Topic Editors

Department of Mechanical Engineering, Universidad de Las Palmas de Gran Canaria, Campus de Tafira s/n, 35017 Las Palmas de Gran Canaria, Spain
Department of Electrical Engineering, University of Las Palmas de Gran Canaria, Campus de Tafira S/N, 35017 Las Palmas de Gran Canaria, Spain
Dr. María José Pérez Molina
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Campus de Tafira s/n, 35017 Las Palmas de Gran Canaria, Spain
Department of Process Engineering, Industrial and Civil Engineering School, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain
Department of Process Engineering, Industrial and Civil Engineering School, University of Las Palmas de Gran Canaria, Campus de Tafira s/n, 35017 Las Palmas de Gran Canaria, Spain
Department of Process Engineering, Industrial and Civil Engineering School, University of Las Palmas de Gran Canaria, Campus de Tafira s/n, 35017 Las Palmas de Gran Canaria, Spain
Department of Processes Engineering, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Las Palmas, Spain
Department of Civil Engineering, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Las Palmas, Spain
Department of Processes Engineering, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Las Palmas, Spain
Department of Processes Engineering, Universidad de Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Las Palmas, Spain

Advances in Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems from ECOS 2023

Abstract submission deadline
closed (30 October 2023)
Manuscript submission deadline
closed (1 February 2024)
Viewed by
15346

Topic Information

Dear Colleagues,

ECOS is the name of a series of international conferences that focus on modern aspects of energy systems. This edition, ECOS 2023 (https://ecos2023.com/), provides a forum for participants to present new research results and exchange views on performance, economics, and environmental impact of energy systems, their design, modelling and possible management advancements. This topic includes original work that contributes to the knowledge of energy engineering field and that offers broad implications for energy process integration, simulation, control and optimization within the transition to a more sustainable energy system.  Topics include, but are not limited to: 

  • Basic and applied thermodynamics;
  • Exergy-based analysis: theories and applications;
  • Heat and mass transfer;
  • Computational Thermo-Fluid Dynamics (CFD);
  • Process integration, process simulation and optimization, process monitoring & control;
  • Sustainability;
  • Resilience;
  • Circular economy;
  • CO2 mitigation;
  • Carbon footprint in the integral water cycle;
  • Water-energy nexus;
  • Environmental impact in energy systems;
  • Renewable energy.

Dr. Pedro Jesús Cabrera Santana
Dr. Enrique Rosales Asensio
Dr. María José Pérez Molina
Dr. Beatriz Del Río-Gamero
Dr. Noemi Melián Martel
Dr. Dunia Esther Santiago García
Dr. Alejandro Ramos Martín
Dr. Néstor Florido Suárez
Dr. Carlos Alberto Mendieta Pino
Dr. Federico León Zerpa
Topic Editors

Keywords

  • energy systems
  • thermodynamics
  • exergy-based analysis
  • computing
  • energy processes

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Entropy
entropy
2.1 4.9 1999 22.4 Days CHF 2600
Energies
energies
3.0 6.2 2008 17.5 Days CHF 2600
Processes
processes
2.8 5.1 2013 14.4 Days CHF 2400
Water
water
3.0 5.8 2009 16.5 Days CHF 2600
Journal of Marine Science and Engineering
jmse
2.7 4.4 2013 16.9 Days CHF 2600

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Published Papers (13 papers)

