Energies

21 pages, 3042 KiB

Open AccessArticle

Synergistic Development Pathways: An Exploratory Study on the Urban–Rural Mutual Assistance Model and Low-Carbon Transformation of Henan’s Power Supply Industry Towards Dual-Carbon Goals

by Xinfa Tang, Guozu Hao, Yonghua Wang, Youwei Wan, Jingjing Wang, Yan Luo and Musa Dirane Nubea

Energies 2024, 17(24), 6497; https://doi.org/10.3390/en17246497 - 23 Dec 2024

Viewed by 535

Abstract

In the midst of the push for dual-carbon goals, urban centers are faced with the imperative of reducing emissions and conserving energy, while rural regions are harnessing their abundant new energy resources to promote balanced urban–rural development. Photovoltaic (PV) power generation, known for [...] Read more.

In the midst of the push for dual-carbon goals, urban centers are faced with the imperative of reducing emissions and conserving energy, while rural regions are harnessing their abundant new energy resources to promote balanced urban–rural development. Photovoltaic (PV) power generation, known for its cleanliness, safety, and emission-free nature, is playing a crucial role in the evolution of Henan Province’s power supply industry. This paper delves into the current state of Henan’s power supply infrastructure, the trajectory of its low-carbon development, and the policies that shape the PV sector. It also examines the establishment of an urban–rural mutual aid model through the lens of alternative energy technologies. By utilizing a combination of case studies and systematic theoretical research, this paper uncovers the economic potential that remains untapped of new energy sources in rural areas and presents strategies for synergistic development in alignment with dual-carbon goals within the power supply industry. The research underscores the significance of an urban–rural mutual assistance model in achieving carbon neutrality, addressing urban–rural development gaps, fostering shared prosperity, and contributing Chinese insights to global climate governance frameworks. Full article

(This article belongs to the Section F1: Electrical Power System)

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32 pages, 5801 KiB

Open AccessReview

Review on Development and Research of Underwater Capacitive Power Transfer

by Ying Liu, Binghe Li, Liangyi Pan, Shunyu Yao, Zhutao Dong, Jiantao Zhang, Chunbo Zhu and Shumei Cui

Energies 2024, 17(24), 6496; https://doi.org/10.3390/en17246496 - 23 Dec 2024

Viewed by 515

Abstract

Wireless power transfer (WPT) technology applied to underwater environments has the advantages of no electrical contact, high safety, and high applicability. Underwater capacitive power transfer (UCPT) technology shows great potential in the field of underwater wireless power transfer as it has more advantages [...] Read more.

Wireless power transfer (WPT) technology applied to underwater environments has the advantages of no electrical contact, high safety, and high applicability. Underwater capacitive power transfer (UCPT) technology shows great potential in the field of underwater wireless power transfer as it has more advantages compared to underwater inductive power transfer (UIPT) technology. This paper begins with the system principles of UCPT and explains the advantages of UCPT technology for underwater applications. It then reviews the coupler and equivalent circuit models currently used for UCPT in various underwater environments, which indicates the direction for the design of underwater couplers in the future. In addition, compensation networks currently applied in UCPT systems are summarized and compared. Furthermore, different application examples of UCPT are introduced, and the key factors constraining UCPT development are pointed out. Research directions for future development of UCPT technology are also investigated. Full article

(This article belongs to the Special Issue Energy, Electrical and Power Engineering: 3rd Edition)

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22 pages, 10873 KiB

Open AccessArticle

Effects of Structure Parameters of Gravity-Type Heat Pipe on Heat Transfer Characteristics for Waste Heat Recovery from Mine Return Air

by Yu Zhai, Zhikun Ling, Xu Zhao and Zhifeng Dong

Energies 2024, 17(24), 6495; https://doi.org/10.3390/en17246495 - 23 Dec 2024

Viewed by 599

Abstract

In the condition of waste heat recovery from mine return air with a temperature of 20~30 °C and velocity about 4 to 8 m/s, the structure of gravity-type heat pipe with fin increases the heat exchange areas and meanwhile increases the resistance of [...] Read more.

In the condition of waste heat recovery from mine return air with a temperature of 20~30 °C and velocity about 4 to 8 m/s, the structure of gravity-type heat pipe with fin increases the heat exchange areas and meanwhile increases the resistance of air flow, which consumes a large amount of main fan power driven by a motor. Furthermore, the resistance of air flow increases greatly with the velocity of the air flow. In this paper, the gravity-type heat pipe with elliptical smooth surface is studied to decrease the resistance and loss of energy of the air flow. In order to obtain the influence of ellipticity on heat transfer efficiency and energy loss under the condition of a certain heat transfer area of the heat pipe, the heat transfer efficiency of a single pipe and a pipe bundle with different ellipticities is studied by using numerical simulation based on the equal section perimeter. The results show that the reasonable change of ellipticity can increase specific enthalpy and decrease entropy production. When the pipe is single, the ellipticity is 0.56 and the specific enthalpy is the largest, increasing by 12.08%. The ellipticity of the pipe bundle is 0.61, and the specific enthalpy is the largest, increasing by 19.28%. The entropy production slightly increased by 10.4%. Moreover, the empirical formula of single pipe heat transfer with an error less than 5% and the empirical formula of pipe bundle heat transfer with an error less than 2.2% are obtained. The empirical formula of pipe bundle heat transfer at different temperatures is modified, and the error is less than 5%, which provides the fundamental data for deep research, development, and engineering design of gravity-type heat pipe heat energy exchange system of underground return airflow in coal mines. Full article

(This article belongs to the Special Issue Heat Transfer in Heat Exchangers)

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20 pages, 16615 KiB

Open AccessArticle

Asymmetric Hairpin Winding Design for Losses Reduction with Thermal Analysis for an Electric Vehicle Case Study

by Sara M. Ismaeel, Mohamed N. Ibrahim, Essam M. Rashad and Peter Sergeant

Energies 2024, 17(24), 6494; https://doi.org/10.3390/en17246494 - 23 Dec 2024

Viewed by 581

Abstract

The asymmetric design of hairpin windings is known as a method for reducing AC losses in electric motors, especially at high frequencies. However, the design of the asymmetric winding is very critical to obtaining the best benefit regarding the efficiency and the thermal [...] Read more.

