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Energies, Volume 17, Issue 15 (August-1 2024) – 259 articles

Cover Story (view full-size image): This feasibility study investigates extracting thermal energy from the Bedretto tunnel in the Swiss Alps. Our findings indicate that flowing water is the most effective heat source. Estimates indicate that the total extractable thermal energy ranges between 0.8 MWth and 1.5 MWth after reducing the water temperature to 4 °C via a heat pump. This study identifies the most suitable energy sourcing locations based on efficiency and investment costs. Cost analyses reveal that the investment in piping and heat pumps can be amortized within the equipment’s lifespan with appropriate economic models. With the same initial investments, district heating systems are viable in villages with over 30 connections. The payback periods are 10 years for 60 connections, 4.5 years for 90 connections, and immediate for 200 connections. View this paper
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32 pages, 6774 KiB  
Review
A Comprehensive Review on the Hydrogen–Natural Gas–Diesel Tri-Fuel Engine Exhaust Emissions
by Hassan Sadah Muhssen, Máté Zöldy and Ákos Bereczky
Energies 2024, 17(15), 3862; https://doi.org/10.3390/en17153862 - 5 Aug 2024
Viewed by 565
Abstract
Natural gas (NG) is favored for transportation due to its availability and lower CO2 emissions than fossil fuels, despite drawbacks like poor lean combustion ability and slow burning. According to a few recent studies, using hydrogen (H2) alongside NG and [...] Read more.
Natural gas (NG) is favored for transportation due to its availability and lower CO2 emissions than fossil fuels, despite drawbacks like poor lean combustion ability and slow burning. According to a few recent studies, using hydrogen (H2) alongside NG and diesel in Tri-fuel mode addresses these drawbacks while enhancing efficiency and reducing emissions, making it a promising option for diesel engines. Due to the importance and novelty of this, the continuation of ongoing research, and insufficient literature studies on HNG–diesel engine emissions that are considered helpful to researchers, this research has been conducted. This review summarizes the recent research on the HNG–diesel Tri-fuel engines utilizing hydrogen-enriched natural gas (HNG). The research methodology involved summarizing the effect of engine design, operating conditions, fuel mixing ratios and supplying techniques on the CO, CO2, NOx and HC emissions separately. Previous studies show that using natural gas with diesel increases CO and HC emissions while decreasing NOx and CO2 compared to pure diesel. However, using hydrogen with diesel reduces CO, CO2, and HC emissions but increases NOx. On the other hand, HNG–diesel fuel mode effectively mitigates the disadvantages of using these fuels separately, resulting in decreased emissions of CO, CO2, HC, and NOx. The inclusion of hydrogen improves combustion efficiency, reduces ignition delay, and enhances heat release and in-cylinder pressure. Additionally, operational parameters such as engine power, speed, load, air–fuel ratio, compression ratio, and injection parameters directly affect emissions in HNG–diesel Tri-fuel engines. Overall, the Tri-fuel approach offers promising emissions benefits compared to using natural gas or hydrogen separately as dual-fuels. Full article
(This article belongs to the Special Issue Renewable Fuels for Internal Combustion Engines: 2nd Edition)
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28 pages, 6533 KiB  
Article
An Improved Cascaded Boost Converter with an Ultra-High Voltage Gain Suitable for Dielectric Quality Tests
by Hossein Gholizadeh, Reza Sharifi Shahrivar, Saeed Amini and Tohid Rahimi
Energies 2024, 17(15), 3861; https://doi.org/10.3390/en17153861 - 5 Aug 2024
Viewed by 467
Abstract
Dielectric quality tests require a high AC voltage with a frequency range of 0.0001 Hz to 1000 Hz. However, providing a high AC voltage with such a frequency variety is challenging. Providing a high DC voltage and then applying such a voltage to [...] Read more.
Dielectric quality tests require a high AC voltage with a frequency range of 0.0001 Hz to 1000 Hz. However, providing a high AC voltage with such a frequency variety is challenging. Providing a high DC voltage and then applying such a voltage to an inverter to adjust the frequency can be an acceptable solution for such a challenge. Notably, a high DC voltage is required for DC tests. This study proposes an improved form of the cascaded boost converter, whose merits are as follows: (i) the high voltage gain providing low duty cycles is possible; (ii) the input current is continuous, which decreases the current ripple of the input filter capacitor; (iii) the current stress of the semiconductors is less than the input current, and most of them have a large difference with it; (iv) the voltage stress of the semiconductors is less than the output voltage with a large difference; (v) only one switch with a simple drive circuit is used; (vi) the common ground of the load and input source decreases the EMI noise; (vii) besides the high voltage gain, the voltage density of the converter based on the number of inductors, capacitors, switches, diodes, and whole components is greater than that of the recently proposed converters; (viii) only two stacked connections of the proposed topology can provide a 2.6 kV voltage for a higher DC voltage test of dielectrics. The functional details of the converter are extracted in ideal and continuous conduction (CCM) modes. Moreover, the converter’s voltage gain and density are compared with the recently proposed converters to show the superiority of the proposed converter. Finally, the experimental results are presented to validate the theoretical relations in a 140 W output power. Full article
(This article belongs to the Section F: Electrical Engineering)
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24 pages, 1465 KiB  
Article
Can Energy-Consuming Rights Trading Policies Help to Curb Air Pollution? Evidence from China
by Mingguang Liu, Jue Zhang and Gaoyang Li
Energies 2024, 17(15), 3860; https://doi.org/10.3390/en17153860 - 5 Aug 2024
Viewed by 434
Abstract
Energy-consuming rights trading policies (ECRTPs) represent a significant institutional innovation for China aimed at achieving the dual control targets of total energy consumption and energy consumption intensity. However, the effectiveness of these policies in curbing air pollution remains uncertain. This study treats ECRTPs [...] Read more.