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19 pages, 2013 KiB  
Article
Exergy-Based Improvements of Sustainable Aviation Fuels: Comparing Biorefinery Pathways
by Pablo Silva Ortiz, Silvio de Oliveira, Jr., Adriano Pinto Mariano, Agnes Jocher and John Posada
Processes 2024, 12(3), 510; https://doi.org/10.3390/pr12030510 - 1 Mar 2024
Viewed by 1573
Abstract
The aeronautical sector faces challenges in meeting its net-zero ambition by 2050. To achieve this target, much effort has been devoted to exploring sustainable aviation fuels (SAF). Accordingly, we evaluated the technical performance of potential SAF production in an integrated first- and second-generation [...] Read more.
The aeronautical sector faces challenges in meeting its net-zero ambition by 2050. To achieve this target, much effort has been devoted to exploring sustainable aviation fuels (SAF). Accordingly, we evaluated the technical performance of potential SAF production in an integrated first- and second-generation sugarcane biorefinery focusing on Brazil. The CO2 equivalent and the renewability exergy indexes were used to assess environmental performance and impact throughout the supply chain. In addition, exergy efficiency (ηB) and average unitary exergy costs (AUEC) were used as complementary metrics to carry out a multi-criteria approach to determine the overall performance of the biorefinery pathways. The production capacity assumed for this analysis covers 10% of the fuel demand in 2020 at the international Brazilian airports of São Paulo and Rio de Janeiro, leading to a base capacity of 210 kt jet fuel/y. The process design includes sugarcane bagasse and straw as the feedstock of the biochemical processes, including diverse pre-treatment methods to convert lignocellulosic resources to biojet fuel, and lignin upgrade alternatives (cogeneration, fast pyrolysis, and gasification Fischer-Tropsch). The environmental analysis for all scenarios shows a GHG reduction potential due to a decrease of up to 30% in the CO2 equivalent exergy base emissions compared to fossil-based jet fuel. Full article
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21 pages, 1980 KiB  
Article
A Novel Layout for Combined Heat and Power Production for a Hospital Based on a Solid Oxide Fuel Cell
by Francesco Calise, Francesco Liberato Cappiello, Luca Cimmino, Massimo Dentice d’Accadia and Maria Vicidomini
Energies 2024, 17(5), 979; https://doi.org/10.3390/en17050979 - 20 Feb 2024
Cited by 1 | Viewed by 779
Abstract
This paper addresses the problem of the reduction in the huge energy demand of hospitals and health care facilities. The sharp increase in the natural gas price, due to the Ukrainian–Russian war, has significantly reduced economic savings achieved by combined heat and power [...] Read more.
This paper addresses the problem of the reduction in the huge energy demand of hospitals and health care facilities. The sharp increase in the natural gas price, due to the Ukrainian–Russian war, has significantly reduced economic savings achieved by combined heat and power (CHP) units, especially for hospitals. In this framework, this research proposes a novel system based on the integration of a reversible CHP solid oxide fuel cell (SOFC) and a photovoltaic field (PV). The PV power is mainly used for balancing the hospital load. The excess power production is exploited to produce renewable hydrogen. The SOFC operates in electrical tracking mode. The cogenerative heat produced by the SOFC is exploited to partially meet the thermal load of the hospital. The SOFC is driven by the renewable hydrogen produced by the plant. When this hydrogen is not available, the SOFC is driven by natural gas. In fact, the SOFC is coupled with an external reformer. The simulation model of the whole plant, including the reversible SOFC, PV, and hospital, is developed in the TRNSYS18 environment and MATLAB. The model of the hospital is calibrated by means of measured data. The proposed system achieves very interesting results, with a primary energy-saving index of 33% and a payback period of 6.7 years. Therefore, this energy measure results in a promising solution for reducing the environmental impact of hospital and health care facilities. Full article
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16 pages, 7344 KiB  
Article
From Local Energy Communities towards National Energy System: A Grid-Aware Techno-Economic Analysis
by Cédric Terrier, Joseph René Hubert Loustau, Dorsan Lepour and François Maréchal
Energies 2024, 17(4), 910; https://doi.org/10.3390/en17040910 - 15 Feb 2024
Cited by 5 | Viewed by 1172
Abstract
Energy communities are key actors in the energy transition since they optimally interconnect renewable energy capacities with the consumers. Despite versatile objectives, they usually aim at improving the self-consumption of renewable electricity within low-voltage grids to maximize revenues. In addition, energy communities are [...] Read more.
