User:John of Paris/sandbox 2

Energy Portal

An engine in the limited sense of a motor is a component of steam plant that works in synergy the boiler/steam generator. It has been defined by Arturo Caprotti as a fluid pressure engine; it can just as well be actuated by compressed air or any other pressure source other than steam. The two principal types are:

• the reciprocating type with a piston working in a cylinder either directly working a reciprocating pump or a wheel through a crank;
• the rotary type applies the working fluid directly to a rotor working inside a sealed casing. Nowadays, the universal manifestation of this principle today is the turbine which incorporates multiple angled blades.

Unlike the internal combustion engine, where the whole process of conversion of heat into work takes place inside the cylinder or inside the turbine casing, the steam engine motor component relies on the existence a pre-processed working fluid. A steam engine may furthermore work as part of a co-generation process; it can equally make use of steam directly tapped from geothermal sources [1].

Reciprocating engines

Steam engine in action (animation). Note that movement of the connecting linkage from the centrifugal governor operating the steam throttle is shown for illustrative purpose only, in practice this link only operates when the engine speeds up or slows down.

Reciprocating engines use the action of steam to move a piston inside a sealed chamber or cylinder. The reciprocating action of the piston can be translated via a mechanical linkage into either linear motion, usually for working water or air pumps, or else into rotative motion to drive the flywheel of a stationary engine, or else the wheel(s) of a vehicle. Turbines translate the steam flow directly into rotary motion. The flow is concentrated directed by casing and by the use of stators.

Steam distribution

Schematic Indicator diagram

In most reciprocating piston engines the steam reverses its direction of flow at each stroke (counterflow), entering and exhausting from the cylinder by the same port. In the case of the uniflow engine, the path is continuous, entering at the cylinder end and exiting by a cantrally located port uncovered at each stroke by the piston. This avoids alternate heating and cooling of the ports. The complete engine cycle occupies one rotation of the crank and two piston strokes; the cycle also comprises four events — admission, expansion, exhaust, compression. These events are controlled by valves often working inside a steam chest adjacent to the cylinder; the valves distribute the steam by opening and closing steam ports communicating with the cylinder end(s) and are driven by valve gear, of which there are many types. The simplest valve gears give events of fixed length during the engine cycle and often make the engine rotate in only one direction. Most however have a reversing mechanism which additionally can provide means for saving steam as speed and momentum are gained by gradually "shortening the cutoff" or rather, shortening the admission event; unfortunately this in turn proportionately lengthens the expansion period. However as one and the same valve usually controls both steam flows, a short cutoff at admission adversely affects the exhaust and compression periods which should ideally always be kept fairly constant; if the exhaust event is too brief, the totality of the exhaust steam cannot evacuate the cylinder, choking it and giving excessive compression ("kick back"). In the 1840s and 50s there were attempts to overcome this problem by means of various patent valve gears with separate variable cutoff valves riding on the back of the main slide valve; the latter usually had fixed or limited cutoff. The combined set-up gave a fair approximation of the ideal events, at the expense of increased friction and wear, and the mechanism tended to be complicated. The usual compromise solution has ever since been to provide lap by lengthening rubbing surfaces of the valve in such a way as to overlap the port on the admission side, with the effect that the exhaust side remains open for a longer period after cut-off on the admission side has occurred. This expedient has since been generally considered satisfactory for most purposes and makes possible the use of the simpler Stephenson, Joy and Walschaerts motions. Later, poppet valve gears had separate admission and exhaust valves driven by cams profiled so as to give ideal events; nevertheless most of these gears never succeeded in ousting conventional gears due to various other issues including leakage and more delicate mechanisms[1][2].

Compression

Before the exhaust phase is quite complete, the exhaust side of the valve closes, shutting a portion of the exhaust steam inside the cylinder. This determines the compression phase where a cushion of steam is formed against which the piston does work whilst its velocity is rapidly decreasing; it moreover reduces the pressure and temperature shock, which would otherwise be caused by the sudden admission of the high pressure steam at the beginning of the following cycle.