The asymmetric design of hairpin windings is known as a method for reducing AC losses in electric motors, especially at high frequencies. However, the design of the asymmetric winding is very critical to obtaining the best benefit regarding the efficiency and the thermal performance of the motor. Compared to the state-of-the-art in this paper, deep investigations are carried out to obtain the optimum design of the asymmetric hairpin windings while still employing a conventional manufacturing method. An analytical model is developed to speed up the investigation process, and the results of the analytical model are validated with a finite element method (FEM) model. The conclusions from the analytical investigation are considered in the design of an electric vehicle (EV) motor. The performance of the motor is studied for two different driving profiles to validate the rules of the asymmetric windings design and check the degree of dependency of the design of asymmetric windings on the application. It is proved that using asymmetric design reduces motor losses and improves thermal performance. Full article

(This article belongs to the Special Issue Optimization and Control of Electric and Hybrid Vehicles)

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32 pages, 11374 KiB

Open AccessReview

Evaluation of Coal Repowering Option with Small Modular Reactor in South Korea

by Semin Joo, Seok Ho Song, Seokjun Oh, Staffan Qvist and Jeong Ik Lee

Energies 2024, 17(24), 6493; https://doi.org/10.3390/en17246493 - 23 Dec 2024

Viewed by 545

Abstract

The Paris Agreement emphasizes the need to reduce greenhouse gas emissions, particularly from coal power. One suggested approach is repowering coal-fired power plants (CPPs) with small modular reactors (SMRs). South Korea plans to retire CPPs in the coming decades and requires alternative options [...] Read more.

The Paris Agreement emphasizes the need to reduce greenhouse gas emissions, particularly from coal power. One suggested approach is repowering coal-fired power plants (CPPs) with small modular reactors (SMRs). South Korea plans to retire CPPs in the coming decades and requires alternative options for coal-fired energy. This study presents a scoping analysis comparing variable renewable energy (VRE) sources with SMRs for repowering CPPs in the Korean context. The analysis indicates that SMRs may be a more favorable option than VRE sources, particularly due to their load-following capabilities. In this study, two types of SMRs were investigated: high-temperature gas reactors (HTGRs) and pressurized water reactors (PWRs). HTGRs are suitable to fit the high-temperature operating conditions of steam turbines but require multiple units due to their low volumetric flow rates. PWRs, while matching the volumetric flow rate of existing CPP turbines, require additional thermal energy sources to meet the high-temperature operating conditions of steam turbines. Lastly, an analysis of necessary regulatory and legislative changes in South Korea’s nuclear framework is presented, identifying several key regulatory issues for repowering coal with nuclear energy. Full article

(This article belongs to the Section B4: Nuclear Energy)

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15 pages, 5344 KiB

Open AccessArticle

Enhancing Power Quality in Standalone Microgrids Powered by Wind and Battery Systems Using HO Algorithm Based Super Twisting Sliding Mode Controllers

by Sana Sahbani, Oumnia Licer, Hassane Mahmoudi, Abdennebi Hasnaoui and Mustapha Kchikach

Energies 2024, 17(24), 6492; https://doi.org/10.3390/en17246492 - 23 Dec 2024

Viewed by 637

Abstract

This paper addresses the challenge of enhancing power quality in a standalone microgrid powered by wind and battery systems. Fluctuations in wind power generation and unpredictable electricity demand significantly impact power quality. To mitigate these issues, a control strategy utilizing Super Twisting Sliding [...] Read more.

This paper addresses the challenge of enhancing power quality in a standalone microgrid powered by wind and battery systems. Fluctuations in wind power generation and unpredictable electricity demand significantly impact power quality. To mitigate these issues, a control strategy utilizing Super Twisting Sliding Mode (STSM) controllers tuned by the Hippopotamus Optimization Algorithm (HOA) is proposed. The HOA algorithm efficiently determines optimal STSM controller parameters, leading to improved system performance and stability. A comparative study was conducted against PI, Fuzzy Logic controllers, and other metaheuristic optimization algorithms (PSO, GWO, WOA). Simulation results, obtained using MATLAB/Simulink, demonstrate the superior performance of the proposed methodology. Specifically, during a simulated abrupt load change, the system exhibited rapid recovery with frequency reaching equilibrium, significantly faster than PI and Fuzzy Logic controllers. Moreover, the DC link voltage remained stable with fluctuations of only 2%, while the three-phase RMS voltages at the Point of Load Bus (PLB) maintained balanced and stable values. These results confirm the enhanced power quality and robust operation achieved with the proposed HOA-tuned STSM control strategy, outperforming other tested methods. The methodology effectively manages both the energy management system and improves power quality in standalone wind and battery-powered microgrids. Full article

(This article belongs to the Section A1: Smart Grids and Microgrids)

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18 pages, 4672 KiB

Open AccessArticle

Impact of Temperature on the Hygroscopic Behavior and Mechanical Properties of Expansive Mudstone

by Lingdong Meng, Wenxiu Zhang, Huakui Yang, Shaoyun Xu, Ming Xu, Lina Zhang and Wenlong Dong

Energies 2024, 17(24), 6491; https://doi.org/10.3390/en17246491 - 23 Dec 2024

Viewed by 481

Abstract

Aiming at the large-scale nonlinear deformation of the roadway in Liangjia Coal Mine, Shandong Province, the mudstone of the 1602 working face is taken as the research object. A high-precision mudstone weathering test system integrating monitoring and control was developed, and the weathering [...] Read more.

Aiming at the large-scale nonlinear deformation of the roadway in Liangjia Coal Mine, Shandong Province, the mudstone of the 1602 working face is taken as the research object. A high-precision mudstone weathering test system integrating monitoring and control was developed, and the weathering tests of expanded mudstone were carried out at 10 °C, 20 °C, 30 °C and 40 °C. The results show that the hygroscopic curves of expanded mudstone demonstrate a nonlinear growth trend at different temperatures, and the influence of temperature on the hygroscopic curves is less than 20%. From the overall law, it can be roughly divided into three stages: the strong hygroscopic stage, the hygroscopic deceleration stage and the stable hygroscopic stage. The maximum expansion rates of the samples were 4.1%, 5.3%, 6.2% and 6.8%, respectively, and the water content and expansion rates corresponding to different ambient temperature and humidity were generally “concave”. The mechanical tests show that the mechanical properties of mudstone decrease as the ambient temperature increases, and the corresponding compressive strength decreases by 16~50%. The linear degradation is obvious, and the gradual expansion of peak strain indicates that the plasticity of the rock increases and the elastic modulus decreases linearly. Full article

(This article belongs to the Section H: Geo-Energy)

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16 pages, 6815 KiB

Open AccessArticle

The Method for Assessing the Causes of Damage to a Bearing in a Rotary Air Preheater

by Paweł Maślak and Grzegorz Przybyłek

Energies 2024, 17(24), 6490; https://doi.org/10.3390/en17246490 - 23 Dec 2024

Viewed by 615

Abstract

This article presents a method for identifying the cause of damage to a rotary air preheater on one of the fluidized bed boilers operating in a power plant. The bearing in question operates under harsh conditions with the exhaust gas temperature reaching 287 [...] Read more.

