only about right because there will be heat exchange with the cylinder wall.) During this compression, the volume decreases, the pressure and temperature increases. At or slightly before 2 (TDC) of fuel is injected and burned in compressed hot air. Chemical energy is released and this is an injection of heat energy (heat) into compressed gas. Burning and heating occur between 2 and 3. In this interval the pressure remains constant since the piston falls, and the volume increases; temperature rises as a consequence of burning energy. In 3 fuel injections and burning is complete, and the cylinder contains gas at a temperature higher than 2. Between 3 and 4 the hot gas is expanding, again approximately adiabatically. The work is done on a system connected to the machine. During this expansion phase the volume of gas increases, and the temperature and pressure drops. At 4 open exhaust valves, and the pressure falls suddenly into the atmosphere (roughly). This is an expansion that is not sustained and no useful work is done by it. Ideally, adiabatic expansion should continue, extending the 3-4 lines to the right until the pressure falls into the surrounding air, but the loss of efficiency caused by this unresolved expansion is justified by the practical difficulties involved in the recovery (machine). should be much larger). After the opening of the exhaust valve, the exhaust follows, but this (and the following induction stroke) is not shown on the diagram. If displayed, they will be represented by a low-pressure loop at the bottom of the diagram. At 1 it is assumed that the exhaust and induced scratches have been completed, and the cylinder again filled with air. The piston-cylinder system absorbs energy between 1 and 2 - this is the job required to compress the air inside the cylinder, and is provided by the mechanical kinetic energy stored in the engine flywheel. The work output is performed by a combination of pistons between 2 and 4. The difference between these two increases is the work output shown per cycle, and is represented by the area covered by the p-V loop. Adiabatic expansion is in a higher pressure range than compression because the gas in the cylinder is hotter during expansion than during compression. For this reason the loop has a limited area, and the net work output during the positive cycle.
Main advantages
Initial fuel injection system
The original Diesel engine injects fuel with the aid of compressed air, which sprays fuel and forces it into the engine through the nozzle (the same principle as aerosol sprays). The opening of the nozzle is closed by the valve pin lifted by the camshaft to start fuel injection before the top dead center (TDC). This is called air-blast injection . Driving the compressor uses some power but efficiency and cleaner power output over other combustion engines at that time.
The diesel engine in service today raises fuel to extreme pressure by the mechanical pump and drives it into the combustion chamber by the pressurized injector switched on without compressed air. With direct injection, the injector sprays fuel through 4 to 12 small holes in the nozzle. The initial air injection diesel always has superior combustion without a sharp increase in pressure during combustion. Research is now underway and patents are being taken again to use some form of air injection to reduce nitrogen oxide and pollution, back to the original implementation of Diesel with superior combustion and possibly quieter operation. In all major aspects, modern diesel engines apply to the original design of Rudolf Diesel, which ignites fuel with compression at very high pressure inside the cylinder. With much higher pressures and high-tech injectors, today's diesel engines use a solid injection system used by George Brayton for the 1887 Brayton direct injection machine. The indirect injection machine can be regarded as the latest development of the hot bulb ignition machine.
Shipping fuel
Over the years, many different methods of injecting have been used. This can be described as follows.
- An air burst, where fuel is blown into the cylinder by the blast of air.
- Solid fuel/hydraulic injection, in which fuel is pushed through a spring loaded valve/injector to produce a combustible fog.
- The injector of the mechanical unit, in which the injector is operated directly by the cam and the fuel quantity is controlled by a shelf or lever.
- Injector of a mechanical electronic unit, in which the injector is operated by the cam and the quantity of fuel is electronically controlled.
- General rail mechanical injection, in which the fuel is at high pressure in the general rail and is mechanically controlled.
- General electronic injection rail, in which the fuel is at high pressure in the general rail and electronically controlled.
