Diesel particulate filter

A diesel particulate filter (DPF) is a device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine. A diesel particulate filter (top left) in a Peugeot Off-road - DPF Installation Mode of action Wall-flow diesel particulate filters usually remove 85% or more of the soot, and under certain conditions can attain soot removal efficiencies approaching 100%. Some filters are single-use, intended for disposal and replacement once full of accumulated ash. Others are designed to burn off the accumulated particulate either passively through the use of a catalyst or by active means such as a fuel burner which heats the filter to soot combustion temperatures. This is accomplished by engine programming to run (when the filter is full) in a manner that elevates exhaust temperature, in conjunction with an extra fuel injector in the exhaust stream that injects fuel to react with a catalyst element to burn off accumulated soot in the DPF filter, or through other methods. This is known as "filter regeneration". Cleaning is also required as part of periodic maintenance, and it must be done carefully to avoid damaging the filter. Failure of fuel injectors or turbochargers resulting in contamination of the filter with raw diesel or engine oil can also necessitate cleaning. The regeneration process occurs at road speeds higher than can generally be attained on city streets; vehicles driven exclusively at low speeds in urban traffic can require periodic trips at higher speeds to clean out the DPF. If the driver ignores the warning light and waits too long to operate the vehicle above 40 miles per hour (64 km/h), the DPF may not regenerate properly, and continued operation past that point may spoil the DPF completely so it must be replaced. Some newer diesel engines, namely those installed in combination vehicles, can also perform what is called a Parked Regeneration, where the engine increases RPM to around 1400 while parked, to increase the temperature of the exhaust. Diesel engines produce a variety of particles during combustion of the fuel/air mix due to incomplete combustion. The composition of the particles varies widely dependent upon engine type, age, and the emissions specification that the engine was designed to meet. Two-stroke diesel engines produce more particulate per unit of power than do four-stroke diesel engines, as they burn the fuel-air mix less completely. Diesel particulate matter resulting from the incomplete combustion of diesel fuel produces soot (black carbon) particles. These particles include tiny nanoparticles—smaller than a thousandth of a millimeter (one micron). Soot and other particles from diesel engines worsen the particulate matter pollution in the air...

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Exhaust manifold

In automotive engineering, an exhaust manifold collects the exhaust gases from multiple cylinders into one pipe. The word manifoldcomes from the Old English word manigfeald (from the Anglo-Saxon manig  and feald ) and refers to the folding together of multiple inputs and outputs (in contrast, an inlet or intake manifold supplies air to the cylinders). Exhaust manifolds are generally simple cast iron or stainless steel units which collect engine exhaust gas from multiple cylinders and deliver it to the exhaust pipe. For many engines, there are aftermarket tubular exhaust manifolds known as headers in American English, as extractor manifolds in British and Australian English, and simply as "tubular manifolds" in British English.These consist of individual exhaust headpipes for each cylinder, which then usually converge into one tube called a collector. Headers that do not have collectors are called zoomie headers. The most common types of aftermarket headers are made of mild steel or stainless steel tubing for the primary tubes along with flat flanges and possibly a larger diameter collector made of a similar material as the primaries. They may be coated with a ceramic-type finish (sometimes both inside and outside), or painted with a heat-resistant finish, or bare. Chrome plated headers are available but these tend to blue after use. Polished stainless steel will also color (usually a yellow tint), but less than chrome in most cases. Another form of modification used is to insulate a standard or aftermarket manifold. This decreases the amount of heat given off into the engine bay, therefore reducing the intake manifold temperature. There are a few types of thermal insulation but three are particularly common: Ceramic paint is sprayed or brushed onto the manifold and then cured in an oven. These are usually thin, so have little insulatory properties; however, they reduce engine bay heating by lessening the heat output via radiation. A ceramic mixture is bonded to the manifold via thermal spraying to give a tough ceramic coating with very good thermal insulation. This is often used on performance production cars and track-only racers. Exhaust wrap is wrapped completely around the manifold. Although this is cheap and fairly simple, it can lead to premature degradation of the manifold. The goal of performance exhaust headers is mainly to decrease flow resistance (back pressure), and to increase the volumetric efficiency of an engine, resulting in a gain in power output. The processes occurring can be explained by the gas laws, specifically the ideal gas law and the combined gas law. Diagram of an exhaust manifold from a Kia Rio. 1. manifold; 2. gasket; 3. nut; 4. heat shield; 5. heat shield bolt Ceramic-coated exhaust manifold on...

