A scale model Allchin traction engine
– an example of a self-propelled steam engine

'Preserved' (but incomplete) portable engine, Tenterfield, NSW – an example of a mobile steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. A traction engine is a self-propelled Steam engine used to move heavy loads on roads plough ground or to provide power at a chosen location A portable engine is a small Steam engine, mounted on wheels or skids which is used for driving machinery using a belt from its Flywheel. A heat engine is a physical or theoretical device that converts Thermal energy to mechanical output In Physics, mechanical work is the amount of Energy transferred by a Force. Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. The working fluid in a machine is the pressurized gas or liquid which actuates the machine ^[1]

Steam engines have a long history, going back almost two thousand years. Early devices were not practical power producers, but more advanced designs become a major source of mechanical power during the industrial revolution. The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the Modern steam turbines generate about half of the electric power in the world. A steam turbine is a mechanical device that extracts Thermal energy from pressurized Steam, and converts it into useful mechanical work Electric power is defined as the rate at which Electrical energy is transferred by an Electric circuit.

Many steam engines are external combustion engines,^[2] although other sources of heat such as solar power, nuclear power or geothermal energy are often used. An external combustion engine (EC engine is a Heat engine where an (internal working Fluid is heated by combustion of an external source through the Engine Solar energy is the Light and radiant heat from the Sun that powers Earth 's Climate and Weather and sustains Life Nuclear power is any Nuclear technology designed to extract usable Energy from atomic nuclei via controlled Nuclear reactions The heat cycle used is known as the Rankine cycle. The Rankine cycle is a thermodynamic cycle which converts heat into work

In general usage, the term 'steam engine' can refer to integrated steam plants such as railway steam locomotives and portable engines, or may refer to the motor unit alone, as in the beam engine and stationary steam engine. A steam locomotive is a Locomotive powered by Steam. The term usually refers to its use on Railways but can also refer to a "road locomotive" A portable engine is a small Steam engine, mounted on wheels or skids which is used for driving machinery using a belt from its Flywheel. A beam engine is a design of Engine based on the principles of a first-class Lever. Stationary steam engines are fixed Steam engines used for pumping or driving mills and factories and for power generation Specialized devices such as steam hammers and steam pile drivers are dependent on steam supplied from a separate, often remotely-located boiler. A steam hammer is a power-driven hammer used to shape Forgings It consists of a hammer-like piston located within a cylinder A pile driver is a mechanical device used to drive Piles into soil to provide foundation support for buildings or other structures A boiler or steam generator is a device used to create Steam by applying Heat energy to Water.

Applications

Since the early 18th century steam power has been set to a variety of practical uses. At first it was applied to reciprocating pumps, but from the 1780s rotative engines (i. e. those converting reciprocating motion into rotary motion) began to appear, driving factory machinery. Reciprocating motion, also called Reciprocation, is an up and down (or back-and-forth motion which repeats over and over again At the turn of the 19th century, steam-powered transport on both sea and land began to make its appearance becoming ever more predominant as the century progressed.

Steam engines can be said to have been the moving force behind the Industrial Revolution and saw widespread commercial use driving machinery in factories and mills, powering pumping stations and transport appliances such as locomotives, steam ship engines and road vehicles. The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the Pumping stations are facilities including Pumps and equipment for pumping fluids from one place to another Their use in agriculture led to an increase in the land available for cultivation.

Very low power engines are used to power models and speciality applications such as the steam clock. A steam clock is a Clock which is fully or partially powered by a Steam engine.

The presence of several phases between heat source and power delivery has meant that it has always been difficult to obtain a power-to-weight ratio anywhere near that obtainable from internal combustion engines; notably this has made steam aircraft extremely rare. The internal combustion engine is an engine in which the Combustion of Fuel and an Oxidizer (typically air occurs in a confined space called a Steam aircraft are Aircraft that are propelled by Steam engines They were unusual devices because of the difficulty in producing a Powerplant with a high Similar considerations have meant that for small and medium-scale applications steam has been largely superseded by internal combustion engines or electric motors, which has given the steam engine an out-dated image. An electric motor uses Electrical energy to produce Mechanical energy. However it is important to remember that the power supplied to the electric grid is predominantly generated using steam turbine plant, so that indirectly the world's industry is still dependent on steam power. Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power Recent concerns about fuel sources and pollution have incited a renewed interest in steam both as a component of cogeneration processes and as a prime mover. Energy recycling Cogeneration (also combined heat and power, CHP) is the use of a Heat engine or a Power station to simultaneously generate both This is becoming known as the Advanced Steam movement. Advanced steam technology (sometimes known as Modern Steam) reflects an approach to the technical development of the Steam engine intended for a wider variety of applications

Steam engines can be classified by their application:

Stationary applications

Stationary steam engines can be classified into two main types:

1. Winding engines, rolling mill engines, steam donkeys, marine engines, and similar applications which need to frequently stop and reverse. A winding engine is a Stationary engine used to control a Cable, for example at a Pit head. A rolling mill is a Machine or Factory for shaping Metal by passing it between a pair of Work rolls. Steam donkey, or "donkey engine" is the common nickname for a steam-powered 'hoist' widely used in past Logging operations though not limited to logging
2. Engines providing power, which stop rarely and do not need to reverse. These include engines used in thermal power stations and those that were used in pumping stations, mills, factories and to power cable railways and cable tramways before the widespread use of electric power. Pumping stations are facilities including Pumps and equipment for pumping fluids from one place to another A grinding mill is a Unit operation designed to break a solid material into smaller pieces A factory (previously manufactory) or manufacturing plant is an industrial Building where workers manufacture goods A cable railway (also known as an Incline or Inclined plane) is a steeply graded Railway that uses a cable or A cable car or cable railway is a Mass transit system using rail cars that are propelled by a continuously moving cable running at a constant speed Electric power is defined as the rate at which Electrical energy is transferred by an Electric circuit.

The steam donkey is technically a stationary engine but is mounted on skids to be semi-portable. Steam donkey, or "donkey engine" is the common nickname for a steam-powered 'hoist' widely used in past Logging operations though not limited to logging It is designed for logging use and can drag itself to a new location. Logging is the process in which Trees are cut down for Forest management and Timber. Having secured the winch cable to a sturdy tree at the desired destination, the machine will move towards the anchor point as the cable is winched in.

A portable engine is a stationary engine mounted on wheels so that it may be towed to a work-site by horses or a traction engine, rather than being fixed in a single location. A portable engine is a small Steam engine, mounted on wheels or skids which is used for driving machinery using a belt from its Flywheel. A traction engine is a self-propelled Steam engine used to move heavy loads on roads plough ground or to provide power at a chosen location

Transport applications

Steam engines have been used to power a wide array of transport appliances:

• Marine: Steamboat, Steamship
• Rail: Steam locomotive, Fireless locomotive
• Agriculture: Traction engine, Steam tractor
• Road: Steam wagon, Steam bus, Steam tricycle, Steam car
• Construction: Steam roller, Steam shovel
• Military: Steam tank (tracked), Steam tank (wheeled)
• Space: Steam rocket

In many mobile applications internal combustion engines are more frequently used due to their higher power-to-weight ratio, steam engines are used when higher efficiency is needed and weight is less of an issue. A steamboat or steamship, sometimes called a steamer, is a ship in which the primary method of propulsion is steam power, typically driving a Propeller A steamboat or steamship, sometimes called a steamer, is a ship in which the primary method of propulsion is steam power, typically driving a Propeller A steam locomotive is a Locomotive powered by Steam. The term usually refers to its use on Railways but can also refer to a "road locomotive" A fireless locomotive was a type of Locomotive designed for use under conditions restricted by either the presence of flammable material (such as in mines or the need A traction engine is a self-propelled Steam engine used to move heavy loads on roads plough ground or to provide power at a chosen location This article refers to the steam-powered agricultural tractor for other types of steam tractor see Traction engine A steam tractor is a vehicle A traction engine is a self-propelled Steam engine used to move heavy loads on roads plough ground or to provide power at a chosen location A steam bus is a Bus powered by a Steam engine. Early steam-powered vehicles designed for carrying passengers were more usually known as steam carriages A steam tricycle is a steam-driven Three-wheeled vehicle. History In the early days of motorised vehicle development a number of experimenters A steam car is a car (automobile powered by a Steam engine. Technology A Steam engine is an External combustion engine A steamroller (or steam roller) is a form of Road roller &ndash a type of heavy construction machinery used for levelling surfaces such as roads or airfields A steam shovel is a large steam-powered excavating machine designed for lifting and moving material such as rock and Soil. The Steam Wheel Tank was the official US Army name for the vehicle also known as the 3 Wheeled Steam Tank, the Holt Steam Tank and the Holt 150 Ton Field A hot water rocket, or steam rocket uses water held in a pressure vessel at a high temperature such that its Saturated vapor pressure is significantly greater than Power-to-weight ratio (specific power is a calculation commonly applied to Engines and other mobile power sources to enable the comparison of one unit or design to another

History

Main article: History of the steam engine

Aeolipile

The history of the steam engine stretches back as far as the first century AD; the first recorded use of steam being the aeolipile described by Hero of Alexandria. This article primarily deals with the history of the reciprocating-type steam engine An aeolipile, a rocket -like Jet engine invented in the first century by Hero of Alexandria, is considered to be the first recorded Steam engine Hero (or Heron) of Alexandria ( Ήρων ο Αλεξανδρεύς) (c In the following centuries, the few engines known about were essentially experimental devices used by inventors to demonstrate the properties of steam. Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work.