Diesel engines are also produced with two different injection sites: "direct" and "indirect." The indirect injection machine puts the injector inside the pre-burning chamber on the head, which, due to heat loss, generally requires a "light plug" to start and a very high compression ratio, usually between 21: 1 and 23: 1. Direct injection machine using the donut-shaped combustion chamber is generally vacuum-shaped on the top of the piston. Thermal efficiency losses are significantly lower in DI engines that facilitate much lower compression ratios, generally between 14: 1 and 20: 1 but most DI engines are closer to 17: 1. The direct injection (DI) process is significantly more internal violence thus requiring careful design and stronger construction. The lower compression ratio also creates challenges for emissions due to partial burns. Turbocharging is particularly suitable for DI engines because low compression ratios facilitate significant forced induction. Increased airflow enables capturing additional fuel efficiency, not only from better combustion, but also decreases the parasitic efficiency loss when operated properly, widening the power curve and efficiency. The rough combustion process of direct injection also creates more noise, but modern designs using a "split shot" injector or similar multishot process have dramatically improved the problem by firing a small load of fuel before the main delivery, which pre-filled the fuel chamber for less suddenly, and in many cases a little cleaner, burning. {reference?}
The vital component of all diesel engines is the mechanical or electronic governor that controls the idle speed and maximum speed of the engine by controlling the fuel delivery rate. Unlike the Otto-cycle engine, the incoming air is not suffocating and the diesel engine without the governor can not have a stable idling speed and can easily surpass the speed, resulting in its destruction. The mechanically adjusted fuel injection system is controlled by the engine gears. This system uses a combination of spring and load to control fuel delivery relative to load and speed. Modern electronically controlled diesel engines control fuel delivery by using electronic control module (ECM) or electronic control unit (ECU). The ECM/ECU receives machine speed signals, as well as other operating parameters such as intake manifold pressure and fuel temperature, from sensors and controls the amount of fuel and start injection time through actuators to maximize power and efficiency while minimizing emissions. Controlling the start time of fuel injection into the cylinder is key to minimizing emissions, and maximizing fuel savings (efficiency), from the engine. The time is measured in the degree of crank piston angle before the upper center dies. For example, if ECM/ECU initiates fuel injection when piston 10 Â ° before TDC, initial injection, or timing, it is said 10 Â ° BTDC. Optimal time will depend on engine design and speed and load, and typically 4 Â ° BTDC at 1,350-6,000 HP, net, "medium speed" locomotives, marine and stationary diesel engines.
Advancing the start of injection (injecting before the piston reaches SOI-TDC) results in higher pressure and temperature in the cylinder, and higher efficiency, but also results in increased engine noise due to faster cylinder pressure increases and increased nitrogen oxide (NO x ) formation due to higher combustion temperatures. Delays begin injection leading to incomplete combustion, reducing fuel efficiency and increased exhaust fumes, containing large amounts of particulate matter and unburned hydrocarbons. {need quotes}
Mechanical and electronic injection
Many fuel injection configurations have been used during the 20th century.
Most current diesels use high pressure mechanical pressure pumps driven by crankshaft engines. For each engine cylinder, the corresponding plunger in the fuel pump measures the correct amount of fuel and determines the timing of each injection. This machine uses an injector which is a very precise spring valve that opens and closes at a certain fuel pressure. A separate high-pressure fuel line connects the fuel pump with each cylinder. The fuel volume for each single combustion is controlled by a sloping groove in a rotating plunger just a few degrees of pressure release and controlled by a mechanical governor, consisting of rotating weights at engine speeds limited by springs and levers. The injector is held open by the fuel pressure. In high-speed engines, the propulsion pumps are united in one unit. The fuel channel length from the pump to each injector is usually the same for each cylinder to obtain the same pressure delay.
The cheaper configuration on high-speed machines with fewer than six cylinders is to use axial-piston distributor pump, which consists of one rotating pump plunger that sends fuel to the valves and channels for each cylinder (functionally analogous to the distributor's point and cap on Otto machine).
Many modern systems have a single fuel pump that supplies constant fuel at high pressure with a common rail (common single fuel line) to each injector. Each injector has a solenoid operated by an electronic control unit, providing more accurate injector opening controls that depend on other control conditions, such as engine speed and loading, and provides better engine performance and fuel economy.
Both mechanical and electronic injection systems can be used either in direct or indirect injection configuration.
Two-stroke diesel engines with mechanical injection pumps can be accidentally run in reverse, albeit in a very inefficient way, possibly damaging the engine. The large two-stroke diesel vessel is designed to run in both directions, negating the need for a gearbox.
