Steam Engine
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Steam engine, machine using steam power to perform mechanical work through the agency of heat. 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.
In 1765 James Watt greatly improved the Newcomen engine by adding a separate condenser to avoid heating and cooling the cylinder with each stroke. Watt then developed a new engine that rotated a shaft instead of providing the simple up-and-down motion of the pump, and he added many other improvements to produce a practical power plant. Watt is known for the invention of the Steam Engine.
Though the steam engine gave way to the internal-combustion engine as a means of vehicle propulsion, interest in it revived in the second half of the 20th century because of increasing air-pollution problems caused by the burning of fossil fuels in internal-combustion engines.
In 1765 James Watt greatly improved the Newcomen engine by adding a separate condenser to avoid heating and cooling the cylinder with each stroke. Watt then developed a new engine that rotated a shaft instead of providing the simple up-and-down motion of the pump, and he added many other improvements to produce a practical power plant. Watt is known for the invention of the Steam Engine.
Though the steam engine gave way to the internal-combustion engine as a means of vehicle propulsion, interest in it revived in the second half of the 20th century because of increasing air-pollution problems caused by the burning of fossil fuels in internal-combustion engines.