This article presents a method for identifying the cause of damage to a rotary air preheater on one of the fluidized bed boilers operating in a power plant. The bearing in question operates under harsh conditions with the exhaust gas temperature reaching 287 °C and causing its casing to heat up intensively. It is therefore important to ensure that the bearing is constantly cooled by water, which lowers the operating temperature and thus extends its service life. Unfortunately, after a short period of operation, the upper double-row spherical roller bearing was damaged, and the tests presented in the assessment method helped to determine the cause of damage to its casing. Full article

(This article belongs to the Section J: Thermal Management)

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35 pages, 2557 KiB

Open AccessReview

The Optimal Integration of Virtual Power Plants for the South African National Grid Based on an Energy Mix as per the Integrated Resource Plan 2019: A Review

by Melissa-Jade Williams and Choong-Koo Chang

Energies 2024, 17(24), 6489; https://doi.org/10.3390/en17246489 - 23 Dec 2024

Viewed by 681

Abstract

The Integrated Resource Plan (IRP) 2019 outlines South Africa’s goal of achieving a diverse and sustainable energy mix. To achieve this, innovative methods must be found to integrate renewable energy sources while preserving grid stability. Virtual Power Plants (VPPs), which combine dispersed energy [...] Read more.

The Integrated Resource Plan (IRP) 2019 outlines South Africa’s goal of achieving a diverse and sustainable energy mix. To achieve this, innovative methods must be found to integrate renewable energy sources while preserving grid stability. Virtual Power Plants (VPPs), which combine dispersed energy resources like solar photovoltaic (PV), wind, and battery storage into a single, intelligent system, are one such approach. This study provides a thorough analysis of the best way to integrate VPPs into South Africa’s national grid, highlighting the associated operational, regulatory, and technological challenges. In order to optimize VPP efficiency, this research looks at a number of key areas, such as enhanced renewable energy forecasting, energy management systems (EMSs), and distributed energy resource (DER) integration. Additionally, it examines how VPPs help demand-side management, reduce intermittency in renewable energy sources, and improve grid flexibility. In addition, this paper analyzes the market and regulatory structures required to permit VPP participation in energy markets and guarantee a smooth transition to a decentralized energy environment. This paper highlights the crucial role VPPs could play in reaching the nation’s renewable energy targets, lowering dependency on fossil fuels, and enhancing energy access. Through this review, this paper offers insights into the technological viability and strategic benefits of VPP implementation in South Africa. The findings highlight that for VPPs to successfully integrate into South Africa’s energy landscape, it will be necessary to overcome technological, regulatory, and market-related barriers. Full article

(This article belongs to the Section A: Sustainable Energy)

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25 pages, 3400 KiB

Open AccessArticle

Planning and Analysis of Microgrids for Fast Charging Stations Considering Net Zero Energy Building Indexes

by Matheus Souza da Cruz, Caroline Beatriz Fucks Darui, Alzenira da Rosa Abaide, Nelson Knak Neto, Leonardo Nogueira Fontoura da Silva and Laura Lisiane Callai dos Santos

Energies 2024, 17(24), 6488; https://doi.org/10.3390/en17246488 - 23 Dec 2024

Viewed by 537

Abstract

Distributed Energy Resources (DERs) aggregation increases the sustainability of the Electric Vehicles (EVs) market. For example, Fast Charging Stations (FCSs) associated with distributed generation and storage systems in a microgrid infrastructure may be beneficial in increasing self-consumption and peak-shaving strategies and mitigating impacts [...] Read more.

Distributed Energy Resources (DERs) aggregation increases the sustainability of the Electric Vehicles (EVs) market. For example, Fast Charging Stations (FCSs) associated with distributed generation and storage systems in a microgrid infrastructure may be beneficial in increasing self-consumption and peak-shaving strategies and mitigating impacts on the grid. However, microgrid sizing planning is a complex challenge, mainly due to numerous factors related to EV market growth and user behavior. This work defines a methodology focusing on sizing planning and analysis of microgrids for FCSs based on quantitative indices formulated according to the Net Zero Energy Building (NZEB) concept, optimizing self-sufficiency and limiting impacts on the primary electrical grid. The methodology is applied to a real case study considering the growth of EVs in southern Brazil. The developed analyses demonstrate that the proposed microgrid meets the energy needs of the FCS and presents the best NZEB indexes within the considered study horizon. Additionally, representative profiles were characterized for different load and generation conditions, complementing the analyses. It was shown that the storage promotes a delay and reduction in the reverse peak power flow, further enhancing the NZEB indexes. Full article

(This article belongs to the Special Issue Measurement Systems for Electric Machines and Motor Drives)

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27 pages, 1222 KiB

Open AccessArticle

Research on the Impact Effects of the Thermal Power Industry and Other High-Haze-Pollution Industries on the Atmospheric Environment

by Yunkai Zhou, Jingkun Zhou and Yating Li

Energies 2024, 17(24), 6487; https://doi.org/10.3390/en17246487 - 23 Dec 2024

Viewed by 545

Abstract

As industrialization accelerates, China’s industrial development pace has been rapidly increasing. However, this growth has been accompanied by an increase in high-pollution and high-emission industries, leading to the release of a significant amount of air pollutants and exacerbating haze pollution nationwide. This article [...] Read more.

As industrialization accelerates, China’s industrial development pace has been rapidly increasing. However, this growth has been accompanied by an increase in high-pollution and high-emission industries, leading to the release of a significant amount of air pollutants and exacerbating haze pollution nationwide. This article utilizes the spatial dynamic Durbin model and panel threshold regression model to analyze the impact of the thermal power industry and other high-haze-pollution industries on atmospheric environmental quality. The results indicate a negative correlation between the thermal power industry and other high-haze pollution industries and atmospheric environmental quality. There is a spatial spillover effect of the thermal power industry and other high-haze-pollution industries on air pollution. Environmental regulations have a single-threshold characteristic in their impact on atmospheric quality in the thermal power industry and other high-haze-pollution industries, as does green technology innovation. Additionally, cumulative rainfall has a significant single-threshold effect on the atmospheric environmental quality in regions with the thermal power industry and other high-haze-pollution industries. The article suggests policies for severely polluted areas, including reducing high-haze-pollution enterprises, optimizing industrial structures rationally, strengthening regional cooperation, enhancing regional haze pollution prevention and control coordination mechanisms, increasing the intensity of environmental regulations, utilizing the threshold effect of environmental regulations, promoting green technological innovation and application in heavily polluted areas, and exploring options to improve air pollution through increased rainfall. These recommendations aim to provide reference points for China to further optimize its industrial structure and comprehensively manage haze pollution. Full article

(This article belongs to the Special Issue Research on Energy, Environment, and Sustainable Development)

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14 pages, 4120 KiB

Open AccessFeature PaperReview

Solid Oxide Electrolysis, Co-Electrolysis, and Methanation Fundamentals of Performance and History

by Katsiaryna Martsinchyk, Aliaksandr Martsinchyk and Jaroslaw Milewski

Energies 2024, 17(24), 6486; https://doi.org/10.3390/en17246486 - 23 Dec 2024

Viewed by 544

Abstract

This manuscript discusses the advancements and historical development of solid oxide electrolysis (SOE), co-electrolysis, and methanation technologies, addressing the performance fundamentals and system integration challenges in the context of the EU’s 2050 climate neutrality goals. SOE technologies, characterized by their high efficiencies and [...] Read more.