Lead

The above effect is further enhanced by providing lead: as was later discovered with the internal combustion engine, it has been found advantageous since the late 1830s to advance the admission phase, giving the valve lead so that admission occurs a little before the end of the exhaust stroke in order to fill the clearance volume comprising the ports and the cylinder ends (not part of the piston-swept volume) before the steam begins to exert effort on the piston.

Technical history of the steam engine

The laying of the foundations

Aeolipile

The first recorded steam-rotated device, the aeolipile, was described by Hero of Alexandria (Heron) in the 1st century AD, in his manuscript Spiritalia seu Pneumatica. Steam ejected tangentally from nozzles caused a pivoted ball to rotate; this suggests that the conversion of steam pressure into mechanical movement was known in Roman Egypt in the 1st century, although no useful function is evident and the device seems to have been used simply to demonstrate a mechanical principle.

More practical was the device described in 1551 by the Arab philosopher and astronomer, Taqi al-Din who exposed a method for rotating a spit by means of a jet of steam playing on rotary vanes around the periphery of a wheel. A similar machine is shown by Giovanni Branca an Italian engineer in 1629 for turning a cylindrical escapement device that alternately lifted and let fall a pair of pestles working in mortars. Although these engines are often described as turbines, the steam flow was in no way concentrated by casing so much of its energy was dissipated in all directions and would have led to considerable waste of energy. In early writings they are (perhaps more aptly) termed “mills”.

Commercial development of the steam engine, however, required an economic climate in which the developers of engines could profit by their creations. Classical, and later Mediaeval and Renaissance civilisations provided no such climate. Even as late as the 17th century, steam engines were created as one-off curiosities. The difficulty in breaking out of this situation is evident judging by the difficulties encountered by Edward Somerset, 2nd Marquess of Worcester and later by his widow in gaining financial investment into the practical application of his ideas for the exploitation of steam power. In 1663, he published designs for, and installed on the wall of the Great Tower at Raglan Castle a steam-powered device for raising water (the grooves in the wall where the engine was installed were still to be seen in the 19th Century). However, no one was prepared to risk money in this revolutionary new concept, and without backers the machine remained undeveloped.

Denis Papin's design for a piston-and-cylinder engine, 1680.

One of Denis Papin’s centres of interest was in the creating of a vacuum in a closed cylinder and in Paris in the mid 1670s he collaborated with the Dutch physicist, Huygens’ working on an engine which drove out the air from a cylinder by exploding gunpowder inside it. Realising the incompleteness of the vacuum produced by this means and on moving to England in 1680, Papin devised a version of the same cylinder that obtained a more complete vacuum from boiling water and then allowing the steam to condense; in this way he was able to raise weights by attaching the end of the piston to a rope passing over a pulley. As a demonstration model the system worked, but in order to repeat the process the whole apparatus had to be dismantled and reassembled. Papin quickly saw that to make an automatic cycle the steam would have to be generated separately in a boiler; however as he did not take the project further all we can say is that he invented the reciprocating steam engine conceptually and thus paved the way to Newcomen’s engine.

Towards the practical application steam power

The English engineer Thomas Savery continued Worcester’s technology, although it is by no means sure if Savery’s was an independent invention. .[7] As with Worcester’s engine, a combination of the vacuum and pressure principles were used: the steam was first produced in a separate boiler and then transferred to a hollow pressure vessel onto which cold water was then sprayed, thus condensing the steam. The vacuum thus formed drew the water from a well which was retained by closing a cock. The next charge of steam under pressure drove the water to a greater height, then the vessel was cooled, repeating the cycle. The water could only be raised to a height of about 50 feet in all which was insufficient for draining deep mines, this in spite of the commercial name (“Miner’s friend”) of the apparatus.

