Energy efficiency: Difference between revisions
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In [[physics]] and [[engineering]], including [[mechanical engineering|mechanical]] and [[electrical engineering|electrical]] engineering, '''energy efficiency''' is a [[dimensionless]] number, with a value between [[0 (number)|0]] and [[1 (number)|1]] or, when multiplied by 100, is given as a percentage. The energy efficiency of a process, denoted by [[Eta (letter) | eta]], is defined as |
In [[physics]] and [[engineering]], including [[mechanical engineering|mechanical]] and [[electrical engineering|electrical]] engineering, '''energy efficiency''' is a [[dimensionless]] number, with a value between [[0 (number)|0]] and [[1 (number)|1]] or, when multiplied by 100, is given as a percentage. The energy efficiency of a process, denoted by [[Eta (letter) | eta]], is defined as |
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\mathrm{efficiency} \ \ |
\mathrm{efficiency} \ \theta = \mathrm{{power \ output} \over \mathrm{power \ input}} \ (= \frac{\text{work} \ W }{ \text{energy} \ E}) \, |
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Revision as of 21:50, 5 June 2007
- For energy efficiency in relation to economics, see energy conservation
In physics and engineering, including mechanical and electrical engineering, energy efficiency is a dimensionless number, with a value between 0 and 1 or, when multiplied by 100, is given as a percentage. The energy efficiency of a process, denoted by eta, is defined as
where W is the amount of useful work done by the process (in joules), and "energy" E is the quantity of energy (again, in joules) used to run the process.
Due to the principle of conservation of energy, energy efficiency within a closed system can never exceed 100%.
See also
- Energy conversion efficiency
- Fuel efficiency
- Thermal efficiency
- Sensitivity (electronics)
- Figure of merit
- Exergy efficiency