Source Title:
Journal of Non-Equilibrium Thermodynamics
|
Volume/Issue:
Volume 42: Issue 2

Pitfalls of Exergy Analysis

Petr Vágner 1 , Michal Pavelka 2 , and František Maršík 3
  • 1 Research Centre, New Technologies, University of West Bohemia, Univerzitní – 8, 306 14 Pilsen, Czech Republic; Charles University, Faculty of Mathematics and Physics, Mathematical Institute, Sokolovská 83, 186 75 Prague, Czech Republic
  • 2 Charles University, Faculty of Mathematics and Physics, Mathematical Institute, Sokolovská 83, 186 75 Prague, Czech Republic; University of Chemistry and Technology Prague, Department of Chemical Engineering, Technická 5, 16628 Prague 6, Czech Republic
  • 3 Research Centre, New Technologies, University of West Bohemia, Univerzitní – 8, 306 14 Pilsen, Czech Republic
Petr Vágner, Michal Pavelka and František Maršík
DOI:
https://doi.org/10.1515/jnet-2016-0043
|
Published online:
10 Jan 2017

Abstract

The well-known Gouy–Stodola theorem states that a device produces maximum useful power when working reversibly, that is with no entropy production inside the device. This statement then leads to a method of thermodynamic optimization based on entropy production minimization. Exergy destruction (difference between exergy of fuel and exhausts) is also given by entropy production inside the device. Therefore, assessing efficiency of a device by exergy analysis is also based on the Gouy–Stodola theorem. However, assumptions that had led to the Gouy–Stodola theorem are not satisfied in several optimization scenarios, e.g. non-isothermal steady-state fuel cells, where both entropy production minimization and exergy analysis should be used with caution. We demonstrate, using non-equilibrium thermodynamics, a few cases where entropy production minimization and exergy analysis should not be applied.

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Article information

Received:
2016-05-12
Revised:
2016-09-13
Accepted:
2016-11-04
Published Online:
2017-01-10
Published in Print:
2017-04-01

The result was developed within the CENTEM project, reg. no. CZ.1.05/2.1.00/03.0088, cofunded by the ERDF as part of the Ministry of Education, Youth and Sports OP RDI programme and, in the follow-up sustainability stage, supported through CENTEM PLUS (LO1402) by financial means from the Ministry of Education, Youth and Sports under the National Sustainability Programme I. The work was supported by Czech Science Foundation (project no. 14-18938S). The study was supported by the Charles University, project GA UK No 70515.

Citation Information: 
Journal of Non-Equilibrium Thermodynamics, Volume 42, Issue 2, Pages 201–216, eISSN 1437-4358, ISSN 0340-0204, DOI: https://doi.org/10.1515/jnet-2016-0043.

© 2017 Walter de Gruyter GmbH, Berlin/Boston.

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Journal + Issues

Journal of Non-Equilibrium Thermodynamics

Online ISSN:
1437-4358
First published:
01 Jan 1976
Language:
English
Publisher:
De Gruyter

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