Steam engine

Steam engine

Overview
A steam engine is a heat engine
Heat engine
In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work. It does this by bringing a working substance from a high temperature state to a lower temperature state. A heat "source" generates thermal energy that brings the working substance...

 that performs mechanical work
Mechanical work
In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...

 using steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

 as its working fluid
Working fluid
A working fluid is a pressurized gas or liquid that actuates a machine. Examples include steam in a steam engine, air in a hot air engine and hydraulic fluid in a hydraulic motor or hydraulic cylinder...

.

Steam engines are external combustion engine
External combustion engine
An external combustion engine is a heat engine where an working fluid is heated by combustion in an external source, through the engine wall or a heat exchanger. The fluid then, by expanding and acting on the mechanism of the engine, produces motion and usable work...

s, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power
Solar power
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available...

, nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 or geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 energy may be used. Water turns to steam in a boiler and reaches a high pressure. When expanded through pistons or turbines, mechanical work is done. The reduced-pressure steam is then condensed, and it is pumped back into the boiler.
Discussion
Ask a question about 'Steam engine'
Start a new discussion about 'Steam engine'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Recent Discussions
Encyclopedia
A steam engine is a heat engine
Heat engine
In thermodynamics, a heat engine is a system that performs the conversion of heat or thermal energy to mechanical work. It does this by bringing a working substance from a high temperature state to a lower temperature state. A heat "source" generates thermal energy that brings the working substance...

 that performs mechanical work
Mechanical work
In physics, work is a scalar quantity that can be described as the product of a force times the distance through which it acts, and it is called the work of the force. Only the component of a force in the direction of the movement of its point of application does work...

 using steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

 as its working fluid
Working fluid
A working fluid is a pressurized gas or liquid that actuates a machine. Examples include steam in a steam engine, air in a hot air engine and hydraulic fluid in a hydraulic motor or hydraulic cylinder...

.

Steam engines are external combustion engine
External combustion engine
An external combustion engine is a heat engine where an working fluid is heated by combustion in an external source, through the engine wall or a heat exchanger. The fluid then, by expanding and acting on the mechanism of the engine, produces motion and usable work...

s, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power
Solar power
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available...

, nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 or geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 energy may be used. Water turns to steam in a boiler and reaches a high pressure. When expanded through pistons or turbines, mechanical work is done. The reduced-pressure steam is then condensed, and it is pumped back into the boiler. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle
Rankine cycle
The Rankine cycle is a cycle that converts heat into work. The heat is supplied externally to a closed loop, which usually uses water. This cycle generates about 90% of all electric power used throughout the world, including virtually all solar thermal, biomass, coal and nuclear power plants. It is...

. Some practical steam engines discard the low-pressure steam instead of condensing it for reuse.

The idea of using boiling water to produce mechanical motion has a long history, going back about 2,000 years. Early devices were not practical power producers, but more advanced designs producing usable power have become a major source of mechanical power over the last 300 years, beginning with applications for removing water from mines using vacuum engines. Subsequent developments used pressurized steam and converted linear to rotational motion which enabled the powering of a wide range of manufacturing machinery. These engines could be sited anywhere that water and coal or wood fuel
Wood fuel
Wood fuel is wood used as fuel. The burning of wood is currently the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling steam engines and steam turbines that generate electricity. Wood fuel may be available as...

 could be obtained, whereas previous installations were limited to locations where water wheel
Water wheel
A water wheel is a machine for converting the energy of free-flowing or falling water into useful forms of power. A water wheel consists of a large wooden or metal wheel, with a number of blades or buckets arranged on the outside rim forming the driving surface...

s or windmills could be used. Significantly, this power source would later be applied to vehicles such as steam tractor
Steam tractor
A steam tractor is a vehicle powered by a steam engine which is used for pulling.In North America, the term steam tractor usually refers to a type of agricultural tractor powered by a steam engine, used extensively in the late 19th and early 20th centuries.In Great Britain, the term steam tractor...

s and railway locomotives
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

. The steam engine was a critical component of the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

, providing the prime mover
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...

 for modern mass-production manufacturing methods. Modern steam turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

s generate about 90% of the electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

 in the United States using a variety of heat sources.

In general usage, the term 'steam engine' can refer to integrated steam plants such as railway steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

s and portable engine
Portable engine
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. It is not self-propelled and is towed to the work site by horses or bullocks, or even a traction engine. Portable engines were used mainly for driving...

s, or may refer to the machinery alone, as in the beam engine
Beam engine
A beam engine is a type of steam engine where a pivoted overhead beam is used to apply the force from a vertical piston to a vertical connecting rod. This configuration, with the engine directly driving a pump, was first used by Thomas Newcomen around 1705 to remove water from mines in Cornwall...

 and stationary steam engine
Stationary steam engine
Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam cars , agricultural engines used for ploughing or...

. Specialized devices such as steam hammer
Steam hammer
A steam hammer is a power-driven hammer used to shape forgings. It consists of a hammer-like piston located within a cylinder. The hammer is raised by the pressure of steam injected into the lower part of a cylinder and falls down with a force by removing the steam. Usually, the hammer is made to...

s and steam pile driver
Pile driver
A pile driver is a mechanical device used to drive piles into soil to provide foundation support for buildings or other structures. The term is also used in reference to members of the construction crew that work with pile-driving rigs....

s are dependent on steam supplied from a separate boiler
Boiler (steam generator)
A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure but, at pressures above this, it is more...

.

History



The history of the steam engine stretches back as far as the first century AD; the first recorded rudimentary steam engine being the aeolipile
Aeolipile
An aeolipile , also known as a Hero engine, is a rocket style jet engine which spins when heated. In the 1st century AD, Hero of Alexandria described the device, and many sources give him the credit for its invention.The aeolipile Hero described is considered to be the first recorded steam engine...

 described by Greek
Greek mathematics
Greek mathematics, as that term is used in this article, is the mathematics written in Greek, developed from the 7th century BC to the 4th century AD around the Eastern shores of the Mediterranean. Greek mathematicians lived in cities spread over the entire Eastern Mediterranean, from Italy to...

 mathematician Hero of Alexandria
Hero of Alexandria
Hero of Alexandria was an ancient Greek mathematician and engineerEnc. Britannica 2007, "Heron of Alexandria" who was active in his native city of Alexandria, Roman Egypt...

. In the following centuries, the few steam-powered 'engines' known about were essentially experimental devices used by inventors to demonstrate the properties of steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...

