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Selected Papers from The First World Energies Forum (WEF-1)

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A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (15 January 2021) | Viewed by 14404

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Prof. Dr. Enrico Sciubba

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Department of Industrial and Civil Engineering, Niccolò Cusano University, Roma, Italy
Interests: thermal sciences; CFD; energy systems
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Prof. Dr. Roberto Capata

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Department of Mechanical and Aerospace Engineering, University of Roma “Sapienza”, 00185 Roma, Italy
Interests: UMGT; hybrid vehicles and systems; machinery design; energy systems; ORC; heat exchangers; diagnostics; turbomachinery; volumetric machinery; biomedical machinery application
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Prof. Dr. Roberto Melli

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Department of Mechanical and Aerospace Engineering, University of Roma “Sapienza”, Roma, Italy
Interests: artificial Intelligence; energy systems

Special Issue Information

Dear Colleagues,

This Special Issue contains a selection of the papers presented at the first World Energies Forum, a conference held in September 2020 in Rome. As a result of COVID travel and distancing restrictions, the organizers were advised to move to a virtual format.

Although this meant a substantial reduction (of about 50%) of the papers actually presented at the online conference, the response of our colleagues was positive and constructive. Thanks to the efforts of the MDPI administration for maintaining the correct connections, updating the conference technological endowment and just keeping to schedule, to the Scientific Committee for conducting the majority of the reviews, and to the organizers who had to adapt to the new critical situation, we had a sufficient amount of accepted manuscripts to make an excellent selection for this Special Issue.

At this time we do not have a list of accepted papers. This message is actually an invitation to the WEF participants to submit their papers for formal review. In general, the topics will reflect the trends of the conference program: analysis of energy demand, supply and use; environmental challenges; more efficient energy technology; and socio-economic and political implications in designing novel energy conversion scenarios.

Prof. Dr. Enrico Sciubba
Prof. Dr. Roberto Capata
Prof. Dr. Roberto Melli
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.

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Published Papers (6 papers)

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Research

22 pages, 7304 KiB

Open AccessArticle

Optimal Integration of Renewable Sources and Latent Heat Storages for Residential Application

by Giulia Mancò, Elisa Guelpa and Vittorio Verda

Energies 2021, 14(17), 5528; https://doi.org/10.3390/en14175528 - 4 Sep 2021

Cited by 4 | Viewed by 1925

Abstract

Given the large amount of energy required in the building sector, an interesting opportunity to reach future sustainable energy systems is the path towards low energy buildings. This work proposes an approach for optimally integrating building-scale energy technologies (both traditional and renewable) to enhance the transformation of the existing buildings (often energetically inefficient) in low-carbon systems. The approach promotes a transition sustainable from both the economic and environmental perspectives. Both operation and design optimization are considered with the aim of suggesting the best set of capacity of the technologies to be installed taking into account the expected operations. The building-scale technologies are integrated with proper storage units: Li-ion batteries and thermal storage (latent heat, that requires low installation space). As a dispatchable renewable technology, a biogas small-scale combined heat and power unit is included in the system. Once the key role played by this component in meeting the loads is proved, an analysis of the impact of the cost of the primary energy carrier of this technology on the system design is carried out. Two optimization approaches have been adopted (both based on non-linear programming). Results show that operation costs can be reduced by up to 29%. The adoption of a combined approach that takes into account both operation and design optimization lead to a reduction in installation and operating costs by up to 27%. In the analyzed cases, the use of the combined optimization confirms that latent heat storage is more suitable to be installed than electric storage (about −4.5% cost). Full article

(This article belongs to the Special Issue Selected Papers from The First World Energies Forum (WEF-1))

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19 pages, 3030 KiB

Open AccessArticle

Finite Physical Dimensions Thermodynamics Analysis and Design of Closed Irreversible Cycles

by Gheorghe Dumitrașcu, Michel Feidt and Ştefan Grigorean

Energies 2021, 14(12), 3416; https://doi.org/10.3390/en14123416 - 9 Jun 2021

Cited by 5 | Viewed by 1689

Abstract

This paper develops simplifying entropic models of irreversible closed cycles. The entropic models involve the irreversible connections between external and internal main operational parameters with finite physical dimensions. The external parameters are the mean temperatures of external heat reservoirs, the heat transfers thermal conductance, and the heat transfer mean log temperatures differences. The internal involved parameters are the reference entropy of the cycle and the internal irreversibility number. The cycle’s design might use four possible operational constraints in order to find out the reference entropy. The internal irreversibility number allows the evaluation of the reversible heat output function of the reversible heat input. Thus the cycle entropy balance equation to design the trigeneration cycles only through external operational parameters might be involved. In designing trigeneration systems, they must know the requirements of all consumers of the useful energies delivered by the trigeneration system. The conclusions emphasize the complexity in designing and/or optimizing the irreversible trigeneration systems. Full article

(This article belongs to the Special Issue Selected Papers from The First World Energies Forum (WEF-1))

