The Principle of Least Action for Reversible Thermodynamic Processes and Cycles

The principle of least action, which is usually applied to natural phenomena, can also be used in optimization problems with manual intervention. Following a brief introduction to the brachistochrone problem in classical mechanics, the principle of least action was applied to the optimization of rev...

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Main Authors: Tian Zhao, Yu-Chao Hua, Zeng-Yuan Guo
Format: Article
Language:English
Published: MDPI AG 2018-07-01
Series:Entropy
Subjects:
Online Access:http://www.mdpi.com/1099-4300/20/7/542
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author Tian Zhao
Yu-Chao Hua
Zeng-Yuan Guo
author_facet Tian Zhao
Yu-Chao Hua
Zeng-Yuan Guo
author_sort Tian Zhao
collection DOAJ
description The principle of least action, which is usually applied to natural phenomena, can also be used in optimization problems with manual intervention. Following a brief introduction to the brachistochrone problem in classical mechanics, the principle of least action was applied to the optimization of reversible thermodynamic processes and cycles in this study. Analyses indicated that the entropy variation per unit of heat exchanged is the mode of action for reversible heat absorption or heat release processes. Minimizing this action led to the optimization of heat absorption or heat release processes, and the corresponding optimal path was the first or second half of a Carnot cycle. Finally, the action of an entire reversible thermodynamic cycle was determined as the sum of the actions of the heat absorption and release processes. Minimizing this action led to a Carnot cycle. This implies that the Carnot cycle can also be derived using the principle of least action derived from the entropy concept.
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spelling doaj.art-0f37616d43774a818d30e56a5f829ee02022-12-22T03:59:35ZengMDPI AGEntropy1099-43002018-07-0120754210.3390/e20070542e20070542The Principle of Least Action for Reversible Thermodynamic Processes and CyclesTian Zhao0Yu-Chao Hua1Zeng-Yuan Guo2Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, ChinaKey Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, ChinaKey Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, ChinaThe principle of least action, which is usually applied to natural phenomena, can also be used in optimization problems with manual intervention. Following a brief introduction to the brachistochrone problem in classical mechanics, the principle of least action was applied to the optimization of reversible thermodynamic processes and cycles in this study. Analyses indicated that the entropy variation per unit of heat exchanged is the mode of action for reversible heat absorption or heat release processes. Minimizing this action led to the optimization of heat absorption or heat release processes, and the corresponding optimal path was the first or second half of a Carnot cycle. Finally, the action of an entire reversible thermodynamic cycle was determined as the sum of the actions of the heat absorption and release processes. Minimizing this action led to a Carnot cycle. This implies that the Carnot cycle can also be derived using the principle of least action derived from the entropy concept.http://www.mdpi.com/1099-4300/20/7/542principle of least actionoptimization problemsreversible thermodynamic processesCarnot cycle
spellingShingle Tian Zhao
Yu-Chao Hua
Zeng-Yuan Guo
The Principle of Least Action for Reversible Thermodynamic Processes and Cycles
Entropy
principle of least action
optimization problems
reversible thermodynamic processes
Carnot cycle
title The Principle of Least Action for Reversible Thermodynamic Processes and Cycles
title_full The Principle of Least Action for Reversible Thermodynamic Processes and Cycles
title_fullStr The Principle of Least Action for Reversible Thermodynamic Processes and Cycles
title_full_unstemmed The Principle of Least Action for Reversible Thermodynamic Processes and Cycles
title_short The Principle of Least Action for Reversible Thermodynamic Processes and Cycles
title_sort principle of least action for reversible thermodynamic processes and cycles
topic principle of least action
optimization problems
reversible thermodynamic processes
Carnot cycle
url http://www.mdpi.com/1099-4300/20/7/542
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