. A rudimentary steam turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

 device was described by Taqi al-Din in 1551 and by Giovanni Branca
Giovanni Branca
Giovanni Branca was an Italian engineer and architect, chiefly remembered today for what some commentators have taken to be an early steam engine.-Life:...

 in 1629.

Following the invention by Denis Papin
Denis Papin
Denis Papin was a French physicist, mathematician and inventor, best known for his pioneering invention of the steam digester, the forerunner of the steam engine and of the pressure cooker.-Life in France:...

 of the steam digester
Steam digester
The steam digester is a high-pressure cooker invented by French physicist Denis Papin in 1679. It is a device for extracting fats from bones in a high-pressure steam environment, which also renders them brittle enough to be easily ground into bone meal...

 in 1679, and a first piston steam engine in 1690, the first practical steam-powered 'engine' was a water pump, developed in 1698 by Thomas Savery
Thomas Savery
Thomas Savery was an English inventor, born at Shilstone, a manor house near Modbury, Devon, England.-Career:Savery became a military engineer, rising to the rank of Captain by 1702, and spent his free time performing experiments in mechanics...

. It proved only to have a limited lift height and was prone to boiler explosion
Boiler explosion
A boiler explosion is a catastrophic failure of a boiler. As seen today, boiler explosions are of two kinds. One kind is over-pressure in the pressure parts of the steam and water sides. The second kind is explosion in the furnace. Boiler explosions of pressure parts are particularly associated...

s, but it still received some use for mines and pumping station
Pumping station
Pumping stations are facilities including pumps and equipment for pumping fluids from one place to another. They are used for a variety of infrastructure systems, such as the supply of water to canals, the drainage of low-lying land, and the removal of sewage to processing sites.A pumping station...

s.

The first commercially successful engine did not appear until around 1712. Incorporating technologies discovered by Savery and Denis Papin
Denis Papin
Denis Papin was a French physicist, mathematician and inventor, best known for his pioneering invention of the steam digester, the forerunner of the steam engine and of the pressure cooker.-Life in France:...

, the atmospheric engine, invented by Thomas Newcomen
Thomas Newcomen
Thomas Newcomen was an ironmonger by trade and a Baptist lay preacher by calling. He was born in Dartmouth, Devon, England, near a part of the country noted for its tin mines. Flooding was a major problem, limiting the depth at which the mineral could be mined...

, paved the way for the Industrial Revolution. Newcomen's engine was relatively inefficient, and in most cases was only used for pumping water. It worked by creating a partial vacuum by condensing steam in a cylinder and 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'.

The next major step occurred when James Watt developed (1763–75) an improved version of Newcomen's engine, with a separate condenser. Watt's engine
Watt steam engine
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...

 used 75% less coal than Newcomen's, and was hence much cheaper to run. 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.

Newcomen's and Watt's early engines were "atmospheric", meaning that they were powered by the partial vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

 generated by condensing
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

 steam instead of the pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 of expanding steam. Cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...

s had to be large, as the only usable force acting on them was atmospheric pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...

. Steam was only used to compensate for the atmosphere allowing the piston to move back to its starting position.

Around 1800, Richard Trevithick
Richard Trevithick
Richard Trevithick was a British inventor and mining engineer from Cornwall. His most significant success was the high pressure steam engine and he also built the first full-scale working railway steam locomotive...

 and separately Oliver Evans
Oliver Evans
Oliver Evans was an American inventor. Evans was born in Newport, Delaware to a family of Welsh settlers. At the age of 14 he was apprenticed to a wheelwright....

 (1801) introduced engines using high-pressure steam. 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.

The Corliss steam engine
Corliss Steam Engine
A Corliss steam engine is a steam engine, fitted with rotary valves and with variable valve timing patented in 1849, invented by and named after the American engineer George Henry Corliss in Providence, Rhode Island....

, a four-valve counterflow engine with separate steam admission and exhaust valves, was called the most significant advance in the steam engine since James Watt. In addition to using 30% less steam it provided more uniform speed, making is well suited to manufacturing, especially cotton spinning.

The final major evolution of the steam engine design was the switch from pistons to turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...

s starting in the early part of the 20th century. Turbines are more efficient than pistons, have fewer moving parts, and provide rotative power directly instead of through a connecting rod
Connecting rod
In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....

 system or similar means.

Steam engines remained the dominant source of power well into the 20th century, when advances in the design of electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s and internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s gradually resulted in the replacement of reciprocating (piston) steam engines in commercial usage, and the ascendancy of steam turbines in power generation. Today most steam power is provided by turbines, and piston engines are limited to historical pieces.

The steam cycle




The Rankine cycle is the fundamental thermodynamic underpinning of the steam engine. The Rankine cycle is a cycle that converts heat into work. The heat is supplied externally to a closed loop, which in steam engines contains water and steam. This cycle generates about 90% of all electric power used throughout the world, including virtually all solar thermal, biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

, coal and nuclear
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 power plants. It is named after William John Macquorn Rankine
William John Macquorn Rankine
William John Macquorn Rankine was a Scottish civil engineer, physicist and mathematician. He was a founding contributor, with Rudolf Clausius and William Thomson , to the science of thermodynamics....

, a Scottish polymath
Polymath
A polymath is a person whose expertise spans a significant number of different subject areas. In less formal terms, a polymath may simply be someone who is very knowledgeable...

.

The Rankine cycle is sometimes referred to as a practical Carnot cycle
Carnot cycle
The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded by Benoit Paul Émile Clapeyron in the 1830s and 40s. It can be shown that it is the most efficient cycle for converting a given amount of thermal energy into work, or conversely,...

 because, when an efficient turbine is used, the TS diagram begins to resemble the Carnot cycle. The main difference is that heat addition (in the boiler) and rejection (in the condenser) are isobaric
Isobaric process
An isobaric process is a thermodynamic process in which the pressure stays constant. The term derives from the Greek isos, , and barus,...

 (constant pressure) in the Rankine cycle and isothermal
Isothermal process
An isothermal process is a change of a system, in which the temperature remains constant: ΔT = 0. This typically occurs when a system is in contact with an outside thermal reservoir , and the change occurs slowly enough to allow the system to continually adjust to the temperature of the reservoir...

 (constant temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

) in the theoretical Carnot cycle. In this cycle a pump is also used to pressurize the working fluid received from the condenser as a liquid instead of as a gas. Pumping the working fluid through the cycle as a liquid requires a very small fraction of the energy needed to transport it as compared to compressing the working fluid as a gas in a compressor (as in the Carnot cycle
Carnot cycle
The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded by Benoit Paul Émile Clapeyron in the 1830s and 40s. It can be shown that it is the most efficient cycle for converting a given amount of thermal energy into work, or conversely,...