The first practical steam-powered 'engine' was a water pump, developed in 1698 by Thomas Savery. Thomas Savery (c 1650 - 1715 was an English Inventor, born at Shilstone a Manor house near Modbury, Devon, England. It proved only to have a limited lift height and was prone to boiler explosions, but it still received some use for mines and pumping stations. Boiler explosions are catastrophic failures of Boilers As seen today boiler explosions are of two kinds Pumping stations are facilities including Pumps and equipment for pumping fluids from one place to another

The first commercially-successful engine did not appear until 1712. Incorporating technologies discovered by Savery and Denis Papin, the atmospheric engine, invented by Thomas Newcomen, paved the way for the Industrial Revolution. Denis Papin ( 22 August 1647 - c 1712 was a French Physicist, Mathematician and Inventor, best known for his pioneering The atmospheric engine invented by Thomas Newcomen in 1712 today referred to as a Newcomen steam engine (or simply Newcomen engine was the first practical Thomas Newcomen (born shortly before 24 February 1664; died 5 August 1729) was an Ironmonger by trade and a Baptist Newcomen's engine was relatively inefficient, and in most cases was only used for pumping water. It was mainly employed for draining mine workings at depths hitherto impossible, but also for providing a reusable water supply for driving waterwheels at factories sited away from a suitable 'head'. A water wheel is a means of extracting power from the flow (or fall of water otherwise known as Hydropower.

Early Watt pumping engine.

The next major step occurred when James Watt developed an improved version of Newcomen's engine. James Watt ( 19 January 1736 &ndash 25 August 1819 Boulton proved to be an excellent businessman and both men eventually made fortunes Watt's engine used 75% less coal than Newcomen's, and was hence much cheaper to run. The Watt steam engine was the first type of Steam engine to make use of steam at a pressure just above atmospheric to drive the piston helped by a partial vacuum Watt proceeded to develop his engine further, modifying it to provide a rotary motion suitable for driving factory machinery. This enabled factories to be sited away from rivers, and further accelerated the pace of the Industrial Revolution.

Around 1800, Richard Trevithick introduced engines using high-pressure steam. Richard Trevithick ( April 13, 1771 &ndash April 22, 1833) was a British These were much more powerful than previous engines and could be made small enough for transport applications. Thereafter, technological developments and improvements in manufacturing techniques (partly brought about by the adoption of the steam engine as a power source) resulted in the design of more efficient engines that could be smaller, faster, or more powerful, depending on the intended application.

Steam engines remained the dominant source of power well into the 20th century, when advances in the design of electric motors and internal combustion engines gradually resulted in the vast majority of reciprocating steam engines being replaced in commercial usage, and the ascendency of steam turbines in power generation. An electric motor uses Electrical energy to produce Mechanical energy. The internal combustion engine is an engine in which the Combustion of Fuel and an Oxidizer (typically air occurs in a confined space called a

See also

The history of steam engine development is a vast subject. The following articles cover aspects of steam engine development in greater detail:

• Timeline of steam power – overview
• History of the steam engine – general history, concentrating on reciprocating engines
• Steam turbine – the parallel development of turbine-type engines
• Steam power during the Industrial Revolution
• History of steam road vehicles

Basic operation of a simple steam engine

• Heat is obtained from fuel burnt in a closed firebox
• The heat is transferred to the water in a pressurised boiler, ultimately boiling the water and transforming it into saturated steam. See Steam engine, Steam power during the Industrial Revolution. This article primarily deals with the history of the reciprocating-type steam engine A steam turbine is a mechanical device that extracts Thermal energy from pressurized Steam, and converts it into useful mechanical work See also the section on steam power in the main Industrial Revolution article During the Industrial Revolution, steam power replaced History of steam road vehicles describes the development of Vehicles powered by a Steam engine for use on land whether for conventional Road use such as Steam in its saturated state is always produced at the temperature of the boiling water, which in turn depends on the steam pressure on the water surface within the boiler.
• The steam is transferred to the motor unit which uses it to push on pistons to power machinery.
• The used, cooler, lower pressure steam is dumped to the environment.

Components of steam engines

There are two fundamental components of a steam engine: the boiler or steam generator, and the motor unit, itself often referred to as a "steam engine". A boiler is a closed vessel in which Water or other Fluid is heated The two components can either be integrated into a single unit or can be placed at a distance from each other, in a variety of configurations.

Other components are often present; pumps to supply water to the boiler during operation, condensers to recirculate the water and recover the latent heat of vaporisation, and superheaters to raise the temperature of the steam above its saturated vapour point, and various mechanisms to increase the draft for fireboxes.

