Exergy Efficiency of Closed and Unsteady-Flow Systems
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Tarih
2025
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Mdpi
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Exergy efficiency is viewed as the degree of approaching reversible operation, with a value of 100 percent for a reversible process characterized by zero entropy generation or equivalently zero exergy destruction since Xdestroyed = T0Sgen. As such, exergy efficiency becomes a measure of thermodynamic perfection. There are different conceptual definitions of exergy efficiency, the most common ones being (1) the ratio of exergy output to exergy input eta ex = Xoutput/Xinput = 1 - (Xdestroyed + Xloss)/Xinput, (2) the ratio of the product exergy to fuel exergy eta ex = Xproduct/Xfuel = 1 - (Xdestroyed + Xloss)/Xfuel, and (3) the ratio of exergy recovered to exergy expended eta ex = Xrecovered/Xexpended = 1 - Xdestroyed/Xexpended. Most exergy efficiency definitions are formulated with steady-flow systems in mind, and they are generally applied to systems in steady operation such as power plants and refrigeration systems whose exergy content remains constant. If these definitions are to be used for closed and unsteady-flow systems, the terms need to be interpreted broadly to account for the exergy change of the systems as exergy input or output, as appropriate. In this paper, general exergy efficiency relations are developed for closed and unsteady-flow systems and their use is demonstrated with applications. Also, the practicality of the use of the term exergy loss Xloss is questioned, and limitations on the definition eta ex = Wact,out/Wrev,out are discussed.
Açıklama
Anahtar Kelimeler
thermodynamics, exergy, exergy analysis, exergy efficiency, exergy destruction, second-law analysis, second-law efficiency
Kaynak
Entropy
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
27
Sayı
9
