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Introduction |
External
Combustion Engines |
Internal
Combustion Engines |
Electric Motors
Until about three hundred years ago, the only forms of transportation power that people used came directly from nature. They included wind, flowing water, and muscle power from people or animals. There were no engines of any kind until the first steam engine was built in England in the 1700s. It was the size of a small building and operated pumps to remove water from coal mines. Steam Engines How do steam engines work? All steam engines are external combustion engines. External means that the power source is outside the engine. Combustion refers to burning. Steam engines use the heat from burning coal or wood to change water into steam. Since the fire is under a boiler, which is outside the engine, the power source is external.
Steam engines have a piston that moves back and forth. A piston is a plug that just barely fits inside a closed cylinder. Expanding steam from a boiler pushes on one end of the piston and causes it to move inside the cylinder. As the piston moves, it closes one valve and opens another. The steam is then sent to the other end of the piston and moves it back to its original position. This back-and-forth movement turns a circular flywheel. On the left is an example of an early steam engines used to pump water from the ground. By connecting the spinning flywheel to a vehicle's wheels,
steam was used to power land transportation. This is a good example
of how technology developed for one setting can be used in another
setting. Steam engines are not used very much in modern-day America because their efficiency is low and they do not produce much power for their size. People's needs and wants have changed. However, today's technologies can be better understood by studying those used in the past.
Steam Turbines What are Steam Turbines? Steam turbines operate from steam pressure, just like steam engines. That is where the similarity ends, however. As you know, steam engines produce power by means of pistons moving up and down. Steam turbines develop power from spinning disks. The two kinds of power sources are very different.
Steam turbines power oceangoing ships. Ship turbines develop as much as 150,000 horsepower. Steam Turbines also turn generators used in electrical plants to produce electricity. The electrical power plant shown on the right is in southern Indiana. The tall smokestack in the center is used for coal smoke. The two hyperbolic chimney-like structures on each side are cooling towers that cool the water after the steam has gone through the turbines.
The drawing on the left is a simple illustration of an electrical power plant. The steam from the boiler flows through the fins of the turbine causing it to spin. The spinning turbine is connected to an electric generator which creates the electricity.
The electricity is then sent by a system of power lines, called a grid, to our homes, schools, factories and businesses throughout the region. A model of a grid of the United States is shown on the right.
Pictured at left is a steam turbine from a modern electrical power plant. Click on the picture to learn more about how steam turbines work.
Introduction | External Combustion Engines | Internal Combustion Engines | Electric Motors Copyright (c) 2006 Harley D. Brown All rights reserved. |
Steam engines were used in some early cars like the Stanley
Steamer. They also powered huge locomotives that pulled passengers
and cargo. The engines made a loud chuffing noise and produced
clouds of steam.
A turbine is a continually spinning disk that
resembles a pinwheel. Blow on a pinwheel and it spins. You
could call the pinwheel a "breath turbine" because your
breath makes it
spin. Steam from a boiler spins steam turbines.
