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Energies
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The Concept of Entropy and Its Application in Thermal Engineering
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The Concept of Entropy and Its Application in Thermal Engineering

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "J: Thermal Management".

Deadline for manuscript submissions: closed (25 September 2021) | Viewed by 20803

Special Issue Editor

Dr. Yousef Haseli

E-Mail Website
Guest Editor
Clean Energy and Fuel Lab, Central Michigan University, Mount Pleasant, MI 48859, USA
Interests: Biomass Combustion; Two-Phase/Reactive Flows; Engineering Thermodynamics

Special Issue Information

Dear Colleagues,

Entropy-based analysis of thermal processes has become popular in recent decades. Countless publications have appeared in the scientific literature with the main (or mere) objective of calculating entropy generation in a thermal process. A common drawback of a large volume of entropy-based studies is the lack of correct interpretation of the computed entropy values. In some extreme cases, misguided claims have been made about the superiority of entropy-based analysis over first law analysis, claiming, erroneously, that results obtained from the latter would be "misleading".

There still exist important issues in the field that need to be addressed, including (i) a lack of correct understanding of second-law related concepts, (ii) incorrect methods of calculating entropy generation in thermal systems, (iii) clueless entropy-related calculations with incorrect or no interpretation of results, (iv) misinterpretation of entropy generation in processes where work is absent, and (v) a lack of differentiation between system level (e.g., a thermal power plant) and component level (e.g., heat exchanger) entropy analyses.

This Special Issue is devoted to clarifying the above issues. Original thinkers, pioneers, and experts are invited to share their critical views and novel work on entropy and the second law, which will serve as a permanent reference on the subject. Manuscripts reporting computed entropy values should discuss and justify how entropy-based results would help improve the performance or design of the systems studied.

Dr. Yousef Haseli
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Entropy concept
  • Second law
  • Entropy generation
  • Thermal processes
  • Thermodynamics
  • Thermal power generation

Published Papers (6 papers)

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Editorial

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2 pages, 148 KiB  
Editorial
The Concept of Entropy and Its Application in Thermal Engineering
by Yousef Haseli
Energies 2021, 14(24), 8485; https://doi.org/10.3390/en14248485 - 16 Dec 2021
Viewed by 1623
Abstract
Today, 156 years after the invention of entropy by Clausius, there remains disagreement among the scientific community on what entropy and the phenomenon of entropy increase mean [...] Full article
(This article belongs to the Special Issue The Concept of Entropy and Its Application in Thermal Engineering)