).

The working fluid in a Rankine cycle follows a closed loop and is reused constantly. While many substances could be used in the Rankine cycle, water is usually the fluid of choice due to its favourable properties, such as non-toxic and unreactive chemistry, abundance, and low cost, as well as its thermodynamic properties.

It is also useful to introduce the historical measure of a steam engine's energy efficiency, its "duty". The concept of duty was first introduced by Watt in order to illustrate how much more efficient his engines were over the earlier Newcomen designs. Duty is the number of foot-pounds of work delivered by burning one bushel
Bushel
A bushel is an imperial and U.S. customary unit of dry volume, equivalent in each of these systems to 4 pecks or 8 gallons. It is used for volumes of dry commodities , most often in agriculture...

 (94 pounds) of coal. The best examples of Newcomen designs had a duty of about 7 million, but most were closer to 5 million. Watt's original low-pressure designs were able to deliver duty as high as 25 million, but averaged about 17. This was a three-fold improvement over the average Newcomen design. Early Watt engines equipped with high-pressure steam improved this to 65 million.

Components of steam engines


There are two fundamental components of a steam plant: the boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

 or steam generator
Boiler (steam generator)
A boiler or steam generator is a device used to create steam by applying heat energy to water. Although the definitions are somewhat flexible, it can be said that older steam generators were commonly termed boilers and worked at low to medium pressure but, at pressures above this, it is more...

, and the "motor unit", referred to itself as a "steam engine". Stationary steam engine
Stationary steam engine
Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam cars , agricultural engines used for ploughing or...

s in fixed buildings may have the two parts in separate buildings some distance apart. For portable or mobile use, such as steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

s, the two are mounted together.

Other components are often present; pumps (such as an injector
Injector
ʎ̩An injector, ejector, steam ejector, steam injector, eductor-jet pump or thermocompressor is a pump-like device that uses the Venturi effect of a converging-diverging nozzle to convert the pressure energy of a motive fluid to velocity energy which creates a low pressure zone that dɯaws in and...

) to supply water to the boiler during operation, condensers to recirculate the water and recover the latent heat
Latent heat
Latent heat is the heat released or absorbed by a chemical substance or a thermodynamic system during a process that occurs without a change in temperature. A typical example is a change of state of matter, meaning a phase transition such as the melting of ice or the boiling of water. The term was...

 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. When coal is used, a chain or screw stoking mechanism and its drive engine or motor may be included to move the fuel from a supply bin (bunker) to the firebox.

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
Combustion chamber
A combustion chamber is the part of an engine in which fuel is burned.-Internal combustion engine:The hot gases produced by the combustion occupy a far greater volume than the original fuel, thus creating an increase in pressure within the limited volume of the chamber...

, firebox). In some cases the heat source is a nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

 or geothermal
Geothermal
Geothermal is related to energy and may refer to:* The geothermal gradient and associated heat flows from within the Earth- Renewable technology :...

 energy.

Boilers




Boilers are pressure vessel
Pressure vessel
A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.The pressure differential is dangerous and many fatal accidents have occurred in the history of their development and operation. Consequently, their design,...

s that contain water to be boiled, and some kind of mechanism for transferring the heat to the water
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...

 so as to boil it.

The two most common methods of transferring heat to the water are:
  1. water-tube boiler
    Water-tube boiler
    A water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes...

     - water is contained in or run through one or several tubes surrounded by hot gases
  2. fire-tube boiler
    Fire-tube boiler
    A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or more tubes running through a sealed container of water...

     - the water partially fills a vessel below or inside which is a combustion chamber or furnace and fire tubes through which the hot gases flow


Once turned to steam, many boilers raise the temperature of the steam further, turning 'wet steam' into 'superheated steam'. This use of superheating
Superheating
In physics, superheating is the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without boiling...

 prevents the steam condensing within the engine, and allows significantly greater efficiency.

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
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....

 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
Steam locomotive condensing apparatus
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 water, or to avoid excessive emissions to the atmosphere, rather than maintaining a vacuum to improve both efficiency and power...

, but remaining heat can be utilized if needed to heat a living space, or to provide warm feedwater for the boiler.

In most reciprocating piston engines, the steam reverses its direction of flow at each stroke
Stroke (engines)
Reciprocating motion, used in reciprocating engines and other mechanisms, is back-and-forth motion. Each cycle of reciprocation consists of two opposite motions: there is a motion in one direction, and then a motion back in the opposite direction. Each of these is called a stroke...

 (counterflow), entering and exhausting from the cylinder by the same port. 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
Valve gear
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 steam to escape, respectively, at the correct points in the cycle...

, 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
Machine
A machine manages power to accomplish a task, examples include, a mechanical system, a computing system, an electronic system, and a molecular machine. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work...

 which additionally can provide means for saving steam as speed and momentum are gained by gradually "shortening the cutoff
Cutoff (steam engine)
In a steam engine, cutoff is the point in the piston stroke at which the inlet valve is closed. On a steam locomotive, the cutoff is controlled by the reverser....

" or rather, shortening the admission event; 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 a separate, variable cutoff expansion valve
Expansion valve
An expansion valve is a slide valve used in a steam engine to control the cut-off. It rides on the back of an adapted main slide valve and is driven by an additional eccentric that has more advance than the main eccentric. The cut-off is adjusted in one of two ways...

 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
Stephenson valve gear
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 steam engine. It is named after Robert Stephenson but was actually invented by his employees....

, Joy
Joy Valve Gear
Joy valve gear is a type of locomotive valve gear, patented in 1870, where the movement is derived from a vertical link connected to the connecting rod. The vertical movement is translated into the horizontal movement required by the valve spindle by a die block moving in a slide which can be...

 and Walschaerts motions. Corliss
Corliss Steam Engine
A Corliss steam engine is a steam engine, fitted with rotary valves and with variable valve timing patented in 1849, invented by and named after the American engineer George Henry Corliss in Providence, Rhode Island....

, and later, poppet valve
Poppet valve
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. The shaft guides the plug portion by sliding through a valve guide...

 gears had separate admission and exhaust valves driven by trip mechanisms
Trip valve
Trip valve mechanisms are a class of steam engine valve gear developed to improve efficiency. The trip mechanism allows the inlet valve to be closed rapidly, giving a short, sharp cut-off. The valve itself can be a drop valve or a Corliss valve....

 or cam
Cam
A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path...

s 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.
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
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the 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.

