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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

A Study of Macroscopic Physical Meaning of Entropy

Get access (open in a dialog) DOI: 10.1615/IHTC15.tdy.009373
pages 7939-7946

要約

At present, it is still a challenging work to give an adequate answer to the question of what is the macroscopic physical meaning of entropy, just as Prigogine said, "...entropy is a very strange concept without hoping to achieve a complete description...". Hence, the microscopic interpretation of entropy, instead of its macroscopic interpretation, is usually presented in most textbooks and literatures. However, it has no help for the analysis and design of thermal systems. In this study, a combined system that consists of a simple compressible thermodynamic system and its environment is taken into consideration and the balance equations of the unavailable energy of the system for reversible heat and work interactions are developed respectively to discuss the macroscopic physical meaning of entropy, which is summarized as followings: (1) The entropy of a system represents its unavailable energy during reversible heat interaction between the system and its environment only, that is, the reversible work interaction has no influence on the entropy of the system; (2) The entropy transfer by heat transfer is of the same dimension of the heat capacity and consequently the entropy transfer is the unavailable energy transfer per unit environmental temperature; (3) Understanding the physical meaning of the entropy, which is a property of the system, must be related to the environmental temperature. Hence, the environmental temperature serves as the role of an auxiliary line as in solving geometrical problems to help clarify the macroscopic physical meaning of entropy.