Research

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14 pages, 10320 KiB  
Article
Interpretation of Entropy Calculations in Energy Conversion Systems
by Yousef Haseli
Energies 2021, 14(21), 7022; https://doi.org/10.3390/en14217022 - 27 Oct 2021
Cited by 3 | Viewed by 1997
Abstract
Often, second law-based studies present merely entropy calculations without demonstrating how and whether such calculations may be beneficial. Entropy generation is commonly viewed as lost work or sometimes a source of thermodynamic losses. Recent literature reveals that minimizing the irreversibility of a heat [...] Read more.
Often, second law-based studies present merely entropy calculations without demonstrating how and whether such calculations may be beneficial. Entropy generation is commonly viewed as lost work or sometimes a source of thermodynamic losses. Recent literature reveals that minimizing the irreversibility of a heat engine may correspond to maximizing thermal efficiency subject to certain design constraints. The objective of this article is to show how entropy calculations need to be interpreted in thermal processes, specifically, where heat-to-work conversion is not a primary goal. We will study four exemplary energy conversion processes: (1) a biomass torrefaction process where torrefied solid fuel is produced by first drying and then torrefying raw feedstock, (2) a cryogenic air separation system that splits ambient air into oxygen and nitrogen while consuming electrical energy, (3) a cogeneration process whose desirable outcome is to produce both electrical and thermal energy, and (4) a thermochemical hydrogen production system. These systems are thermodynamically analyzed by applying the first and second laws. In each case, the relation between the total entropy production and the performance indicator is examined, and the conditions at which minimization of irreversibility leads to improved performance are identified. The discussion and analyses presented here are expected to provide clear guidelines on the correct application of entropy-based analyses and accurate interpretation of entropy calculations. Full article
(This article belongs to the Special Issue The Concept of Entropy and Its Application in Thermal Engineering)
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8 pages, 239 KiB  
Article
Nonequilibrium Entropy Conservation and the Transport Equations of Mass, Momentum, and Energy
by Michael H. Peters
Energies 2021, 14(8), 2196; https://doi.org/10.3390/en14082196 - 14 Apr 2021
Cited by 5 | Viewed by 1460
Abstract
Nonequilibrium statistical mechanics or molecular theory has put the transport equations of mass, momentum and energy on a firm or rigorous theoretical foundation that has played a critical role in their use and applications. Here, it is shown that those methods can be [...] Read more.
Nonequilibrium statistical mechanics or molecular theory has put the transport equations of mass, momentum and energy on a firm or rigorous theoretical foundation that has played a critical role in their use and applications. Here, it is shown that those methods can be extended to nonequilibrium entropy conservation. As already known, the “closure” of the transport equations leads to the theory underlying the phenomenological laws, including Fick’s Law of Diffusion, Newton’s Law of Viscosity, and Fourier’s Law of Heat. In the case of entropy, closure leads to the relationship of entropy flux to heat as well as the Second Law or the necessity of positive entropy generation. It is further demonstrated how the complete set of transport equations, including entropy, can be simplified under physically restrictive assumptions, such as reversible flows and local equilibrium flows. This analysis, in general, yields a complete, rigorous set of transport equations for use in applications. Finally, it is also shown how this basis set of transport equations can be transformed to a new set of nonequilibrium thermodynamic functions, such as the nonequilibrium Gibbs’ transport equation derived here, which may have additional practical utility. Full article
(This article belongs to the Special Issue The Concept of Entropy and Its Application in Thermal Engineering)
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19 pages, 3315 KiB  
Article
Thermodynamic Analysis of a High-Temperature Latent Heat Thermal Energy Storage System
by David W. MacPhee and Mustafa Erguvan
Energies 2020, 13(24), 6634; https://doi.org/10.3390/en13246634 - 16 Dec 2020
Cited by 5 | Viewed by 1573
Abstract
Thermal energy storage (TES) technologies are becoming vitally important due to intermittency of renewable energy sources in solar applications. Since high energy density is an important parameter in TES systems, latent heat thermal energy storage (LHTES) system is a common way to store [...] Read more.
Thermal energy storage (TES) technologies are becoming vitally important due to intermittency of renewable energy sources in solar applications. Since high energy density is an important parameter in TES systems, latent heat thermal energy storage (LHTES) system is a common way to store thermal energy. Though there are a great number of experimental studies in the field of LHTES systems, utilizing computational codes can yield relatively quick analyses with relatively small expense. In this study, a numerical investigation of a LHTES system has been studied using ANSYS FLUENT. Results are validated with experiments, using hydroquinone as a phase-change material (PCM), which is external to Therminol VP-1 as a heat transfer fluid (HTF) contained in pipes. Energy efficiency and entropy generation are investigated for different tube/pipe geometries with a constant PCM volume. HTF inlet temperature and flow rate impacts on the thermodynamic efficiencies are examined including viscous dissipation effects. Highest efficiency and lowest entropy generation cases exist when when flow rates are lowest due to low viscous heating effects. A positive relation is found between energy efficiency and volume ratio while it differs for entropy generation for higher and lower velocities. Both efficiency and entropy generation decreased with decreasing HTF inlet temperature. The novelty of this study is the analysis of the effect of volume ratio on system performance and PCM melting time which ultimately proved to be the most dominant factor among those considered herein. However, as PCM solidification and melting time is of primary importance to system designers, simply minimizing entropy generation by decreasing volume ratio in this case does not lead to a practically optimal system, merely to decrease heat transfer entropy generation. Therefore, caution should be taken when applying entropy analyses to any LHTES storage system as entropy minimization methods may not be appropriate for practicality purposes. Full article
(This article belongs to the Special Issue The Concept of Entropy and Its Application in Thermal Engineering)
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Review

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25 pages, 5256 KiB  
Review
Purpose in Thermodynamics
by Adrian Bejan and George Tsatsaronis
Energies 2021, 14(2), 408; https://doi.org/10.3390/en14020408 - 13 Jan 2021
Cited by 19 | Viewed by 4442
Abstract
This is a review of the concepts of purpose, direction, and objective in the discipline of thermodynamics, which is a pillar of physics, natural sciences, life science, and engineering science. Reviewed is the relentless evolution of this discipline toward accounting for evolutionary design [...] Read more.
This is a review of the concepts of purpose, direction, and objective in the discipline of thermodynamics, which is a pillar of physics, natural sciences, life science, and engineering science. Reviewed is the relentless evolution of this discipline toward accounting for evolutionary design with direction, and for establishing the concept of purpose in methodologies of modeling, analysis, teaching, and design optimization. Evolution is change after change toward flow access, with direction in time, and purpose. Evolution does not have an ‘end’. In thermodynamics, purpose is already the defining feature of methods that have emerged to guide and facilitate the generation, distribution, and use of motive power, heating, and cooling: thermodynamic optimization, exergy-based methods (i.e., exergetic, exergoeconomic, and exergoenvironmental analysis), entropy generation minimization, extended exergy, environomics, thermoecology, finite time thermodynamics, pinch analysis, animal design, geophysical flow design, and constructal law. What distinguishes these approaches are the purpose and the performance evaluation used in each method. Full article
(This article belongs to the Special Issue The Concept of Entropy and Its Application in Thermal Engineering)
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Other

8 pages, 1203 KiB  
Perspective
Discipline in Thermodynamics
by Adrian Bejan
Energies 2020, 13(10), 2487; https://doi.org/10.3390/en13102487 - 15 May 2020
Cited by 22 | Viewed by 8853
Abstract
Thermodynamics is a discipline, with unambiguous concepts, words, laws and usefulness. Today it is in danger of becoming a Tower of Babel. Its key words are being pasted brazenly on new concepts, to promote them with no respect for their proper meaning. In [...] Read more.
Thermodynamics is a discipline, with unambiguous concepts, words, laws and usefulness. Today it is in danger of becoming a Tower of Babel. Its key words are being pasted brazenly on new concepts, to promote them with no respect for their proper meaning. In this brief Perspective, I outline a few steps to correct our difficult situation. Full article
(This article belongs to the Special Issue The Concept of Entropy and Its Application in Thermal Engineering)
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