This manuscript discusses the advancements and historical development of solid oxide electrolysis (SOE), co-electrolysis, and methanation technologies, addressing the performance fundamentals and system integration challenges in the context of the EU’s 2050 climate neutrality goals. SOE technologies, characterized by their high efficiencies and ability to operate at elevated temperatures, offer significant advantages in hydrogen production and power generation. Co-electrolysis of steam and carbon dioxide in SOEs provides a promising pathway for syngas production, leveraging carbon capture and utilization strategies to mitigate carbon emissions. Additionally, catalytic methanation processes described within facilitate the synthesis of methane from carbon oxides and hydrogen, which could be integral to renewable energy storage and grid-balancing solutions. Historical analysis provides insights into the evolution of these technologies from early experiments to modern applications, including their role in space programmes and potential for industrial scale-up. The current state of research and commercialization, highlighted through various system designs and operational enhancements, suggests that SOEs are crucial for sustainable energy transformations, underscoring the necessity for continued innovation and deployment in relevant sectors. Full article

(This article belongs to the Section D2: Electrochem: Batteries, Fuel Cells, Capacitors)

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28 pages, 2198 KiB

Open AccessReview

A Survey on Energy-Efficient Design for Federated Learning over Wireless Networks

by Xuan-Toan Dang, Binh-Minh Vu, Quynh-Suong Nguyen, Thi-Thuy-Minh Tran, Joon-Soo Eom and Oh-Soon Shin

Energies 2024, 17(24), 6485; https://doi.org/10.3390/en17246485 - 23 Dec 2024

Viewed by 707

Abstract

Federated learning (FL) has emerged as a decentralized, cutting-edge framework for training models across distributed devices, such as smartphones, IoT devices, and local servers while preserving data privacy and security. FL allows devices to collaboratively learn from shared models without exchanging sensitive data, [...] Read more.

Federated learning (FL) has emerged as a decentralized, cutting-edge framework for training models across distributed devices, such as smartphones, IoT devices, and local servers while preserving data privacy and security. FL allows devices to collaboratively learn from shared models without exchanging sensitive data, significantly reducing privacy risks. With these benefits, the deployment of FL over wireless communication systems has gained substantial attention in recent years. However, implementing FL in wireless environments poses significant challenges due to the unpredictable and fluctuating nature of wireless channels. In particular, the limited energy resources of mobile and IoT devices, many of which operate on constrained battery power, make energy management a critical concern. Optimizing energy efficiency is therefore crucial for the successful deployment of FL in wireless networks. However, existing reviews on FL predominantly focus on framework design, wireless communication, and security/privacy concerns, while paying limited attention to the system’s energy consumption. To bridge this gap, this article delves into the foundational principles of FL and highlights energy-efficient strategies tailored for various wireless architectures. It provides a comprehensive overview of FL principles and introduces energy-efficient designs, including resource allocation techniques and communication architectures, tailored to address the unique challenges of wireless communications. Furthermore, we explore emerging technologies aimed at enhancing energy efficiency and discuss future challenges and opportunities for continued research in this field. Full article

(This article belongs to the Section K: State-of-the-Art Energy Related Technologies)

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26 pages, 5031 KiB

Open AccessArticle

Effect of the Heterogeneity of Coal on Its Seepage Anisotropy: A Micro Conceptual Model

by Xiuling Chen, Guanglei Cui, Jiaming Luo, Chunguang Wang and Jian Zhang

Energies 2024, 17(24), 6484; https://doi.org/10.3390/en17246484 - 23 Dec 2024

Viewed by 455

Abstract

Coal is a typical dual-porosity structural material. The injection of CO₂ into coal seams has been shown to be an effective method for storing greenhouse gasses and extracting coal bed methane. In light of the theory of dual-porosity media, we investigate the [...] Read more.

Coal is a typical dual-porosity structural material. The injection of CO₂ into coal seams has been shown to be an effective method for storing greenhouse gasses and extracting coal bed methane. In light of the theory of dual-porosity media, we investigate the impact of non-homogeneity on seepage anisotropy and examine the influence of CO₂ gas injection on the anisotropy of coal and the permeability of fractures. The results demonstrate that under constant pressure conditions, coal rock has the greatest permeability variation in the direction of face cleats and the smallest changes in the direction of vertical bedding. The more pronounced the heterogeneity, the more evident the change in permeability and the less pronounced the decreasing stage of permeability. Additionally, the larger the diffusion coefficient is, the less pronounced the permeability change. The change in permeability is inversely proportional to the size of the adsorption constant and directly proportional to the size of the fracture. As the matrix block size increases, the permeability also increases, whereas the decrease in permeability becomes less pronounced. The findings of this study offer a theoretical basis for further research into methods for enhancing the CO₂ sequestration rate. Full article

(This article belongs to the Special Issue Advances in the Development of Geoenergy: 2nd Edition)

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28 pages, 11832 KiB

Open AccessFeature PaperReview

Technological Trends for Electrical Machines and Drives Used in Small Wind Power Plants—A Review

by Daniel Fodorean

Energies 2024, 17(24), 6483; https://doi.org/10.3390/en17246483 - 23 Dec 2024

Viewed by 474

Abstract

High-power-range wind generators mainly employ classical variants, with the advantages of low cost, high robustness and acceptable energetic performance, while for low-power applications, the available electrical drive solutions are more numerous. This paper investigates the current trend in this field, indicating simple or [...] Read more.

High-power-range wind generators mainly employ classical variants, with the advantages of low cost, high robustness and acceptable energetic performance, while for low-power applications, the available electrical drive solutions are more numerous. This paper investigates the current trend in this field, indicating simple or complex structures, with or without self-excitation and with or without mechanical or magnetic transmission. The discussed variants are compared in terms of complexity, cost, fault-tolerance capability and estimated energetic performances but also the grid connectivity for standard conditions. The review is completed by testing options and conditions, as well as the methods for parameter determination, which have an important effect on the controllability of the entire system. Full article

(This article belongs to the Special Issue Advanced Topologies and Control Strategies in Electric Machines and Drives)

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19 pages, 3151 KiB

Open AccessFeature PaperArticle

Catalyst-Free Depolymerization of Methanol-Fractionated Kraft Lignin to Aromatic Monomers in Supercritical Methanol

by Shubho Ghosh, Masud Rana and Jeong-Hun Park

Energies 2024, 17(24), 6482; https://doi.org/10.3390/en17246482 - 23 Dec 2024

Viewed by 541

Abstract

Lignin is considered a renewable source for the production of valuable aromatic chemicals and liquid fuel. Solvent depolymerization of lignin is a fruitful strategy for the valorization of lignin. However, Kraft lignin is highly prone to produce char (a by-product) during the hydrothermal [...] Read more.