It was Thomas Newcomen with his "atmospheric-engine"of 1712 who seems to have brought together most of the essential elements established by Papin in order to develop the first practical industrial steam engine for which there could be a commercial demand in the shape of a beam engine that worked exculusively on the atmospheric, or vacuum, principle. [2] Although Savery's patent of 2 July1698 claimed, in addition to "the raising of water", the ability to "occasion... motion to all sorts of mill-works" there is no evidence that they were used for any purpose other than pumping. Such engines operated by admitting steam at extremely low pressure into an operating cylinder. The inlet valve was then closed and the steam cooled, condensing it to a smaller volume of water and thus creating a vacuum in the cylinder. The upper end of the cylinder being open to the atmospheric pressure operated on the opposite side of a piston, the pressure differential pushing it to the bottom of the cylinder.

Engraving of Newcomen engine. This appears to be copied from a drawing in Desaguliers' 1744 work: "A course of experimental philosophy", itself believed to have been a reversed copy of Henry Beighton's engraving dated 1717 representing what is probably the second Newcomen engine erected around 1714 at Griff colliery, Warwickshire. (See Hulse p.84)

The piston was connected by a chain to the end of a large beam pivoted near its middle. A weighted force pump was connected by another chain to the opposite end of the beam which gave the pumping stroke and returned the piston to the top of the cylinder by force of gravity, the low pressure steam being insufficient to move the piston upwards. In the Newcomen engine the cooling water was sprayed directly into the cylinder, the still-warm condensate running off into a hot well. [3] . Repeated and wasteful cooling and reheating of the working cylinder was a source of inefficiency, however these engines enabled the pumping of greater volumes of water and/or from greater depths than had been hitherto possible. Watt's version of this engine as developed and marketed from 1774 onwards in partnership with Matthew Boulton, was meant to improve efficiency through use of a separate condensing chamber immersed in a tank of cold water, connected to the working cylinder by a pipe and controlled by a valve. A small vacuum pump connected to the pump side of the beam drew off the warm condensate and delivered it to the hot well, at the same time helping to create the vacuum and draw the condensate out of the cylinder.

Early Watt pumping engine.

The hot well was further a source of pre-heated water for the boiler. Another radical change was the closing off the top of the cylinder and the introduction of ultra-low-pressure steam above the piston and inside steam jackets that maintained cylinder temperature constant. On the upward return stroke, the steam on top was transferred through a pipe to the underside of the piston to be condensed for the downward stroke. Thus the engine was thus no longer "atmospheric", the power stroke depending on the differential between the low-pressure steam and the partial vacuum. Sealing of the piston on a Newcomen engine was achieved by maintaining a small quantity of water on its upper side; this was no longer possible in Watt's engine due to the presence of the steam, so sealing of the piston and its lubrication were obtained by applying a mixture of tallow and oil. The piston rod also passed through a gland on the top cylinder cover sealed in a similar way. [4] Humphrey Gainsborough produced a model condensing steam engine in the 1760s, which he showed to Richard Lovell Edgeworth, a member of the Lunar Society . In 1769 James Watt, another member of the Lunar Society, patented the first significant improvements to the Newcomen type vacuum engine that made it much more fuel efficient. Gainsborough believed that Watt had used his ideas for the invention, but overwhelming evidence to shows that Watt developed his ideas separately and took the technology much further.

