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Selected Papers from ECOS 2021—34th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "B: Energy and Environment".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 10830

Special Issue Editors


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Guest Editor
Department of Mechanical Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
Interests: thermal sciences; energy systems

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Guest Editor
Department of Applied Mechanics and Aerospace Engineering, Waseda University, Tokyo 1620044, Japan
Interests: thermal sciences; CFD; energy systems

Special Issue Information

Dear Colleagues,

The 34th International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems—ECOS 2021 was held from 28 June to 2 July 2021 in Giardini Naxos, Taormina, Sicily (Italy). The purpose of the conference is for participants to present new research results and exchange views on theoretical and applied engineering topics related to performance, economics, and environmental impact of energy conversion systems. The topics are as follows:

  • Basic and applied thermodynamics;
  • Heat and mass transfer;
  • Fluid dynamics and CFD;
  • Energy/exergy analysis and optimization;
  • Process integration, analysis, and optimization;
  • ORC and low-grade thermal energy recovery;
  • Refrigeration, air-conditioning, and heat pumps;
  • Fuel cells;
  • Power generation and CHP;
  • Renewable energy (solar, wind, hydro, etc.);
  • Energy storage (batteries, thermal, hydrogen, etc.);
  • Distributed generation and smart grids;
  • District energy supply and networks;
  • Biomass and biofuels;
  • Combustion, gasification, and CO2 mitigation;
  • Energy use (building, transportation, desalination, etc.);
  • Industrial energy use;
  • Energy conservation and management;
  • Environmental impacts of energy conversion;
  • Energy policy and planning.

The SI shall contain only the selected ECOS 2021 papers that have passed the rigorous review process of Energies.

Prof. Dr. Enrico Sciubba
Prof. Dr. Brian Elmegaard
Prof. Dr. Yoshiharu Amano
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.

Published Papers (5 papers)