Oscillating cylinder steam engines


An oscillating cylinder steam engine is a variant of the simple expansion steam engine which does not require valves
Valve gear
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 steam to escape, respectively, at the correct points in the cycle...

 to direct steam into and out of the cylinder. Instead of valves, the entire cylinder rocks, or oscillates, such that one or more holes in the cylinder line up with holes in a fixed port face or in the pivot mounting (trunnion
Trunnion
A trunnion is a cylindrical protrusion used as a mounting and/or pivoting point. In a cannon, the trunnions are two projections cast just forward of the centre of mass of the cannon and fixed to a two-wheeled movable gun carriage...

). These engines are mainly used in toys and models, because of their simplicity, but have also been used in full size working engines, mainly on ships where their compactness is valued.

Compound engines


As steam expands in a high pressure engine its temperature drops because no heat is added to the system; this is known as adiabatic expansion
Adiabatic process
In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which the net heat transfer to or from the working fluid is zero. Such a process can occur if the container of the system has thermally-insulated walls or the process happens in an extremely short time,...

 and results in steam entering the cylinder at high temperature and leaving at low temperature. 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
Arthur Woolf
Arthur Woolf was a Cornish engineer, most famous for inventing a high-pressure compound steam engine. As such he made an outstanding contribution to the development and perfection of the Cornish engine.Woolf left Cornwall in 1785 to work for Joseph Bramah's engineering works in London...

, who patented his Woolf high pressure compound engine in 1805. 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 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 low pressure cylinder can be split with one high pressure 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
    Connecting rod
    In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion....

  • 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
Vauclain compound
The Vauclain compound was a type of compound steam locomotive that was briefly popular around 1900. Developed at the Baldwin Locomotive Works, it featured two pistons moving in parallel, driving a common crosshead and controlled by a common valve gear using a single, complex piston...

), 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
Loading gauge
A loading gauge defines the maximum height and width for railway vehicles and their loads to ensure safe passage through bridges, tunnels and other structures...

 (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 engines



It is a logical extension of the compound engine (described 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 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
Olympic class ocean liner
The Olympic-class ocean liners were a trio of ocean liners built by the Harland & Wolff shipyard for the White Star Line in the early 20th century...

), but was ultimately replaced by the virtually vibration-free turbine (see below).

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.

Land-based steam engines could exhaust much of their steam, as feed water was usually readily available. Prior to and during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, the expansion engine dominated marine applications where high vessel speed was not essential. It was however superseded by the British invention steam turbine
Steam turbine
A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

 where speed was required, for instance in warships, such as the dreadnought battleships, and ocean liner
Ocean liner
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. Liners may also carry cargo or mail, and may sometimes be used for other purposes .Cargo vessels running to a schedule are sometimes referred to as...

s. of 1905 was the first major warship to replace the proven technology of the reciprocating engine with the then-novel steam turbine.

Uniflow (or unaflow) 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 each stroke making the steam flow only in one direction. By this means, thermal efficiency
Thermal efficiency
In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a boiler, a furnace, or a refrigerator for example.-Overview:...

 is improved by having a steady temperature gradient
Temperature gradient
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in units of degrees per unit length...

 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.

All common steam admission valves, such as slide valves, piston valves and rotary Corliss type valves, have been used on uniflow engines, usually actuated by common eccentrics. The most advanced uniflow engines used poppet valves, which allow high steam inlet temperatures. The inlet valves may be driven by a double cam system whose phasing and duration is controllable; this allows adjustments for high torque and power when needed with more restrained use of steam and greater expansion for economical cruising.

Uniflow engines have been produced in single-acting, double-acting, simple, and compound versions. Skinner 4-crank 8-cylinder single-acting tandem compound engines power two Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...

 ships still trading today (2007). These are the Saint Marys Challenger, that in 2005 completed 100 years of continuous operation as a powered carrier (the Skinner engine was fitted in 1950) and the car ferry, .

In the early 1950s, the Ultimax engine – a 2-crank 4-cylinder arrangement similar to Skinner's – was developed by Abner Doble
Abner Doble
Abner Doble , was an American mechanical engineer who built and sold steam-powered automobiles. His father was William Ashton Doble, inventor of the Doble water wheel, and his grandfather and namesake was the founder of the Abner Doble Company.Abner Doble began apprenticing at his family's factory...

 for the Paxton car project with tandem opposed single-acting cylinders giving effective double-action.

Small uniflow steam engines have been made as conversions of two-stroke internal combustion engines, by feeding the cylinder with steam via a "bash valve" in the spark plug hole which is knocked open by the piston reaching the top of its stroke.

Turbine engines



A steam turbine consists of one or more rotors (rotating discs) mounted on a drive shaft, alternating with a series of stators (static discs) fixed to the turbine casing. 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 surface 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 are only effective if they rotate at very high speed, therefore they are usually connected to reduction gearing to drive another mechanism, such as a ship's propeller, at a lower speed. This gearbox can be mechanical but today it is more common to use an alternator/generator set to produce electricity that later is used to drive an electric motor. A turbine rotor is also only capable of providing power when rotating in one direction. 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 main use for steam turbines is in electricity generation
Electricity generation
Electricity generation is the process of generating electric energy from other forms of energy.The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday...

 (about 90% of the world's electric production is by use of steam turbines) 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; in the latter (pioneered on the Turbinia
Turbinia
Turbinia was the first steam turbine-powered steamship. Built as an experimental vessel in 1894, and easily the fastest ship in the world at that time, Turbinia was demonstrated dramatically at the Spithead Navy Review in 1897 and set the standard for the next generation of steamships, the...

), the light weight, high efficiency and high power are highly desirable.

Virtually all nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 plants generate electricity by heating water to provide steam that drives a turbine connected to an electrical generator
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...

. Nuclear-powered ships and submarines
Nuclear marine propulsion
Nuclear marine propulsion is propulsion of a ship by a nuclear reactor. Naval nuclear propulsion is propulsion that specifically refers to naval warships...

 either use a steam turbine directly for main propulsion, with generators providing auxiliary power, or else employ turbo-electric
Turbo-electric
A turbo-electric transmission uses electric generators to convert the mechanical energy of a turbine into electric energy and electric motors to convert it back into mechanical energy to power the driveshafts....

 propulsion, where the steam drives a turbine-generator set with propulsion provided by electric motors. A limited number of steam turbine railroad locomotives
Steam turbine locomotive
A steam turbine locomotive is a steam locomotive which transmits steam power to the wheels via a steam turbine. Numerous attempts at this type of locomotive were made, mostly without success...

 were manufactured. Some non-condensing direct-drive locomotives did meet with some success for long haul freight operations in Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 and for express passenger work in Britain
LMS Turbomotive
The Turbomotive was a modified Princess Royal Class steam locomotive designed by William Stanier and built by the London, Midland and Scottish Railway in 1935. It used turbines instead of cylinders...