Energy-consuming rights trading policies (ECRTPs) represent a significant institutional innovation for China aimed at achieving the dual control targets of total energy consumption and energy consumption intensity. However, the effectiveness of these policies in curbing air pollution remains uncertain. This study treats ECRTPs as a quasi-natural experiment to empirically analyze their impact on air pollution, utilizing panel data encompassing 277 prefecture-level cities in China covering the period from 2011 to 2021. Analytical methods applied include a Difference-in-Differences model, a mediation effects model, and a triple differences model to explore the effects of ECRTPs on air pollution. The findings reveal that ECRTP can significantly suppress air pollution, and this conclusion remains valid even after conducting robustness tests. Mechanism analysis indicates that ECRTPs suppress air pollution by boosting energy efficiency, advancing industrial structure upgrading, and facilitating technological innovation. Further heterogeneous studies show that ECRTPs have a more pronounced inhibitory effect on air pollution in cities that are economically and socially developed, exhibit greater energy-saving potential, are characterized as resource-based cities, and serve as key regions for the prevention and control of air pollution. The research conclusion provides empirical evidence and policy implications for evaluating the environmental effects of ECRTPs and further improving China’s energy-consuming rights trading system, as well as offering references and guidance for other developing countries to put forward ECRTPs. Full article
(This article belongs to the Special Issue Circular Economy, Environmental and Energy Management)
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23 pages, 9785 KiB  
Article
Applying a Current Sharing Method Based on Partial Energy Processing to Multiphase LLC Resonant Converters
by Yue-Lin Lee, Han-Hsiang Chen and Kuo-Ing Hwu
Energies 2024, 17(15), 3859; https://doi.org/10.3390/en17153859 - 5 Aug 2024
Viewed by 393
Abstract
In this paper, partial energy processing is applied to the current sharing technique for multiphase LLC resonant converters. The proposed circuit consists of an LLC resonant converter and a flyback converter, where the flyback converter is only used for partial energy processing. The [...] Read more.
In this paper, partial energy processing is applied to the current sharing technique for multiphase LLC resonant converters. The proposed circuit consists of an LLC resonant converter and a flyback converter, where the flyback converter is only used for partial energy processing. The input voltage of the LLC resonant converter is fine-tuned by the flyback converter to solve the problem of a voltage gain difference between the two phases of the LLC resonant converter caused by the error of the resonant tank components, which prevents the output current from being nonequalized. Since the compensation power is much smaller than the output power, and only one phase will be during circuit operation, the impact on the overall efficiency is minimal. Due to the low dependence between the LLC resonant converter and the flyback converter, they are operated at different switching frequencies. In addition, due to the low dependence between each phase, the circuit can be expanded using odd and even phases. Full article
(This article belongs to the Special Issue Optimal Design and Application of High-Performance Power Converters)
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43 pages, 11046 KiB  
Review
Review of Compensation Topologies Power Converters Coil Structure and Architectures for Dynamic Wireless Charging System for Electric Vehicle
by Narayanamoorthi Rajamanickam, Yuvaraja Shanmugam, Rahulkumar Jayaraman, Jan Petrov, Lukas Vavra and Radomir Gono
Energies 2024, 17(15), 3858; https://doi.org/10.3390/en17153858 - 5 Aug 2024
Viewed by 475
Abstract
The increasing demand for wireless power transfer (WPT) systems for electric vehicles (EVs) has necessitated advancements in charging solutions, with a particular focus on speed and efficiency. However, power transfer efficiency is the major concern in static and dynamic wireless charging (DWC) design. [...] Read more.
The increasing demand for wireless power transfer (WPT) systems for electric vehicles (EVs) has necessitated advancements in charging solutions, with a particular focus on speed and efficiency. However, power transfer efficiency is the major concern in static and dynamic wireless charging (DWC) design. Design consideration and improvements in all functional units are necessary for an increase in overall efficiency of the system. Recently, different research works have been presented regarding DWC at the power converter, coil structure and compensators. This paper provides a comprehensive review of power converters incorporating high-order compensation topologies, demonstrating their benefits in enhancing the DWC of EVs. The review also delves into the coupling coil structure and magnetic material architecture, pivotal in enhancing power transfer efficiency and capability. Moreover, the high-order compensation topologies used to effectively mitigate low-frequency ripple, improve voltage regulation, and facilitate a more compact and portable design are discussed. Furthermore, optimal coupling and different techniques to achieve maximum power transfer efficiency are discussed to boost magnetic interactions, thereby reducing power loss. Finally, this paper highlights the essential role of these components in developing efficient and reliable DWC systems for EVs, emphasizing their contribution to achieving high-power transfer efficiency and stability. Full article
(This article belongs to the Special Issue Advances in Wireless Power Transmission Techniques for Electric Vehicle Charging Applications)
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14 pages, 277 KiB  
Review
Trends and Challenges after the Impact of COVID-19 and the Energy Crisis on Financial Markets
by Charalampos Basdekis, Apostolos G. Christopoulos, Ioannis Katsampoxakis and Stylianos Xanthopoulos
Energies 2024, 17(15), 3857; https://doi.org/10.3390/en17153857 - 5 Aug 2024
Viewed by 688
Abstract
This review aims to examine the impact of increasing energy costs on the global economy, social cohesion, economic growth, and capital markets, with a particular focus on the consequences of the COVID-19 pandemic and the energy crisis intensified by the war in Ukraine. [...] Read more.
This review aims to examine the impact of increasing energy costs on the global economy, social cohesion, economic growth, and capital markets, with a particular focus on the consequences of the COVID-19 pandemic and the energy crisis intensified by the war in Ukraine. The methodology involves an extensive review of recent academic literature to cast light on these impacts. The study identifies significant disruptions in supply chains and heightened volatility in international capital markets due to these crises. Furthermore, the findings highlight the resulting challenges for policymakers, academics, market analysts, and professionals in addressing corporate sustainability in an increasingly uncertain environment. This paper underscores the continued relevance of energy issues as a central concern, both independently and in connection with broader economic sectors. Additionally, it discusses the importance of policy measures to enhance energy security and the transition towards sustainable energy solutions to mitigate these challenges and foster economic resilience. Full article
(This article belongs to the Section B: Energy and Environment)
14 pages, 7892 KiB  
Article
The Influence of Cyclic Loading on the Mechanical Properties of Well Cement
by Zhen Zhang, Zhongtao Yuan, Sutao Ye, Yang Li, Lvchao Yang, Xueyu Pang, Kaihe Lv and Jinsheng Sun
Energies 2024, 17(15), 3856; https://doi.org/10.3390/en17153856 - 5 Aug 2024
Viewed by 476
Abstract
The cyclic loading generated by injection and production operations in underground gas storage facilities can lead to fatigue damage to cement sheaths and compromise the integrity of wellbores. To investigate the influence of cyclic loading on the fatigue damage of well cement, uniaxial [...] Read more.