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24 pages, 12768 KiB

Open AccessArticle

Design of a Tandem Compressor for the Electrically-Driven Turbocharger of a Hybrid City Car

by Nicolò Cuturi and Enrico Sciubba

Energies 2021, 14(10), 2890; https://doi.org/10.3390/en14102890 - 17 May 2021

Cited by 9 | Viewed by 2457

Abstract

Within a broader national project aimed at the hybridization of a standard city car (the 998 cc Mitsubishi-derived gasoline engine of the Smart W451), our team tackled the problem of improving the supercharger performance and response. The originally conceived design innovation was that of eliminating the mechanical connection between the compressor and the turbine. In the course of the study, it turned out that it is also possible to modify both components to extract extra power from the engine and to use it to recharge the battery pack. This required a redesign of both compressor and turbine. First, the initial configuration was analyzed on the basis of the design data provided by the manufacturer. Then, a preliminary performance assessment of the turbocharged engine allowed us to identify three “typical” operating points that could be used to properly redesign the turbomachinery. It was decided to maintain the radial configuration for both turbine and compressor, but to redesign the latter by adding an inducer. For the turbine, only minor modifications to the nozzle guide vanes (NGV) and rotor blades shape were deemed necessary, while a more substantial modification was in order for the compressor. Fully 3-D computational fluid dynamics simulations of the rotating machines were performed to assess their performance at three operating points: the kick-in point of the original turbo (2000 rpm), the maximum power regime (5500 rpm), and an intermediate point (3500 rpm) close to the minimum specific fuel consumption for the original engine. The results presented in this paper demonstrate that the efficiency of the compressor is noticeably improved for steady operation at all three operating points, and that its choking characteristics have been improved, while its surge line has not been appreciably affected. The net energy recovery was also calculated and demonstrated interesting returns in terms of storable energy in the battery pack. Full article

(This article belongs to the Special Issue Selected Papers from The First World Energies Forum (WEF-1))

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21 pages, 6739 KiB

Open AccessArticle

Extended Exergy Analysis (EEA) of Italy, 2013–2017

by Alfonso Biondi and Enrico Sciubba

Energies 2021, 14(10), 2767; https://doi.org/10.3390/en14102767 - 12 May 2021

Cited by 10 | Viewed by 2645

Abstract

In recent years, many studies have been published on the applications of exergy analyses to complex systems, including entire countries. Oddly, the results, although consistent, appear to lead to divergent conclusions. The underlying problem is that in a “pure” thermodynamic analysis, the so-called “externalities”, i.e., labor, capital, and environmental costs, are often neglected or only approximately included in the picture. In 1998, an extension of the theory that included the exergy content of the externalities was introduced, called “extended exergy accounting” (EEA). Its novelty consisted of the explicit inclusion of the exergy embodied in the externalities. The aim of this work is to use the results of the extended exergy accounting to obtain an indicator that can be used to assess the sustainable development of a country. First, a novel methodological approach to the theory is presented, based on the exploitation of a very large dataset obtained from several national and European statistical institutions. After a brief discussion of the theory, an application to the case of Italy is developed over a 5 years time window (2013–2017). The paper includes a comparison with the concurrent evolution of other sustainability indicators and of the gross domestic product (GDP) indicator. The results show a consistent trend for EE as compared with those of other indicators, and also convincingly proves that this trend is incompatible with that of the GDP. The EE indicator is called the exergy footprint, which also displays a remarkable sensitivity to both environmental and economic factors. Full article

(This article belongs to the Special Issue Selected Papers from The First World Energies Forum (WEF-1))

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17 pages, 641 KiB

Open AccessArticle

Entropy Rates and Efficiency of Convecting-Radiating Fins

by Claudio Giorgi and Federico Zullo

Energies 2021, 14(6), 1643; https://doi.org/10.3390/en14061643 - 16 Mar 2021

Cited by 2 | Viewed by 1633

Abstract

We present a novel indicator for the effectiveness of longitudinal, convecting-radiating fins to dissipate heat. Starting from an analysis of the properties of the entropy rate of the steady state, we show how it is possible to assess the efficiency of such devices by looking at the amount of entropy produced in the heat transfer process. Our study concerns both purely convective fins and convection-radiant fins and takes advantage of explicit expressions for the distribution of heat along the fin. It is shown that, in a suitable limit, the standard definition of efficiency and the entropic definition coincide. The role of the fluid temperature is explicit in the new definition and in the purely convective case. An application to an aluminium fin is given. Analytical and numerical results are discussed. Full article

(This article belongs to the Special Issue Selected Papers from The First World Energies Forum (WEF-1))

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24 pages, 1512 KiB

Open AccessArticle

Environmental Vulnerability in Pre-Salt Oil and Gas Operations

by Tatiana Farane Mein, André Luiz Veiga Gimenes, Eduardo Mario Dias, Maria Lídia Rebello Pinho Dias Scoton and Miguel Edgar Morales Udaeta

Energies 2021, 14(3), 732; https://doi.org/10.3390/en14030732 - 30 Jan 2021

Cited by 1 | Viewed by 2825

Abstract

The objective of this work is to analyze disturbances in the environment caused by anthropic activities in the oil and gas extraction sector. Methodologically, focusing on environmental vulnerability (EV), hydrocarbons (oil and gas) are considered through a qualitative and quantitative analysis of environmental impacts, including the research of Environmental Impact Studies and procedures like EIA/RIMA (institutional Environmental Impact Reports in Brazil). This study focuses on the operation and demobilization of the offshore drilling activity and the installation and operation of the Santos Basin pre-salt oil and gas production (Stages 1, 2, and 3). The criteria addressed in the EIA/RIMAs are used, focusing on those that correlate with EV and oil and gas extraction. Impacts for long-term, permanent, partially reversible, or irreversible disturbances are filtered, totaling 53 impacts (31 effective/21 potential). We concluded that the criteria and methodologies of EIAs vary between stages. At times, the variation is so drastic that the same impact can have a completely different rating from one stage to another, despite referring to the same area. This condition makes it impossible to define a single vulnerability index for the pre-salt venture. This work does not offer a concrete resolution, but exposes the EV issue and its inconsistencies. Full article

(This article belongs to the Special Issue Selected Papers from The First World Energies Forum (WEF-1))

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