Double-acting and rotative engines

A rotative engine converts reciprocating to rotary motion. Unlike the Newcomen engine, a later Watt engine operated smoothly enough to be connected to a drive shaft—via sun and planet gears—to provide rotary power. Watt, together with his business partner Matthew Boulton, developed these patents in 1883 into the Watt steam engine in Birmingham, England. The increased efficiency of the Watt engine finally led to the general acceptance and use of steam power in industry. This was in all essentials the engine that we know today. In early steam engines the piston was usually connected to a balanced beam, rather than directly via a connecting rod, and these engines are therefore known as beam engines. In the double-acting engine, steam is admitted alternately to each side of the piston whilst the opposite side is exhausting which requires inlet and exhaust ports at either end of the cylinder (see the animated expansion engine below) with steam flow being controlled by valves. The system increases the speed and smoothness of the reciprocation. A double-acting piston engine provides as much power as a more expensive 2-piston single-acting engine, and also allows the use of a much smaller flywheel than what would be required by a one-piston single-acting engine. Both of these considerations made the double-acting piston engine smaller and less expensive to produce for a given power range. Atmospheric and low pressure engines, although in general limited in their efficiency, were at least relatively safe, use of very low pressure steam being preferable due to the primitive state of 18th century boiler technology. Power was limited by the low pressure, the displacement of the cylinder, combustion and evaporation rates and—where present— condenser capacity. Efficiency was limited by the narrow pressure differential on either side of the piston; this mean that in order to obtain a usable amount of power, the first industrial production engines had to be very large, and were thus expensive to build and install. James Watt, erring on the side of safety, fought tooth and nail against the introduction of higher pressures and his low-pressure engines were built by Boulton and Watt well into the 19th Century after both men’s deaths.

Towards higher pressures

Trevithick pumping engine (Cornish system).

Simple expansion, condensing

This means that a charge of steam works only once in the cylinder. It is then exhausted directly into the atmosphere or into a condenser, but remaining heat can be recuperated if needed to heat a living space, or to provide warm feedwater for the engine itself.

Around 1811 Richard Trevithick was required to update a Watt linear pumping engine in order to adapt it to one of his new Cornish boilers. Steam pressure above the piston was increased, eventually reaching 40 psi (276 kPa) and now provided much of the power for the downward stroke; at the same time condensing was improved. This considerably increased the pressure differential and efficiency and further pumping engines on the Cornish system (often known as Cornish engines) were built new throughout the 19th Century, older Watt engines being updated to conform. Many of these engines were supplied worldwide and gave reliable and efficient service over a great many years with greatly reduced coal consumption. Some of them were very large and the type continued to be built right down to the 1890’s.

Richard Trevithick's No. 14 Engine, built by Hazeldine and Co., Bridgnorth, about 1804. This was a double-acting, stationary high pressure engine that operated at a working pressure of 50 psi (350 kPa).

Non-condensing "high pressure" engine

In a non-condensing pressure engine steam is raised in a boiler to a pressure well above that of the atmosphere: it is then admitted to a cylinder where it expands, acts upon a piston and is exhausted at higher than atmosphere pressure. The idea of "strong steam" was first mooted by Ernest Leupold around 1725, although no actual engine seems to have been built. Early developers of “strong steam” were the American Oliver Evans[12][13]and the Cornishman Richard Trevithick. Strong steam brought the advantage that engines could be much smaller for a given power range, and thus less expensive to produce and market. Around the year 1800, "high pressure" or "strong steam" amounted to what today would be considered very low pressure, i.e. 40-50 psi (276 - 345 kPa), — although Oliver Evans recommended pressures as high as 200 psi. The blast of the exhausting steam into the chimney (US: smokestack) could be further exploited to create induced draught through the fire grate and thus increase the rate of burning, hence creating more heat in a smaller furnace.

The outcome was that for a given power output, engines could be made much smaller and portable than previously. There was also the benefit that steam engines then could now be developed that were small and powerful enough to propel themselves and other objects. As a result, steam power for transportation now became a practicality in the form of ships and land vehicles, which revolutionised cargo businesses, travel, military strategy, and essentially every aspect of society at the time; this gave rise to radical breakaway from the traditional beam engine leading to various new engine layouts adapted to precise conditions.