The cyclic loading generated by injection and production operations in underground gas storage facilities can lead to fatigue damage to cement sheaths and compromise the integrity of wellbores. To investigate the influence of cyclic loading on the fatigue damage of well cement, uniaxial and triaxial loading tests were conducted at different temperatures, with maximum cyclic loading intensity ranging from 60% to 90% of the ultimate strength. Test results indicate that the compressive strength and elastic modulus of well cement subjected to monotonic loading under high-temperature and high-pressure (HTHP) testing conditions were 14–21% lower than those obtained under ambient testing conditions. The stress–strain curve exhibits stress–strain hysteresis loops during cyclic loading tests, and the plastic deformation capacity is enhanced at HTHP conditions. Notably, a higher intensity of cyclic loading results in more significant plastic strain in oil-well cement, leading to the conversion of more input energy into dissipative energy. Furthermore, the secant modulus of well cement decreased with cycle number, which is especially significant under ambient test conditions with high loading intensity. Within 20 cycles of cyclic loading tests, only the sample tested at a loading intensity of 90% ultimate strength under an ambient environment failed. For samples that remained intact after 20 cycles of cyclic loading, the compressive strength and stress–strain behavior were similar to those obtained before cyclic loading. Only a slight decrease in the elastic modulus is observed in samples cycled with high loading intensity. Overall, oil-well cement has a longer fatigue life when subjected to HTHP testing conditions compared to that tested under ambient conditions. The fatigue life of well cement increases significantly with a decrease in loading intensity and can be predicted based on the plastic strain evolution rate. Full article
(This article belongs to the Section H: Geo-Energy)
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18 pages, 8627 KiB  
Article
Investigation of Dead Time Losses in Inverter Switching Leg Operation: GaN FET vs. MOSFET Comparison
by Vincenzo Barba, Salvatore Musumeci, Fausto Stella, Fabio Mandrile and Marco Palma
Energies 2024, 17(15), 3855; https://doi.org/10.3390/en17153855 - 5 Aug 2024
Viewed by 460
Abstract
This paper investigates the commutation transients of MOSFET and GaN FET devices in motor drive applications during hard-switching and soft-switching commutations at dead time operation. This study compares the switching behaviors of MOSFETs and GaN FETs, focusing on their performance during dead time [...] Read more.
This paper investigates the commutation transients of MOSFET and GaN FET devices in motor drive applications during hard-switching and soft-switching commutations at dead time operation. This study compares the switching behaviors of MOSFETs and GaN FETs, focusing on their performance during dead time in inverter legs for voltage source inverters. Experimental tests at various phase current levels reveal distinct switching characteristics and energy dissipation patterns. A validated simulation model estimates the experimental energy exchanged and dissipated during switching transients. The results demonstrate that GaN FETs exhibit lower overall losses at shorter dead times compared to MOSFETs, despite higher reverse conduction voltage drops. The study provides a quantitative framework for selecting optimal dead times to minimize energy losses, enhancing the efficiency of GaN FET-based inverters in low-voltage motor drive applications. Finally, a dead time optimization strategy is proposed and described. Full article
(This article belongs to the Special Issue Advanced Switching Power Converters: Topologies, Control, and Devices)
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20 pages, 3460 KiB  
Article
Hydroprocessing Microbial Oils for Advanced Road Transportation, Aviation, and Maritime Drop-In Fuels: Industrially Relevant Scale Validation
by Athanasios Dimitriadis, Loukia P. Chrysikou, Ioanna Kosma, Nikos Tourlakidis and Stella Bezergianni
Energies 2024, 17(15), 3854; https://doi.org/10.3390/en17153854 - 5 Aug 2024
Viewed by 437
Abstract
Triacylglycerides (TAGs) produced via the syngas fermentation of biogenic residues and wastes were evaluated as a potential feedstock for advanced road transportation, aviation, and maritime drop-in fuels via hydroprocessing technology. Due to the limited availability of TAGs, a simulated feedstock (SM TAGs) was [...] Read more.
Triacylglycerides (TAGs) produced via the syngas fermentation of biogenic residues and wastes were evaluated as a potential feedstock for advanced road transportation, aviation, and maritime drop-in fuels via hydroprocessing technology. Due to the limited availability of TAGs, a simulated feedstock (SM TAGs) was utilized by blending various commercial oils, simulating the fatty acid composition of TAGs. At first, the simulated feedstock and the real TAGs were hydrotreated on a TRL 4 (technology readiness level) pilot plant to evaluate the potential of the SM feedstock to simulate the TAGs based on product quality. The hydrotreatment technology was evaluated and optimized on a TRL 4 plant. The research was further extended to a TRL 5 hydrotreatment plant with the optimum operating window for scaling up the technology. The resulting product was fractionated on a batch fractionation unit under vacuum to separate the jet and diesel fractions. The produced fuels were analyzed and evaluated based on the aviation Jet A1, EN590, EN15940, and marine diesel DMA specifications. The results show that the TAG composition was successfully simulated via a blend of vegetable oils. In addition, the hydrotreatment of the real TAGs and simulated feedstock resulted in similar-quality liquid products. The technology was successfully scaled up on a TRL 5 unit, leading to advanced, high-quality aviation and diesel drop-in fuels from TAGs, while the reaction pathways of hydrotreating can be controlled via the operating parameters of pressure, temperature, and H2/oil ratio. The hydrotreatment process’s optimum conditions were 13.8 MPa pressure, 643 K temperature, 1 h−1 liquid hourly space velocity (LHSV), and 5000 scfb hydrogen-to-oil ratio. Finally, a storage stability study of the hydrotreated liquid product showed that it can be stored for more than 6 months at ambient conditions without any noticeable changes to its properties. Full article
(This article belongs to the Special Issue Renewable Fuels for Internal Combustion Engines: 2nd Edition)
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17 pages, 4542 KiB  
Review
Supercapacitor-Assisted Energy Harvesting Systems
by Kasun Subasinghage and Kosala Gunawardane
Energies 2024, 17(15), 3853; https://doi.org/10.3390/en17153853 - 5 Aug 2024
Viewed by 542
Abstract
Energy harvesting from energy sources is a rapidly developing cost-effective and sustainable technique for powering low-energy consumption devices such as wireless sensor networks, RFID, IoT devices, and wearable electronics. Although these devices consume very low average power, they require peak power bursts during [...] Read more.
Energy harvesting from energy sources is a rapidly developing cost-effective and sustainable technique for powering low-energy consumption devices such as wireless sensor networks, RFID, IoT devices, and wearable electronics. Although these devices consume very low average power, they require peak power bursts during the collection and transmission of data. These requirements are satisfied by the use of energy-storage devices such as batteries or supercapacitors (SCs). Batteries offer significantly higher energy density but are subject to regular replacement, thermal runaway risk, and environmental concerns. On the other hand, SCs provide over a million-fold increase in capacitance compared to a traditional capacitor of the same volume. They are considered as the energy-storing devices that bridge the gap between conventional capacitors and batteries. They also offer fast charging times, a long lifecycle, and low equivalent series resistance (ESR). Most importantly, they are capable of handling the high transient currents produced by energy harvesters and provide a stable power source for external loads. This study encompasses a brief exploration of the three fundamental SC types. Then, the discussion delves into the integration of SCs into energy harvesting applications. The collective knowledge presented aims to guide future research endeavors fostering the development of novel energy harvesting systems using SCs. Full article
(This article belongs to the Special Issue Energy Harvesting State of the Art and Challenges II)
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16 pages, 6470 KiB  
Article
Experimental Study of Electromagnetic Interference from Concentrated Discharge Channels within the Soil to Adjacent Directly Buried Cables during Lightning Current Inflow to the Ground
by Tao Yuan, Qian Chen, Rongquan Fan and Wenhui Zeng
Energies 2024, 17(15), 3852; https://doi.org/10.3390/en17153852 - 5 Aug 2024
Viewed by 386
Abstract
Independent lightning rods are often installed in substation grounding systems for lightning protection. The concentrated discharge channel formed when a lightning current flows to the ground through a grounding electrode will cause electromagnetic interference to the directly buried secondary cable. And the three-dimensional [...] Read more.