Energy communities are key actors in the energy transition since they optimally interconnect renewable energy capacities with the consumers. Despite versatile objectives, they usually aim at improving the self-consumption of renewable electricity within low-voltage grids to maximize revenues. In addition, energy communities are an excellent opportunity to supply renewable electricity to regional and national energy systems. However, effective price signals have to be designed to coordinate the needs of the energy infrastructure with the interests of these local stakeholders. The aim of this paper is to demonstrate the integration of energy communities at the national level with a bottom–up approach. District energy systems with a building scale resolution are modeled in a mixed-integer linear programming problem. The Dantzig–Wolfe decomposition is applied to reduce the computational time. The methodology lies within the framework of a renewable energy hub, characterized by a high share of photovoltaic capacities. Both investments into equipment and its operation are considered. The model is applied on a set of five typical districts and weather locations representative of the Swiss building stock. The extrapolation to the national scale reveals a heterogeneous photovoltaic potential throughout the country. Present electricity tariffs promote a maximal investment into photovoltaic panels in every region, reaching an installed capacity of 67.2 GW and generating 80 TWh per year. Placed in perspective with the optimal PV capacity forecast at 15.4 GW peak at the national level, coordinated investment between local and national actors is needed to prevent dispensable expenses. An uncoordinated design is expected to increase the total costs for residential energy systems from 12% to 83% and curtails 48% of local renewable electricity. Full article
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15 pages, 4279 KiB  
Article
Performance Analysis of a Waste Heat Recovery System for a Biogas Engine Using Waste Resources in an Industrial Complex
by Kyung-Chul Cho, Ki-Yeol Shin, Jaesool Shim, San-Su Bae and Oh-Dae Kwon
Energies 2024, 17(3), 727; https://doi.org/10.3390/en17030727 - 2 Feb 2024
Cited by 1 | Viewed by 1397
Abstract
To achieve carbon neutrality and address global energy supply issues by 2050, there is active progress in the industrial sector for waste energy recovery and commercialization projects. It is necessary to consider both the energy recovery efficiency and economic feasibility based on the [...] Read more.
To achieve carbon neutrality and address global energy supply issues by 2050, there is active progress in the industrial sector for waste energy recovery and commercialization projects. It is necessary to consider both the energy recovery efficiency and economic feasibility based on the production volume for the resource utilization of waste energy, along with eco-friendly processing methods. In this study, a waste heat recovery system was designed to recover a large amount of thermal energy from high-temperature exhaust gases of gas engines for power generation by using biogas produced from organic waste in industrial complexes. Types and sizes of components for a waste heat recovery system that were suitable for various engine sizes depending on biogas production were designed, and the energy recovery efficiency was analyzed. The waste heat recovery system consisted of a smoke tube boiler that generated superheated steam at 161 °C under 490 kPa of pressure from the exhaust gas as the heat source, along with two economizers for heating both supply water and hot water. Heat exchangers that were suitable for three different engine sizes were configured, and their performance and energy flow were calculated. In particular, when operating two engines with a power output of 100 kW, the boiler showed the highest steam production efficiency, and the superheated steam production from high-temperature exhaust gas at 600 °C was designed to be 191 kg/h, while hot water at 58 °C was designed to be produced at 1000 kg/h. In addition, further research on the heat exchanger capacity ratio confirmed that it was within a certain range despite the difference in heat exchanger capacity and efficiency depending on the engine size. It was confirmed that the heat exchange capacity ratio of the boiler was important as an optimal-capacity design value for the entire system, as it ranged from 46% to 47% of the total heat exchanger size. Full article
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27 pages, 2596 KiB  
Article
Landlord–Tenant Dilemma: How Does the Conflict Affect the Design of Building Energy Systems?
