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Frontiers on Thermal Machines and Energy Systems

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

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 4323

Special Issue Editors


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Guest Editor
Department of Industrial and Information Engineering and Economics, University of L’Aquila, v. G. Gronchi, 18, 67100 L’Aquila, Italy
Interests: engine thermal management; thermal machines; energy systems; energy efficiency; energy recovery; energy planning
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Industrial and Information Engineering and Economics (DIIIE), University of L’Aquila, 67100 L’Aquila, Italy
Interests: energy recovery; engine thermal management; thermal machines; energy systems; energy efficiency; ORC-based power unit; volumetric machine
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Industrial and Information Engineering and Economics, University of L’Aquila, 67100 L’Aquila, Italy
Interests: engine thermal management; thermal machines; energy systems; energy efficiency; energy recovery; energy planning; carbon finance
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The aim of this Special Issue is to collect papers related to recent advances in energy systems and their thermal components, with a particular focus on thermal machines. This field involves compressors, pumps, turbines, expanders, and heat exchangers. Papers in which overall energy conversion systems are studied and where different components are integrated and optimized are particularly welcome.

Nowadays, energy systems play a crucial role in the path towards the need to reduce primary energy consumption and CO2 emissions. Indeed, energy conversion systems are present in every sector: power generation, residential, transportation, and industry. They are needed to transform primary energy into useful forms: thermal, mechanical, or electrical. Global energy demand is still increasing, particularly during the recovery from COVID-19, which caused a decline in global energy consumption in 2020, and about 80% of global primary energy is still derived from fossil fuels. Therefore, much effort is needed to improve energy conversion efficiency, not only for traditional energy systems, but also for renewable-based ones.

Hence, in this Special Issue recent advances in energy systems are related to efficiency improvements in renewable-based systems, which are particularly involved in energy reduction methods: waste heat recovery opportunities, refrigeration plants, optimized thermal management options, and transportation powertrains. Energy efficiency assessment can be related to innovative layouts and system arrangements or to original control strategies, but improvements in thermal components are the ones that have the most important impact. They can be achieved through prototyping and testing or thanks to analytical and numerical studies aimed at designing devices and verifying their thermal and fluid-dynamic behaviour in off-design conditions.

Prof. Dr. Davide Di Battista
Dr. Fabio Fatigati
Prof. Dr. Roberto Cipollone
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 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

  • energy efficiency
  • waste heat recovery
  • turbine
  • compressor
  • expander
  • heat exchanger
  • pump
  • volumetric machines
  • dynamic machines
  • organic Rankine cycle
  • power plant
  • refrigeration plant
  • combined plant
  • fluid dynamic

Published Papers (3 papers)