Independent lightning rods are often installed in substation grounding systems for lightning protection. The concentrated discharge channel formed when a lightning current flows to the ground through a grounding electrode will cause electromagnetic interference to the directly buried secondary cable. And the three-dimensional structure of the discharge channel will affect the transient electromagnetic field distribution, thereby affecting the electromagnetic transients on cable shields. In order to explore the influence of soil discharge phenomena on the electromagnetic interference of the directly buried secondary cable, in this paper, we carried out experiments on cables in two different grounding modes, single-ended and double-ended grounding, and captured image of soil discharge channels. The results show that the cable grounding mode will affect the coupling mode that causes the shielding layer current. The relative spatial position of the soil discharge channel and the cable has a significant impact on the magnitude of the shielding layer current under both grounding modes. The water content and salt content of the soil also have different degrees of influence on the coupling current of the shielding layer in different grounding modes. Full article
(This article belongs to the Topic Power System Protection)
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18 pages, 7338 KiB  
Article
Droop Frequency Limit Control and Its Parameter Optimization in VSC-HVDC Interconnected Power Grids
by Han Jiang, Yichen Zhou, Yi Gao and Shilin Gao
Energies 2024, 17(15), 3851; https://doi.org/10.3390/en17153851 - 5 Aug 2024
Viewed by 475
Abstract
With the gradual emergence of trends such as the asynchronous interconnection of power grids and the increasing penetration of renewable energy, the issues of ultra-low-frequency oscillations and low-frequency stability in power grids have become more prominent, posing serious challenges to the safety and [...] Read more.
With the gradual emergence of trends such as the asynchronous interconnection of power grids and the increasing penetration of renewable energy, the issues of ultra-low-frequency oscillations and low-frequency stability in power grids have become more prominent, posing serious challenges to the safety and stability of systems. The voltage-source converter-based HVDC (VSC-HVDC) interconnection is an effective solution to the frequency stability problems faced by regional power grids. VSC-HVDC can participate in system frequency stability control through a frequency limit controller (FLC). This paper first analyses the basic principles of how VSC-HVDC participates in system frequency stability control. Then, in response to the frequency stability control requirements of the sending and receiving power systems, a droop FLC strategy is designed. Furthermore, a multi-objective optimization method for the parameters of the droop FLC is proposed. Finally, a large-scale electromagnetic transient simulation model of the VSC-HVDC interconnected power system is constructed to verify the effectiveness of the proposed droop FLC method. Full article
(This article belongs to the Special Issue Modelling, Analysis and Control of AC/DC Power Systems with High Penetration of Renewable Energy)
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15 pages, 3610 KiB  
Article
Fuel Cell System Modeling Dedicated to Performance Estimation in the Automotive Context
by Antony Plait, Pierre Saenger and David Bouquain
Energies 2024, 17(15), 3850; https://doi.org/10.3390/en17153850 - 5 Aug 2024
Viewed by 407
Abstract
In this paper, a meticulous modeling approach is proposed not only for a fuel cell stack itself but also for all auxiliary components that collectively form the fuel cell system. This comprehensive modeling approach encompasses a wide range of components, including, but not [...] Read more.
In this paper, a meticulous modeling approach is proposed not only for a fuel cell stack itself but also for all auxiliary components that collectively form the fuel cell system. This comprehensive modeling approach encompasses a wide range of components, including, but not limited to, the hydrogen recirculation pump and the air compressor. Each component is thoroughly analyzed and modeled based on the detailed specifications provided by suppliers. This involves considering factors such as efficiency, operating parameters, response times, and interactions with other system elements. By integrating these detailed models, a holistic understanding of the entire fuel cell system’s performance can be attained. Such an approach enables engineers and designers to simulate various operating scenarios, predict system behavior under different conditions, and optimize the system design for maximum efficiency and reliability. Moreover, it allows for informed decision-making throughout the system’s development, deployment, and operational phases, ultimately leading to more robust and effective energy systems. The model validation is performed by comparing experimental data to theoretical results, and the observed difference does not exceed 3%. Full article
(This article belongs to the Special Issue Current Status and Future Prospects of Hydrogen and Fuel Cell Technologies)
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17 pages, 5757 KiB  
Article
Study on Geological Deformation of Supercritical CO2 Sequestration in Oil Shale after In Situ Pyrolysis
by Heping Yan, Xiurong Wu, Qiang Li, Yinghui Fang and Shuo Zhang
Energies 2024, 17(15), 3849; https://doi.org/10.3390/en17153849 - 5 Aug 2024
Viewed by 474
Abstract
After the completion of in situ pyrolysis, oil shale can be used as a natural place for CO2 sequestration. However, the effects of chemical action and formation stress-state changes on the deformation of oil shale should be considered when CO2 is [...] Read more.
After the completion of in situ pyrolysis, oil shale can be used as a natural place for CO2 sequestration. However, the effects of chemical action and formation stress-state changes on the deformation of oil shale should be considered when CO2 is injected into oil shale after pyrolysis. In this study, combined with statistical damage mechanics, a transverse isotropic model of oil shale with coupled damage mechanisms was established by considering the decreased mechanical properties and the chemical damage caused by CO2 injection. The process of injecting supercritical CO2 into oil shale after pyrolysis was simulated by COMSOL6.0. The volume distribution of CO2 and the stress evolution in oil shale were analyzed. It is found that CO2 injection into oil shale after pyrolysis will not produce new force damage, and the force damage caused by the decrease in the mechanical properties of oil shale after pyrolysis can offset the ground uplift caused by CO2 injection to a certain extent. Under the combined action of chemical damage and mechanical damage, the uplift of a formation with a thickness of 200 m is only 10 cm. The injection of supercritical CO2 is beneficial for maintaining the stability of oil shale after in situ pyrolysis. Full article
(This article belongs to the Special Issue Recent Advances in Oil Shale Conversion Technologies)
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17 pages, 3959 KiB  
Article
A Dual-Function Design of an Oscillating Water Column Integrated with a Slotted Breakwater: A Wave Flume Study
by Clint C. M. Reyes, Mayah Walker, Zhenhua Huang and Patrick Cross
Energies 2024, 17(15), 3848; https://doi.org/10.3390/en17153848 - 5 Aug 2024
Viewed by 470
Abstract
Wave energy conversion holds promise for renewable energy, but challenges like high initial costs hinder commercialization. Integrating wave-energy converters (WECs) into shore-protection structures creates dual-function structures for both electricity generation and coastal protection. Oscillating water columns (OWCs) have been well studied in the [...] Read more.