, but were not repeated. 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
Pistonless rotary engine
A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does, but instead uses one or more rotors, sometimes called rotary pistons...

 such as the Wankel engine
Wankel engine
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into a rotating motion instead of using reciprocating pistons. Its four-stroke cycle takes place in a space between the inside of an oval-like epitrochoid-shaped housing and a rotor that...

 in place of the cylinders and valve gear
Valve gear
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 steam to escape, respectively, at the correct points in the cycle...

 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
Thermal expansion
Thermal expansion is the tendency of matter to change in volume in response to a change in temperature.When a substance is heated, its particles begin moving more and thus usually maintain a greater average separation. Materials which contract with increasing temperature are rare; this effect is...

; the resulting leakage made them very inefficient. Lack of expansive working, or any means of control of the cutoff
Cutoff (steam engine)
In a steam engine, cutoff is the point in the piston stroke at which the inlet valve is closed. On a steam locomotive, the cutoff is controlled by the reverser....

 is also a serious problem with many such designs.
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
Beauchamp Tower
Beauchamp TowerBeauchamp Tower is just one of the 21 towers which, together, form the Tower of London castle complex. Its present name probably refers to the residence in it as a prisoner of Thomas, third Earl of Warwick, of the Beauchamp family, who was attainted under Richard II in 1397, but...

 are notable. Tower's engines were used by the Great Eastern Railway
Great Eastern Railway
The Great Eastern Railway was a pre-grouping British railway company, whose main line linked London Liverpool Street to Norwich and which had other lines through East Anglia...

 to drive lighting dynamos on their locomotives, and by the Admiralty
Admiralty
The Admiralty was formerly the authority in the Kingdom of England, and later in the United Kingdom, responsible for the command of the Royal Navy...

 for driving dynamos on board the ships of the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. They were eventually replaced in these niche applications by steam turbines.

Rocket type


The aeolipile
Aeolipile
An aeolipile , also known as a Hero engine, is a rocket style jet engine which spins when heated. In the 1st century AD, Hero of Alexandria described the device, and many sources give him the credit for its invention.The aeolipile Hero described is considered to be the first recorded steam engine...

 represents the use of steam by the rocket-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.

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.

Cold sink



As with all heat engines, a considerable quantity of waste heat
Waste heat
Waste heat sometimes called Secondary heat or Low-grade heat refers to heat produced by machines, electrical equipment and industrial processes for which no useful application is found. Energy is often produced by a heat engine, running on a source of high-temperature heat...

 at relatively low temperature is produced and must be disposed of.

The simplest cold sink is to vent the steam to the environment. This is often used on steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

s, as the released steam is released in the chimney so as to increase the draw on the fire, which greatly increases engine power, but is inefficient. Steam locomotive condensing apparatus
Steam locomotive condensing apparatus
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 water, or to avoid excessive emissions to the atmosphere, rather than maintaining a vacuum to improve both efficiency and power...

 can be employed to improve efficiency.

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
Combined Heat and Power
Combined Heat and Power may refer to:* Cogeneration* Combined Heat and Power Solar...

 (CHP) systems use the waste steam for district heating
District heating
District heating is a system for distributing heat generated in a centralized location for residential and commercial heating requirements such as space heating and water heating...

.

Where CHP is not used, steam turbines in power stations use surface condensers as a cold sink. The condensers are cooled by water flow from oceans, rivers, lakes, and often by cooling towers which evaporate water to provide cooling energy removal. The resulting condensed hot water output from the condenser is then put back into the boiler via a pump. The water vapour
Vapor
A vapor or vapour is a substance in the gas phase at a temperature lower than its critical point....

 with entrained droplets often seen billowing from power stations is generated by the cooling systems (not from the closed-loop Rankine power cycle) and represents the waste energy heat (pumping and vaporization) that could not be converted to useful work in the turbine. Note that cooling tower
Cooling tower
Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or in the case of closed circuit dry cooling towers rely...

s operate using the latent heat of vaporization of the cooling fluid. The white billowing clouds that form in cooling tower operation are the result of water droplets in the atmosphere that become entrained in the cooling tower airflow; they are not, as commonly thought, released steam.

Water pump



The Rankine cycle and most practical steam engines have a water pump to recycle or top up the boiler water, so that they may be run continuously. The water pump can be of almost any type although special types, such as an injector
Injector
ʎ̩An injector, ejector, steam ejector, steam injector, eductor-jet pump or thermocompressor is a pump-like device that uses the Venturi effect of a converging-diverging nozzle to convert the pressure energy of a motive fluid to velocity energy which creates a low pressure zone that dɯaws in and...

, which is a pump that uses a steam jet usually supplied from the boiler and is present on many steam locomotives.

Monitoring equipment



For safety reasons, nearly all steam engines are equipped with mechanisms to monitor the boiler, such as a pressure gauge and a sight glass
Sight glass
A sight glass or water gauge is a transparent tube through which the operator of a tank or boiler can observe the level of liquid contained within.-Liquid in tanks:...

 to monitor the water level.

Many engines, stationary and mobile, are also fitted with a governor
Governor (device)
A governor, or speed limiter, is a device used to measure and regulate the speed of a machine, such as an engine. A classic example is the centrifugal governor, also known as the Watt or fly-ball governor, which uses a rotating assembly of weights mounted on arms to determine how fast the engine...

 to regulate the speed of the engine without the need for human interference (similar to cruise control in some cars).

The most useful instrument for analyzing the performance of steam engines is the steam engine indicator. It was developed for high speed engine inventor and manufacturer Charles Porter by Charles Richard and exhibited at London Exhibition in 1862. The steam engine indicator traces on paper the pressure in the cylinder throughout the cycle, which can be used to spot various problems and calculate developed horsepower. It was routinely used by engineers, mechanics and insurance inspectors. The engine indicator can also be used on internal combustion engines. See image of indicator diagram above.

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.

Similar advantages are found in a different type of external combustion engine, the Stirling engine
Stirling engine
A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work....

, 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 . 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
Diesel-electric
Diesel-electric transmission or diesel-electric powertrain is used by a number of vehicle and ship types for providing locomotion.A diesel-electric transmission system includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors...

 units of equivalent sea level power. These were quickly replaced by much more powerful locomotives capable of producing sufficient power at high altitude.

For road vehicles, steam propulsion has the advantage of having high torque from stationary, removing the need for a clutch and transmission, though start-up time and sufficiently compact packaging remain a problem.

