Michel Pons
Irreversibility in energy processes: Non-dimensional quantification and balance
The concept of thermodynamic efficiency (ratio of real cycle efficiency by Carnot
efficiency) is well-known. The concept of numbers of entropy-production and of
exergy-loss proposed by A. Bejan are also known, but rarely used. The present study
firstly evidences that these two last numbers are actually identical, thus being a
common number of irreversibility, independent of the method used for obtaining it.
The study also evidences a non-dimensional irreversibility balance that applies to any
energy conversion process. This balance correlates the thermodynamic efficiency of a
whole process (which in most cases equals the exergetic efficiency) and the numbers
of irreversibility of the different components or sub-processes involved in this process.
Moreover, the basic additivity of entropy-productions and exergy-losses is
maintained in this balance. This balance applies to the basic cycles (heat-engines,
refrigerators, heat-pumps and heat-transformers), either work- or heat-powered. It
also applies to more complex cycles (heat-powered cycles consuming electricity,
four-temperature heat-powered cycles, cogeneration processes), thus giving a robust
framework for analyzing these cycles.
Journal of Non-Equilibrium Thermodynamics, Walter de Gruyter
Print ISSN: 0340-0204
Volume: 29, 06/2004
Pages: 157 - 175
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