Wave energy conversion holds promise for renewable energy, but challenges like high initial costs hinder commercialization. Integrating wave-energy converters (WECs) into shore-protection structures creates dual-function structures for both electricity generation and coastal protection. Oscillating water columns (OWCs) have been well studied in the past with their simple generation mechanism and their out-of-water power take-off (PTO) system, which can minimize bio-fouling effects and maintenance costs compared to other submerged WECs. In addition, a slotted barrier allows for better circulation behind the breakwater while dissipating incoming wave energy through viscous damping. This study examines the performance of a new design which combines an OWC with a slotted breakwater. Small-scale (1:49) laboratory tests were performed with a piston-type wave generator. The performance is evaluated in terms of wave transmission, wave energy extraction, and wave loading under various wave conditions while focusing on the effects of the porosity of the slotted barrier and tide level changes. Results show that under larger waves, a decreasing wave transmission, increasing power extraction from the OWC, and energy dissipation from the slotted barrier are observed. On the other hand, under increasing wavelengths, wave transmission is observed to be constant; this is important for harbor design, which means that the breakwater is effective under a wider range of wavelengths. Porosity allows for more transmission while inducing less horizontal force on the structure. Full article
(This article belongs to the Topic Energy from Sea Waves)
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23 pages, 1509 KiB  
Article
Sustainable Energy Usage for Africa: The Role of Foreign Direct Investment in Green Growth Practices to Mitigate CO2 Emissions
by Verena Dominique Kouassi, Hongyi Xu, Chukwunonso Philip Bosah, Twum Edwin Ayimadu and Mbula Ngoy Nadege
Energies 2024, 17(15), 3847; https://doi.org/10.3390/en17153847 - 5 Aug 2024
Viewed by 512
Abstract
In line with Africa’s commitment to keeping up with the United Nations Framework Convention on Climate Change, achieving a sustainable future requires balancing economic growth with environmental sustainability. This study investigates the long-term impacts of foreign direct investment, economic growth, agricultural production, and [...] Read more.
In line with Africa’s commitment to keeping up with the United Nations Framework Convention on Climate Change, achieving a sustainable future requires balancing economic growth with environmental sustainability. This study investigates the long-term impacts of foreign direct investment, economic growth, agricultural production, and energy consumption on CO2 emissions across 43 African nations from 1990 to 2021. Despite significant research on the individual effects of these factors, the combined influence on CO2 emissions remains underexplored. Addressing this gap, this study employs cross-sectional augmented distributed lag estimators (CS-DL and AMG) and updated estimation packages to effectively examine the relationships between variables. Our findings are as follows: firstly, economic growth and energy use was shown to have a significant positive influence on CO2 in the long term. Also, foreign direct investment significantly promotes CO2 emissions. Secondly, the causality test shows a unidirectional causal relationship between CO2 emissions and foreign direct investment. The test also revealed a bidirectional relationship between GDP and CO2 emissions, as well as between energy consumption and CO2 emissions. Again, a bidirectional causation was observed between agricultural production and CO2 emissions. Thirdly, the impulse response analysis shows that GDP will contribute more to emissions over the 10-year forecast period. This study also proposes policy implications to lessen CO2 across the continent and advocates for the judicious adoption of existing policy frameworks like the 2030 Agenda for environmental Sustainability. Full article
(This article belongs to the Section B: Energy and Environment)
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21 pages, 3157 KiB  
Article
Uncertain Scheduling of the Power System Based on Wasserstein Distributionally Robust Optimization and Improved Differential Evolution Algorithm
by Jie Hao, Xiuting Guo, Yan Li and Tao Wu
Energies 2024, 17(15), 3846; https://doi.org/10.3390/en17153846 - 5 Aug 2024
Viewed by 468
Abstract
The rapid development of renewable energy presents challenges to the security and stability of power systems. Aiming at addressing the power system scheduling problem with load demand and wind power uncertainty, this paper proposes the establishment of different error fuzzy sets based on [...] Read more.
The rapid development of renewable energy presents challenges to the security and stability of power systems. Aiming at addressing the power system scheduling problem with load demand and wind power uncertainty, this paper proposes the establishment of different error fuzzy sets based on the Wasserstein probability distance to describe the uncertainties of load and wind power separately. Based on these Wasserstein fuzzy sets, a distributed robust chance-constrained scheduling model was established. In addition, the scheduling model was transformed into a linear programming problem through affine transformation and CVaR approximation. The simplex method and an improved differential evolution algorithm were used to solve the model. Finally, the model and algorithm proposed in this paper were applied to model and solve the economic scheduling problem for the IEEE 6-node system with a wind farm. The results show that the proposed method has better optimization performance than the traditional method. Full article
(This article belongs to the Section F1: Electrical Power System)
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19 pages, 5893 KiB  
Article
Dead-Time Free Modulation Scheme for IM Drive System Fed by Voltage Source Inverter
by Qiwei Xu, Liangwu Yi, Xuehan Long, Lingyan Luo and Yiru Miao
Energies 2024, 17(15), 3845; https://doi.org/10.3390/en17153845 - 5 Aug 2024
Viewed by 386
Abstract
During the modulation process of the VSI motor drive system, the nonlinear errors caused by the dead-time and conduction voltage drop will increase the phase current harmonic distortion and the torque ripple. To solve this problem, a novel dead-time free modulation scheme is [...] Read more.
