Steam engine

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A steam engine in the narrower sense is a piston heat engine. They produced in a steam generator, which is considered part of the machine, combustion steam and converts the heat energy contained in the steam (called pressure energy) by means of piston in mechanical work. Steam engines are heat engines with external combustion, which distinguishes them from internal combustion engines.

As a steam engine in a broader sense can colloquially be understood any other machine, which is driven directly or indirectly by steam. These are both combustion engines such as the steam turbine, and steam-powered machinery. Sometimes steam-powered transport and transport, agricultural machinery and even some equipment are called steam engine.

The earliest applications of the steam engines were found in the mining water containment. After gradual improvements they have also been used in the growing textile industry to drive textile machinery and eventually spread in other industries. They also played an important role in transport, in particular for driving steam ships and steam locomotives. Also not insignificant also was used as traction engines. With little success, however, their application was in steam cars and trucks Also, the first airship in 1852 driven by a steam engine.

The following article covers only piston engines ( steam engines in the narrow sense ).

• 2.1 England 2.1.1 Thomas Newcomen
• 2.1.2 James Watt
• 2.1.3 High-pressure and superheated steam

• 2.2.1 Prussia
• 2.2.2 Other German States

Operation of a reciprocating steam engine

The reciprocating steam engine is thermodynamic energy to (vapor pressure ) of steam generators into mechanical rotational energy. Here, a piston moves in the associated cylinder back and forth, it performs an oscillating motion. However, is needed for the useful mechanical energy mostly a rotational movement.

The forward movement of the piston is carried out with pressure of the steam as a working clock. The return movement is performed at one side impinged piston of stored rotational kinetic energy. When acted upon on two sides, however, the piston return movement of the piston is also performed as the working clock, by controlling the vapor pressure is now on the underside of the piston.

The supply of steam into the cylinder controls a slider. The piston is displaced by the pressure until the bottom or in the direction of the crankshaft. The linear movement of the piston is implemented by means of the crosshead and the connecting rod as a coupling member to the crank pin of the crankshaft in a rotational movement. The connecting rod then pushes ( in the one-sided operation) with the rotational energy stored in the flywheel and the crankshaft the piston back from the lower layer linearly back to its upper position.

The working process of a steam engine is thus divided into two cycles, and is therefore a two-stroke method.

Atmospheric steam engine

In an atmospheric steam engine, the cylinder chamber is filled under the piston with water vapor. In the next clock water is injected into the cylinder, so that the water vapor cools and condenses there. There is generated a negative pressure, so that the piston is pushed by the external atmosphere pressure in the cylinder. = Extending movement of the piston is open, steam valve and through a flywheel which is attached to a lever arm, the so-called balancing.

The best known representative of this type was the atmospheric steam engine by Thomas Newcomen in 1712 (see below). The steam engine was used primarily for water drainage in coal mines. The energy efficiency of the engine was less than 1 %.

Low-pressure steam engine

At the low-pressure steam engine, the steam is fed at a slight positive pressure of a few 100 mbar. In contrast to Newcomen steam engine work is performed not only during the condensation, but also during the filling of the cylinder. This leads to increase performance and was the starting point for the further development of the steam engine to higher vapor pressures. The best known representatives of this type were the steam engines of James Watt from about 1769 ( see below).

Watt developed the single-acting steam engine, which is applied only from the bottom of the flask, to the double-acting steam engine, in which the piston is acted upon by both the upper and lower sides, further, thus increasing the efficiency. Also, the expansion engine, where only steam flows at the beginning of a stroke, then expanded and occurs at a lower pressure from the cylinder, was an evolution of the low-pressure steam engine and brought an efficiency increase compared to the full press that receives throughout the stroke full steam pressure.

High-pressure steam engine

For high pressure steam engine, the steam is well above 100 ° C is heated so that a higher pressure is built up. On cooling of the exiting from the cylinder water vapor can be omitted ( exhaust mode). The capacitor can be omitted so what makes this type of machine in conjunction with the higher energy density of the pressurized steam considerably lighter and thus the use of steam engines in steam locomotives enabled only. Representatives of this type are virtually all piston steam engines in vehicles since Oliver Evans and Richard Trevithick from about 1802 (see below).

Compound steam engine

A compound steam engine or multiple - expansion engine is a steam engine having at least two steam direction successively connected units of work.

History of the steam engine

The history of the steam engine stretches back to the first century AD - the first report of a technical, rudimentary as a " steam engine " to be designated apparatus which Aeolipile (also called Heronsball ), comes from the pen of the Greek mathematician Heron of Alexandria. In the centuries that preceded the first modern steam engines, steam-powered "machines" were built mainly for demonstration purposes to illustrate the principle of steam power. The first trials of a steam engine came, among others, Blasco de Garay in 1543, Denis Papin in 1690 and Thomas Savery 1698th But they were all to no avail.