Heat source

The heat required for boiling the water and supplying the steam can be derived from various sources, most commonly from burning combustible materials with an appropriate supply of air in a closed space (called variously combustion chamber, firebox). A combustion chamber is the part of an Engine in which Fuel is burned In some cases the heat source is a nuclear reactor) or geothermal energy. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled

Cold sink

As with all heat engines, a considerable quantity of waste heat is produced at relatively low temperature. This must be disposed of.

The simplest cold sink is simply to vent the steam to the environment. This is often used on Steam locomotives, but is quite inefficient. A steam locomotive is a Locomotive powered by Steam. The term usually refers to its use on Railways but can also refer to a "road locomotive" Steam locomotive condensing apparatus can be employed to improve efficiency. A steam locomotive condensing apparatus differs in purpose from the usual closed cycle Steam engine condenser, in that its function is primarily either to recover

Steam turbines in power stations often use cooling towers which are essentially one form of condenser. Cooling towers are heat removal devices used to transfer process waste heat to the Atmosphere. For other Condensers not involving heat transfer see Condenser (disambiguation

Sometimes the 'waste heat' is useful in and of itself, and in those cases very high overall efficiency can be obtained; for example combined heat and power uses the waste heat for district heating. Energy recycling Cogeneration (also combined heat and power, CHP) is the use of a Heat engine or a Power station to simultaneously generate both District heating (less commonly called teleheating) is a system for distributing heat generated in a centralized location for residential and commercial heating requirements

Boilers

Main article: boiler (steam generator)

Boilers are pressure vessels that contain water to be boiled, and some kind of mechanism for transferring the heat to the water so as to boil it. A boiler or steam generator is a device used to create Steam by applying Heat energy to Water. A pressure vessel is a closed container designed to hold gases or liquids at a Pressure different from the ambient Pressure. A heat exchanger is a device built for efficient Heat transfer from one medium to another whether the media are separated by a solid wall so that they never mix or the media

The two most common methods of transferring heat to the water according are:

1. water tube boiler - water is contained in or run through one or several tubes surrounded by hot gases
2. firetube boiler - the water partially fills a vessel below or inside of which is a combustion chamber or furnace and fire tubes through which the hot gases flow

Once turned to steam, some boilers use superheating to raise the temperature of the steam further. A water-tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire A fire-tube boiler is a type of boiler in which hot gases from the fire pass through one or more tubes within the boiler See Superheater for the device used in Steam engines In Physics, superheating (sometimes referred to as boiling retardation This allows for greater efficiency. A heat engine is a physical or theoretical device that converts Thermal energy to mechanical output

Motor units

A motor unit takes a supply of steam at high pressure and temperature and gives out a supply of steam at lower pressure and temperature, using as much of the difference in steam energy as possible to do mechanical work.

A motor unit is often called 'steam engine' in its own right. They will also operate on compressed air or other gas.

Simple expansion

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 boiler. A steam locomotive condensing apparatus differs in purpose from the usual closed cycle Steam engine condenser, in that its function is primarily either to recover

Schematic Indicator diagram showing the four events in a double piston stroke

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. Schematic indicator diagrampng|thumb|Indicator diagram for steam locomotive]] In the Technology of the Steam engine, the indicator diagram was a device developed A stroke is a single action of certain Engines In a steam, Otto or Diesel Piston Engine, a stroke is the action of 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 valve gear of a Steam engine is the mechanism that operates the inlet and exhaust Valves to admit Steam into the cylinder and allow exhaust

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; this in turn proportionately lengthens the expansion period. In a Steam engine, cutoff is the point in the Piston stroke at which the inlet valve is closed 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 setup 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 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. The Stephenson valve gear or Stephenson link or shifting link is a simple design of Valve gear that was widely used throughout the world for all kinds of Joy valve gear is a type of Locomotive Valve gear, Patented in 1870 where the movement is derived The Walschaerts valve gear is a type of Steam engine Valve gear invented by Belgian railway mechanical engineer Egide Walschaerts Corliss, and later, poppet valve gears had separate admission and exhaust valves driven by trip mechanisms or cams profiled so as to give ideal events; most of these gears never succeeded outside of the stationary marketplace due to various other issues including leakage and more delicate mechanisms. A Corliss steam engine (or Corliss engine) is a Steam engine, fitted with Rotary valves and with Variable valve timing, invented by and named A poppet valve is a Valve consisting of a hole usually round or oval and a tapered plug usually a disk shape on the end of a shaft also called a valve stem A cam is a projecting part of a rotating Wheel or shaft that strikes a Lever at one or more points on its circular path ^[3][4]

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 obviates 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 effects are 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. The internal combustion engine is an engine in which the Combustion of Fuel and an Oxidizer (typically air occurs in a confined space called a ^[5]

