Background (Encyclopedia of Global Resources)
The chemical energy that is contained within fossil fuels such as oil and coal can be converted into thermal energy (heat) by burning the fuel. This thermal energy can be used to create steam in a boiler. A steam engine converts the thermal energy of steam into the mechanical energy of a rotating shaft, and this shaft can drive a pump, a ventilating fan, a ship’s propeller, and many other devices.
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History (Encyclopedia of Global Resources)
Although there were attempts to use steam to drive mechanical devices as early as 60 c.e. by Hero of Alexandria, the first real steam engine was designed and built by Thomas Newcomen in 1712. That year Newcomen successfully used a steam engine to pump water from a coal mine near Dudley Castle, England. In 1765, as he walked across Glasgow Green in the city of Glasgow, Scotland, James Watt conceived the idea of connecting the steam engine to a separate condenser. The first full-size engines based on this concept were built in 1776: one at John Wilkinson’s blast furnace near Broseley, England, and the other at Bloomfield coal mine near Tipton, England. Newcomen’s design and Watt’s early designs used steam at constant pressure. Over the course of his life, Watt invented many improvements to the steam engine, including rotary engines, a device for measuring engine performance, and engines in which the steam expanded during the piston stroke. Expanding steam engines soon drove the earlier type off the market, because the fuel consumption associated with the boiler of an expanding steam engine is far less than that of a constant pressure engine. While modern steam engines operate at much higher pressure than Watt’s, they are similar in design.
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Principles of Operation (Encyclopedia of Global Resources)
Early steam engines would be considered upside-down by modern standards. The piston was connected to a rod that emerged from the top of the engine, and steam was fed into the cylinder below the piston. A chain connected the piston rod to one end of a pivoted beam suspended above the engine, and the other end of the beam was connected to a pump that drew water up from the bottom of a mine. The weight of the pump rod was sufficient to pull the pump end of the pivoted beam downward, which caused the other end of the beam to rise and lift the piston upward. As the piston rose, steam at just above atmospheric pressure flowed from the boiler into the growing space below the piston. When the piston reached the top of its stroke, the valve between boiler and cylinder closed, and in Newcomen’s engine water was sprayed into the cylinder. As the water absorbed heat from the steam, the steam condensed, which created a partial vacuum. This vacuum, combined with atmospheric pressure acting on the upper side of the piston, caused the piston to move downward. When the piston reached the bottom of its stroke, the steam valve opened again. The steam pressure balanced the atmospheric pressure on the other side of the piston, and the weight of the pump rod again raised the piston to the top of its stroke.
Watt recognized that spraying cold water directly into the cylinder not only condensed the steam but also cooled off the cylinder...
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Applications of the Steam Engine (Encyclopedia of Global Resources)
The first applications were to drive dewatering pumps in mines and to supply pressurized air for blast furnaces that produced cast iron. It was soon realized that rotary steam engines could be used to drive all kinds of machinery. Without the invention of the steam engine, the Industrial Revolution would not have occurred in the time and place that it did. Steam engines drove spinning and weaving machines in the textile industry. Ships and railroad locomotives powered by steam engines revolutionized transportation. There were steam-powered farm tractors, automobiles, and construction machines. Early electric generators were also driven by steam engines. Many of these applications are now powered by electric motors, gasoline and diesel engines, and steam turbines, but it was the steam engine that showed the way.
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Further Reading (Encyclopedia of Global Resources)
Barton, D. B. The Cornish Beam Engine: A Survey of Its History and Development in the Mines of Cornwall and Devon from Before 1800 to the Present Day, with Something of Its Use Elsewhere in Britain and Abroad. New ed. Truro, Cornwall, England: Author, 1966.
Bray, Stan. Making Simple Model Steam Engines. Ramsbury, England: Crowood, 2005.
Briggs, Asa. The Power of Steam: An Illustrated History of the World’s Steam Age. Chicago: University of Chicago Press, 1982.
Crump, Thomas. A Brief History of the Age of Steam: The Power That Drove the Industrial Revolution. New York: Carroll & Graf, 2007.
Marsden, Ben. Watt’s Perfect Engine: Steam and the Age of Invention. New York: Columbia University Press, 2002.
Rose, Joshua. Modern Steam Engines. Philadelphia: H.C. Baird, 1886. Reprint. Mendham, N.J.: Astragal Press, 2003.
Steingress, Frederick M., Harold J. Frost, and Daryl R. Walker. Stationary Engineering. 3d ed. Homewood, Ill.: American Technical, 2003.
How Stuff Works. How Steam Engines Work. http://www.howstuffworks.com/steam.htm
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Steam Engine (Encyclopedia of Science)
A steam engine is a machine that converts the heat energy of steam into mechanical energy. A steam engine passes its steam into a cylinder, where it then pushes a piston back and forth. It is with this piston movement that the engine can do mechanical work. The steam engine was the major power source of the Industrial Revolution in Europe in the eighteenth and nineteenth centuries. It dominated industry and transportation for 150 years.
The first steam-powered machine was built in 1698 by the English military engineer Thomas Savery (c. 1650715). His invention, designed to pump water out of coal mines, was known as the Miner's Friend. The machine, which had no moving parts, consisted of a simple boiler steam chamber whose valves were located on the surfacend a pipe leading to the water in the mine below. Water was heated in the boiler chamber until its steam filled the chamber, forcing out any remaining water or air. The valves were then closed and cold water was sprayed over the chamber. This chilled and condensed the steam inside to form a vacuum. When the valves were reopened, the vacuum sucked up the water from the mine, and the process could then be repeated.
A few years later, an English engineer and partner of Savery named Thomas Newcomen (1663729) improved the steam pump. He increased efficiency by setting a moving piston inside...
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