During the modulation process of the VSI motor drive system, the nonlinear errors caused by the dead-time and conduction voltage drop will increase the phase current harmonic distortion and the torque ripple. To solve this problem, a novel dead-time free modulation scheme is proposed in this paper. In the non-zero crossing region of the phase current, the switching tube, whose body diode can provide a continuation path, is set as off-state, the driving signal is only implemented on another switching tube with the same bridge arm, and the errors caused by the conduction voltage drop and switching delay are compensated to the pulse duration. At the same time, to suppress the zero current clamp effect that exists near the zero crossing point of the phase current, another modulation scheme for the phase current crossing zero in advance is proposed, which avoids the complicated determination and calculation of the current polarity near the zero crossing point of the current. Both of the above modulation schemes eliminate the dead-time, and the switching principle is presented. In addition, to suppress the impact of the current ripple and high-frequency noise on the accuracy of the phase current detection, a second-order resonance digital filter without phase shift is introduced. Finally, compared to two deadtime compensation methods, the effectiveness and superiority of the proposed dead-time free modulation scheme are verified by the experimental results. Full article
(This article belongs to the Topic Advanced Energy and Propulsion Technology for Electric and Intelligent Transportation)
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13 pages, 4231 KiB  
Article
On the Influence of Engine Compression Ratio on Diesel Engine Performance and Emission Fueled with Biodiesel Extracted from Waste Cooking Oil
by Jasem Ghanem Alotaibi, Ayedh Eid Alajmi, Talal Alsaeed, Saddam H. Al-Lwayzy and Belal F. Yousif
Energies 2024, 17(15), 3844; https://doi.org/10.3390/en17153844 - 5 Aug 2024
Viewed by 513
Abstract
Despite the extensive research on biodiesels, further investigation is warranted on the impact of compression ratios on emissions and engine performance. This study addresses this gap by evaluating the effects of increasing the engine’s compression ratio on engine performance metrics—brake-specific fuel consumption (BSFC), [...] Read more.
Despite the extensive research on biodiesels, further investigation is warranted on the impact of compression ratios on emissions and engine performance. This study addresses this gap by evaluating the effects of increasing the engine’s compression ratio on engine performance metrics—brake-specific fuel consumption (BSFC), power, torque, and exhaust gas temperature—and emissions—unburnt hydrocarbons (HCs), carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), and oxygen (O2)—when fueled with a 20% blend of waste cooking oil biodiesel (WCB20) and petroleum diesel (PD) under various operating conditions. The viscosity of the prepared fuels was measured at 25 °C and 40 °C. Experiments were conducted on a single-cylinder diesel engine under wide-open throttle conditions at three different speeds (1400 rpm, 2000 rpm, and 2600 rpm) and two compression ratios (16:1 and 18:1). The results revealed that at a lower compression ratio, both WCB20 and petroleum diesel exhibited reduced BSFC compared to higher compression ratios. However, increasing the compression ratio from 16:1 to 18:1 significantly decreased HC emissions but increased CO2 and NOx emissions. Engine power increased with engine speed for both fuels and compression ratios, with WCB20 initially producing less power than diesel but surpassing it at higher compression ratios. WCB20 demonstrated improved combustion quality with lower unburnt hydrocarbons and carbon monoxide emissions due to its higher oxygen content, promoting complete combustion. This study provides critical insights into optimizing engine performance and emission characteristics by manipulating compression ratios and utilizing biodiesel blends, paving the way for more efficient and environmentally friendly diesel engine operations. Full article
(This article belongs to the Topic Advanced Engines Technologies)
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18 pages, 3155 KiB  
Article
Discovering the Properties of a Problem of Scheduling Battery Charging Jobs to Minimize the Total Time with the Use of Harmonic Numbers
by Rafał Różycki, Zofia Walczak and Grzegorz Waligóra
Energies 2024, 17(15), 3843; https://doi.org/10.3390/en17153843 - 4 Aug 2024
Viewed by 595
Abstract
In this work, we consider a problem from the field of power-aware scheduling in which a fleet of electric vehicles have to be charged in a minimum time. Each vehicle is equipped with a lithium-ion battery of a given capacity. The initial power [...] Read more.
In this work, we consider a problem from the field of power-aware scheduling in which a fleet of electric vehicles have to be charged in a minimum time. Each vehicle is equipped with a lithium-ion battery of a given capacity. The initial power used for charging each battery is known, whereas it is assumed that the power drops to zero at the moment when the battery gets fully loaded. The power usage function is linear and decreasing. The charging jobs are nonpreemptable and independent, whereas the total available amount of power is limited. The objective is to minimize the schedule length. In this paper, we analyze the case of a problem with identical jobs that already cover a wide variety of practical situations. By employing inverses of natural numbers, similar to harmonic series, we prove two properties of this case, and we also discuss the phenomenon of the stabilization of the difference between the start times of two successive jobs in a schedule. We also take under examination a few special cases of the problem. Some conclusions and directions for future research are given. Full article
(This article belongs to the Special Issue Energy, Electrical and Power Engineering 2024)
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17 pages, 4168 KiB  
Article
Study on the Multiphase Flow Behavior in Jet Pump Drainage and Natural Gas Hydrate Production Wells with Combined Depressurization and Thermal Stimulation Method
by Xiaolin Ping, Jiqun Zhang, Guoqing Han, Junhua Chang and Hongliang Wang
Energies 2024, 17(15), 3842; https://doi.org/10.3390/en17153842 - 4 Aug 2024
Viewed by 556
Abstract
Natural gas hydrate (NGH) trials have been performed successfully with different development methods and gas recovery drainage technologies. Multiphase flow in a wellbore and the drainage of natural gas hydrate are two important parts for its whole extraction process. Additionally, the choice of [...] Read more.
Natural gas hydrate (NGH) trials have been performed successfully with different development methods and gas recovery drainage technologies. Multiphase flow in a wellbore and the drainage of natural gas hydrate are two important parts for its whole extraction process. Additionally, the choice of the drainage method is linked to the development method, making the drainage of NGH more complex. Jet pump drainage is usable for NGH production wells with the combined depressurization and thermal stimulation method. The objective of this study is to shed more light on the multiphase flow behavior in jet pump drainage and NGH production wells and put forward suggestions for adjusting heat injection parameters. The mechanism of jet pump drainage recovery technology for NGH wells was analyzed and its applicability to NGH development by the combined depressurization and thermal stimulation method was demonstrated. In addition, multiphase flow models of tubing and annulus were established, respectively, for the phenomenon of the countercurrent flow of heat exchange in the process of jet pump drainage and gas production, and the corresponding multiphase flow laws were derived. On the basis of these studies, sensitivity analysis and the optimization of thermal stimulation parameters were conducted. It is demonstrated that jet pump drainage gas recovery technology is feasible for the development of onshore NGH with the combined depressurization and thermal stimulation method. The laws of multiphase flow in the tubing and annulus of jet pump drainage and NGH production wells were disclosed in this study. Numerical simulation results show that the temperature and pressure profiles along the wellbore of jet pump drainage and NGH production wells during the drainage recovery process are affected by injection conditions. Increasing injection rate and injection temperature can both improve the effect of heat injection and reduce the hydrate reformation risk in the bottom of the annulus. This study offers a theoretical basis and technical support for production optimization and hydrate prevention and control in the wellbore of jet pump drainage and NGH production wells. Full article
(This article belongs to the Special Issue Investigations of Heat Transfer with Estimation of Temperature Uncertainty Measurements)
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22 pages, 2695 KiB  
Article
Eco-Innovation Method for Sustainable Development of Energy-Producing Products Considering Quality and Life Cycle Assessment (QLCA)
by Dominika Siwiec and Andrzej Pacana
Energies 2024, 17(15), 3841; https://doi.org/10.3390/en17153841 - 4 Aug 2024
Viewed by 604
Abstract
The sustainability of products remains a challenge, mainly due to the lack of consistent approaches for simultaneously taking into account the key criteria of the concept in the process. This research aims to develop an eco-innovative QLCA method to create new product solutions [...] Read more.