Compounding

As steam expands in a high pressure engine its temperature drops due to a given density of steam occupying a greater volume adiabatic expansion; this results in steam entering the cylinder at high temperature and leaving at low temperature and causes a cycle of heating and cooling of the cylinder with every stroke which is a source of inefficiency. A method to lessen the magnitude of this heating and cooling was invented in 1804 by British engineer Arthur Woolf, who patented his Woolf high pressure compound engine in 1805. In the compound engine, steam from the boiler expands in a high pressure (HP) cylinder and then enters one or more subsequent lower pressure (LP) cylinders. The complete expansion of the steam now occurs across multiple cylinders and as less expansion now occurs in each cylinder so less heat is lost by the steam in each. This reduces the magnitude of cylinder heating and cooling, increasing the efficiency of the engine. To derive equal work from lower pressure steam requires a larger cylinder volume as this steam occupies a greater volume. Therefore the bore, and often the stroke, are increased in low pressure cylinders resulting in larger cylinders. Double expansion (usually known as compound) engines expanded the steam in two stages. The pairs may be duplicated or the work of the large LP cylinder can be split with one HP cylinder exhausting into one or the other, giving a 3-cylinder layout where cylinder and piston diameter are about the same making the reciprocating masses easier to balance. Two-cylinder compounds can be arranged as: • Cross compounds - The cylinders are side by side. • Tandem compounds - The cylinders are end to end, driving a common connecting rod • Angle compounds - The cylinders are arranged in a vee (usually at a 90° angle) and drive a common crank. With two-cylinder compounds used in railway work, the pistons are connected to the cranks as with a two-cylinder simple at 90° out of phase with each other (quartered). When the double expansion group is duplicated, producing a 4-cylinder compound, the individual pistons within the group are usually balanced at 180°, the groups being set at 90° to each other. In one case (the first type of Vauclain compound), the pistons worked in the same phase driving a common crosshead and crank, again set at 90° as for a two-cylinder engine. With the 3-cylinder compound arrangement, the LP cranks were either set at 90° with the HP one at 135° to the other two, or in some cases all three cranks were set at 120°. The adoption of compounding was common for industrial units, for road engines and almost universal for marine engines after 1880; it was not universally popular in railway locomotives where it was often perceived as complicated. This is partly due to the harsh railway operating environment and limited space afforded by the loading gauge (particularly in Britain, where compounding was never common and not employed after 1930). However although never in the majority it was popular in many other countries

Multiple expansion

An animation of a simplified triple-expansion engine.
High-pressure steam (red) enters from the boiler and passes through the engine, exhausting as low-pressure steam (blue) to the condenser.

Model of a triple expansion engine

Triple expansion steam engine

It is a logical extension of the compound engine above to split the expansion into yet more stages to increase efficiency. The result is the multiple expansion engine. Such engines use either three or four expansion stages and are known as triple and quadruple expansion engines respectively. These engines use a series of cylinders of progressively increasing diameter and/or stroke and hence volume. The cylinders are designed to divide the work into three or four, as appropriate, equal portions for each expansion stage. As with the double expansion engine, where space is at a premium, two smaller cylinders of a large sum volume may be used for the low pressure stage. Multiple expansion engines typically had the cylinders arranged inline, but various other formations were used. The images to the right show a model and an animation of a triple expansion engine. The steam travels through the engine from left to right. The valve chest for each of the cylinders is to the left of the corresponding cylinder. The development of this type of engine was important for its use in steamships as by exhausting to a condenser the water can be reclaimed to feed the boiler, which is unable to use seawater. Land-based steam engines could exhaust much of their steam, as feed water was usually readily available.

