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Final Answers
© 2000-2014   Gérard P. Michon, Ph.D.

 Sadi Carnot 
 1796-1832
 Hermann von Helmholtz 
1821-1894

Heat Engines
and the Fate of the Universe

In this house, we obey the laws 
of thermodynamics
 [young lady].
 Homer Simpson 
 at DrawingNow.com Homer Simpson
(about the perpetual motion  
machine of his daughter Lisa)  
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Related articles on this site:

Related Links (Outside this Site)

Hero of Alexandria   |   Steam Engine History
Animated Engines  by Matt Keveney.
 
Wikipedia :   Empedocles (c.490-c.430 BC)   |   Democritus (c.460-c.370 BC)   |   Socrates (c.470-399 BC)

Videos :

Coffee-powered Stirling engine   |   Richard Feynman's rubber-band heat engine
 
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Introduction

Around the turn of the third millenium, people thought about what a short list of the most significant inventions of the second millenium (1001-2000) would necessarily entail...

Herb Brody (Technology Review  senior editor) came up with the following list, in chronological order:  compass, clock, lens, printing press, steam engine, telegraph, electrical power, radio, antibiotics, and transistor.  That's just about it.  Improvements and applications of those great inventions were ruled out, including the telephone, television, computer and other consumer electronics.  (So was the PN junction, which is overshadowed by its offspring, the  transistor.)

The internal combustion engine did not make the list either, because it is perceived as an improvement over the steam engine, at least by nontechnical people.  However, the internal combustion engine is a radically new technical idea, transcending fundamental limitations of steam engines.  Simply put, some chemical energy is directly put to work in an internal combustion engine, whereas all of it is first transformed into heat in a steam engine...  The fundamental difference is the push provided by a chemical explosion.  The French have a better term for the internal combustion engine: moteur à explosion.

To realize how important this is, you have to gain some exposure to the fundamentals of steam engines, which were poorly understood for centuries, until the theory of thermodynamics and its infamous second law were discovered.  The second law was first stated to explain the limited efficiency of steam engines, but it ultimately explains a lot more about the Universe around us and within us...

What follows is a guided tour through this fascinating history of practical inventions and theoretical discoveries.  From water pumps to the elusive idea of entropy...

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Heat Engines and the Fate of the Universe

 Aeolipile
 (Knight's American Mechanical Dictionary, 1876)
(2004-02-15)     The Aeolipile
Greatest ball of water wind and fire on Earth    Great Balls of Fire

The first documented steam engine was merely a toy.  It consisted of a boiler whose steam was routed through hollow supports into a spherical chamber, which rotated on a polar axis as steam escaped from two jet tubes along the equator.

This is described, with many other pneumatic or hydraulic devices, in  Spiritalia seu Pneumatica  by  Hero / Heron of Alexandria (c.AD 10-75).

The term aeolipile  (French éolipyle,  Latin Aeoli pylae,  "ball of Aeolus")  may have been coined in the 17th century, when other steam engines first appeared.

Some authors have attributed to a prolific inventor called Cestesibus many of the contraptions described by Heron  (who offers no clues on the matter).  The  aeolipile  may or may not have been the work of Cestesibus.  Heron himself is much better known for the formula named after him, which schoolchildren use to find the areas of scalene triangles.

The Pneumatics of Hero of Alexandria,  translated (1851) from the original Greek


(2005-06-26)     Edward Somerset of Worcester (c.1601-1667)
A blueprint for a steam-powered fountain (1662).

Edward Somerset was known as Lord Herbert after 1628.  In 1644, he became earl of Glamorgan, before inheriting the title of sixth earl and second marquis of Worcester, in 1646.

Worcester published his design but apparently never built an actual steam engine.  He proposed using the partial vacuum created when steam condenses to obtain mechanical work from atmospheric pressure.  This was the key idea used by Newcomen in his successful  atmospheric engine, half a century later.


(2004-02-15)     Denis Papin (1647-1714)
Beyond the pressure cooker:  The first actual piston engine (1690).

The Frenchman Denis Papin invented the pressure cooker  A pressure cooker is a heated closed container.  Food cooks faster in it because the temperature of water can be higher than the boiling point under ordinary atmospheric pressure.  A critical feature of the pressure cooker is, of course, its safety valve.

In 1690, Papin had the idea of fitting a piston over a boiler with a limited amount of water in it.  When the boiler is heated, water becomes steam and the piston is pushed upward.  When the boiler is allowed to cool, the steam condenses and atmospheric pressure pushes the piston down, back to the original volume.

Although considerable forces can be involved, the power of Papin's engine is low, because the heating and cooling of a single chamber is a  slow  process.