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
Swiss Locomotive and Machine Works
Swiss Locomotive and Machine Works were a railway equipment manufacturer based in Winterthur in Switzerland...

 (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 railway
Rack railway
A rack-and-pinion railway is a railway with a toothed rack rail, usually between the running rails. The trains are fitted with one or more cog wheels or pinions that mesh with this rack rail...

s, 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
Radio control
Radio control is the use of radio signals to remotely control a device. The term is used frequently to refer to the control of model vehicles from a hand-held radio transmitter...

. 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 escapes and boiler explosion
Boiler explosion
A boiler explosion is a catastrophic failure of a boiler. As seen today, boiler explosions are of two kinds. One kind is over-pressure in the pressure parts of the steam and water sides. The second kind is explosion in the furnace. Boiler explosions of pressure parts are particularly associated...

s (typically BLEVE
BLEVE
A boiling liquid expanding vapor explosion occurs when a vessel containing a pressurized liquid above its boiling point ruptures.-Mechanism:...

s) 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 may include:
  • over-pressurisation 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


Steam engines frequently possess two independent mechanisms for ensuring that the pressure in the boiler does not go too high; one may be adjusted by the user, the second is typically designed as an ultimate fail-safe.

Lead fusible plug
Fusible plug
A fusible plug is a threaded metal cylinder usually of bronze, brass or gunmetal, with a tapered hole drilled completely through its length. This hole is sealed with a metal of low melting point that flows away if a pre-determined, high temperature is reached...

s may be present in the crown of the firebox. If the water level drops, such that the temperature of the firebox crown increases significantly, the lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 melts and the steam escapes, warning the operators, who may then manually drop the fire. Except in the smallest of boilers the steam escape has little effect on dampening the fire. The plugs are also too small in area to lower steam pressure significantly, depressurizing the boiler. If they were any larger, the volume of escaping steam would itself endanger the crew.

Efficiency


See also: Engine efficiency#Steam engine


The efficiency of an engine can be calculated by dividing the energy output of mechanical work that the engine produces by the energy input to the engine by the burning fuel.

No heat engine can be more efficient than the Carnot cycle
Carnot cycle
The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded by Benoit Paul Émile Clapeyron in the 1830s and 40s. It can be shown that it is the most efficient cycle for converting a given amount of thermal energy into work, or conversely,...

, in which heat is moved from a high temperature reservoir to one at a low temperature, and the efficiency depends on the temperature difference. For the greatest efficiency, steam engines should be operated at the highest steam temperature possible (superheated steam
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...

), and release the waste heat at the lowest temperature possible.

The efficiency of a Rankine cycle is usually limited by the working fluid. Without the pressure reaching super critical
Critical point (thermodynamics)
In physical chemistry, thermodynamics, chemistry and condensed matter physics, a critical point, also called a critical state, specifies the conditions at which a phase boundary ceases to exist...

 levels for the working fluid, the temperature range the cycle can operate over is quite small; in steam turbines, turbine entry temperatures are typically 565°C (the creep
Creep (deformation)
In materials science, creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses. It occurs as a result of long term exposure to high levels of stress that are below the yield strength of the material....

 limit of stainless steel) and condenser temperatures are around 30°C. This gives a theoretical Carnot efficiency of about 63% compared with an actual efficiency of 42% for a modern coal-fired power station. This low turbine entry temperature (compared with a gas turbine
Gas turbine
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....

) is why the Rankine cycle is often used as a bottoming cycle in combined-cycle gas turbine
Combined cycle
In electric power generation a combined cycle is an assembly of heat engines that work in tandem off the same source of heat, converting it into mechanical energy, which in turn usually drives electrical generators...

 power stations.

One of the principal advantages the Rankine cycle holds over others is that during the compression stage relatively little work is required to drive the pump, the working fluid being in its liquid phase at this point. By condensing the fluid, the work required by the pump consumes only 1% to 3% of the turbine power and contributes to a much higher efficiency for a real cycle. The benefit of this is lost somewhat due to the lower heat addition temperature. Gas turbine
Gas turbine
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....

s, for instance, have turbine entry temperatures approaching 1500°C. Nonetheless, the efficiencies of actual large steam cycles and large modern gas turbines are fairly well matched.

In practice, a steam engine exhausting the steam to atmosphere will typically have an efficiency (including the boiler) in the range of 1-10%, but with the addition of a condenser and multiple expansion, it may be greatly improved to 25% or better.

A modern large electrical power station (producing several hundred megawatts of electrical output) with steam reheat, economizer
Economizer
Economizers , or economisers , are mechanical devices intended to reduce energy consumption, or to perform another useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, powerplant, and heating, ventilating, and air-conditioning uses are...

 etc. will achieve efficiency in the mid 40% range, with the most efficient units approaching 50% thermal efficiency.

It is also possible to capture the waste heat using cogeneration
Cogeneration
Cogeneration is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat....

 in which the waste heat is used for heating a lower boiling point working fluid or as a heat source for district heating via saturated low pressure steam. By this means it is possible to use as much as 85-90% of the input energy.

Applications


Since the early 18th century, steam power has been applied 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
Reciprocating motion
Reciprocating motion, also called reciprocation, is a repetitive up-and-down or back-and-forth motion. It is found in a wide range of mechanisms, including reciprocating engines and pumps. The two opposite motions that comprise a single reciprocation cycle are called strokes...

 into rotary motion) began to appear, driving factory machinery such as spinning mule
Spinning mule
The spinning mule was a machine used to spin cotton and other fibres in the mills of Lancashire and elsewhere from the late eighteenth to the early twentieth century. Mules were worked in pairs by a minder, with the help of two boys: the little piecer and the big or side piecer...

s and power loom
Power loom
A power loom is a mechanized loom powered by a line shaft. The first power loom was designed in 1784 by Edmund Cartwright and first built in 1785. It was refined over the next 47 years until a design by Kenworthy and Bullough, made the operation completely automatic. This was known as the...

s. At the turn of the 19th century, steam-powered transport on both sea and land began to make its appearance becoming ever more dominant as the century progressed.

Steam engines can be said to have been the moving force behind the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...

 and saw widespread commercial use driving machinery in factories, mills and mines; powering pumping station
Pumping station
Pumping stations are facilities including pumps and equipment for pumping fluids from one place to another. They are used for a variety of infrastructure systems, such as the supply of water to canals, the drainage of low-lying land, and the removal of sewage to processing sites.A pumping station...

s; and propelling transport appliances such as railway locomotives, ships and road vehicles. Their use in agriculture led to an increase in the land available for cultivation.