Indirect injection
The indirect diesel injection engine (IDI) system sends fuel into a small space called a vortex chamber, pre combustion chamber, pre or ante-chamber chamber, which is connected to the cylinder by a narrow air passage. Generally the purpose of pre space is to create increased turbulence for better air/fuel mixing. The system also allows the engine to run smoother and quieter, and since fuel mixing is aided by turbulence, the injector pressure can be lower. Most IDI systems use one orifice injector. Pre-chamber has a weakness in lowering efficiency due to increased heat loss to the engine cooling system, limiting combustion combustion, thus reducing efficiency by 5-10%. IDI machines are also more difficult to start and usually require the use of light plugs. IDI machines may be cheaper to build but generally require higher compression ratios than DI peers. IDI also makes it easier to build smoother and quieter machines with a simple mechanical injection system because the right injection timing is not so important. Most modern automotive engines are DIs that have higher efficiency advantages and easier startups; However, IDI machines can still be found in many ATVs and small diesel applications.
Direct injection
Direct injection diesel engines inject fuel directly into the cylinder. There is usually a burning cup at the top of the piston where fuel is sprayed. Many different injectable methods can be used.
Electronic control of the fuel injection alters the direct injection engine by allowing greater control over combustion.
Direct Injection unit
The direct injection unit also injects fuel directly into the engine cylinder. In this system the injectors and pumps are combined into one unit positioned above each cylinder controlled by the camshaft. Each cylinder has its own unit which removes the high pressure fuel line, achieving more consistent injection. This type of injection system, also developed by Bosch, is used by Volkswagen AG in automobiles (where it is called Pumpe-DÃÆ'¼se-System - literally <-a nozzle pump system ) and by Mercedes-Benz ("PLD") and most of the diesel engine manufacturers in large commercial machines (MAN SE, CAT, Cummins, Detroit Diesel, Electro-Motive Diesel, Volvo). With recent advances, pump pressure has been increased to 2,400 bar (240 MPa, 35,000 psi), allowing injection parameters similar to common rail systems.
Direct rail direct injection
The "Common Rail" injection was first used in production by Atlas Imperial Diesel in the 1920s. Railway pressure is kept at 2,000 - 4,000 psi. In the needle injector is mechanically lifted from the chair to make the injection event. Modern common rail systems use very high pressure. In this system, a machine-driven pump presses fuel up to 2,500 bar (250 MPa; 36,000 psi), in "common rail". A common rail is a tube that supplies each computer-controlled injector containing a precision-engine nozzle and a propellant driven by a solenoid or piezoelectric actuator.
Cold weather issue
Start
In cold weather, high-speed diesel engines can be difficult to start because the mass of cylinder blocks and cylinder heads absorb compression heat, preventing ignition due to higher surface to volume ratio. The pre-chamber machine utilizes a small electrical heater inside the pre-chamber called glowplugs, while the direct-injected engine has these glowplugs in the combustion chamber.
Many machines use resistive heaters in the intake manifold to warm the incoming air to start, or until the engine reaches its operating temperature. The engine block heater (electric resistivity heater in the engine block) connected to the utility grid is used in cold climates when the engine is shut down for longer periods (more than one hour), to reduce engine start and wear time. Heating block is also used for emergency standby powered diesel generator that must quickly take the load on power failure. In the past, a wider variety of cold-start methods were used. Some machines, such as the Detroit Diesel engine, use a system to introduce small amounts of ether into the inlet cuff to start combustion. Others use a mixed system, with a resistive heater that burns methanol. The impromptu method, especially on unsuitable engines, is to manually spray aerosol cans from the ether-based starter engine into the inlet air stream (usually through an intake air filter assembly).
Gelling
Diesel fuel is also susceptible to waxing or gelling in cold weather; both of which are terms for compacting diesel oil into partial crystals. Crystals are formed in the fuel system (especially in the fuel filter), eventually discharging the fuel engine and causing it to stop running. Low output electric heaters in the fuel tank and around the fuel line are used to solve this problem. Also, most machines have a spill return system, in which any excess fuel from the injector and injector pumps is returned to the fuel tank. Once the engine gets warm, the warm fuel back prevents waxing in the tank.
