Energy conversion
From Wikipedia, the free encyclopedia
In physics and engineering, energy conversion is any process of converting energy from one form to another. Energy found in fossil fuels, solar radiation, or nuclear fuels needs to be converted into other energy forms such as electrical, propulsive, or heating to be useful. Often, machines are used to convert energy from one form to another. The efficiency of a machine characterizes how well (how efficiently) it can perform such a convesion.
Energy may be converted so that it may be used by other machines, or else to provide some service to society (such as heat, light, or motion). For example, an internal combustion engine converts the potential chemical energy in gasoline and oxygen into the propulsive energy that moves a vehicle. A solar cell converts solar radiation into electrical energy that can then be used to light a bulb or power a computer. The generic name for a device which converts energy from one form to another is transducer
[edit] Example heat engines
The steam engine illustrates the energy conversion process. In a steam engine, burning coal heats water (the working fluid), which expands as a gas (steam) and moves a piston. The steam is then cooled in a radiator and once again brought near the hot coals in a cycle that keeps the steam engine moving. The steam engine uses the temperature difference between the hot coal and the radiator to move the piston. The operation of the steam engine is described from an energy perspective by the machine cycles of thermodynamics, from the fluid flows by fluid mechanics, and from the heat flow by the science of heat transfer.
In a steam turbine, steam is used to turn the blades of the turbine, which may then be used to turn a generator to produce electricity. This process also requires that the steam be cooled at some point in the process, or else it will not move from one place to another, which what causes the blades of the turbine to turn.
In a nuclear power plant atoms of fissionble material such as uranium are split into fast-moving ions, and these products produce intense heat after they strike the materials of the fuel rods and reactor cooling fluid. This heat is then used to generate steam from water, which in turn is used conventionally in a steam turbine to produce electricity.
Conversion of one form of energy to another may be done with very high or even perfect efficiency, unless the energy is in the form of heat. The conversion of heat to other forms of energy is never perfect, and (according to the second law of thermodynamics) must always be accompanied by further dissipation of some of the heat into colder bodies, as heat. Some of the heat energy in a steam engine or turbine must therefore always be lost as heat, which must be dissipated at a lower temperature without being turned into useful work.
Specific examples: Humans Chemical energy vonverts to Mechanical energy when lifitng up a weight. The sun Electromagnetic radiation energy transforms to chemical during a plants photosynthisis.
[edit] Other energy conversion machines
There are many different machines that convert one energy form into another:
- Fuel cells
- Geothermal power
- Heat engines, such as the internal combustion engine used in cars or the steam engine
- Hydroelectric dams
- Jet engine
- Nuclear reactor
- Nuclear fusion
- Ocean thermal power
- Solar cells
- Solar thermal
- Steam engine
- Wave power
- Windmills
- Piezoelectrics
- Dielectric materials
[edit] See also
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