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Research

13 pages, 4206 KiB  
Article
How to Reduce the Design of Disc-Shaped Heat Exchangers to a Zero-Degrees-of-Freedom Task
by Enrico Sciubba
Energies 2022, 15(3), 1250; https://doi.org/10.3390/en15031250 - 08 Feb 2022
Viewed by 1596
Abstract
The continuous quest for improving the performance of heat exchangers, together with ever more stringent volume and weight constraints, especially in enclosed applications like internal combustion engines and electronic devices, has stimulated the search for compact, high-performance units. One of the shapes that [...] Read more.
The continuous quest for improving the performance of heat exchangers, together with ever more stringent volume and weight constraints, especially in enclosed applications like internal combustion engines and electronic devices, has stimulated the search for compact, high-performance units. One of the shapes that has emerged from a vast body of research is the disc-shaped heat exchanger, in which the fluid to be heated/cooled flows through radial—often bifurcated—channels carved inside a metallic disc. The disc in turn exchanges thermal energy with the hot/cold source (the environment or another body). Several studies have been devoted to the identification of an “optimal shape” of the channels: most of them are based on the extremization of some global property of the device, like its monetary or resource cost, its efficiency, the outlet temperature of one of the fluids, the total irreversibility of the process, etc. The present paper demonstrates that-for all engineering purposes there is only one correct design procedure for such a heat exchanger, and that if a few basic rules of engineering common sense are adopted, this procedure depends solely on the technical specifications (type of operation, thermal load, materials, surface quality): the design in fact reduces to a zero-degree of freedom problem. The procedure is described in detail, and it is shown that a proper application of the constraints completely identifies the shape, size and similarity indices of both the disc and the internal channels. The goal of this study is to demonstrate that-in this, as in many similar cases-a straightforward application of prime principles and of diligent engineering rules, may generate “optimal” designs: these principles guarantee a sort of “embedded optimality”. Full article
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35 pages, 2683 KiB  
Article
Energy Transition Planning with High Penetration of Variable Renewable Energy in Developing Countries: The Case of the Bolivian Interconnected Power System
by Marco Navia, Renan Orellana, Sulmayra Zaráte, Mauricio Villazón, Sergio Balderrama and Sylvain Quoilin
Energies 2022, 15(3), 968; https://doi.org/10.3390/en15030968 - 28 Jan 2022
Cited by 10 | Viewed by 2574
Abstract
The transition to a more environmentally friendly energy matrix by reducing fossil fuel usage has become one of the most important goals to control climate change. Variable renewable energy sources (VRES) are a central low-carbon alternative. Nevertheless, their variability and low predictability can [...] Read more.
The transition to a more environmentally friendly energy matrix by reducing fossil fuel usage has become one of the most important goals to control climate change. Variable renewable energy sources (VRES) are a central low-carbon alternative. Nevertheless, their variability and low predictability can negatively affect the operation of power systems. On this issue, energy-system-modeling tools have played a fundamental role. When exploring the behavior of the power system against different levels of VRES penetration through them, it is possible to determine certain operational and planning strategies to balance the variations, reduce the operational uncertainty, and increase the supply reliability. In many developing countries, the lack of such proper tools accounting for these effects hinders the deployment potential of VRES. This paper presents a particular energy system model focused on the case of Bolivia. The model manages a database gathered with the relevant parameters of the Bolivian power system currently in operation and those in a portfolio scheduled until 2025. From this database, what-if scenarios are constructed allowing us to expose the Bolivian power system to a set of alternatives regarding VRES penetration and Hydro storage for that same year. The scope is to quantify the VRES integration potential and therefore the capacity of the country to leapfrog to a cleaner and more cost-effective energy system. To that aim, the unit-commitment and dispatch optimization problem are tackled through a Mixed Integer Linear Program (MILP) that solves the cost objective function within its constraints through the branch-and-cut method for each scenario. The results are evaluated and compared in terms of energy balancing, transmission grid capability, curtailment, thermal generation displacement, hydro storage contribution, and energy generation cost. In the results, it was found that the proposed system can reduce the average electricity cost down to 0.22 EUR/MWh and also reduce up to 2.22 × 106 t (96%) of the CO2 emissions by 2025 with very high penetration of VRES but at the expense of significant amount of curtailment. This is achieved by increasing the VRES installed capacity to 10,142 MW. As a consequence, up to 7.07 TWh (97%) of thermal generation is displaced with up to 8.84 TWh (75%) of load covered by VRES. Full article
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20 pages, 5492 KiB  
Article
Evaluating the Potential Contribution of District Heating to the Flexibility of the Future Italian Power System
by Chiara Magni, Sylvain Quoilin and Alessia Arteconi
Energies 2022, 15(2), 584; https://doi.org/10.3390/en15020584 - 14 Jan 2022
Cited by 4 | Viewed by 1481
Abstract