The sustainability of products remains a challenge, mainly due to the lack of consistent approaches for simultaneously taking into account the key criteria of the concept in the process. This research aims to develop an eco-innovative QLCA method to create new product solutions that integrate quality (customer satisfaction) and environmental impact assessment throughout the product life cycle. The QLCA method includes: (i) product prototyping according to quality and environmental criteria; (ii) prospective assessment of the quality of prototypes, taking into account customer requirements; (iii) prospective life cycle assessment of product prototypes using a cradle-to-grave approach in accordance with ISO 14040; and (iv) setting the direction of product development while taking into account the fulfilment of customer expectations and the need to care for the environment throughout the product life cycle. Owing to the lack of previous research in this area, as well as the popularity of photovoltaic (PV) panels in reducing greenhouse gases, an illustration was obtained and test of the method was carried out on the example of silicon photovoltaic panel modules (Crystalline Si PV Module). In accordance with the adopted assumptions, the results of the QLCA method test showed that the modelled PV prototypes will, in most cases, be satisfactory for customers, but they still require improvement actions to reduce carbon dioxide (CO2) emissions throughout their life cycle. These activities should be consistent so as to achieve quality that satisfies customers. The QLCA method can be used by designers, managers, and decision-makers at the early stages of design, but also during the product maturity phase for its sustainable development. Full article
(This article belongs to the Special Issue Advanced Application for Renewable Energy Sources: Modelling, Management Control, Data Monitoring, Health Management, Design and Improvement)
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18 pages, 25759 KiB  
Article
An Efficiency Evaluation and Driving Effect Analysis of the Green Transformation of the Thermal Power Industrial Chain: Evidence Based on Impacts and Challenges in China
by Hui Zhu, Yijie Bian, Fangrong Ren and Xiaoyan Liu
Energies 2024, 17(15), 3840; https://doi.org/10.3390/en17153840 - 4 Aug 2024
Viewed by 471
Abstract
The high carbon emissions and pollution of China’s thermal power industry chain have exacerbated environmental and climate degradation. Therefore, accelerating the green transformation process is of great significance in promoting the sustainable development of enterprises. This study selected 30 listed thermal power enterprises [...] Read more.
The high carbon emissions and pollution of China’s thermal power industry chain have exacerbated environmental and climate degradation. Therefore, accelerating the green transformation process is of great significance in promoting the sustainable development of enterprises. This study selected 30 listed thermal power enterprises in China as research objects, analyzed their data from 2018 to 2022, set targeted input–output indicators for different stages, and used a two-stage dynamic data envelopment analysis (DEA) model to evaluate and measure the efficiency of the green transformation of Chinese thermal power enterprises. In addition, this study also uses the logarithmic mean Divisia index (LMDI) method to analyze the driving effects of green transformation. The results indicate that in terms of overall efficiency, there is a significant difference in the overall performance of these 30 thermal power enterprises, with a large difference in average efficiency values. Efficiency values are related to enterprise size. In terms of stage efficiency, the average efficiency value of thermal power enterprises in the profit stage was significantly higher than that in the transformation stage, and the profitability of Chinese thermal power enterprises was better. In terms of sub-indicator efficiency, the efficiency of each indicator shows a “U”-shaped trend, and there is a certain correlation between the operating costs and revenue of thermal power enterprises, the market value of green transformation, and related indicators. In addition, the most important factor affecting the efficiency of green transformation is the sewage cost they face, whereas their operational capabilities have the least impact on their green transformation. In this regard, thermal power enterprises should increase their investment in the research and development of key technologies for thermal power transformation and continuously optimize their energy structure. The government will increase financial support for thermal power green transformation enterprises and correspondingly increase emission costs. Full article
(This article belongs to the Special Issue Industrial Chain, Supply Chain and Value Chain in the Energy Industry: Impacts and Challenges in the Green and Low-Carbon Transition)
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20 pages, 6461 KiB  
Article
Textile-Integrated Conductive Layers for Flexible Semiconductor-Based Photovoltaic Structures
by Przemysław Czarnecki, Bartosz Szudziel, Daniel Janczak, Łukasz Ruta, Maciej Sibiński and Katarzyna Znajdek
Energies 2024, 17(15), 3839; https://doi.org/10.3390/en17153839 - 3 Aug 2024
Viewed by 754
Abstract
This paper presents the results of research on conductive layers dedicated to flexible photovoltaic cells based on semiconductors integrated with a textile substrate. The presented work is part of a broader project aimed at producing flexible solar cells based on the CdTe semiconductor [...] Read more.
This paper presents the results of research on conductive layers dedicated to flexible photovoltaic cells based on semiconductors integrated with a textile substrate. The presented work is part of a broader project aimed at producing flexible solar cells based on the CdTe semiconductor component and manufactured directly on textiles. The research focuses on the selection of textile substrates and contact materials, as well as the methods of their application. This study compares three types of fabrics (basalt, glass, and silicone fibers) and three metals (copper, molybdenum, and silver), evaluating their mechanical and electrical properties. During the experiments, flexible metallic layers with a thickness ranging from 160 to 415 nm were obtained. Preliminary experiments indicated that metallic layers deposited directly on textiles do not provide adequate conductivity, reaching the levels of several hundred Ω/sq and necessitating the introduction of intermediate layers, such as screen-printed graphite. The results show that molybdenum layers on basalt fabrics exhibit the lowest increase in resistance after dynamic bending tests. The obtained relative resistance changes in Mo layers varied from 50% to as low as 5% after a complete set of 200 bending cycles. This article also discusses current challenges and future research directions in the field of textile-integrated photovoltaics, emphasizing the importance of further technological development to improve the energy efficiency and durability of such solutions. Full article
(This article belongs to the Special Issue Advances on Solar Energy Materials and Solar Cells)
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19 pages, 7468 KiB  
Article
Linear Active Disturbance Rejection Control for Flexible Excitation System of Pumped Storage Units
by Bo Zhao, Jiandong Zheng, Jun Qin, Dan Wang, Jiayao Li, Xinyu Cheng and Sisi Jia
Energies 2024, 17(15), 3838; https://doi.org/10.3390/en17153838 - 3 Aug 2024
Viewed by 659
Abstract
The role of pumped storage in global energy structure transformation is becoming increasingly prominent. This article introduces a flexible excitation system based on fully controlled device converters into pumped storage units (PSUs). It can address the issues of insufficient excitation capacity and limited [...] Read more.