Lignin is considered a renewable source for the production of valuable aromatic chemicals and liquid fuel. Solvent depolymerization of lignin is a fruitful strategy for the valorization of lignin. However, Kraft lignin is highly prone to produce char (a by-product) during the hydrothermal depolymerization process due to its poor solubility in organic solvents. Therefore, the minimization of char formation remains challenging. The purpose of the present study was to fractionate Kraft lignin in methanol to obtain low-molecular-weight fractions that could be further depolymerized in supercritical methanol to produce aromatic monomers and to suppress char formation. The results showed that the use of methanol-soluble lignin achieved a bio-oil yield of 45.04% and a char yield of 39.6% at 280 °C for 2 h compared to 28.57% and 57.73%, respectively, when using raw Kraft lignin. Elemental analysis revealed a high heating value of 30.13 MJ kg⁻¹ and a sulfur content of only 0.09% for the bio-oil derived from methanol-soluble lignin. The methanol extraction process reduced the oxygen content and increased the hydrogen and carbon contents in the modified lignin and bio-oil, indicating that the extracted lignin fraction had an enhanced deoxygenation capability and a higher energy content. These findings highlight the potential of methanol-soluble Kraft lignin as a valuable resource for sustainable energy production and the production of aromatic compounds. Full article

(This article belongs to the Special Issue Cutting-Edge Developments in Waste-to-Energy Technologies)

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26 pages, 10603 KiB

Open AccessArticle

Laser Surface Texturing for the Intensification of Boiling Heat Transfer in a Minichannel

by Kinga Strąk and Magdalena Piasecka

Energies 2024, 17(24), 6481; https://doi.org/10.3390/en17246481 - 23 Dec 2024

Viewed by 374

Abstract

This study investigates the effects of using laser-textured surfaces in boiling heat transfer during cooling fluid flow in a minichannel. Several laser-textured surfaces, varied in roughness, were created on the heated plate surface that contacted FC-72 during flow in a single minichannel. Infrared [...] Read more.

This study investigates the effects of using laser-textured surfaces in boiling heat transfer during cooling fluid flow in a minichannel. Several laser-textured surfaces, varied in roughness, were created on the heated plate surface that contacted FC-72 during flow in a single minichannel. Infrared thermography was used to measure temperature changes on the untextured side of the plate, while two-phase flow patterns were observed through a glass pane. Three vibration-assisted laser surface textures, previously investigated by the authors, and five novel laser surface textures were tested experimentally. The results were presented as relationships between heated wall temperature, heat transfer coefficient and distance along the minichannel, boiling curves, and flow patterns. The main interest of the authors was to provide a comparative analysis of the heat transfer results at the same value of heat flux supplied to the minichannel heated wall when either a laser-textured surface or a smooth base one was applied. It was noticed that the use of the 90-degree dense grid pattern type 2 (shallow) surface in the research helped achieve the highest local heat transfer coefficient in the subcooled boiling region compared to other surfaces tested. Furthermore, the 90-degree dense grid pattern type 1, characterised by larger maximum depth and height surfaces, performed best in the saturated boiling region. The results obtained for the laser-textured heated plate surface were compared to those collected for the smooth base heated plate surface, generally indicating an intensification of heat transfer processes in boiling heat transfer during FC-72 flow in a minichannel. Full article

(This article belongs to the Section J: Thermal Management)

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42 pages, 19761 KiB

Open AccessArticle

Aerodynamic Effect of Winglet on NREL Phase VI Wind Turbine Blade

by Ziaul Huque, Mahmood Sabria Chowdhury, Haidong Lu and Raghava Rao Kommalapati

Energies 2024, 17(24), 6480; https://doi.org/10.3390/en17246480 - 23 Dec 2024

Viewed by 604

Abstract

The primary goal in designing wind turbine blades is to maximize aerodynamic efficiency. One promising approach to achieve this is by modifying the blade geometry, with winglets to the tip. Winglets are intended to reduce the strength of the tip vortices, thereby reducing [...] Read more.

The primary goal in designing wind turbine blades is to maximize aerodynamic efficiency. One promising approach to achieve this is by modifying the blade geometry, with winglets to the tip. Winglets are intended to reduce the strength of the tip vortices, thereby reducing induced drag, increasing torque, and, ultimately, improving the power output of the wind turbines. In this study, computational fluid dynamics (CFD) simulations were utilized to assess the aerodynamic performance of wind turbine blades with and without winglets at various wind speeds (5, 7, 10, 13, 15, 20, and 25 m/s). The results indicate that winglets have a limited effect at low (5 and 7 m/s) and high (20 and 25 m/s) wind speeds due to fully attached and separated flows over the blade surface. However, within the 10–15 m/s range, winglets significantly enhance torque and power output. While this increased power generation is beneficial, it is essential to consider the potential impact of the associated increase in thrust force on turbine stability. Full article

(This article belongs to the Special Issue Wind Turbine and Wind Farm Flows)

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22 pages, 7247 KiB

Open AccessArticle

Technological Innovations in Decarbonisation Strategies: A Text-Mining Approach to Technological Readiness and Potential

by Paulo Moisés Costa, António Duarte, Paulo Tomé, Nuno Bento and Margarida Fontes

Energies 2024, 17(24), 6479; https://doi.org/10.3390/en17246479 - 23 Dec 2024

Viewed by 511

Abstract

This study presents a novel, multifaceted approach to evaluating decarbonisation technologies by integrating advanced text-mining tools with comprehensive data analysis. The analysis of scientific documents (2011–2021) and mapping 368 technologies from the IEA’s Energy Technology Perspectives identified 41 technology domains, including 20 with [...] Read more.

This study presents a novel, multifaceted approach to evaluating decarbonisation technologies by integrating advanced text-mining tools with comprehensive data analysis. The analysis of scientific documents (2011–2021) and mapping 368 technologies from the IEA’s Energy Technology Perspectives identified 41 technology domains, including 20 with the highest relevance and occurrence. Domain readiness was assessed using mean Technology Readiness Levels (TRLs) and linked to six decarbonisation pathways. The “Electrification of uses” pathway ranked highest, demonstrating significant CO₂ mitigation potential and high readiness (mean TRL 7.4, with two-thirds of technologies scoring over 7) despite challenges in hard-to-electrify sectors. The findings provide actionable insights for policymakers, highlighting the need for pathway-specific strategies, a deeper understanding of synergies between pathways, and balancing innovation with deployment to accelerate decarbonisation. Full article

(This article belongs to the Section B1: Energy and Climate Change)

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16 pages, 5440 KiB

Open AccessArticle

Investigation of Hydrogen Transport Behavior in Polyethylene Terephthalate Membrane by Prolonged Hydrogen Exposure Treatments

by Elman Abdullayev, Thorsten Fladung, Paul-Ludwig Michael Noeske and Bernd Mayer

Energies 2024, 17(24), 6478; https://doi.org/10.3390/en17246478 - 23 Dec 2024

Viewed by 533

Abstract

Polyethylene terephthalate (PET) is one of the most used polymeric substances in production of packaging materials, fibers, textiles, coatings, and engineering materials. This paper elucidates the transport parameters of hydrogen gas through a PET membrane, which was selected to be a sufficiently permeable [...] Read more.