Denis Papin (1647-1714)


(2005-06-25)     Thomas Savery (c.1650-1715):  Separate Boiler
The Miner's Friend,  Savery's two-piston steam engine (1698).

The English engineer Thomas Savery built an engine consisting of two pistons over copper vessels which were alternately fed with steam from a separate boiler.

This high-pressure engine could raise water about 20 feet (6 m).  Thomas Savery obtained several patents before Thomas Newcomen made his own entrance.  (At some point, Savery may have employed Newcomen, whose blacksmith shop was only 15 miles away from Savery's residence at Modbury.)


(2005-06-30)     John Theophile Desaguliers (1683-1744)
.../...

 Come back later, we're
 still working on this one...


(2005-06-25)     Thomas Newcomen (1663-1729):  Inner Cooling
Newcomen's atmospheric steam engine (1712).

Thomas Newcomen was an English blacksmith born in Dartmouth (Devonshire) who set up shop there in 1685, in partnership with a plumber named John Calley [also spelled "Cawley"] (d.1717) who shared his interest in engines.

In 1698, Newcomen started corresponding with Thomas Savery and attempted to improve on Savery's machine to produce a safe and reliable steam engine.

 The Newcomen engine (1712) 
 'Practical Physics' illustration (1914)

In 1708, Newcomen obtained a patent (jointly with Savery) for what's usually considered to be the first practical steam engine.  The use of low-pressure steam (5 psi) made it extremely safe.  The key idea was to spray cold water inside the piston's chamber when is was filled with steam.  This caused steam to condense rapidly, and the atmosphere pushed the piston back to a smaller volume.

In 1712, the first operational engine was built over a mine near Dudley Castle.  It ran at 6 to 8 strokes per minute, with manual valves.  Automatic valves later allowed a typical regime of  10 to 12 rpm.

Newcomen's engine was successfully used to pump water from coal mines throughout Europe.  It was even exported to North America in 1755.


 Nicolas Joseph Cugnot 
 1736-1819 (2005-07-06)     Nicolas Joseph Cugnot (1725-1804)
Le Fardier de Cugnot  was the first automobile  (October 1769).

Joseph Cugnot was a French military engineer.  Ostensibly, he designed his  fardier à vapeur  (steam dray)  for the purpose of hauling artillery pieces.

The second prototype, which was completed by June 1771, is religiously preserved in Paris, at the Conservatoire National des Arts et Métiers.


 James E. Watt 
 1736-1819 (2004-02-15)     James E. Watt (1736-1819)
The steam engine comes of age:  Steam condenser and governor.

The water-cooled steam condenser, patented by James Watt in 1769, was the key to a dramatic improvement in the efficiency of steam engines.

Although the fundamental issue was not fully understood until 1824  (see Carnot's limit below)  this improved efficiency came from a greater temperature difference  [or ratio, rather]  between active parts of the engine throughout its cycle.

Watt's engine has two separate chambers:  The piston's cylinder remains at the temperature of hot steam, while the steam condenser is water-cooled.

Among many other innovations, Watt also introduced an ingenious speed regulator in 1788, which is probably the earliest technological example of a feedback mechanism:  The so-called  Watt governor  (also known as the centrifugal or flyball governor) made steam engines safer and easier to use.

By 1790, the new and improved Watt engines had all but completely replaced Newcomen engines.  Watt's clever innovations were so successfull that it's now necessary to stress that James Watt  did not  invent the steam engine!


(2005-06-26)   Richard Trevithick (1771-1833):  Steam Locomotive
The inventor of the railroad locomotive was not George Stephenson.

In 1796, Richard Trevithick experimented with high-pressure noncondensing steam engines and built his first miniature locomotive.  On Christmas eve of 1801, he took 7 of his friends on a trip aboard a "road locomotive".  He is credited with the idea that smooth wheels on smooth iron rails would provide enough traction for most practical purposes.

In February 1804, Trevithick tested the first locomotive ever to run on rails.  This locomotive featured a single vertical cylinder, an 8-foot flywheel and an innovative exhaust steam chimney  (producing an efficient updraft).  It hauled 5 wagons, 10 tons of iron and 70 passengers, but made only 3 short trips on a projected 9-mile railroad between the Merthyr-Cardiff Canal and the ironworks at Pen-y-darren  (whose owner, Samuel Homfray, was financing the enterprise).  Each time, the locomotive broke some cast-iron rails.  The sponsor gave up.

George Stephenson himself stressed the importance of the experiments of Trevithick in the development of locomotives.  However, in February 1828, the House of Commons denied a pension to Trevithick, who died in poverty.