by Larissa Kühn, Nico Fuchs, Lars Braun, Laura Maier and Dirk Müller
Energies 2024, 17(3), 686; https://doi.org/10.3390/en17030686 - 31 Jan 2024
Viewed by 971
Abstract
To achieve climate goals, the European Union needs to increase building renovation rates. In owner-occupied buildings, energy cost savings provide financial incentives for renovation. However, 30% of all Europeans live in rented property, where conflicting stakeholder interests arise. Landlords are responsible for renovation [...] Read more.
To achieve climate goals, the European Union needs to increase building renovation rates. In owner-occupied buildings, energy cost savings provide financial incentives for renovation. However, 30% of all Europeans live in rented property, where conflicting stakeholder interests arise. Landlords are responsible for renovation decisions (building envelope and energy system) and the corresponding investments. Tenants face rising rents and only slightly benefit from falling energy costs. The literature calls this conflict the landlord–tenant dilemma. However, publications lack a quantification, leaving gaps in understanding its impact on technology choices and the heat transition. To address this, we incorporate the perspectives of landlords and tenants in a model-based approach for optimized technology choice (mixed-integer linear program). We compare optimal individual technology choices with the total cost optimum (including costs for landlords and tenants) for renovation decisions. Additionally, we examine how changes in the regulatory framework affect the economically driven landlord’s technology choice. Our study reveals that total costs and emissions are up to 60% and 283% higher for landlords deciding for rented houses compared to owner-occupied properties. Current approaches to solve the dilemma partly favor the development of climate-friendly energy systems. However, the renovation of the building envelope and operation costs are mostly disregarded in the decisions of landlords. Full article
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21 pages, 1905 KiB  
Article
Scenario Development for Evaluating Carbon Capture and Utilization Concepts Using Steel Mill Exhaust Gases with Linear Optimization Models
by Matthias Sadlowski and Chae Eon Lim
Energies 2024, 17(2), 496; https://doi.org/10.3390/en17020496 - 19 Jan 2024
Viewed by 774
Abstract
Utilizing exhaust gases from the steel mill generation to produce chemicals presents a promising avenue for carbon capture and utilization (CCU) concepts. Employing a model-based mathematical approach, specifically mixed-integer linear programming (MILP), enables the identification of optimal production concepts. To evaluate the long-term [...] Read more.
Utilizing exhaust gases from the steel mill generation to produce chemicals presents a promising avenue for carbon capture and utilization (CCU) concepts. Employing a model-based mathematical approach, specifically mixed-integer linear programming (MILP), enables the identification of optimal production concepts. To evaluate the long-term feasibility under uncertain future conditions, the construction of hypothetical scenarios to depict possible future states is necessary. This study introduces novel and tailored scenarios for a specific CCU concept aimed at producing methanol, ammonia, urea and/or acetic acid from steel mill exhaust gases by the year 2040 to enhance decision-making processes for identifying the optimal concept. These scenarios provide comprehensive insights into potential future conditions, spanning technical, economic and ecological domains. Unlike prior studies that focus on individual key factors, this approach involves analyzing the interactions of 24 identified key factors within the investigated CCU concept. The method yields five distinct scenarios: (1) Business as Usual (BAU), (2) CO2 Reduction and Renewable Energy Target (RE-Boom), (3) Technical Improvement and Market Booming (Market-Boom), (4) Energy and Market Crisis (Crisis) and (5) Hydrogen Booming (H2-Boom). These five scenarios can be directly integrated into MILP models, enhancing the significance of the optimization results for identifying the optimal CCU concept. Full article
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20 pages, 1160 KiB  
Article
Thermodynamic, Economic and Maturity Analysis of a Carnot Battery with a Two-Zone Water Thermal Energy Storage for Different Working Fluids
by Josefine Koksharov, Lauritz Zendel, Frank Dammel and Peter Stephan
Energies 2024, 17(2), 437; https://doi.org/10.3390/en17020437 - 16 Jan 2024
Viewed by 985
Abstract
The rising share of renewable energies leads to increased fluctuations in electrical power supply. One possibility to shift the surplus energy based on demand is a Carnot battery (CB). A CB uses a heat pump or resistance heater to convert and store thermal [...] Read more.