England

Thomas Newcomen

The first usable steam engine was constructed in 1712 by Thomas Newcomen and served to empty the water in a mine. These so- called atmospheric steam engine produced by injecting water into a vapor-filled cylinder has a negative pressure relative to the atmosphere. This pressure difference of piston is pressed in the work cycle from atmospheric pressure down and then pulled by the weight of the pump rod to be driven back up to the starting position. The transmission of force between the piston rod and balancing was done by means of a chain. The efficiency of the human machine newcounter was 0.5 percent.

James Watt

James Watt, an often misdiagnosed, the invention of the steam engine is attributed to the efficiency of the Newco people steam engine greatly improved. He moved with his 1769 patented design on the one hand the cooling out of the cylinder in a separate capacitor, on the other hand, he supplied the piston alternately from one side and the other with steam. On the opposite side, he opened the outlet to the condenser. So Watt could do without the mechanical recycling of the piston, and let the machine do work in two piston strokes. Together with the invention of Watt's parallelogram, it was possible to let the machine rotate a flywheel. James Watt described this invention as his most important; it is still regarded as a model for the solution of the problem of converting a linear movement in a circular only with the help of hinges.

James Watt is regarded as the discoverer of the benefits of steam expansion. In the steam engine of this effect is achieved by premature closing of the valves; characterized the supply of steam in the cylinder is interrupted while the vapor trapped therein further performs work. Furthermore, by James Watt in 1788 the governor for regulating the speed of his machine. Before this machine element had already been used in the construction and operation of mills.

To demonstrate the ability of its steam engines, Watt invented the power unit horsepower. The Watt's steam engine saved by these improvements over their predecessors a multiple of the heat energy that was needed to operate the machine. The efficiency of the watt between machine finally reached three percent. With its commercial partner Matthew Boulton, he did not sell his machines, but placed them available to its customers to cash out a portion of the savings in fuel costs. Thus was born an early form of contracting. With these developments, as well as further technical improvements steam engines were from the second half of the 18th century - at least in the coal mining - now also economically. Although gradually further applications were developed in industry and transport, it was not until the 1860s, were to steam engines in England used en masse. In other countries, such as France and the United States, where water power was a strong competitor, the final breakthrough of the steam engine was a little later.

High pressure and superheated steam

The high-pressure steam engine was designed in 1784 by Oliver Evans. The first copy was however built by him until 1812. He previously was Richard Trevithick, the first high-pressure steam engine einbaute in a road vehicle 1801. Prerequisite for the functioning of the high-pressure steam engines was the progress in the metal production and processing at this time, because in high-pressure machines the parts must fit very accurately. There was also the danger of explosion of the boiler.

The continuous development of pressure-driven steam engine, which first worked with so-called " saturated steam ", led on the single-cylinder steam engine for two - or three cylindrical compound machine and last for more cylindrical hot high-pressure steam engine, as it was offered by Kemna. When saturated steam machine located in the boiler all boiler tubes for steam generation in the waterbed, the hot steam machine has a second tube system, which is coated by the fire or the hot flue gases. Thereby, the steam " overheated " and reaches temperatures of around 350 degrees Celsius. The compound machine or composite machine has a high-pressure cylinders with a small bore and one or more connected in series ( n ) low-pressure cylinder. The as hot steam into the high pressure cylinder fed, now partially relaxed and cool escaping vapor still has enough working capacity to operate the provided with a much larger bore low pressure cylinder. An attempt is made, the cylinder bores align so that the generated torque of the two cylinders to the crankshaft is approximately equal. The volume of both cylinders must be matched to the speed of the steam engine, so that the relaxation of the steam is distributed to both cylinders. Kemna built from 1908 steam engine with two high-pressure cylinders.

The best machines had already in 1910 and reached a very high efficiency with medium grade coal consumption of about 0.5 kg / hp - hour.

Germany

Prussia

In Prussia it was in 1769 became aware of the " fire engine " from England. Especially the Oberkonsistorialrat Johann Esaias silver strike that had also made a name as a scientist, recognized early on the benefits of this machine and made until 1771 more extensive report about it to. 1785 then the first replica in Prussia steam engine watt shear design was taken at Burgörner in operation. Already in 1778, James Watt had agreed to leave the Prussian Mining Administration to his improved steam engine to lift water under expert guidance. However, his firm Boulton & Watt called for a 14 - year supply monopoly, a condition for which you did not want to go in the mercantilist Prussia. Under the pretext of a purchase intention of Oberbergrat Waitz of ash and the Assessor Carl Friedrich Kipper (1756-1812) by the Prussian minister Friedrich Anton sent by Heynitz to England. Waitz should do specifically with the function of the machine and make bloater real building. Well only an English steam engine was purchased in 1779 and used on a brown coal mine at Altenweddingen.