Uniflow (or unaflow) engine

Main article: Uniflow steam engine

This is intended to remedy the difficulties arising from the usual counterflow cycle mentioned above which means that at each stroke the port and the cylinder walls will be cooled by the passing exhaust steam, whilst the hotter incoming admission steam will waste some of its energy in restoring working temperature. The aim of the uniflow is to remedy this defect by providing an additional port uncovered by the piston at the end of its half-stroke making the steam flow only in one direction. Thermal efficiency is thus improved by having a steady temperature gradient along the cylinder bore. The simple-expansion uniflow engine is reported to give efficiency equivalent to that of classic compound systems with the added advantage of superior part-load performance. It is also readily adaptable to high-speed uses and was a common way to drive electricity generators towards the end of the 19th Century before the coming of the steam turbine. Uniflow engines have been produced in single-acting, double-acting, simple, and compound versions. Skinner 4-crank 8-cylinder single-acting tandem compound [5] engines power two Great Lakes engines power two Great Lakes ships still trading today (2007). These are the Saint Marys Challenger,[6] that in 2005 completed 100 years of continuous operation as a powered carrier (the Skinner engine was fitted in 1950) and the car ferry, Badger.[7] In the early 1950s the Ultimax engine, a 2-crank 4-cylinder in-line arrangement similar to Skinner’s, was developed by Abner Doble for the Paxton car project with tandem opposed single-acting cylinders giving effective double-action. [8]. The simple expansion unifow employed by Ted Pritchard since 1960 is a two-cylinder double-acting engine with the cylinders set at 90°. This layout gives as many pulses per revolution as a V8 IC engine.

Rotary engines

Steam turbines

Main article: Steam turbine

A turbine is a rotary engine consisting of an alternating series of rotating discs mounted on a drive shaft, rotors, and static blades, or stators fixed to the turbine casing. The rotors have a propeller-like arrangement of radial blades. Fluid pressure acts upon these blades, producing rotary motion. The stator consists of a similar, but fixed, series of blades that serve to redirect the flow onto the next rotor stage. Turbines can equally well work on the internal combustion principle or as fluid pressure engines. A steam turbine is of the latter variety and generally exhausts into a condenser that provides a vacuum and increases the pressure differential. The stages of a steam turbine are typically arranged to extract the maximum potential work from a specific velocity and pressure of steam, giving rise to a series of variably sized high and low pressure stages. Turbines rotate at very high speed, therefore are usually connected to reduction gearing to drive another mechanism, such as a ship's propeller, at a lower speed. A turbine rotor is only capable of providing power when rotating in one direction. Therefore a reversing stage or gearbox is usually required where power is required for the opposite direction. Steam turbines provide direct rotational force and therefore do not require a linkage mechanism to convert reciprocating to rotary motion. Thus, they produce smoother rotational forces on the output shaft. This contributes to a lower maintenance requirement and less wear on the machinery they power than a comparable reciprocating engine. The main current use for steam turbines is in electricity generation (about 86% of the world's electric production is by use of steam turbines)[citation needed] and to a lesser extent as marine prime movers. In the former, the high speed of rotation is an advantage, and in both cases the relative bulk is not a disadvantage. Prior to and during World War II, the multiple expansion engine dominated marine applications where high vessel speed was not essential. It was however superseded by the British-invented steam turbine where speed was required, for instance in warships and ocean liners. HMS Dreadnought of 1905 was the first major warship to replace the proven technology of the reciprocating engine with the then novel steam turbine. Virtually all nuclear power plants and some nuclear submarines, generate electricity by heating water to provide steam that drives a turbine connected to an electrical generator for main propulsion. A limited number of steam turbine railroad locomotives were manufactured. Some non-condensing direct-drive locomotives did meet with some success for long haul freight operations in Sweden, but were not repeated. Elsewhere, notably in the U.S.A., more advanced designs with condensing and electric transmission were built experimentally, but not reproduced. It was found that steam turbines were not ideally suited to the railroad environment and these locomotives failed to oust the classic reciprocating steam unit in the way that modern diesel and electric traction has done.

Other rotary engine types

Direct displacement engines

These devices are most often used as pumps. However like any pump they can equally serve as a pressure engine. Many types have been produced and proposed, but have not been nearly so widely adopted as reciprocating or turbine engines. By the 1840s it was clear that the concept had inherent problems and rotary engines were treated with some derision in the technical press. However, the arrival of electricity on the scene, and the obvious advantages of driving a dynamo directly from a high-speed engine, led to something of a revival in interest in the 1880s and 1890s, and a few designs had some limited success. As they usually provide no means of using the steam expansively, their use as mainly been confined to driving auxiliary equipment such as feed pumps and cooling fans where continuous low pressure output is required; Ted Pritchard’s “exhaust motor”, a modified Roots blower is a good example of this.