The rising share of renewable energies leads to increased fluctuations in electrical power supply. One possibility to shift the surplus energy based on demand is a Carnot battery (CB). A CB uses a heat pump or resistance heater to convert and store thermal energy into electrical energy. Later, the stored thermal energy is converted back into electrical energy using a heat engine. This study investigates a CB with a two-zone tank for thermal energy storage. A transcritical process with CO2 is applied for charging, while discharging employs a transcritical process with CO2 and six refrigerants operating in a subcritical process. The transcritical process with CO2 and the four most promising subcritical processes are compared regarding round trip efficiency and levelized cost of electricity (LCOE) depending on the pinch points 5 K and 1 K in the heat exchangers. Additionally, the technology readiness level (TRL) is determined for these configurations. The results show round-trip efficiencies between 11.3% and 33.5% and LCOEs ranging from EUR 0.95 (kWh)1 to EUR 2.09 (kWh)1 for the considered concepts with TRLs of up to six. Full article
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17 pages, 3715 KiB  
Article
Combined Physics- and Data-Driven Modeling for the Design and Operation Optimization of an Energy Concept Including a Storage System
by Rushit Kansara, Michael Lockan and María Isabel Roldán Serrano
Energies 2024, 17(2), 350; https://doi.org/10.3390/en17020350 - 10 Jan 2024
Viewed by 821
Abstract
The industrial sector accounts for a huge amount of energy- and process-related CO2 emissions. One decarbonization measure is to build an energy concept that provides electricity and heat for industrial processes using a combination of different renewable energy sources, such as photovoltaic, [...] Read more.
The industrial sector accounts for a huge amount of energy- and process-related CO2 emissions. One decarbonization measure is to build an energy concept that provides electricity and heat for industrial processes using a combination of different renewable energy sources, such as photovoltaic, wind turbine, and solar thermal collector systems, integrating also energy conversion power-to-heat components such as heat pumps, electric boilers, and thermal energy storage. The challenge for the industries is the economic aspect of the decarbonization, as industries require a cost-efficient solution. Minimizing cost and emissions together is a complex problem, which requires two major tasks: (I) modeling of components and (II) multi-objective coupled design and operation optimization of the energy concept. The optimal design and capacity of the components and optimal system operation depend majorly on component modeling, which is either physics-driven or data-driven. This paper shows different types of physics- and data-driven modeling of energy components for multi-objective coupled optimization in order to minimize costs and emissions of a specific industrial process as a case study. Several modeling techniques and their influence on the optimization are compared in terms of computational effort, solution accuracy, and optimal capacity of components. The results show that the combination of physics- and data-driven models has a computational time reduction of up to 37% for an energy concept without thermal energy storage and 29% for that with thermal energy storage, both with high-accuracy solutions compared to complete physics-driven models for the considered case study. Full article
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13 pages, 2493 KiB  
Article
Improving Computation Time for Optimization Runs of Modelica-Based Energy Systems
by Sven Klute, Markus Hadam, Mathias van Beek and Marcus Budt
Energies 2024, 17(1), 241; https://doi.org/10.3390/en17010241 - 2 Jan 2024
Viewed by 1052
Abstract
Mathematical optimization is a widespread method in order to improve, for instance, the efficiency of energy systems. A simulation approach based on partial differential equations can typically not be formulated as an optimization problem, thus requiring interfacing to an external optimization environment. This [...] Read more.
