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A steam engine is a heat engine that performs mechanical work using steam as its working fluid. In a steam engine, hot steam, usually supplied by a boiler, expands under pressure, and part of the heat energy is converted into work. The remainder of the heat may be allowed to escape, or, for maximum engine efficiency, the steam may be condensed in a separate apparatus, a condenser, at comparatively low temperature and pressure. For high efficiency, the steam must fall through a wide temperature range as a consequence of its expansion within the engine. The most efficient performance that is, the greatest output of work in relation to the heat supplied - is secured by using a low condenser temperature and a high boiler pressure. The steam may be further heated by passing it through a superheater on its way from the boiler to the engine. A common superheater is a group of parallel pipes with their surfaces exposed to the hot gases in the boiler furnace. By means of superheaters, the steam may be heated beyond the temperature at which it is produced by boiling water. Steam engines are of various types but most are reciprocal piston or turbine devices.
History
The first crude steam engine was based on Denis Papin's Digester or pressure cooker of 1679. It was invented and patented by an english military engineer and inventor Thomas Savery, in 1698. Thomas Savery had been working on solving the problem of pumping water out of coal mines, his machine consisted of a closed vessel filled with water into which steam under pressure was introduced. This forced the water upwards and out of the mine shaft. Then a cold water sprinkler was used to condense the steam. This created a vacuum which sucked more water out of the mine shaft through a bottom valve. But it had only limited lift height and was prone to boiler explosions, but it still received some use for mines and pumping stations.
Thomas Savery later worked with Thomas Newcomen on the atmospheric steam engine which were known so because they were powered by the vacuum generated by condensing steam instead of the pressure of expanding steam. Thomas Newcomen was an english blacksmith, who invented the atmospheric steam engine, an improvement over Thomas Slavery's previous design. The Newcomen steam engine used the force of atmospheric pressure to do the work. Thomas Newcomen's engine pumped steam into a cylinder. The steam was then condensed by cold water which created a vacuum on the inside of the cylinder. The resulting atmospheric pressure operated a piston, creating downward strokes. In Newcomen's engine the intensity of pressure was not limited by the pressure of the steam, unlike Thomas Savery's engine. In 1712, Thomas Newcomen together with John Calley built their first engine on top of a water filled mine shaft and used it to pump water out of the mine. The Newcomen engine was the predecessor to the Watt engine and it was one of the most interesting pieces of technology developed during the 1700's.
Development in the invention of Steam Engine
In 1765 James Watt while working for the University of Glasgow was assigned the task of repairing a Newcomen engine, which was deemed inefficient but the best steam engine of its time. That started the inventor to work on several improvements to Newcomen's design. The Scottish inventor and mechanical engineer was given his 1769 patent for a separate condenser connected to a cylinder by a valve. It was a major improvement of the time. Unlike Newcomen's engine, Watt's design had a condenser that could be cool while the cylinder was hot. Watt's engine used 75% less coal than Newcomen's, and was hence much cheaper to run. Watt's engine soon became the dominant design for all modern steam engines. He is credited with inventing the first practical and modern steam engine. His invention marked the real beginning of the industrial revolution. A unit of power called the Watt was named after James Watt. the Watt symbol is W, and it is equal to 1/746 of a horsepower, or one Volt times one Amp.
In 1769, a French military engineer called Nicolas Cugnot invented the steam powered road vehicle.
In 1787, John Fitch (1743-1798) made the first successful trial of a forty-five-foot steamboat on the Delaware River in America.
Around 1800, Richard Trevithick introduced engines using high-pressure steam. These were much more powerful than previous engines and could be made small enough for transport applications.
Canadian, Benjamin Franklin Tibbets invented the world's first practical compound marine engine, used in the steamer "Reindeer." The Reindeer was the fastest steamer in the 1820's.
In 1867, American inventors George Herman Babcock and Stephen Wilcox patented their Water Tube Boiler which was used for for heating water and generating steam above atmospheric pressure.
On april 1884, Charles Parsons patented his new steam turbine engine and immediately used the engine to drive an electrical generator, which he also designed.
Further technological developments and improvements in manufacturing techniques enabled the design of more efficient engines that could be smaller, faster, or more powerful, depending on the intended application. Steam engines remained the dominant source of power well into the 20th century, when advances in the design of electric motors and internal combustion engines gradually replaced steam engines.
Role of Steam Engine in the Improvement Of Human Life