Compounding engines

Main article: Compound engine

As steam expands in a high pressure engine its temperature drops; because no heat is released from the system, this is known as adiabatic expansion and results in steam entering the cylinder at high temperature and leaving at low temperature. A compound engine unit is a type of Steam engine where steam is expanded in two phases This article covers adiabatic processes in Thermodynamics. For adiabatic processes in Quantum mechanics, see Adiabatic process (quantum mechanics This 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. Arthur Woolf (born November 1766 Camborne, Cornwall; died October 26, 1837, Guernsey) was a Cornish engineer In the compound engine, high pressure 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). A loading gauge is the envelope or contoured shape within which all Railroad cars, Locomotives coaches Buses Trucks and other However although never in the majority it was popular in many other countries ^[6]

Multiple expansion engines

Main article: Compound_engine#Multiple_expansion_engines

An animation of a simplified triple-expansion engine. A compound engine unit is a type of Steam engine where steam is expanded in two phases
High-pressure steam (red) enters from the boiler and passes through the engine, exhausting as low-pressure steam (blue) to the condenser.

1890s-vintage triple-expansion marine engine that powered the SS Christopher Columbus

Model of a triple expansion engine

SS Ukkopekka triple expansion steam engine

It is a logical extension of the compound engine (described above) to split the expansion into yet more stages to increase efficiency. Background and proposal See also Whaleback The history of the Columbus is linked with that of the whalebacks an innovative but not widely accepted ship History The ship was built in Helsinki, Finland in 1938 and was at the time a modern icebreaking inspection vessel 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 double-acting cylinders of progressively increasing diameter and/or stroke and hence volume. These 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. In the late 19th century, the Yarrow-Schlick-Tweedy balancing 'system' was used on some marine triple expansion engines. Y-S-T engines divided the low pressure expansion stages between two cylinders, one at each end of the engine. This allowed the crankshaft to be better balanced, resulting in a smoother, faster-responding engine which ran with less vibration. This made the 4-cylinder triple-expansion engine popular with large passenger liners (such as the Olympic class), but was ultimately replaced by the virtually vibration-free turbine (see below). Fatalities

The image to the right shows 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. Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3 Land-based steam engines could exhaust much of their steam, as feed water was usually readily available. Prior to and during World War II, the expansion engine dominated marine applications where high vessel speed was not essential. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including It was however superseded by the British invention steam turbine where speed was required, for instance in warships, such as the pre-dreadnought battleships, and ocean liners. A steam turbine is a mechanical device that extracts Thermal energy from pressurized Steam, and converts it into useful mechanical work Pre-dreadnought battleship is the general term for all of the types of sea going Battleships built between the mid-1890s and 1905 An ocean liner is a ship designed to transport people from one Seaport to another along regular long-distance Maritime routes according to a schedule HMS Dreadnought of 1905 was the first major warship to replace the proven technology of the reciprocating engine with the then-novel steam turbine. Genesis Battleships of the era typically carried four large guns mounted fore and aft in twin turrets with a number of smaller-calibre guns ranged along the sides of the

Uniflow (or unaflow) engine

Main article: Uniflow steam engine

Schematic animation of a uniflow steam engine. The uniflow type of Steam engine uses steam that flows in one direction only in each half of the cylinder
The poppet valves are controlled by the rotating camshaft at the top. High pressure steam enters, red, and exhausts, yellow.

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. By this means, thermal efficiency is 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 [1] engines power two Great Lakes ships still trading today (2007). The Laurentian Great Lakes are a chain of freshwater lakes located in eastern North America, on the Canada–United States border. These are the Saint Marys Challenger,[2] that in 2005 completed 100 years of continuous operation as a powered carrier (the Skinner engine was fitted in 1950) and the car ferry, S. S. Badger. [3]

In the early 1950s the Ultimax engine, a 2-crank 4-cylinder 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. Abner Doble ( March 26, 1890 &ndash July 16, 1961) was an American mechanical engineer who built and sold steam-powered [4]

Turbine engines

A rotor of a modern steam turbine, used in a power plant

Main article: Steam turbine

A steam turbine consists of an alternating series of rotating discs mounted on a drive shaft, rotors, and static discs fixed to the turbine casing, stators. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of A steam turbine is a mechanical device that extracts Thermal energy from pressurized Steam, and converts it into useful mechanical work A turbine is a rotary Engine that extracts Energy from a Fluid flow The stator is the stationary part of an Electric generator or Electric motor. The rotors have a propeller-like arrangement of blades at the outer edge. Steam acts upon these blades, producing rotary motion. The stator consists of a similar, but fixed, series of blades that serve to redirect the steam flow onto the next rotor stage. A steam turbine often exhausts into a condenser that provides a vacuum. 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 also capable of providing power when rotating in one direction only. Therefore a reversing stage or gearbox is usually required where power is required in 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 Turbinia - the first steam turbine-powered ship