Due to improved fuel technology with additives, waxing is rare in all but the coldest weather when diesel and kerosene mixtures can be used to run vehicles. Gas stations in areas with cold climates are required to offer winter diesel in winter that allows operation under a special Cold Filtering Filtering Point. In Europe the diesel characteristics are described in EN 590 standard.
Supercharging and turbocharging
Many diesels are now turbocharged and there are both turbo charged and supercharged. Turbocharged engines can generate more power than natural aspirated engines of the same configuration. The supercharger is mechanically driven by the crankshaft engine, while the turbocharger is powered by an exhaust engine. Turbocharging can improve the fuel economy of diesel engines by recovering waste heat from the exhaust, increasing the excess air factor, and increasing the engine output ratio to frictional losses.
Two-stroke engines do not have different exhaust and input and are thus unable to self-aspirate. Therefore, all two-step engines must be equipped with a blower or some form of compressor to fill the cylinder with air and assist in dispensing the flue gas, a process known as scavenging. In some cases, the engine may also be equipped with a turbocharger, whose output is directed to the blower inlet.
Some designs use a hybrid/turbocharger blower to scroll and fill cylinders, which are mechanically driven at crank and low speeds to act as blowers, but which act as true turbochargers at higher speeds and loads. The hybrid turbocharger can return to compressor mode during commands for large increases in engine output power.
Because a turbocharged or supercharged engine produces more power for a given engine size than a naturally aspirated engine, attention should be paid to the mechanical design of components, lubrication and cooling to handle power. Pistons are usually cooled with lubricating oil sprayed on the underside of the piston. A large "low speed" engine can use water, seawater, or oil supplied through a telescoping pipe attached to the chapter title to cool the piston.
Maps Diesel engine
Type
Group size
There are three groups of diesel engine sizes
- Small - under 188 kW (252Ã, hp) output
- Medium
- Large
Basic types
There are two basic types of Diesel Engines
- Four stroke cycles
- Two stroke cycles
Initial
In 1897, when the first Diesel engine was completed, Adolphus Busch traveled to Cologne and negotiated exclusive rights to produce Diesel engines in the US and Canada. In the inspection of the engine, it was noted that Diesel at the time operated at a thermodynamic efficiency of 27%, while the regular expansion steam engine would operate at about 7-10%.
In the early decades of the 20th century, when a large diesel engine was first used, the engine took a shape similar to the common steam engine at the time, with a piston connected to the connecting rod by a crosshead bearing. After steam engine drills, some manufacturers make two-stroke diesel engines and two double steps to increase power output, with combustion taking place on both sides of the piston, with two sets of valve gears and fuel injection. While it produces large amounts of power, the main problem of diesel engines in double action is to produce a good seal where the piston rod passes the bottom of the lower combustion chamber to the crosshead bearings, and nothing else is built. In the 1930s turbochargers were fitted to multiple machines. Crosshead bearings are still used to reduce wear on cylinders in main engines of long-strokes.
High speed and medium modern machines
Like gasoline engines, there are two classes of diesel engines used today: two-stroke and four-stroke. The four-stroke type is the "classic" version, tracing its line back to Rudolf Diesel's prototype. It is also a more common form of use, becoming the preferred source of electricity for many motor vehicles, especially buses and trucks. Larger machines, such as those used for marine propulsion and railway propulsion, are often a two-step unit, offering a more favorable weight-to-weight ratio, as well as better fuel economy. The most powerful engine in the world is a two-stroke diesel engine from the mammoth dimension.
The operation of a two-stroke diesel engine is the same as that of a gasoline counterpart, except that the fuel is not mixed with air before induction, and the crankcase does not take an active role in the cycle. The traditional two-step design relies on a mechanically-driven positive displacement blower to fill the cylinder with air before compression and ignition. The charging process also helps in warding off the burning residue from the previous power remaining.