Very low power engines are used to power models and toys, and speciality applications such as the steam clock
Steam clock
A steam clock is a clock which is fully or partially powered by a steam engine. Only a few functioning steam clocks exist, most designed and built by Canadian horologist Raymond Saunders for display in urban public spaces...

.

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 engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s; notably this has made steam aircraft
Steam aircraft
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 enough power-to-weight ratio to be practical...

 extremely rare. Similar considerations have meant that for small and medium-scale applications steam has been largely superseded by internal combustion engines or electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

s, which has given the steam engine an out-dated image. However it is important to remember that the power supplied to the electric grid is predominantly generated using steam turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...

 plant, so that indirectly the world's industry is still dependent on steam power. Recent concerns about fuel sources and pollution have incited a renewed interest in steam both as a component of cogeneration
Cogeneration
Cogeneration is the use of a heat engine or a power station to simultaneously generate both electricity and useful heat....

 processes and as a prime mover. This is becoming known as the Advanced Steam
Advanced steam technology
Advanced steam technology reflects an approach to the technical development of the steam engine intended for a wider variety of applications than has recently been the case...

 movement.

Steam engines can be classified by their application:

Stationary applications


Stationary steam engine
Stationary steam engine
Stationary steam engines are fixed steam engines used for pumping or driving mills and factories, and for power generation. They are distinct from locomotive engines used on railways, traction engines for heavy steam haulage on roads, steam cars , agricultural engines used for ploughing or...

s can be classified into two main types:
  1. Winding engine
    Winding engine
    A winding engine is a stationary engine used to control a cable, for example to power a mining hoist at a pit head. Electric hoist controllers have replaced proper winding engines in modern mining, but use electric motors that are also traditionally referred to as winding engines.Most proper...

    s, rolling mill engines, steam donkey
    Steam donkey
    Steam donkey, or donkey engine is the common nickname for a steam-powered winch, or logging engine widely used in past logging operations, though not limited to logging...

    s, marine engines, and similar applications which need to frequently stop and reverse.
  2. Engines providing power, which rarely stop and do not need to reverse. These include engines used in thermal power stations and those that were used in pumping station
    Pumping station
    Pumping stations are facilities including pumps and equipment for pumping fluids from one place to another. They are used for a variety of infrastructure systems, such as the supply of water to canals, the drainage of low-lying land, and the removal of sewage to processing sites.A pumping station...

    s, mills
    Steam mill
    A steam mill is a type of grinding mill using a stationary steam engine to power its mechanism.-Reference to Marx:For Karl Marx, what defined feudalism was that the power of the ruling class rested on their control of arable land, leading to a class society based upon the exploitation of the...

    , factories
    Factory
    A factory or manufacturing plant is an industrial building where laborers manufacture goods or supervise machines processing one product into another. Most modern factories have large warehouses or warehouse-like facilities that contain heavy equipment used for assembly line production...

     and to power cable railway
    Cable railway
    A cable railway is a steeply graded railway that uses a cable or rope to haul trains.-Introduction:...

    s and cable tramway
    Cable car (railway)
    A cable car or cable railway is a mass transit system using rail cars that are hauled by a continuously moving cable running at a constant speed. Individual cars stop and start by releasing and gripping this cable as required...

    s before the widespread use of electric power
    Electric power
    Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

    .


The steam donkey
Steam donkey
Steam donkey, or donkey engine is the common nickname for a steam-powered winch, or logging engine widely used in past logging operations, though not limited to logging...

 is technically a stationary engine
Stationary engine
A stationary engine is an engine whose framework does not move. It is normally used not to propel a vehicle but to drive a piece of immobile equipment such as a pump or power tool. They may be powered by steam; or oil-burning or internal combustion engines....

 but is mounted on skids to be semi-portable. It is designed for logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

 use and can drag itself to a new location. 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
Portable engine
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. It is not self-propelled and is towed to the work site by horses or bullocks, or even a traction engine. Portable engines were used mainly for driving...

 is a stationary engine mounted on wheels so that it may be towed to a work-site by horses or a traction engine
Traction engine
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. The name derives from the Latin tractus, meaning 'drawn', since the prime function of any traction engine is to draw a load behind it...

, rather than being fixed in a single location.

Transport applications


Steam engines have been used to power a wide array of transport appliances:
  • Marine: Steamboat
    Steamboat
    A steamboat or steamship, sometimes called a steamer, is a ship in which the primary method of propulsion is steam power, typically driving propellers or paddlewheels...

    , steamship, steam yacht
    Steam yacht
    A steam yacht is a class of luxury or commercial yacht with primary or secondary steam propulsion in addition to the sails usually carried by yachts.-Origin of the name:...

  • Rail: Steam locomotive
    Steam locomotive
    A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

    , fireless locomotive
    Fireless locomotive
    A fireless locomotive is a type of locomotive designed for use under conditions restricted by either the presence of flammable material or the need for cleanliness...

  • Agriculture: Traction engine
    Traction engine
    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. The name derives from the Latin tractus, meaning 'drawn', since the prime function of any traction engine is to draw a load behind it...

    , steam tractor
    Steam tractor
    A steam tractor is a vehicle powered by a steam engine which is used for pulling.In North America, the term steam tractor usually refers to a type of agricultural tractor powered by a steam engine, used extensively in the late 19th and early 20th centuries.In Great Britain, the term steam tractor...

  • Road: Steam wagon
    Steam wagon
    A steam wagon is a steam-powered road vehicle for carrying freight. It was the earliest form of lorry and came in two basic forms: overtype and undertype – the distinction being the position of the engine relative to the boiler...

    , steam bus
    Steam bus
    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, although this term was sometimes used to describe other early experimental vehicles too.-History:...

    , steam tricycle
    Steam tricycle
    A steam tricycle is a steam-driven three-wheeled vehicle.-History:In the early days of motorised vehicle development, a number of experimenters built steam-powered vehicles with three wheels....

    , steam car
    Steam car
    A steam car is a light car powered by a steam engine.Steam locomotives, steam engines capable of propelling themselves along either road or rails, developed around one hundred years earlier than internal combustion engine cars although their weight restricted them to agricultural and heavy haulage...

  • Construction: Steam roller
    Steamroller
    A steamroller is a form of road roller – a type of heavy construction machinery used for levelling surfaces, such as roads or airfields – that is powered by a steam engine...

    , steam shovel
    Steam shovel
    A steam shovel is a large steam-powered excavating machine designed for lifting and moving material such as rock and soil. It is the earliest type of power shovel or excavator. They played a major role in public works in the 19th and early 20th century, being key to the construction of railroads...