After bloater was still sent a second time to England, he was able to exact blueprints to design for its own steam engine along the lines of watts between the participation of the Prussian Academy of Sciences. Until 1783 a reduced, functional model was built, from then on, the parts were manufactured in original size and reassembled. On August 23, 1785, the first German steam engine watt shear design on the King Friedrich shaft at Hettstedt was officially put into operation. Your susceptibility brought the machine initially a lot of ridicule.

Other German States

Around the same time was in the Duchy of Saxe-Gotha in a small vitriol mine at Miihlberg ( Thuringia) on the subsequent engineering Lieutenant Carl Christoph Better that until 1774 worked at the mine from 1763, built the first functional steam engine in Thuringia and in over weeks of operation held, she served for permanent pumping mine water and was held by two heaters or machinists day and night running. The much talented hand Better was later used by the Duke Ernst as an engineer and architect in the construction of the Seeberg Observatory in Gotha and other projects and so lost interest in mechanical engineering.

Due to the enticement of the British steam engine mechanic William Richards the problems in Hettstedt could be eliminated by 1787. The machine became a commercial success. 1794 was replaced by a stronger and now situated in a coal mine in Löbejün, where she was still working until 1848. In Mansfeld Museum in Hettstedt since 1985 is a 1:1 replica of the steam engine, which can be demonstrated in motion. In today Polish Upper Silesia Tarnowitz a steam engine was put into operation on 19 January 1788 which was used to dewater the Tarnowitzer mines. From this steam engine is falsely claims to be the first on the European mainland have been.

Another early steam engine of Germany and first steam engine of the Aachen coalfield was 1793 in Eschweiler, where it was also used for water drainage in mining. 1803 Franz Dinnendahl built the first steam engine in Essen in the Ruhr. Two years earlier Dinnendahl had supervised the deployment of the first steam engine to water retention in the Ruhr mining. Made in England, this was taken on the bill full moon in Bochum- Langendreer in operation. The engine model may be shown in movement.

From these early beginnings to the widespread use of the steam engine in the economy, however, was several decades. 1836 created one of the first German steam engines statistics, namely for the administrative district of Dusseldorf. Technical improvements, the starting concentration of the emergent industry, increasingly -utilized hydropower potential and the massive cheapening of coal transport by railway steam engines were always economically viable. After a less than full statistics there were 1846 Zollverein 1518 steam engines. 1861 the number had increased to 8695 pieces.

In the steel industry, steam engines were used among other things for driving fans, pumps and mills. Two-roll tractors with a maximum performance of 10,000 hp, built in 1913, and 15,000 horsepower, built in 1911, worked reliably in the Maxhiitte ( Sulzbach -Rosenberg ) up to its closure in 2002. They were among the strongest steam engines around the world.

Steam engines today

As a vehicle drive steam engines have been largely superseded by internal combustion engines that start without warm-up time, have a higher efficiency, offer greater performance with less weight and are more comfortable to use. Furthermore, the steam engine has lost its function as the central energy source of an industrial enterprise by the nationwide supply of electrical energy, which she held for a long time. Were in coal mines and steam engines are still used in conveyors, because there the steam engine used both as carrier for lifting of coal as well as a brake for lowering backfill material. During braking, the energy for heating of the steam is used.

Although the time the piston steam engine seems to be long gone, a renaissance is not excluded. One of its advantages over the internal combustion engine is its continuous combustion process, which can be designed with lower emissions. Another advantage of the steam engine is its extreme overload in demand for power peaks. By today's conventional closed circuit of steam and feed water, a low-emission lubrication of cylinders and pistons of the engine. In this sense, has been developed as a modernized steam engine, the steam engine.

On behalf of Volkswagen AG, IAV GmbH has developed in the late 1990s, such a modern " steam engine " that generates an extremely low-emission external combustion a certain supply of high-pressure steam, which is then injected depending on the energy needs such as the diesel engine via nozzles. End of 2000, the company emerged from this Enginion is and has from the ZEE prototypes (Zero Emission Engine) today's " SteamCell " evolved. This machine worked in the two-cycle method and also came out without the usual lubricant because the wear parts were made of modern carbon components. Enginion was forced to declare bankruptcy in 2005.