The main use for steam turbines is in electricity generation (about 80% of the world's electric production is by use of steam turbines) and to a lesser extent as marine prime movers. Development Charles Algernon Parsons invented the steam turbine in 1884 and having foreseen its potential to power ships he set up the Marine Steam Turbine Company Electricity generation is the process of converting non-electrical Energy to Electricity. In the former, the high speed of rotation is an advantage, and in both cases the relative bulk is not a disadvantage; in the latter (pioneered on the Turbinia), the light weight, high efficiency and high power are highly desirable. Development Charles Algernon Parsons invented the steam turbine in 1884 and having foreseen its potential to power ships he set up the Marine Steam Turbine Company

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. Nuclear power is any Nuclear technology designed to extract usable Energy from atomic nuclei via controlled Nuclear reactions A nuclear submarine is a Submarine powered by Atomic energy. Previously conventional submarines used diesel engines that required air for moving on the In Electricity generation, an electrical generator is a device that converts Mechanical energy to Electrical energy, generally using Electromagnetic A limited number of steam turbine railroad locomotives were manufactured. A steam turbine locomotive is a Steam locomotive which transmits steam power to the wheels via a Steam turbine. Some non-condensing direct-drive locomotives did meet with some success for long haul freight operations in Sweden, but were not repeated. "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. Elsewhere, notably in the U. S. A. , more advanced designs with 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.

Rotary steam engines

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. This article is about Internal combustion engines that do not use conventional Pistons See also Rotary engine (disambiguation for other uses of this The Wankel engine is a type of Internal combustion engine which uses a rotary design to convert pressure into a rotating motion instead of using reciprocating The valve gear of a Steam engine is the mechanism that operates the inlet and exhaust Valves to admit Steam into the cylinder and allow exhaust 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. Lack of expansive working, or any means of control of the cutoff is also a serious problem with many such designs. In a Steam engine, cutoff is the point in the Piston stroke at which the inlet valve is closed 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.

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. Beauchamp Tower ( January 13 1845 &ndash December 31 1904) was an English Inventor and railway Engineer who 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. The Great Eastern Railway (GER was a pre-grouping British railway company whose main line linked London Liverpool The Admiralty was formerly the authority in the United Kingdom responsible for the command of the Royal Navy. The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore known as the Senior Service) They were eventually replaced in these niche applications by steam turbines.

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. Professor Alan Burns is a professor in the Computer Science Department at the University of York. specific --->A jet engine is a Reaction engine that discharges a fast moving jet of Fluid to 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 rocket-reaction principle, although not for direct propulsion. An aeolipile, a rocket -like Jet engine invented in the first century by Hero of Alexandria, is considered to be the first recorded Steam engine

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. ^[7]

Advantages

The strength of the steam engine for modern purposes is in its ability to convert heat from almost any source into mechanical work. Unlike the internal combustion engine, the steam engine is not particular about the source of heat. Most notably, without the use of a steam engine it would be more difficult to harness nuclear energy for useful work, as a nuclear reactor does not directly generate either mechanical work or electrical energy—the reactor itself simply heats or boils water. Nuclear Energy is released by the splitting (fission or merging together (fusion of the nuclei of Atom (s It is the steam engine which converts the heat energy into useful work. Steam may also be produced without combustion of fuel, through solar concentrators. A demonstration power plant has been built using a central heat collecting tower and a large number of solar tracking mirrors, (called heliostats). A Heliostat (from Helios, the Greek word for sun, and stat, as in stationary is a device that tracks the movement of the Sun. (see Whitecliffs Project[5])

Similar advantages are found in a different type of external combustion engine, the Stirling engine, which can offer efficient power (with advanced regenerators and large radiators) at the cost of a much lower power-to-size/weight ratio than even modern steam engines with compact boilers. White Cliffs Solar Power Station is Australia 's first solar Power station. A Stirling engine is a closed-cycle regenerative Heat engine with a Gaseous working fluid These Stirling engines are not commercially produced, although the concepts are promising.

Steam locomotives are especially advantageous at high elevations as they are not adversely affected by the lower atmospheric pressure. This was inadvertently discovered when steam locomotives operated at high altitudes in the mountains of South America were replaced by diesel-electric units of equivalent sea level power. These were quickly replaced by much more powerful locomotives capable of producing sufficient power at high altitude.