  • Military: steam tank (tracked)
    Steam tank (vehicle)
    The Steam Tank was an early U.S. tank design of 1918 imitating the design of the British Mark IV tank but powered by steam.The type was designed by an officer from the U.S. Army's Corps Of Engineers. The project was started by General John A...

    , steam tank (wheeled)
    Steam Wheel Tank
    The Steam Wheel Tank was the official US Army name for the vehicle also known as the three-wheeled steam tank, the Holt Steam Tank and the Holt 150 Ton Field Monitor. It was an early U.S. produced tank built by the Holt Manufacturing Company sometime between late 1916 and early 1917. It was the...

    , steam catapult
  • Space: Steam rocket


In these applications internal combustion engines are now used due to their higher power-to-weight ratio
Power-to-weight ratio
Power-to-weight ratio is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power sources...

, lower maintenance and space requirements .

Modern applications


Although the reciprocating steam engine is no longer in widespread commercial use, various companies are exploring or exploiting the potential of the engine as an alternative to internal combustion engines.

The company Energiprojekt AB in Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 has made progress in using modern materials for harnessing the power of steam. The efficiency of Energiprojekt's steam engine reaches some 27-30% on high-pressure engines. It is a single-step, 5-cylinder engine (no compound) with superheated steam and consumes approx. 4 kg (8.8 lb) of steam per kWh.

See also


  • Aeolipile
    Aeolipile
    An aeolipile , also known as a Hero engine, is a rocket style jet engine which spins when heated. In the 1st century AD, Hero of Alexandria described the device, and many sources give him the credit for its invention.The aeolipile Hero described is considered to be the first recorded steam engine...

  • Compound locomotive
    Compound locomotive
    A compound engine unit is a type of steam engine where steam is expanded in two or more stages.A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger...

  • Geared steam locomotive
    Geared steam locomotive
    A geared steam locomotive is a type of steam locomotive which uses reduction gearing in the drivetrain, as opposed to the common directly driven design....

  • Giovanni Battista della Porta
  • History of steam road vehicles
    History of steam road vehicles
    The history of steam road vehicles describes the development of vehicles powered by a steam engine for use on land and independent of rails; whether for conventional road use, such as the steam car and steam waggon, or for agricultural or heavy haulage work, such as the traction engine.The first...

  • Lean's Engine Reporter
    Lean's Engine Reporter
    Lean's Engine Reporter was founded in 1810 to publicize the performances of different Cornish engines used for mine pumping in Cornwall. The first Reporter of Duty was Joel Lean. The Reporter, published monthly, gave, for each engine and its pumps, the number of strokes , and the amount of coal used...

  • List of steam museums
  • List of steam fairs
  • List of steam technology patents
  • Live steam
    Live steam
    Live steam is steam under pressure, obtained by heating water in a boiler. The steam is used to operate stationary or moving equipment.A live steam machine or device is one powered by steam, but the term is usually reserved for those that are replicas, scale models, toys, or otherwise used for...

  • Marine steam engine
    Marine steam engine
    A marine steam engine is a reciprocating steam engine that is used to power a ship or boat. Steam turbines and diesel engines largely replaced reciprocating steam engines in marine applications during the 20th century, so this article describes the more common types of marine steam engine in use...

  • Model steam engine
    Model steam engine
    A model steam engine is a small steam engine built as an educational toy for children or for adult live steam enthusiasts...

  • Portable engine
    Portable engine
    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. It is not self-propelled and is towed to the work site by horses or bullocks, or even a traction engine. Portable engines were used mainly for driving...

  • Reciprocating engine
    Reciprocating engine
    A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This article describes the common features of all types...

  • Salomon de Caus
    Salomon de Caus
    Salomon de Caus was a French engineer and once credited with the development of the steam engine.Salomon was the elder brother of Isaac de Caus. Being a Huguenot, he spent his life moving across Europe....


  • Steamboat
    Steamboat
    A steamboat or steamship, sometimes called a steamer, is a ship in which the primary method of propulsion is steam power, typically driving propellers or paddlewheels...

  • Steam locomotive
    Steam locomotive
    A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

  • Steampunk
    Steampunk
    Steampunk is a sub-genre of science fiction, fantasy, alternate history, and speculative fiction that came into prominence during the 1980s and early 1990s. Steampunk involves a setting where steam power is still widely used—usually Victorian era Britain or "Wild West"-era United...

  • Steam power during the Industrial Revolution
    Steam power during the Industrial Revolution
    During the Industrial Revolution, steam power began to replace water power and muscle power as the primary source of power in use in industry. Its first use was to pump water from mines...

  • Steamroller
    Steamroller
    A steamroller is a form of road roller – a type of heavy construction machinery used for levelling surfaces, such as roads or airfields – that is powered by a steam engine...

  • Steam tricycle
    Steam tricycle
    A steam tricycle is a steam-driven three-wheeled vehicle.-History:In the early days of motorised vehicle development, a number of experimenters built steam-powered vehicles with three wheels....

  • Steam turbine
    Steam turbine
    A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884....

  • Still engine
    Still engine
    The Still engine was a piston engine that simultaneously used both steam power from an external boiler, and internal combustion from gasoline or diesel, in the same unit...

  • Timeline of steam power
    Timeline of steam power
    Steam power developed slowly over a period of several hundred years, progressing through expensive and fairly limited devices in the early 17th century, to useful pumps for mining in 1700, and then to Watt's improved steam engine designs in the late 18th century...

  • Traction engine
    Traction engine
    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. The name derives from the Latin tractus, meaning 'drawn', since the prime function of any traction engine is to draw a load behind it...

  • Valve gear
    Valve gear
    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 steam to escape, respectively, at the correct points in the cycle...



Further reading

  • Crump, Thomas. A Brief History of the Age of Steam: From the First Engine to the Boats and Railways (2007)
  • Marsden, Ben. Watt's Perfect Engine: Steam and the Age of Invention (Columbia University Press, 2004)
  • Robinson, Eric H. "The Early Diffusion of Steam Power," Journal of Economic History Vol. 34, No. 1, (March 1974), pp. 91–107 in JSTOR
  • Rose, Joshua. Modern Steam Engines (1887, reprint 2003)
  • Stuart, Robert, A Descriptive History of the Steam Engine (London: J. Knight and H. Lacey, 1824.) online
  • Van Riemsdijk, J. T. Pictorial History of Steam Power (1980) An engineering handbook widely used by those involved with various types of boilers. Contains numerous illustrations, graphs and useful formulas. Contains a history of the steam engine.

External links