Steam Engine Essay Research Paper The steam

Steam Engine Essay, Research Paper

The steam engine is a machine used for converting heat energy into mechanical energy,

using steam as the conversion medium. When water is boiled into steam its volume increases

about 1,600 times, producing a force that can be used to move a piston back and forth in a

cylinder. The piston is attached to a crankshaft that converts the piston’s back-and-forth motion

into rotary motion for driving machinery. From the Greek inventor hero of Alexandria to the

Englishman Thomas Newcomen, many persons contributed to the work of harnessing steam.

However, James Watt’s steam engine, patented 1769 offered the first practical solution by

providing a separate chamber for condensing the steam and by using steam pressure to move the

piston in both directions. These and other improvements by Watt prepared the steam engine for a

major role in manufacturing and transportation during the Industrial Revolution. Today steam

engines have been largely replaced by more efficient devices, for example, the steam turbine, the

electric motor, the international combustion.

Since the early 1900s, steam turbines have replaced most steam engines in large

electric-power plants (see ). Turbines are more efficient and more powerful than steam engines.

In most areas, steam locomotives have been supplanted by more reliable and economical

diesel-electric locomotives. Early steam automobiles have been superseded by cars powered by

lightweight, convenient, and more powerful gasoline and diesel engines. Because of all this,

steam engines today generally are regarded as museum pieces. Nonetheless, the invention of the

steam engine played a major role in the Industrial Revolution by creating a society less

dependent on animal power, waterwheels, and windmills

In 1690 the first steam piston engine was developed by French physicist Denis Papin for

pumping water. In this crude device a small amount of water was placed in a single cylinder over

a fire. As the water evaporated, the steam pressure forced a piston upward. The heat source was

then removed, allowing the steam to cool and condense. This created a partial vacuum (a

pressure below that of the atmosphere). Because the air located above the piston was at a higher

pressure (at atmospheric pressure), it would force the piston downward, performing work. More

practical devices powered by steam were the steam pump–patented in 1698 by the English

engineer Thomas Savery–and the so-called atmospheric steam engine–first built in 1712 by

Thomas Newcomen and John Calley. In the Newcomen engine, steam generated in a boiler was

fed into a cylinder located directly above the boiler. A piston was pulled to the top of the

cylinder by a counterweight. After the cylinder was filled with steam, water was injected into it,

causing the steam to condense. This reduced the pressure inside the cylinder and allowed the

outside air to push the piston back down. A chain-beam lever linkage was connected to a pump

rod, which lifted the pump plunger as the piston moved downward. Some modified Newcomen

engines were in service as late as 1800.

The Scottish instrument maker James Watt noticed that use of the same chamber for

alternating hot steam and cold condensate resulted in poor fuel utilization. In 1765 he devised a

separate water-cooled condenser chamber. It was equipped with a pump to maintain a partial

vacuum and periodically steam was fed from the cylinder through a valve. Watt and his business

partner, Matthew Boulton, sold these engines on the basis that one third of the fuel savings be

paid to them. The fuel costs for the Watt and Boulton engines were 75 percent less than those for

a similar Newcomen engine. Among Watt’s many other improvements was the crankshaft, which

was used to produce rotating power; the use of double-acting pistons, by which steam was fed

alternately into the top and bottom sections of the piston-cylinder assembly to nearly double the

power output of a given engine; a governor, which regulated the flow of steam to the engine; and

the flywheel, which smoothed out the jerky action of the cylinders. Watt also recognized that

using high-pressure steam in the engine would be more economical than using steam at external

atmospheric pressure. Due to limitations in boiler design, however, his engines never operated at

high pressures.

Engines were further improved after the development of boilers that could operate at

higher pressures. By the end of the 18th century, two types of high-pressure boilers were in use:

water-tube boilers and fire-tube boilers. Their shells were made of iron plates fastened together

with rivets. In water-tube boilers, water was heated in coiled or vertical tubes that ran through

the fire chamber and received heat from the hot combustion gases. The steam would collect at

the top of the boilers. These boilers were the precursors of modern power-plant boilers. In

fire-tube boilers,

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