 George Stephenson  
 1781-1848

The immediate successors to the Trevithick locomotives were used in mining operations.  This included the  Blutcher  locomotive, built in 1814 by the British engineer George Stephenson (1781-1848).  In 1829, the  Liverpool and Manchester Railroad  ran a locomotive competition for a railway intended to carry both passengers and freight.  The trials took place at Rainhill, near Liverpool, in October 1829.  The award went to Stephenson, for a legendary locomotive dubbed  Rocket.


 Sadi Carnot 
 1796-1832 (2005-06-23)     Sadi Carnot (1796-1832):  The Carnot Cycle
Fundamental limitations:  The second law of thermodynamics.
 Nicolas Leonard Sadi Carnot 
 (1796-1832) X1812

After the dramatic innovations of James Watt, many engineers wondered if anything could be done to further increase the low efficiency of steam engines.  By offering a sobering upper limit to that efficiency, a young Frenchman helped create the new science of thermodynamics:  In 1824, [Nicolas Léonard] Sadi Carnot analyzed an ideal engine transforming into work some of the heat going from a hot source to a cold one...

Carnot defined the  efficiency  of an heat engine as the ratio of the  net  work done by the engine to the heat it received from its boiler  (whatever heat is spend by the engine to warm up the condenser is, indeed, pure waste).

This efficiency can't exceed the following function of the hot  (T)  and cold  (T) temperatures above absolute zero, known as  Carnot's limit :

-  T /  T1

The unavoidable "waste" is thus equal to the ratio of the absolute temperatures.  This example was ultimately generalized into what became the  Second Law of Thermodynamics, even before the  First Law  was generally accepted.

Carnot's limit is  not  directly applicable to an internal combustion engine, which may involve some direct transformation of chemical energy into mechanical work.


 Sir Charles Parsons 
 1854-1931 (2005-06-22)     Sir Charles Algernon Parsons (1854-1931)
Steam turbines (1884) are still used in nuclear power plants.

In 1629, Italian engineer Giovanni Branca (1571-1640) ran a double-pestle stamp mill with a  steam blower  (directing a jet to vanes on a wheel).

In 1791, the British inventor John Barber obtained a patent for a gas turbine.

In 1884, Charles Parsons (6th son of the 3rd earl of Rosse) patented the modern steam turbine, with multiple staging.  Each stage in such a turbine improves overall efficiency by making use of the steam of the previous stage and is optimized for its task in this chain of successively lower steam pressures.  Parsons' first prototype produced about 10 hp at 20000 rpm  (by contrast, a reciprocating steam engine is limited to about 1500 rpm, at best).

 Gustaf de Laval 
 (1845-1913) In 1887, the Swedish engineer  Carl Gustaf Patrik de Laval (1845-1913) built a small demonstration steam turbine which rotated at 42000 rpm.  In 1890, he invented the convergent-divergent nozzle now named after him, to optimize the efficiency of a single-stage steam turbine  (the de Laval nozzle is commonly used in modern rocketry).  De Laval also came up with innovative reduction gearing which could accomodate the high rotational speed of steam turbines.

De Laval was an inventor of the same caliber as Thomas Edison.  He described his inventions meticulously in over 1000 diaries.  In the 1890s, he employed over 100 engineers to put them to good use.

Turbinia :

Although he had no training as a naval architect, Parsons designed and built Turbinia, the first ship ever to be powered by steam turbines.  He demonstrated her astounding speed on June 22, 1897, during  Queen Victoria's Diamond Jubilee Fleet Review.  Parsons piloted the ship himself, at the astounding speed of 34.5 knots  (64 km/h, 40 mph).  Charles Parsons was knighted in 1911.


(2011-08-31)     The Drinking Bird
A clever heat engine based on evaporative cooling.

The  drinking bird  was invented by  Miles V. Sullivan 

The son of Miles Sullivan confirmed that Albert Einstein could not figure out the operating principle of the toy when he was first confronted to it.  Neither could most physicists...

The fluid contained in the vessel  (which is usually colored)  must have a fairly high vapor pressure at room temperature.  The original patent (1946) mentions  "ether, alcohol, carbon tetrachloride or chloroform".  Formerly, the toy was manufactured with  trichloromonofluoromethane  (Freon-11)  before its harmful impact on the environment was recognized.  Nowadays, dichloromethane is most commonly used  (it's a moderately hazardous substance heralded as the least toxic of the simple organochlorides).

 Come back later, we're
 still working on this one...

Drinking Bird (Wikipedia)   |  
US Patent 2402463 (1946)  by  Miles V. Sullivan
Video :   Drinking Bird by  Phil Moriarty  (in "Sixty Symbols"  by  Brady Haran)

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