In Switzerland (Brienz Rothhorn) and Austria (Schafberg Bahn) new rack steam locomotives have proved very successful. They were designed based on a 1930s design of Swiss Locomotive and Machine Works (SLM) but with all of today's possible improvements like roller bearings, heat insulation, light-oil firing, improved inner streamlining, one-man-driving and so on. These resulted in 60 percent lower fuel consumption per passenger and massively reduced costs for maintenance and handling. Economics now are similar or better than with most advanced diesel or electric systems. Also a steam train with similar speed and capacity is 50 percent lighter than an electric or diesel train, thus, especially on rack railways, significantly reducing wear and tear on the track. Also, a new steam engine for a paddle steam ship on Lake Geneva, the Montreux, was designed and built, being the world's first full-size ship steam engine with an electronic remote control[6]. Radio control (often abbreviated to R/C or simply RC) is the use of radio signals to remotely control a device The steam group of SLM in 2000 created a wholly-owned company called DLM to design modern steam engines and steam locomotives.

Safety

Steam engines possess boilers and other components that are pressure vessels that contain a great deal of potential energy. Steam explosions can and have caused great loss of life in the past. While variations in standards may exist in different countries, stringent legal, testing, training, care with manufacture, operation and certification is applied to try to minimise or prevent such occurrences.

Failure modes include:

• overpressurisation of the boiler
• insufficient water in the boiler causing overheating and vessel failure
• pressure vessel failure of the boiler due to inadequate construction or maintenance.
• escape of steam from pipework/boiler causing scalding

Efficiency

Main article: thermodynamic efficiency

The efficiency of an engine can be calculated by dividing the number of joules of mechanical work that the engine produces by the number of joules of energy input to the engine by the burning fuel. In Thermodynamics, the thermal efficiency (\eta_{th} \ is a dimensionless performance measure of a thermal device such as an Internal combustion The rest of the energy is dumped into the environment as heat.

No pure heat engine can be more efficient than the Carnot cycle, in which heat is moved from a high temperature reservoir to one at a low temperature, and the efficiency depends on the temperature difference. The Carnot cycle is a particular Thermodynamic cycle, modeled on the hypothetical Carnot heat engine, proposed by Nicolas Léonard Sadi Carnot in 1824 and Hence, steam engines should ideally be operated at the highest steam temperature possible (superheated steam), and release the waste heat at the lowest temperature possible. See Superheating for the physics process A superheater is a device in a Steam engine that heats the steam generated by the

In practice, a steam engine exhausting the steam to atmosphere will have an efficiency (including the boiler) of 1% to 8%, but with the addition of a condenser and multiple expansion engines the efficiency may be greatly improved to 25% or better. A power station with steam reheat, etc. will achieve 30% to 42% efficiency. Combined cycle in which the burning material is first used to drive a gas turbine can produce 50% to 60% efficiency. A combined cycle is characteristic of a power producing engine or plant that employs more than one Thermodynamic cycle. A gas turbine, also called a combustion turbine, is a rotary Engine that extracts energy from a flow of Combustion gas It is also possible to capture the waste heat using cogeneration in which the residual steam is used for heating. Energy recycling Cogeneration (also combined heat and power, CHP) is the use of a Heat engine or a Power station to simultaneously generate both It is therefore possible to use as much as 90% of the energy produced by burning fuel—only 10% of the energy produced by the combustion of the fuel goes wasted into the atmosphere.

The reason for varying efficiencies is because of the thermodynamic rule of the Carnot Cycle. In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning " The Carnot cycle is a particular Thermodynamic cycle, modeled on the hypothetical Carnot heat engine, proposed by Nicolas Léonard Sadi Carnot in 1824 and The efficiency is the absolute temperature of the cold reservoir over the absolute temperature of the steam, subtracted from one. Thermodynamic temperature is the absolute measure of Temperature and is one of the principal parameters of Thermodynamics. As the temperature changes in seasons, the efficiency changes with it, unless the cold reservoir is kept in an isothermal state. An isothermal process is a Thermodynamic process in which the Temperature of the System stays Constant: &Delta T = 0 It should be noted that the Carnot Cycle calculations require absolute temperatures.

One source of inefficiency is that the condenser causes losses by being somewhat hotter than the outside world, although this can be mitigated by condensing the steam in a heat exchanger and using the recovered heat, for example to pre-heat the air being used in the burner of an external combustion engine. A heat exchanger is a device built for efficient Heat transfer from one medium to another whether the media are separated by a solid wall so that they never mix or the media

The operation of the engine portion alone is not dependent upon steam; any pressurized gas may be used. Compressed air is sometimes used to test or demonstrate small model "steam" engines.