Tower engine

Of the few designs that were manufactured in quantity, those of the Hult Brothers Rotary Steam Engine Company of Stockholm, Sweden, and the spherical engine of Beauchamp Tower are notable. Tower's engines were used by the Great Eastern Railway to drive lighting dynamos on their locomotives, and by the Admiralty for driving dynamos on board the ships of the Royal Navy. They were eventually replaced in these niche applications by normal steam turbines.

Wankel engine

It is possible to use a mechanism based on a pistonless rotary engine such as the Wankel engine in place of the cylinders and valve gear of a conventional reciprocating steam engine. Many such engines have been designed, from the time of James Watt to the present day, but relatively few were actually built and even fewer went into quantity production; see link at bottom of article for more details. The major problem is the difficulty of sealing the rotors to make them steam-tight in the face of wear and thermal expansion; the resulting leakage made them very inefficient.

[edit]Quasiturbine

As with the the turbine and the Wankel, this engine can also work on the Internal combustion principle. The steam Quasiturbine has mainly been made to run on compressed air to date where it has met with some success.

Jet type

Invented by Australian engineer Alan Burns and developed in Britain by engineers at Pursuit Dynamics, this underwater jet engine uses high pressure steam to draw in water through an intake at the front and expel it at high speed through the rear. When steam condenses in water, a shock wave is created and is focused by the chamber to blast water out of the back. To improve the engine's efficiency, the engine draws in air through a vent ahead of the steam jet, which creates air bubbles and changes the way the steam mixes with the water. Unlike in conventional steam engines, there are no moving parts to wear out, and the exhaust water is only several degrees warmer in tests. The engine can also serve as pump and mixer. This type of system is referred to as 'PDX Technology' by Pursuit Dynamics.

Rocket type

The aeolipile represents the use of steam by the reaction principle, although not for direct propulsion. In more modern times there has been limited use of steam for rocketry—particularly for rocket cars. The technique is simple in concept, simply fill a pressure vessel with hot water at high pressure, and open a valve leading to a suitable nozzle. The drop in pressure immediately boils some of the water and the steam leaves through a nozzle, giving a significant propulsive force. It might be expected that water in the pressure vessel should be at high pressure; but in practice the pressure vessel has considerable mass, which reduces the acceleration of the vehicle. Therefore a much lower pressure is used, which permits a lighter pressure vessel, which in turn gives the highest final speed. There are even speculative plans for interplanetary use. Although steam rockets are relatively inefficient in their use of propellant, this very well may not matter as the solar system is believed to have extremely large stores of water ice which can be used as propellant. Extracting this water and using it in interplanetary rockets requires several orders of magnitude less equipment than breaking it down to hydrogen and oxygen for conventional rocketry.[15]

Festivals and museums

• Antique Gas & Steam Engine Museum - Bi-Annual show in Vista, CA, Specializing in farm equipment, engines, and machinery from 1850-1950

• Great Dorset Steam Fair - 5-day annual show in England - specialises in showing engines being used in their original context: heavy haulage, threshing, sawing, road making, etc

• Annual Steam Show in America North American Model Engineering Society (NAMES)

• Annual Steam-Up in America New England Wireless and Steam Museum

• Newcomen Engine House, Dartmouth, Devon, England, UK

• Black Country Living Museum in Dudley, Staffs U.K.: full-size working replica of the first Newcomen atmospheric engine of 1712.

• Kew Bridge Steam Museum

• Crofton Beam Engines. Movie of engines operating

• Bancroft Mill Engine[7], Barnoldswick. Movie of engine operating here [10]

• Kempton Park Steam Engines

• Steam Era in Milton, Ontario

• Ontario Agricultural Museum in Milton, Ontario • Missouri River Valley Steam Engine Association Back to the Farm Reunion in central Missouri, USA. This is not a steam-only festival, but it has always had a good showing of running steam engines.