Polyethylene terephthalate (PET) is one of the most used polymeric substances in production of packaging materials, fibers, textiles, coatings, and engineering materials. This paper elucidates the transport parameters of hydrogen gas through a PET membrane, which was selected to be a sufficiently permeable substrate for setting up an empirical strategy that aims at developing hydrogen barrier coatings. An examination of the structural degradation of PET by prolonged hydrogen exposure was performed. Hydrogen permeation tests were performed on a PET membrane with a thickness of 50 μm. To investigate the behavior of the material by prolonged hydrogen treatment, hydrogen-exposure experiments were carried out at a certain hydrogen pressure and time. Comparisons of the mechanical properties of the material were documented both before and after hydrogen exposure. A strong impact of comparatively transient hydrogen exposure on the mechanical and hydrogen transport properties of PET was observed. After 72 h of hydrogen exposure at 10³ hPa and 300 K, the tensile strength decreased by 19%, the diffusion coefficients more than doubled, and material fracture behavior changed from ductile to distinctly brittle. This underlines the importance of developing effective hydrogen barrier coatings in case PET tubing is intended for use in hydrogen transport or storage. Full article

(This article belongs to the Special Issue Hydrogen Storage and Transportation: Materials, Technologies, and Infrastructure Development)

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21 pages, 24831 KiB

Open AccessArticle

CFD-Based Investigation of the Operation Process of Radial Labyrinth Machinery Under Different Geometrical Configurations

by Przemyslaw Szulc and Janusz Skrzypacz

Energies 2024, 17(24), 6477; https://doi.org/10.3390/en17246477 - 23 Dec 2024

Viewed by 382

Abstract

This study explores the performance and flow characteristics of radial labyrinth pumps (RLPs) under various geometrical configurations and operating conditions. Experimental investigations and numerical simulations were conducted to evaluate the impact of design parameters such as blade geometry, channel width and blade angle [...] Read more.

This study explores the performance and flow characteristics of radial labyrinth pumps (RLPs) under various geometrical configurations and operating conditions. Experimental investigations and numerical simulations were conducted to evaluate the impact of design parameters such as blade geometry, channel width and blade angle on pump hydraulic performance. The numerical model, developed using the realizable k-ε turbulence model, was validated with experimental data, achieving satisfactory convergence (4.8%—bladed active disc operating with a smooth passive disc and 3.0%—bladed active disc operating with a bladed passive disc). Analysis of the velocity profiles and vortex structures formed between the active and passive discs was performed. These findings underscore the importance of optimizing disc geometry to balance centrifugal effects and momentum exchange. The obtained head for the model with a bladed active disc operating with a smooth passive disc was H = 24.1 m, while, for the bladed active disc operating with a bladed passive disc, it was almost 1.7 times higher at H = 40.3 m. Additionally, the research identifies potential zones within the pump where energy transfer processes differ, providing insight into targeted design improvements. The findings provide valuable information on the optimization of RLP designs and their broader applicability. Full article

(This article belongs to the Special Issue CFD Simulation in Energy Engineering Research)

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22 pages, 1959 KiB

Open AccessEditor’s ChoiceArticle

Integration of Plant Pomace into Extruded Products: Analysis of Process Conditions, Post-Production Waste Properties and Biogas Potential

by Jakub Soja, Tomasz Oniszczuk, Iryna Vaskina, Maciej Combrzyński and Agnieszka Wójtowicz

Energies 2024, 17(24), 6476; https://doi.org/10.3390/en17246476 - 23 Dec 2024

Viewed by 478

Abstract

Waste streams from cereal-based food production processes, rich in organic matter and carbohydrates, have untapped potential for biogas production. This study uniquely investigated the extrusion-cooking process conditions, physical properties and biogas efficiency of snack pellets enriched with plant pomace (apple, chokeberry, pumpkin, flaxseed [...] Read more.

Waste streams from cereal-based food production processes, rich in organic matter and carbohydrates, have untapped potential for biogas production. This study uniquely investigated the extrusion-cooking process conditions, physical properties and biogas efficiency of snack pellets enriched with plant pomace (apple, chokeberry, pumpkin, flaxseed and nigella seeds) at different levels (10, 20 and 30%), produced using a single-screw extruder-cooker. The highest efficiency obtained in the extrusion-cooking process (18.20 kg/h) was observed for pellets with the addition of 30% flaxseed pomace. The SME value during the entire process was in the range of 0.015–0.072 kWh/kg. New insights into the interaction between the inclusion of pomace, the physical properties of the extrudate and the anaerobic fermentation efficiency were obtained. The results show that 30% chokeberry extrudate maximized methane production (51.39% gas), demonstrating a double innovation: improving snack pellet quality and converting food waste into renewable energy. Full article

(This article belongs to the Special Issue From Waste to Energy: Towards Resource Recovery Optimization from Waste)

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25 pages, 3319 KiB

Open AccessArticle

Load Optimization for Connected Modern Buildings Using Deep Hybrid Machine Learning in Island Mode

by Seyed Morteza Moghimi, Thomas Aaron Gulliver, Ilamparithi Thirumarai Chelvan and Hossen Teimoorinia

Energies 2024, 17(24), 6475; https://doi.org/10.3390/en17246475 - 23 Dec 2024

Viewed by 533

Abstract

This paper examines Connected Smart Green Buildings (CSGBs) in Burnaby, BC, Canada, with a focus on townhouses with one to four bedrooms. The proposed model integrates sustainable materials and smart components such as recycled insulation, Photovoltaic (PV) solar panels, smart meters, and high-efficiency [...] Read more.

This paper examines Connected Smart Green Buildings (CSGBs) in Burnaby, BC, Canada, with a focus on townhouses with one to four bedrooms. The proposed model integrates sustainable materials and smart components such as recycled insulation, Photovoltaic (PV) solar panels, smart meters, and high-efficiency systems. These elements improve energy efficiency and promote sustainability. Operating in island mode, CSGBs can function independently of the grid, providing resilience during power outages and reducing reliance on external energy sources. Real data on electricity, gas, and water consumption are used to optimize load management under isolated conditions. Electric Vehicles (EVs) are also considered in the system. They serve as energy storage devices and, through Vehicle-to-Grid (V2G) technology, can supply power when needed. A hybrid Machine Learning (ML) model combining Long Short-Term Memory (LSTM) and a Convolutional Neural Network (CNN) is proposed to improve the performance. The metrics considered include accuracy, efficiency, emissions, and cost. The performance was compared with several well-known models including Linear Regression (LR), CNN, LSTM, Random Forest (RF), Gradient Boosting (GB), and hybrid LSTM–CNN, and the results show that the proposed model provides the best results. For a four-bedroom Connected Smart Green Townhouse (CSGT), the Mean Absolute Percentage Error (MAPE) is 4.43%, the Root Mean Square Error (RMSE) is 3.49 kWh, the Mean Absolute Error (MAE) is 3.06 kWh, and

R^{2}

is 0.81. These results indicate that the proposed model provides robust load optimization, particularly in island mode, and highlight the potential of CSGBs for sustainable urban living. Full article

(This article belongs to the Section A: Sustainable Energy)

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23 pages, 3549 KiB

Open AccessArticle

Experimental Assessment of Green Waste HTC Pellets: Kinetics, Efficiency and Emissions

by Yaniel Garcia Lovella, Abhishek Goel, Louis Garin, Julien Blondeau and Svend Bram

Energies 2024, 17(24), 6474; https://doi.org/10.3390/en17246474 - 23 Dec 2024

Viewed by 436

Abstract

The combustion of renewable solid fuels, such as biomass, is a reliable option for heat and power production. The availability of biomass resources within urban areas, such as tree leaves, small branches, grass, and other green city waste, creates an opportunity to valorize [...] Read more.