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Tuned exhaust

A tuned exhaust system is an exhaust system for an internal combustion engine which improves its efficiency by using precise geometry to reflect the pressure waves from the exhaust valve or port back to the valve or port at a particular time in the cycle. Ferrari V10 engine showing one of its two tuned extractor manifolds Two-stroke engines Yasuni aftermarket motor scooterexhaust system. The exhaust passes first through the expansion chamber at the bottom and then exits through the muffler above it. A conceptual animation of a two-stroke engine with a tuned exhaust system using an expansion chamber. Exhaust gases are in grey, fuel/air mixture is green. In practice the fuel/air mix is unlikely to progress as far down the exhaust pipe as shown. In many two-stroke engines, the exhaust port is opened and closed directly by the position of the piston rather than by a separate valve, which restricts the timing of its operation; Typically, the port remains open long after is optimum, allowing some of the incoming charge to escape. This can be partly addressed by use of a tuned exhaust system to deliver a pulse of positive pressure prior to the port closing, to retain the charge. Alternatives Direct-injection two-stroke diesel engines tend to use exhaust valves actuated either by camshafts or electronic control, rather than exhaust ports. This system is called uniflow scavenging. Opposed piston engines are inherently uniflow-scavenged, but these do use piston-controlled cylinder ports. Two-stroke opposed piston engines such as the Napier Deltic and Junkers Jumo 204 engines use one piston to control the inlet port and the other the exhaust, allowing more flexibility in timing. A variation of this approach is taken by the split-single engine, in which two cylinders share one combustion chamber, with the piston in one cylinder controlling the transfer portand the other the exhaust port. Four-stroke engines Extractor manifolds Most non-turbo performance cars and high-performance four-stroke motorcycles use extractor manifolds (headers in American English), as do most non-turbo racing cars. Extractor manifolds are also available as aftermarket accessories to suit many engines. Extractor manifolds offer the following advantages over the simple manifolds often fitted to non-performance engines: Separating the gas flows from the individual cylinders so that undesirable inter-cylinder interference is avoided. Maintaining an optimum gas velocity by carefully chosen tube diameter. Allowing the individual cylinders to assist one another by means of the negative pressure waves generated at the collector, where the individual exhausts merge. This type of exhaust system can be used with or without a muffler, and so can be used on both race and road vehicles. Aftermarket extractor manifold Rotax 912s aero engine showing the tuned exhaust system Collector on a racing car Zoomie headers on a dragster References The Design and Tuning of Competition...

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Expansion chamber

On a two-stroke engine, an expansion chamber or tuned pipe is a tuned exhaust system used to enhance its poweroutput by improving its volumetric efficiency. Scooter exhaust with expansion chamber and silencer History Direct comparison between different types of exhausts for the two-stroke engine, on the left you can see the engine and its exhaust, in the center the progression curves of the pressures (effective pressure in atmospheres) to the exhaust port (detection area highlighted in red), on the right the power curves of the various drains. A) Traditional discharge with constant section B) Discharge with divergent section C) Resonant expansion chamber with expansion chamber, in the power graph the influence of the exhaust back pressure valve is also highlighted Expansion chambers were invented and successfully manufactured by Limbach, a German engineer, in 1938, to economize fuel in two stroke engines. Germany was running short of petrol, which was at that stage produced using coal and sewerage transformation. An unexpected bonus was that the two stroke engines using tuned exhausts produced far more power than if running with a normal silencer. After the end of the second world war, some time passed before the concept was re-developed by East German Walter Kaaden during the Cold War. They first appeared in the west on Japanese motorcycles after East German motorcycle racer Ernst Degner defected to the west while racing for MZ in the 1961 Swedish Grand Prix. He later passed his knowledge to Japan's Suzuki. How it works The high pressure gas exiting the cylinder initially flows in the form of a "wavefront" as all disturbances in fluids do. The exhaust gas pushes its way into the pipe which is already occupied by gas from previous cycles, pushing that gas ahead and causing a wave front. Once the gas flow stops, the wave continues, passing the energy to the next gas down stream and so on to the end of the pipe. If this wave encounters any change in cross section or temperature it will reflect a portion of its strength in the opposite direction to its travel. For example, a strong acoustic wave encountering an increase in area will reflect a weaker acoustic wave in the opposite direction. A strong acoustic wave encountering a decrease in area will reflect a strong acoustic wave in the opposite direction. The basic principle is described in wave dynamics. An expansion chamber makes use of this phenomenon by varying its diameter (cross section) and length to cause these reflections to arrive back at the cylinder at the desired time in the cycle. An approximation of an expansion chamber in operation....

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Exhaust system

An exhaust system is usually piping used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall system design, the exhaust gas may flow through one or more of: Cylinder head and exhaust manifold A turbocharger to increase engine power. A catalytic converter to reduce air pollution. A muffler (North America) / silencer (UK/India), to reduce noise. Exhaust manifold (chrome plated) on a car engine Muffler and tailpipe on a car Design criteria Exhaust system of the Opel Corsa B 1.2 petrol An exhaust pipe must be carefully designed to carry toxic and/or noxious gases away from the users of the machine. Indoor generatorsand furnaces can quickly fill an enclosed space with poisonous exhaust gases such as hydrocarbons, carbon monoxide and nitrogen oxides, if they are not properly vented to the outdoors. Also, the gases from most types of machines are very hot; the pipe must be heat-resistant, and it must not pass through or near anything that can burn or can be damaged by heat. A chimney serves as an exhaust pipe in a stationary structure. For the internal combustion engine it is important to have the exhaust system "tuned" (refer to tuned exhaust) for optimal efficiency. Also this should meet the regulation norms maintained in each country. In China, China 5; In European countries, EURO 5; In India, BS-4, etc., In the vehicle type category, the passenger cars segment is highly lucrative and is estimated to reach a significant market value by the end of the year of assessment. This segment is the fastest growing and is projected to grow at a value CAGR of 4.2% throughout the period of forecast 2017-2027.  Motorcycles Exhaust piping and silencer (muffler) on a Ducati Monster motorcycle In most motorcycles all or most of the exhaust system is visible and may be chrome plated as a display feature. Aftermarket exhausts may be made from steel, aluminium, titanium, or carbon fiber. Motorcycle exhausts come in many varieties depending on the type of engine and its intended use. A twin cylinder may flow its exhaust into separate exhaust sections, such as seen in the Kawasaki EX250 (also known as the Ninja 250 in the US, or the GPX 250). Or, they may flow into a single exhaust section known as a two-into-one (2-1). Larger engines that come with 4 cylinders, such as Japanese super-sport or super-bikes (such the Kawasaki ZX series, Honda's CBR series, Yamaha's YZF series, also known as R6 and R1, and Suzuki's GSX-R series) often come with a twin exhaust system. A "full system" may be bought as an aftermarket accessory, also called a 4-2-1 or 4-1,...

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