The modern form of a two-stroke diesel is based on the efforts of Charles F. "Boss" Kettering and his colleagues at General Motors Corporation, who devised an aspirating system in which the blower suppressed the space in the engine block often referred to as "air box," and the exhaust gas which is scavenged under pressure from the air intake (uniflow scavenging). The concept was introduced to the Winton 201A machine in 1933, which was used in locomotive manufacture from 1934 to 1938 and on submarines. Experience with Winton 201A was used in the development of GM 567 locomotive engine introduced in 1938, which launched the American railway dieselization and from which then 645 and 710 engines originated. However, the significant improvement built into most of the next EMD engines is a mechanically assisted turbo-compressor, which provides air charge using mechanical assistance during start (thereby eliminating the need for blown root decay), and providing air charge using the exhaust gas which are turbine driven during normal operation - thereby providing the actual turbocharging and also increasing the engine power output by at least fifty percent. Also in 1938, GM piloted two-stroke Diesel engine with the Detroit Diesel Series 71 engine (high speed), bringing Diesel power into shape suitable for smaller trucks, buses and boats. In 2015, Electro-Motive Diesel shifted its emphasis to four-stroke locomotive in order to meet ASEP Tier 4 emission requirements, introducing the 1010J engine.
In a two-step diesel engine, when the cylinder piston approaches the bottom port or the lower exhaust valve is opened, releases most of the excess pressure, after which the channel between the air box and the cylinder is opened, allowing airflow into the cylinder. The airflow blows the remaining combustion gases from the cylinder - this is a scavenging process. When the piston passes through the bottom center and starts up, the channel is closed and compression begins, culminating in fuel injection and ignition. See the two-stroke diesel engine for a more detailed coverage of the aspiration type and supercharging of a two-stroke diesel engine.
Typically, the number of cylinders is used in multiples of two, although a number of cylinders can be used as long as the load on the crankshaft is offset to prevent excessive vibration. The inline six-cylinder design is the most productive in light to medium-sized engines, although the small V8 engine and the larger inline-four displacement engine are also common. Small-capacity engines (generally considered to be below five liters) are typically four or six cylinders, with four cylinders the most common type found in automotive use. The five-cylinder diesel engine has also been produced, being a compromise between the smoothness of the six-cylinder and the space-efficient dimensions of the four-cylinder. Diesel engines for smaller engine plants, ships, tractors, generators and pumps may consist of four, three or two cylinders, with one-cylinder diesel engine remaining for light stationary work. Direct reversible two-stroke marine diesels require at least three cylinders to reliably restart forward and backward, while four-stroke diesels require at least six cylinders.
The desire to increase the power-to-weight ratio of diesel engines results in several new cylindrical arrangements to extract more power from the given capacity. The uniflow opponent-piston engine uses two pistons in a single cylinder with a central combustion cavity and an inlet gas and an outlet at the end. This makes the engine relatively lightweight, powerful, fast and economical for use in flight. An example is Junkers Jumo 204/205. The Delicate Napier engine, with three cylinders arranged in a triangular formation, each containing two opposing pistons, the entire engine having three crankshafts, is one of the better known.
Gas generator
Prior to 1950, Sulzer began experimenting with a two-stroke engine with a high-level boost pressure of 6 atmospheres, in which all the output power was taken from the exhaust gas turbine. The direct two-stroke piston pushes the air compressor piston to create a positive displacement gas generator. Supported pistons are connected by relationships rather than crankshafts. Some of these units can be connected to provide gas power to one large output turbine. The overall thermal efficiency is approximately twice that of a simple gas turbine. This system is derived from the work of RaÃÆ'ºl Pateras Pescara on a free piston engine in the 1930s.
The advantages and disadvantages of spark plug engines
Fuel economy
Low-speed diesel engine MAN S80ME-C7 uses 155 grams (5.5 oz) of fuel per kWh for an overall energy conversion efficiency of 54.4%, which is the highest conversion of fuel into power by any single internal or external combustion engine cycle (System efficiency combined cycle gas turbines may exceed 60%.) Diesel engines are more efficient than gasoline (petrol) engines with the same power rating, resulting in lower fuel consumption. The same margin is 40% more miles per gallon for efficient turbodiesel. For example, the current model? Koda Octavia, using the Volkswagen Group engine, has a combined Euro rating of 6.2Ã, L/100Ã, km (46 mpg -imp ; 38 mpg -US ) for
Source of the article : Wikipedia
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