The combustion of renewable solid fuels, such as biomass, is a reliable option for heat and power production. The availability of biomass resources within urban areas, such as tree leaves, small branches, grass, and other green city waste, creates an opportunity to valorize such resources. The energy densification of such resources using hydrothermal carbonization (HTC) and pelletization of the carbonized material could create a new generation of domestic boiler biofuel. However, combustion efficiency and emission assessments should be carried out for HTC pellets. The primary objective of this study is to assess HTC pellets, provided by a waste upgrade company, in terms of kinetics, combustion efficiency, and emissions, taking as reference base ENplus A1 certified softwood pellets. Therefore, thermogravimetric analysis and combustion tests were conducted for both fuels to achieve this. It was observed that a third peak of the burning rate during the solid carbon oxidation of HTC pellets indicated a high activation energy. Combustion tests showed a 7% increase in boiler efficiency for HTC pellets compared to softwood pellets. However, higher particulate matter (PM), NO_x, and CO emissions were recorded during the HTC pellets test. The results suggest that optimizing the air/fuel ratio could further improve the performance of HTC pellets in domestic boilers. Full article

(This article belongs to the Section B: Energy and Environment)

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11 pages, 5171 KiB

Open AccessArticle

Impact of Multi-Valve Exhaust Gas Recirculation (EGR) System on Nitrogen Oxides Emissions in a Multi-Cylinder Engine

by Konrad Krakowian

Energies 2024, 17(24), 6473; https://doi.org/10.3390/en17246473 - 23 Dec 2024

Viewed by 427

Abstract

Exhaust gas recirculation (EGR) systems, in addition to catalytic reactors, are now widely used in reciprocating internal combustion engines to reduce oxides of nitrogen (NOx) in the exhaust gases. They are characterized by the fact that part of the exhaust gas from the [...] Read more.

Exhaust gas recirculation (EGR) systems, in addition to catalytic reactors, are now widely used in reciprocating internal combustion engines to reduce oxides of nitrogen (NOx) in the exhaust gases. They are characterized by the fact that part of the exhaust gas from the exhaust manifold is recycled and directed to the intake manifold through a special valve. This valve, depending on the current engine load and velocity, doses an appropriate amount of exhaust gas which, with each new charge, is fed to the individual engine cylinders. In addition, the positioning of the valve has a significant effect on the formation of nitrogen oxides in the exhaust gas from individual engine cylinders, which is due to the uneven distribution of exhaust gas into the intake manifold channels. Tests were carried out on a power unit equipped with a symmetrical intake manifold with a centrally located EGR valve. The article presents the results of tests on a system in which each cylinder was supplied with a separate EGR valve. This solution made it possible to charge each cylinder with the same mass of recirculated exhaust gas, which was dependent on engine velocity and load. The exhaust nitrogen oxides emissions were measured for the originally manufactured system and compared with the multi-valve system. The results confirmed the need for individual selection of the dose of recirculated exhaust gas for particular cylinders, as the multi-valve system equalized the levels of nitrogen oxides emissions in the exhaust gases coming from individual cylinders of the internal combustion engine. Full article

(This article belongs to the Special Issue Advanced Combustion Technologies and Emission Control)

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19 pages, 3882 KiB

Open AccessArticle

Research on Thyristor Reverse Recovery Behavior in High-Voltage Direct Current Transmission Converter Valves and Its Application in Integrated Protection Systems

by Cao Wen, Liang Song, Yu Huang, Dong Peng, Peng Zhang, Jianquan Liao, Longjie Yang and Shilin Gao

Energies 2024, 17(24), 6472; https://doi.org/10.3390/en17246472 - 23 Dec 2024

Viewed by 430

Abstract

The performance of converter valves is essential for the reliability and efficiency of high-voltage direct current (HVDC) transmission systems. Converter valves consist of multiple thyristor levels, each requiring regular testing to ensure proper functionality. Protective triggering tests play a crucial role in evaluating [...] Read more.

The performance of converter valves is essential for the reliability and efficiency of high-voltage direct current (HVDC) transmission systems. Converter valves consist of multiple thyristor levels, each requiring regular testing to ensure proper functionality. Protective triggering tests play a crucial role in evaluating the safety and performance of these thyristors during maintenance. This study introduces a high-power experimental setup designed to investigate the effects of varying current levels and thermal stresses on the reverse recovery behavior of thyristors—a key performance indicator. Results indicate that the reverse recovery time increases rapidly with higher current levels before reaching a saturation point. Additionally, prolonged exposure to high temperatures significantly reduces both the storage time and the amount of charge recovered during the reverse recovery process. These findings enable the optimization of protective test settings, thereby enhancing the effectiveness of the Thyristor Control Unit (TCU) in protecting converter valves. Improved testing methodologies derived from this research contribute to more reliable maintenance practices and increased overall stability of HVDC transmission systems. Full article

(This article belongs to the Special Issue Leveraging Flexibility Resources to Enhance Renewable Energy Integration and Grid Stability)

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19 pages, 7235 KiB

Open AccessArticle

Study on the Influence of an Internal Stiffening System on the Structural Strength of the Semi-Submersible Structures for a Floating Offshore Wind Turbine

by Hao Yu Dou, Han Koo Jeong and Jian Lun Jiang

Energies 2024, 17(24), 6471; https://doi.org/10.3390/en17246471 - 23 Dec 2024

Viewed by 452

Abstract

This study presents the development and comparative analysis of a new Y-type floating offshore wind turbine platform based on the existing T-type model. Utilizing advanced simulation tools, such as MSC, Patran and Nastran 2022.3, FEGate For Ship 5.0, and Ansys AQWA 2021 R2, [...] Read more.