Flexibility is crucial to enable the penetration of high shares of renewables in the power system while ensuring the security and affordability of the electricity dispatch. In this regard, heat–electricity sector coupling technologies are considered a promising solution for the integration of flexible [...] Read more.
Flexibility is crucial to enable the penetration of high shares of renewables in the power system while ensuring the security and affordability of the electricity dispatch. In this regard, heat–electricity sector coupling technologies are considered a promising solution for the integration of flexible devices such as thermal storage units and heat pumps. The deployment of these devices would also enable the decarbonization of the heating sector, responsible for around half of the energy consumption in the EU, of which 75% is currently supplied by fossil fuels. This paper investigates in which measure the diffusion of district heating (DH) coupled with thermal energy storage (TES) units can contribute to the overall system flexibility and to the provision of operating reserves for energy systems with high renewable penetration. The deployment of two different DH supply technologies, namely combined heat and power units (CHP) and large-scale heat pumps (P2HT), is modeled and compared in terms of performance. The case study analyzed is the future Italian energy system, which is simulated through the unit commitment and optimal dispatch model Dispa-SET. Results show that DH coupled with heat pumps and CHP units could enable both costs and emissions related to the heat–electricity sector to be reduced by up to 50%. DH systems also proved to be a promising solution to grant the flexibility and resilience of power systems with high shares of renewables by significantly reducing the curtailment of renewables and cost-optimally providing up to 15% of the total upward reserve requirements. Full article
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26 pages, 16077 KiB  
Article
Improving Thermoeconomic and Environmental Performance of District Heating via Demand Pooling and Upscaling
by Jaume Fitó, Neha Dimri and Julien Ramousse
Energies 2021, 14(24), 8546; https://doi.org/10.3390/en14248546 - 18 Dec 2021
Cited by 1 | Viewed by 1762
Abstract
This study evaluates the effects of pooling heat demands in a district for the purpose of upscaling heat production units by means of energy, exergy, economic, exergoeconomic, and environmental indicators, as well as the sensitivity to investment and fuel costs. The following production [...] Read more.
This study evaluates the effects of pooling heat demands in a district for the purpose of upscaling heat production units by means of energy, exergy, economic, exergoeconomic, and environmental indicators, as well as the sensitivity to investment and fuel costs. The following production systems to satisfy the heat demands (domestic hot water production and space heating) of a mixed district composed of office (80%), residential (15%), and commercial (5%) buildings are considered: gas- and biomass-fired boilers, electric boilers and heat pumps (grid-powered or photovoltaic -powered), and solar thermal collectors. For comparison, three system sizing approaches are examined: at building scale, at sector scale (residential, office, and commerce), or at district scale. For the configurations studied, the upscaling benefits were up to 5% higher efficiency (energy and exergy), there was lower levelized cost of heat for all systems (between 20% and 54%), up to 55% lower exergy destruction costs, and up to 5% greater CO2 mitigations. In conclusion, upscaling and demand pooling tend to improve specific efficiencies, reduce specific costs, reduce total investment through the peak power sizing method, and mitigate temporal mismatch in solar-driven systems. Possible drawbacks are additional heat losses due to the distribution network and reduced performance in heat pumps due to the higher temperatures required. Nevertheless, the advantages outweigh the drawbacks in most cases. Full article
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23 pages, 46924 KiB  
Article
Experimental and Numerical Study of Multiple Jets Impinging a Step Surface
by Flavia V. Barbosa, Senhorinha F. C. F. Teixeira and José C. F. Teixeira
Energies 2021, 14(20), 6659; https://doi.org/10.3390/en14206659 - 14 Oct 2021
Cited by 3 | Viewed by 1816
Abstract
Multiple jet impingement is a widely implemented convective process for enhancing heat transfer over target surfaces. Depending on the engineering application, the impinging plate can have different configurations. However, the increased complexity of the surface induces complicated thermal behaviors that must be analyzed. [...] Read more.
Multiple jet impingement is a widely implemented convective process for enhancing heat transfer over target surfaces. Depending on the engineering application, the impinging plate can have different configurations. However, the increased complexity of the surface induces complicated thermal behaviors that must be analyzed. In that sense, this study consisted of the experimental and numerical analysis of multiple jets impinging on a step surface. A particle image velocimetry technique was applied to measure velocity fields, while a heat flux sensor was mounted on the surface to determine the heat transfer. Numerical simulations, for both flat and non-flat plates, were conducted in ANSYS FLUENT applying the SST k-ω model, and experimental results were used to validate the model. Three surface configurations were analyzed, flat, 1 D, and 2 D steps, and the results show an increase in the average Nusselt number compared with the flat plate, 9% and 20%, respectively. This increase was mainly due to the intensification of the flow turbulence induced by the step. Numerical results were in good agreement with the experiments, but the heat transfer was slightly underpredicted for the 2 D step case due to the difficulty of predicting with accuracy the velocity field near the step. Full article
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