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Energy Transition: Exergy, Emissions and Optimization

A Special Issue of Entropy (ISSN 1099-4300) belonging to the section "Thermodynamics".

Deadline for manuscript submissions: 15 December 2026 | Viewed by 1366

Editors


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Guest Editor
Department of Renewable Energy Engineering, Federal University of Paraíba (UFPB), Joao Pessoa 58051-970, Brazil
Interests: life cycle assessment; thermodynamics; renewable energy; energy efficiency
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Renewable Energy Engineering, Federal University of Paraíba (UFPB), Joao Pessoa 58051-970, Brazil
Interests: thermal engineering; exergy; thermoeconomics; life cycle assessment; polygeneration

Special Issue Information

Dear Colleagues,

There is a global demand for low-carbon, efficient, and resilient energy systems, highlighting the need to address both thermodynamic performance and environmental impact. Exergy analysis, as a powerful tool for quantifying system efficiency and resource utilization, has emerged as a cornerstone in evaluating sustainable technologies. Along with emissions assessment, it provides a comprehensive framework to guide the energy transition toward low-carbon and carbon-neutral pathways.

This Special Issue on Energy Transition: Exergy, Emissions and Optimization invites contributions from a wide range of disciplines. Potential topics include renewable and hybrid energy systems, low-carbon fuels such as hydrogen and bioenergy, carbon capture and utilization, sustainable industrial processes, and the integration of circular economy strategies. We also welcome studies on the life cycle assessment of energy systems, techno-economic evaluations, and policy or regulatory perspectives.

By highlighting recent advances and practical applications, this issue seeks to provide a platform for interdisciplinary dialogue among researchers, engineers, and policymakers. The goal is to accelerate the development of sustainable energy systems that minimize emissions, maximize resource efficiency, and support the global transition toward a net-zero future.

Prof. Dr. Monica Carvalho
Prof. Dr. Adriano Da Silva Marques
Guest Editors

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 250 words) can be sent to the Editorial Office for assessment.

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-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Entropy is an international peer-reviewed open access monthly 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

  • life cycle assessment
  • thermoeconomics
  • exergoeconomics
  • exergoenvironmental assessment
  • energy optimization

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Published Papers (2 papers)

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42 pages, 18026 KB  
Article
Comprehensive Exergy and Exergoeconomic Analyses and Optimization of a Three-Stage Cascade Refrigeration System Using Environmentally Friendly Refrigerants
by Cenker Aktemur and Ezgi Gurgenc
Entropy 2026, 28(8), 834; https://doi.org/10.3390/e28080834 - 23 Jul 2026
Viewed by 422
Abstract
Ultra-low-temperature (ULT) refrigeration systems are widely required in applications such as biomedical storage, cryogenic processing, and advanced scientific facilities, where both exergy efficiency and economic performance are critical. In this study, a comprehensive analysis and optimization of the exergy and exergoeconomic performance evaluation [...] Read more.
Ultra-low-temperature (ULT) refrigeration systems are widely required in applications such as biomedical storage, cryogenic processing, and advanced scientific facilities, where both exergy efficiency and economic performance are critical. In this study, a comprehensive analysis and optimization of the exergy and exergoeconomic performance evaluation of a triple-stage cascade refrigeration system under ULT refrigeration is presented using ethylene (R1150), ethane (R170), propylene (R1270), difluoroethane (R152a), propane (R290), and fluoroethane (R161). A detailed exergy/exergoeconomic analysis, along with an optimization procedure, is performed at both the overall system level and the component-wise level in order to determine the key performance indicators. Minimizing the total cost product rate for each evaporator and condenser temperature is achieved by optimizing the condensing temperatures of the low-temperature cycle and the medium-temperature cycle. The component-wise analysis reveals that major thermodynamic irreversibilities occur in the HTC compressor and throttling valves, with maximum relative exergy destruction reaching 24.71% in TV-3 and the highest exergy destruction ratio reaching 14.92% in the HTC compressor. From an exergoeconomic perspective, the evaporator exhibits the largest combined exergy destruction and capital investment, and operational and maintenance cost rate (up to 24.73 $/h), while the condenser shows the highest exergoeconomic factor (up to 14.24%). The system-level results show that R1150/R170/R152a has the best exergetic and exergoeconomic performance compared to the other refrigeration combinations within the temperature ranges. Compared with R1150/R170/R290, this combination increases exergy efficiency by up to 5.05% for evaporator temperature variations and up to 7.84% for condenser temperature variations while reducing exergy destruction by up to 7.50% and 11.14%, respectively. Furthermore, the same combination decreases the total exergy destruction cost rate and product cost rate by up to 11.15% and 7.88%, respectively. In contrast, R1150/R170/R290 generally exhibits the poorest overall performance. The findings demonstrate that the refrigerant choice is crucial in achieving better exergetic and exergoeconomic performance for ULTs under various evaporator and condenser conditions. Full article
(This article belongs to the Special Issue Energy Transition: Exergy, Emissions and Optimization)
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16 pages, 15543 KB  
Technical Note
Exergy Efficiency Is a Key Performance Indicator to Rank Advanced Active Energy Technologies at the District Level
by Daniel Favrat
Entropy 2026, 28(6), 693; https://doi.org/10.3390/e28060693 - 16 Jun 2026
Viewed by 347
Abstract
Supplying electricity, heat and cold is an essential part of the development of more sustainable city districts. Previous studies have illustrated interest in using the exergy efficiency concept to decompose the problem and rank the technology combinations for heating or cooling according to [...] Read more.
Supplying electricity, heat and cold is an essential part of the development of more sustainable city districts. Previous studies have illustrated interest in using the exergy efficiency concept to decompose the problem and rank the technology combinations for heating or cooling according to their overall efficiency. This methodology is extended herein to include network losses that depend on the temperature level and grid losses that play a role when comparing electricity supplied by the grid rather than by local cogeneration units. This extended method is then applied by considering two emerging technologies. The first is very-low-temperature district heating and cooling (DHC), directly supplying air-conditioning needs via simple heat exchangers, as well as heating needs via local heat pumps. It is part of what are called fifth-generation DHCs or “anergy networks” and based on water or, better, on CO2 heat-transfer fluid. The main features of the five generations of networks, as well as the average aggregate user needs, are summarized in pinch technology composites, but replacing the temperature axis with a heat exergy axis to graphically highlight exergy losses. The average aggregate heating and cooling needs of users result from the application of a geographic information system to a district in a real city. The second emerging technology considers hybrid SOFC–GT cogeneration units, with or without CO2 separation, supplying electricity to all network users, including decentralized heat pumps, while optimizing the recovery of waste heat. The full synergy between heat providers and users is highlighted, allowing districts without cooling towers or chimneys except at one energy balancing plant. Integration of the advanced SOFC–GT cogeneration unit considered herein into the same anergy network allows an increase in exergy efficiency from 13.6% to 21.3%, as compared with electricity being supplied entirely from the grid and produced with a similar natural gas fuel. Full article
(This article belongs to the Special Issue Energy Transition: Exergy, Emissions and Optimization)
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