This study presents the development and comparative analysis of a new Y-type floating offshore wind turbine platform based on the existing T-type model. Utilizing advanced simulation tools, such as MSC, Patran and Nastran 2022.3, FEGate For Ship 5.0, and Ansys AQWA 2021 R2, extensive evaluations are conducted on the structural strength, stability, and dynamic response of both the T-type and the newly proposed Y-type platforms. In this research, the structural optimization algorithm based on the above simulation tools is adopted, and its results are compared with preoptimization results to demonstrate the improvements made in design precision and reliability. Results indicate that the Y-type model achieves a maximum reduction in von Mises stress by 30.21 MPa compared to the T-type model, and its heave and pitch motion amplitudes are reduced by 4.3412 m and 4.9362°, respectively, under extreme sea state conditions. Through structural optimization using the Nastran SOL200 module, the column structure weight is reduced by 11.31%, meeting the strength requirements while enhancing efficiency. These findings highlight the Y-type platform’s improved performance and provide robust design strategies for floating offshore wind turbines in deep-water regions, crucial for advancing global renewable energy solutions. Future research should focus on the impacts of different marine conditions on platform performance and consider integrating new materials or innovative design enhancements to further optimize platform functionality. Additionally, due to potential limitations from model simplification, emphasis on real-world testing and validation under operational conditions is recommended. Overall, this research clarifies the differences in structural performance between the T-type and Y-type floating platforms and introduces an improved platform design approach, offering valuable insights and guidance for the future development of floating offshore wind turbine technology. Full article

(This article belongs to the Section A3: Wind, Wave and Tidal Energy)

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17 pages, 6439 KiB

Open AccessArticle

Performance Analysis of a Micro-Photovoltaic Concentrator Designed for Automotive Applications

by Salima El Ayane and Ali Ahaitouf

Energies 2024, 17(24), 6470; https://doi.org/10.3390/en17246470 - 23 Dec 2024

Viewed by 590

Abstract

This research paper delves into the potential use of solar energy as an alternative energy source for future vehicles. The study introduces a system that overcomes the limitations of traditional solar panels by achieving a reduced thickness of less than 35 mm, while [...] Read more.

This research paper delves into the potential use of solar energy as an alternative energy source for future vehicles. The study introduces a system that overcomes the limitations of traditional solar panels by achieving a reduced thickness of less than 35 mm, while acknowledging the challenges faced by vehicles, such as the inability to maintain a fixed orientation towards the sun and frequent shading from surrounding objects. To tackle these challenges, our system incorporates the design of an asymmetrical and extended polynomial lens and optimizes it to widen the acceptance angle of incident sunlight, enabling the solar panels to capture a wider range of solar radiation, even when the vehicle is not ideally aligned with the sun. The goal of this innovative design is not only to maximize energy output in urban conditions, ensuring efficient solar utilization despite shading challenges, but also to maintain a compact, lightweight structure suitable for installation on vehicle rooftops and competitive with ordinary PV panels. Additionally, our system is a tracking and heat spreader-free structure. This simple structure enables cheaper mass production and the lightweight nature of the structure results in affordable manufacturing and assembly processes. Through collaboration with micro-fabrication, macro-electronic industries, and micro-LED technologies, our system is a strong candidate for a low-cost, high-efficiency system. The results show an optical efficiency of around 52.53% for incident rays at a 45° angle, with the remaining rays captured by adjacent lenses resulting in a total optical efficiency around 76%. Full article

(This article belongs to the Section B: Energy and Environment)

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20 pages, 4443 KiB

Open AccessArticle

Heat Exchange Analysis of Brushless Direct Current Motors

by Maciej Mazur, Wojciech Skarka, Maciej Kobielski, Damian Kądzielawa, Robert Kubica, Clemens Haas and Hubert Unterberger

Energies 2024, 17(24), 6469; https://doi.org/10.3390/en17246469 - 23 Dec 2024

Viewed by 696

Abstract

The brushless DC (BLDC) motor is crucial in a variety of industrial and consumer applications due to its efficiency and precise control. This study investigates the heat transfer and cooling mechanisms in liquid-cooled BLDC motors in dishwashers, which are fundamental to maintaining optimal [...] Read more.

The brushless DC (BLDC) motor is crucial in a variety of industrial and consumer applications due to its efficiency and precise control. This study investigates the heat transfer and cooling mechanisms in liquid-cooled BLDC motors in dishwashers, which are fundamental to maintaining optimal operating temperatures. Elevated temperatures can reduce operational efficiency, emphasizing the importance of effective heat dissipation. Liquid cooling proves to be very effective and offers advantages over air cooling by providing even temperature distribution and more accurate temperature control. Integrating liquid cooling systems into dishwasher designs provides a viable solution for managing motor temperatures while preheating dishwashing water. Using existing water infrastructure, these systems dissipate heat generated during motor operation, increasing energy efficiency and reliability, as analyzed using computational fluid dynamics (CFDs). The aim of this study is to optimize thermal management strategies in BLDC motors, particularly in dishwashers, by filling a critical gap in the existing literature. The goal of this comprehensive analysis is to develop resistant and efficient cooling solutions tailored to dishwasher environments, ultimately extending the life of BLDC motors in home appliances while using heat transfer to preheat water for wash cycles. Full article

(This article belongs to the Special Issue Computational Fluid Dynamics (CFD) Study for Heat Transfer)

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13 pages, 2716 KiB

Open AccessArticle

Design, Control, and Evaluation of a Photovoltaic Snow Removal Strategy Based on a Bidirectional DC-DC Converter for Photovoltaic–Electric Vehicle Application

by Salma Elakkad, Mohamed Hesham, Hany Ayad Bastawrous and Peter Makeen

Energies 2024, 17(24), 6468; https://doi.org/10.3390/en17246468 - 22 Dec 2024

Viewed by 727

Abstract

A novel self-heating technique is proposed to clear snow from photovoltaic panels as a solution to the issue of winter snow accumulation in photovoltaic (PV) power plants. This approach aims to address the shortcomings of existing methods. It reduces PV cell wear, resource [...] Read more.

A novel self-heating technique is proposed to clear snow from photovoltaic panels as a solution to the issue of winter snow accumulation in photovoltaic (PV) power plants. This approach aims to address the shortcomings of existing methods. It reduces PV cell wear, resource loss, and safety risks, without the need for additional devices. A self-heating current is applied to the solar panel to melt the snow covering its surface, which is then allowed to slide off the panel due to gravity. The proposed system consists of a bidirectional DC-DC converter, which removes the snow cover by heating the solar PV modules using electricity from the grid or electric vehicle (EV) batteries. It also charges the EV battery pack and/or supplies the DC bus when no EV is plugged into the charging station. For each mode of operation, a current-controlled system was implemented using a PI controller and a model predictive controller (MPC). The MPC approach achieved a faster rise time, shorter settling time, very low current ripples, and high stability for the proposed system. Specifically, the settling time decreased from 9 ms and 155 ms when using the PI controller at 20 µs and 35 µs with the MPC controller for both the buck and boost modes, respectively. Full article

(This article belongs to the Section A2: Solar Energy and Photovoltaic Systems)

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Energies, Volume 17, Issue 24 (December-2 2024) – 287 articles

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