See also

Steam fairs

UK

• Carter's Steam Fair - touring vintage fairground, including several rides powered by steam engines
• Great Dorset Steam Fair - 5-day annual show in England - specialises in showing engines being used in their original context: heavy haulage, threshing, ploughing, sawing, road making, etc

USA

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

Steam museums

See also: List of pumping stations, many of which are, or were, steam-powered. See Steam engine, Steam power during the Industrial Revolution. See also the section on steam power in the main Industrial Revolution article During the Industrial Revolution, steam power replaced History of steam road vehicles describes the development of Vehicles powered by a Steam engine for use on land whether for conventional Road use such as The valve gear of a Steam engine is the mechanism that operates the inlet and exhaust Valves to admit Steam into the cylinder and allow exhaust A compound engine unit is a type of Steam engine where steam is expanded in two phases Live steam is Steam under pressure obtained by heating water in a Boiler. A reciprocating engine, also often known as a piston engine, is a Heat engine that uses one or more reciprocating Pistons to convert The Heat Regenerative Cyclone Engine is a new approach to an old design the Steam engine developed by James Watt in the 18th Carter's Royal Berkshire Steam Fair is a traveling Fair based in southeast England. The Great Dorset Steam Fair is an annual show featuring steam-powered vehicles and machinery The Antique Gas & Steam Engine Museum (AGSEM is a living-history museum founded in 1969 located on 55 acres of county-owned land on the outskirts of Vista California. Pumping stations are facilities including Pumps and equipment for pumping fluids from one place to another

UK

• Bolton Steam Museum
• Crofton Beam Engines (Movie of Crofton engines operating)
• Hollycombe Steam Collection
• Kempton Park Steam Engines
• Kew Bridge Steam Museum

Canada

• Ontario Agricultural Museum in Milton, Ontario
• Steam Era in Milton, Ontario

Notes

^ E. Bolton Steam Museum is a museum in Bolton, Greater Manchester, England, which houses a variety of preserved Steam engines It is owned and Crofton Pumping Station is a Pumping station near the village of Great Bedwyn in the English county of Wiltshire: it supplies the Summit The Hollycombe Steam Collection is a collection of steam-powered vehicles rides and attractions based at Liphook in Hampshire. The Kempton Park Steam Engines (also known as the Kempton Great Engines) are two large triple-expansion steam engines, dating from 1926-1929 at the Kempton Park Kew Bridge Steam Museum houses a museum of water supply and a collection of water pumping Steam engines The museum is an Anchor Point of ERIH The European Route of The Country Heritage Park (Formerly the Ontario Agricultural Museum) is located in Milton Ontario and recreates rural life in the 1800s in Ontario. Milton ( 2006 census population 53939 is a town in southern Ontario, Canada, part of the Greater Steam Era is a festival held every Labour Day Weekend in the Town of Milton Ontario featuring historic Steam tractors See also C. E. :  An external combustion engine has heat supplied to the working fluid of the power cycle by an external source. The working fluid in a machine is the pressurized gas or liquid which actuates the machine The external combustion engine allows the burning of virtually any fuel as the heat source for the engine. This explains the success of this engine, because less expensive and/or more renewable or sustainable fuel or heat sources can be used, because the working fluid remains separated from the fuel, and therefore cleaner, which results in less maintenance and longer engine life.

This is contrasted to the generally more familiar form of heat engine (known as an internal combustion engine) in which the working fluid of the power cycle is the gaseous products of the combustion process, and the heat is added to the cycle by combustion of fuel internal to the machine. The internal combustion engine is an engine in which the Combustion of Fuel and an Oxidizer (typically air occurs in a confined space called a Typical gasoline/petrol and diesel engines are internal combustion engines. (see: Otto cycle)

Steam engines have therefore been classed among external combustion engines. Today Internal combustion engines in cars, Trucks motorcycles aircraft construction machinery and many others most commonly use a four-stroke cycle. An external combustion engine (EC engine is a Heat engine where an (internal working Fluid is heated by combustion of an external source through the Engine

^ Patents:  Harold Holcroft in his 7859 25 patent dated November 1909: Improvements in or relating to valve gears for engines worked by fluid pressure[Holcroft steamindex], as does Arturo Caprotti:170,877 Improvements in valve gears for elastic-fluid engines. Published: 4 November 1921. Application number: 12341/1920. Applied: 4 May 1920; 13261/1907. Improvements in steam turbines and other multiple expansion elastic fluid prime movers. Applied 7 June 1907 (in Italy 7 June 1906). Published 7 August 1908.

References

External links

A steam-powered bicycle. A steam engine is a Heat engine that performs Mechanical work using Steam as its Working fluid.

• 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
• A history of the growth of the steam-engine
• Uniflow engines
• Steam powered lawn mower
• Rotary steam engines
• Beauchamp Tower's spherical steam engine
• Miniature live steam site
• 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
• Steam Engineering Tutorials
• A history of the growth of the steam engine Cornell University Library Historical Monographs Collection. {Reprinted by} Cornell University Library Digital Collections