Mathematical optimization is a widespread method in order to improve, for instance, the efficiency of energy systems. A simulation approach based on partial differential equations can typically not be formulated as an optimization problem, thus requiring interfacing to an external optimization environment. This is, among others, also true for the programming language Modelica. Because of high computation time, such coupled approaches are often limited to small-scale optimization problems. Since simulation models tend to get more complex, simulation time and, in turn, associated optimization time rise significantly. To enable proper sampling of the search space, individual optimization runs need to be solved in acceptable times. This paper addresses the search for a proper optimization approach and tool to couple with Modelica/Dymola. The optimization is carried out on an exemplary power plant model from the ClaRa-Library using an evolutionary algorithm (SPEA2-based) with Ansys optiSlang. To verify and evaluate the results, a comparison with the standard Dymola optimization library is performed. Both parallelization and indirect optimization with surrogate models achieved a significant runtime reduction by a factor of up to 5.4. The use of meta models is particularly advantageous for repetitive optimization runs of the same optimization problem but may lead to deviations due to the calculated approximations. Full article
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17 pages, 2607 KiB  
Article
Quantifying the Operational Flexibility of Distributed Cross-Sectoral Energy Systems for the Integration of Volatile Renewable Electricity Generation
by Sebastian Berg, Lasse Blaume and Benedikt Nilges
Energies 2024, 17(1), 90; https://doi.org/10.3390/en17010090 - 22 Dec 2023
Viewed by 685
Abstract
As a part of the transition in higher-level energy systems, distributed cross-sectoral energy systems (DCESs) play a crucial role in providing flexibility in covering residual load (RL). However, there is currently no method available to quantify the potential flexibility of DCESs in covering [...] Read more.
As a part of the transition in higher-level energy systems, distributed cross-sectoral energy systems (DCESs) play a crucial role in providing flexibility in covering residual load (RL). However, there is currently no method available to quantify the potential flexibility of DCESs in covering RL. This study aimed to address this gap by comparing the RL demand of a higher-level energy system with the electricity flow between a DCES and the electricity grid. This can allow for the quantification of the flexibility of DCES operation. Our approach was to categorize existing methods for flexibility quantification and then propose a new method to assess the flexibility of DCESs in covering RL. For this, we introduced a new quantification indicator called the Flexibility Deployment Index (FDI), which integrates two factors: the RL of the higher-level energy system and the electricity purchase and feed-in of a DCES. By normalizing both factors, we could compare the flexibility to cover RL with respect to different DCES concepts and scenarios. To validate the developed quantification method, we applied it to a case study of a hospital’s DCES in Germany. Using an MILP optimization model, we analyzed the variation in FDI for different technology concepts and scenarios, including fixed electricity tariffs, dynamic electricity tariffs, and CO2-emission-optimized operation. The results of our calculations and the application of the FDI indicate that high-capacity combined heat and power units combined with thermal storage units provide higher flexibility. Additionally, the results highlight higher flexibility provision during the winter period compared to the summer period. However, further application and research are needed to confirm the robustness and validity of the FDI assessment. Nonetheless, the case study demonstrates the potential of the new quantification method. Full article
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15 pages, 2058 KiB  
Article
CO2 Marine Transportation from a Techno-Energetic Perspective
by Eduardo Pérez-Bódalo, Rafael d’Amore-Domenech and Teresa J. Leo
J. Mar. Sci. Eng. 2024, 12(1), 12; https://doi.org/10.3390/jmse12010012 - 20 Dec 2023
Viewed by 1041
Abstract
CCUS (Carbon Capture, Utilization, and Storage) is a cornerstone of most proposed carbon dioxide (CO2) emissions strategies, as it is necessary to keep atmospheric CO2 concentrations below 450 parts per million by the year 2100 and, as such, prevent global [...] Read more.
CCUS (Carbon Capture, Utilization, and Storage) is a cornerstone of most proposed carbon dioxide (CO2) emissions strategies, as it is necessary to keep atmospheric CO2 concentrations below 450 parts per million by the year 2100 and, as such, prevent global warming. The Intergovernmental Panel on Climate Change (IPCC) predicts a removal capacity of 12 GtCO2/yr by 2050, whereas the present capability is 41 MtCO2/yr. Decarbonization may not be able to proceed quickly enough to reach net-zero emissions without CCUS technologies. In the maritime sector, CCUS serves a dual purpose: capturing CO2 from fossil fuel combustion and transporting the captured CO2 for its storage or utilization. This paper examines the importance of vessels as liquid CO2 carriers, emphasizing the transportation conditions associated with CO2. A techno-energetic analysis is carried out by studying various combinations of temperature and pressure. From a transport viewpoint, the findings indicate that reducing CO2 pressure is more cost-effective. In terms of pre-processing, higher CO2 pressures may lead to energy and, potentially, cost savings. However, the optimal pressure in the entire logistical chain remains uncertain. Further research is advised to broaden the scope of the chain to be analyzed. Full article