• Hamilton Museum of Steam and Technology in Hamilton, Ontario. An old municipal pumphouse dating to 1860 with its original two Woolf Compound Rotative Beam Engines, one of which still operates.

• Buckley Old Engine Show Northwest Michigan Engine & Thresher Club. Annual show (39 years) showing steam engines and equipment, antique gas and oil engines, antique agricultural equipment, mills, blacksmithing, and foundries. Show includes steam building seminars.

• Hollycombe Steam Collection

• Old Threshers' Reunion - 5-day annual show (around Labor Day) at Mt. Pleasant, Iowa, US. Steam engines of all kinds.

See also

{{Wikimedia Commons has media related to: Steam engines • Timeline of steam power • Steam power during the Industrial Revolution • Boiler • Valve gear • Compound locomotive • Live steam • Steam clock • Steam car • Steamboat • Steampunk • Reciprocating engine}}

References

1. ^ Riemsdijk, John van: (1994) Compound Locomotives, pp. 2-3; Atlantic Publishers Penrhyn, England . ISBN No 0 906899 61 3

2. ^ Carpenter, George W. & contributors (2000): La locomotive à vapeur (English translation of André Chapelon's seminal work (1938): pp. 56-72; 120 et seq; Camden Miniature Steam Services, U.K. ISBN 0 9536523 0 0

3. ^ Riemsdijk, John van: (1994) Compound Locomotives, Atlantic Publishers Penrhyn, England . ISBN No 0 906899 61 3

4. ^ Heron Alexandrinus (Hero of Alexandria) (c. 62 CE): Spiritalia seu Pneumatica. Reprinted 1998 by K G Saur GmbH, Munich. ISBN 3-519-01413-0.

5. ^ Ahmad Y Hassan (1976). Taqi al-Din and Arabic Mechanical Engineering, p. 34-35. Institute for the History of Arabic Science, University of Aleppo.

6. ^ name=rochestercapone>University of Rochester, NY, The growth of the steam engine online history resource, chapter one.

7. ^ Carlyle, E I; revised Lyndsey, Christopher F (2004): Oxford Dictionary of National Biography. Oxford University Press.

8. ^ University of Rochester, NY, The growth of the steam engine online history resource, chapter seven.

9. ^ 10. ^ Hulse David K (1999): "The early development of the steam engine"; TEE Publishing, Leamington Spa, U.K., ISBN, 85761 107 1

11. ^ a b Tyler, David (2004): Oxford Dictionary of National Biography. Oxford University Press.

12. ^ Suttcliffe, Andrea (2004): Steam: The Untold Story of America's First Great Invention. Paulgrave Macmillan, New York. ISBN 1-4039-6261-8.

13. ^ ’op. cit.’ Thurston 1878

14. ^ Burton, Anthony (2000): Richard Trevithick, Giant of Steam. Aurum Press, London. ISBN 1-85410-728-3. 15. ^ Near Earth Object Fuel website, accessed on 2 November 2006.

External links

• Photos of toy steam engines • Interactive Animation – (in German)

• Titanic's Triple Expansion Engines on Titanic-Titanic.com

• Howstuffworks - "How Steam Engines Work"

• Animated engines - Illustrates a variety of steam engines

• The World's Smallest Steam Engine

• A history of the growth of the steam-engine

• Uniflow engines

• Steam powered lawn mower

• Rotary steam engines

• Beauchamp Tower's spherical steam engine

• Finnish miniature live steam site

• S/S Ukkopekka in Finland

• Steamboat revival on Lake Geneva

• New Scientist jet steam engine article

• Dual pistons with linear generator as microCHP

• An art project underway that aims to build a steam powered victorian house on tractor treads

• A short movie of a mill engine under steam at Barnoldswick, Lancashire, England

• Steam Engineering Tutorials

• Annual Steam Tractor Parade De-activated code whilst in sandbox:

Categories: British Wikipedians | British inventions | Energy conversion | Piston engines | Steam engine.