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Research

21 pages, 2747 KiB  
Article
Liquid CO2 and Liquid Air Energy Storage Systems: A Thermodynamic Analysis
by Matteo Marchionni and Roberto Cipollone
Energies 2023, 16(13), 4941; https://0-doi-org.brum.beds.ac.uk/10.3390/en16134941 - 25 Jun 2023
Cited by 1 | Viewed by 1136
Abstract
Energy storage is a key factor to confer a technological foundation to the concept of energy transition from fossil fuels to renewables. Their solar dependency (direct radiation, wind, biomass, hydro, etc. …) makes storage a requirement to match the supply and demand, with [...] Read more.
Energy storage is a key factor to confer a technological foundation to the concept of energy transition from fossil fuels to renewables. Their solar dependency (direct radiation, wind, biomass, hydro, etc. …) makes storage a requirement to match the supply and demand, with fulfillment being another key factor. Recently, the most attention is directed toward the direct electrical storage inside batteries, probably driven by interest in the transportation sector, which today is the main focus in the transition path. On the contrary, for the generation of electrical energy and, more generally, for industrial sectors whose CO2 emissions are defined as hard-to-abate, electrical storage is not a feasible answer to many political and non-technological concerns. Therefore, other storage methods must be considered to address excess electricity, the most characteristics of which being both the capacity and rate of charging/delivering. Among the efforts under consideration, the liquid storage of gases at ambient conditions is certainly an interesting option. This is the case with air and CO2. The paper focused on the storage of CO2 in liquid form, comparing its performance with those of air liquefaction, which well-studied in the literature. The paper proposed a novel plant layout design for a liquid CO2 energy storage system that can improve the round-trip efficiency by up to 57%. The system was also compared to a liquid air energy storage unit considering a state-of-the-art level of technology for components, showing better efficiency but lower energy density. Finally, a sensitivity analysis was used to discuss the most relevant variables for a plant design. Particular focus was devoted to the discharging time of the plant, one of the most relevant variables that matches the energy demand. Full article
(This article belongs to the Special Issue Frontiers on Thermal Machines and Energy Systems)
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24 pages, 4622 KiB  
Article
Experimental and Numerical Dynamic Investigation of an ORC System for Waste Heat Recovery Applications in Transportation Sector
by Matteo Marchionni, Fabio Fatigati, Marco Di Bartolomeo, Davide Di Battista and Mario Petrollese
Energies 2022, 15(24), 9339; https://0-doi-org.brum.beds.ac.uk/10.3390/en15249339 - 09 Dec 2022
Cited by 9 | Viewed by 1052
Abstract
ORC power units represent a promising technology for the recovery of waste heat in Internal Combustion Engines (ICEs), allowing to reduce emissions while keeping ICE performance close to expectations. However, the intrinsic transient nature of exhaust gases represents a challenge since it leads [...] Read more.
ORC power units represent a promising technology for the recovery of waste heat in Internal Combustion Engines (ICEs), allowing to reduce emissions while keeping ICE performance close to expectations. However, the intrinsic transient nature of exhaust gases represents a challenge since it leads ORCs to often work in off-design conditions. It then becomes relevant to study their transient response to optimize performance and prevent main components from operating at inadequate conditions. To assess this aspect, an experimental dynamic analysis was carried out on an ORC-based power unit bottomed to a 3 L Diesel ICE. The adoption of a scroll expander and the control of the pump revolution speed allow a wide operability of the ORC. Indeed, the refrigerant mass flow rate can be adapted according to the exhaust gas thermal power availability in order to increase thermal power recovery from exhaust gases. The experimental data confirmed that when the expander speed is not regulated, it is possible to control the cycle maximum pressure by acting on the refrigerant flow rate. The experimental data have also been used to validate a model developed to extend the analysis beyond the experimental operating limits. It was seen that a 30% mass flow rate increase allowed to raise the plant power from 750 W to 830 W. Full article
(This article belongs to the Special Issue Frontiers on Thermal Machines and Energy Systems)
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19 pages, 4240 KiB  
Article
Experimental Determination of an Optimal Performance Map of a Steam Ejector Refrigeration System
by Kittiwoot Sutthivirode and Tongchana Thongtip
Energies 2022, 15(12), 4208; https://0-doi-org.brum.beds.ac.uk/10.3390/en15124208 - 07 Jun 2022
Cited by 2 | Viewed by 1598
Abstract
An experimental determination of optimal performance of a steam ejector refrigerator was proposed which aims to indicate the optimal performance under various heat source temperatures. A small-scale steam ejector refrigerator test bench was constructed to carry out the experiment and to determine the [...] Read more.
An experimental determination of optimal performance of a steam ejector refrigerator was proposed which aims to indicate the optimal performance under various heat source temperatures. A small-scale steam ejector refrigerator test bench was constructed to carry out the experiment and to determine the optimal performance map. Three primary nozzles with throat diameters of 1.4, 1.6, and 1.8 mm, were tested with an ejector throat diameter of 14.5 mm, providing the ejector area ratios of 107, 82, and 65, respectively. For a particular working condition, the boiler temperature was varied to determine the maximum COP which is recognized as the optimal operation. It was found that the secondary fluid stream is first choked at the optimal boiler temperature. This optimal point varied significantly with the evaporator temperature, condenser pressure, and ejector area ratios. It was found that this steam ejector refrigerator could be operated under the optimal boiler temperature between 102.5 and 117.5 °C depending on the ejector area ratio, evaporator temperature, and condenser pressure. The optimal performance map is beneficial to further control the heat source temperature so that the maximum COP is achieved. Full article
(This article belongs to the Special Issue Frontiers on Thermal Machines and Energy Systems)
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