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25 pages, 3200 KiB  
Article
Multi-Objective Production and Scheduling Optimization of Offshore Wind Turbine Steel Pipe Piles Based on Improved Hesitant Fuzzy Method
by Weihan Wang, Jinchao Xiao, Dongying Feng, Sanxi Wei and Zhongze Wang
J. Mar. Sci. Eng. 2023, 11(8), 1505; https://doi.org/10.3390/jmse11081505 - 28 Jul 2023
Cited by 1 | Viewed by 1197
Abstract
This paper investigates the multi-objective optimization problem in the production of offshore wind turbine steel pipe piles (OWTSPP). Considering the particularity of the steel pipe pile production process, it is divided into a flexible flow shop scheduling (FFSS) stage and an open parallel [...] Read more.
This paper investigates the multi-objective optimization problem in the production of offshore wind turbine steel pipe piles (OWTSPP). Considering the particularity of the steel pipe pile production process, it is divided into a flexible flow shop scheduling (FFSS) stage and an open parallel shop scheduling (OPSS) stage, respectively. Mathematical models are established for each stage, and the critical path and production time information are obtained using a disjunctive graph model. Due to the inability of existing empirical scheduling methods to balance production goals, an improved Pythagorean hesitant fuzzy method (IPHFM) is proposed to solve the multi-objective optimization problem in steel pipe pile production. Specifically, the maximum completion time, machine total load, and total completion time are taken as optimization objectives. The improved Lagrange multiplier method with penalty terms is used to handle the constraints and objective functions, and a Lagrange objective function is generated. Then, the Lagrange objective function matrix is obtained by normalization and same-scale processing, and an algorithm is designed to obtain the Pareto front solution set. Finally, this paper compares the optimal scheduling plans under the empirical scheduling method and the improved method. The results show that the improved method can significantly improve production efficiency in both small-scale and large-scale production, with improvements of 15.7% and 22.16%, respectively. Full article
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22 pages, 6252 KiB  
Article
Influence of Central Air on Flow and Combustion Characteristics and Low-Load Stabilization Performance of a Babcock Burner
by Chunchao Huang, Zhengqi Li, Yufei Wang, Yue Lu, Huacai Liu and Zhichao Chen
Processes 2023, 11(7), 1916; https://doi.org/10.3390/pr11071916 - 26 Jun 2023
Cited by 2 | Viewed by 1173
Abstract
On a cold single-phase test stand, the effect of central air on the exit flow field of Babcock, Germany, burner was investigated. Industrial measurements were taken for a 700 MW wall-fired pulverized-coal utility boiler with above burners. Gas temperature, gas composition and concentration [...] Read more.
On a cold single-phase test stand, the effect of central air on the exit flow field of Babcock, Germany, burner was investigated. Industrial measurements were taken for a 700 MW wall-fired pulverized-coal utility boiler with above burners. Gas temperature, gas composition and concentration in the burner area were measured at 444 MW, 522 MW and 645 MW loads, respectively. Only when the central air mass flow was zero did a center reflux zone exist in the burner outlet area. The steady combustion of faulty coal was aided by early mixing of primary and secondary air, which was made possible by the decreased central air mass flow. At all different loads, the pulverized coal in center region took a long distance to ignite. The temperature in center steadily dropped as central air mass flow decreased, while the temperature in secondary air region gradually rose. Within 1.5 m from the primary air duct outlet, the highest CO concentration was 25 ppm and the highest O2 concentration was close to 21% under all loads. The gas concentration near sidewall was more influenced by load. With all valves opening of burner center air at 30%, the boiler was able to operate safely and stably without oil at a load of 262 MW. The furnace chamber temperature in burner area reached 1056.1 °C. Full article
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