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As anergy of the component is an energy called, in a process no work can do.

In an ideal, i. H. reversibly operating heat engine between a heat reservoir (z. B. oven) and a heat sink (the cooler environment with T res  > T Umg works) can be only a part of the thermal energy , namely, the exergy , in technical work to be converted ; another part (the anergy) has to be dissipated to the heat sink and can then no longer be converted into other forms of energy. In thermal power plants , the heat sink that transfers the anergy to the environment, e.g. B. a cooling tower , a large oneRivers or a district heating network.

So the anergy is what remains after the exergy has been withdrawn:

Energy = anergy + exergy.

The two terms anergy and exergy go back to work by Zoran Rant and differentiate thermal energy into two parts. All other forms of energy (mechanical, electrical , etc.) are pure exergy.

The proportion of the anergy in the total energy results in the reversible, i.e. H. ideal thermal power process from the Carnot efficiency  η:


thus depends only on the temperatures T max of the heat reservoir and T min of the heat sink, between which the heat engine operates. In a real heat engine, there are losses that lead to the anergy increasing at the expense of exergy.

The energy of the environment is pure anergy. This assumption is based on the fact that the environment is so large that a process does not measurably influence the temperature or pressure of the environment.

An exception arises when the heat engine works between the environment and a cold reservoir (T res  <T Umg ); in this case the energy of the environment can be converted into exergy.

See also


  • Fran Bošnjaković , Karl-Friedrich Knoche : Technical Thermodynamics Part 1 . 8th edition. Steinkopff Verlag, Darmstadt 1998, ISBN 3-642-63818-X , 12.4 Anergy.
  • Hans Dieter Baehr, Stephan Kabelac: Thermodynamics . 16th edition. Springer-Verlag GmbH, 2016, ISBN 978-3-662-49567-4 , 3.3 The application of the 2nd law on energy conversions: exergy and anergy.
  • Norbert Elsner, Achim Dittmann: Fundamentals of technical thermodynamics, Volume 1, energy theory and material behavior. Akademie Verlag, Berlin 1993, ISBN 3-05-501390-5 , p. 122 ff.

Individual evidence

  1. quoted from Fran Bošnjaković, Karl-Friedrich Knoche: Technical Thermodynamics Part 1 . 8th edition. Steinkopff Verlag, Darmstadt 1998, ISBN 3-642-63818-X , 12.4 Anergy.