The role of pumped storage in global energy structure transformation is becoming increasingly prominent. This article introduces a flexible excitation system based on fully controlled device converters into pumped storage units (PSUs). It can address the issues of insufficient excitation capacity and limited stability associated with traditional thyristor excitation systems. The study focuses on linear active disturbance rejection control (LADRC) for the flexible excitation control system of pumped storage units and utilizes intelligent optimization algorithms to optimize the controller parameters. This addresses the inherent problem of traditional PID controllers, which are unable to alleviate the trade-off between response speed and overshoot. At the same time, the robustness and anti-interference of the control system are improved, effectively enhancing the performance of the pumped storage flexible excitation control system. Simulation verifies the feasibility and superiority of the proposed method. Full article
(This article belongs to the Section F1: Electrical Power System)
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19 pages, 3060 KiB  
Article
Study of a Numerical Integral Interpolation Method for Electromagnetic Transient Simulations
by Kaiyuan Sun, Kun Chen, Haifeng Cen, Fucheng Tan and Xiaohui Ye
Energies 2024, 17(15), 3837; https://doi.org/10.3390/en17153837 - 3 Aug 2024
Viewed by 602
Abstract
In the fixed time-step electromagnetic transient (EMT)-type program, an interpolation process is applied to deal with switching events. The interpolation method frequently reduces the algorithm’s accuracy when dealing with power electronics. In this study, we use the Butcher tableau to analyze the defects [...] Read more.
In the fixed time-step electromagnetic transient (EMT)-type program, an interpolation process is applied to deal with switching events. The interpolation method frequently reduces the algorithm’s accuracy when dealing with power electronics. In this study, we use the Butcher tableau to analyze the defects of linear interpolation. Then, based on the theories of Runge–Kutta integration, we propose two three-stage diagonally implicit Runge–Kutta (3S-DIRK) algorithms combined with the trapezoidal rule (TR) and backward Euler (BE), respectively, with TR-3S-DIRK and BE2-3S-DIRK for the interpolation and synchronization processes. The proposed numerical integral interpolation scheme has second-order accuracy and does not produce spurious oscillations due to the size change in the time step. The proposed method is compared with the critical damping adjustment method (CDA) and the trapezoidal method, showing that it does not produce spurious numerical oscillations or first-order errors. Full article
(This article belongs to the Topic Numerical Methods and Computer Simulations in Energy Analysis, 2nd Edition)
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13 pages, 4241 KiB  
Article
Design of Inductive Power Transfer Charging System with Weak Coupling Coefficient
by Yuhang Chen, Shichun Yang, Mengchao Zheng and Xiaoyu Yan
Energies 2024, 17(15), 3836; https://doi.org/10.3390/en17153836 - 3 Aug 2024
Viewed by 436
Abstract
Inductive power transfer (IPT) technology is used in various applications owing to its safety features, robust environmental adaptability, and convenience. In some special applications, the charging pads are required to be as compact as possible to accommodate practical spatial requirements, and even size [...] Read more.
Inductive power transfer (IPT) technology is used in various applications owing to its safety features, robust environmental adaptability, and convenience. In some special applications, the charging pads are required to be as compact as possible to accommodate practical spatial requirements, and even size requirements dictate that the diameter of the charging pad matches the air gap. However, such requirements bring about a decrease in the transmission efficiency, power, and tolerance to misalignment of the system. In this paper, by comparing a double-sided inductor–capacitor–capacitor (LCC), double-sided inductor–capacitor–inductor (LCL), series–series (SS), and inductor–capacitor–capacitor–series (LCC-S) compensation topologies in IPT systems, we identified a double-sided LCC compensation topology that is suitable for weak coupling coefficients. Furthermore, this study modeled and simulated the typical parameters of coreless coils in circular power pads, such as the number of coil layers, turns, wire diameter, and wire spacing, to enhance the mutual inductance of the magnetic coupler during misalignment and long-distance transmission. A wireless charging system with 640 W output power was built, and the experimental results show that a maximum dc-dc efficiency of over 86% is achieved across a 200 mm air gap when the circular power pad with a diameter of 200 mm is well aligned. The experimental results show that using a suitable compensation topology and optimizing the charging pad parameters enables efficient IPT system operation when the coupling coefficient is 0.02. Full article
(This article belongs to the Section F1: Electrical Power System)
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37 pages, 12671 KiB  
Article
IntiGIS-Local: A Geospatial Approach to Assessing Rural Electrification Alternatives for Sustainable Socio-Economic Development in Isolated Communities—A Case Study of Guasasa, Cuba
by Javier Domínguez, Carlo Bellini, Luis Arribas, Julio Amador, Mirelys Torres-Pérez and Ana M. Martín
Energies 2024, 17(15), 3835; https://doi.org/10.3390/en17153835 - 3 Aug 2024
Viewed by 791
Abstract
Rural electrification is a crucial step for the socio-economic development of isolated communities. Decentralized power generation, typically more favorable for renewable energies, requires an accurate analysis of the different electrification options, whose convenience depends on multiple factors. The application of Geographical Information Systems [...] Read more.
Rural electrification is a crucial step for the socio-economic development of isolated communities. Decentralized power generation, typically more favorable for renewable energies, requires an accurate analysis of the different electrification options, whose convenience depends on multiple factors. The application of Geographical Information Systems (GISs) to energy planning allows the assessment at a local level, considering the variability and demand distribution of spatial resources. This work introduces IntiGIS-local, a GIS-based model implemented in the ArcGIS environment, designed to calculate the levelized energy cost (LEC) for different electrification options. The model allows the comparison between three power generation alternatives: solar system, diesel generator set and solar–diesel hybrid system. Configurations are adjustable through input variables, with a special focus on the confrontation between individual systems and microgrids. The objective is to provide an adequate groundwork for developing a decision-making tool to assess diverse rural electrification options in future studies. The model IntiGIS-local is tested in the case study of the Guasasa community (Cuba). Full article
(This article belongs to the Section A: Sustainable Energy)
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18 pages, 3333 KiB  
Article
A Study on the Thermal Physical Property Changes in Formation Rocks during Rapid Preheating of SAGD
by Jie Tian, Shiwen Huang, Mingda Dong, Wende Yan and Zhilin Qi
Energies 2024, 17(15), 3834; https://doi.org/10.3390/en17153834 - 3 Aug 2024
Viewed by 444
Abstract
The incorporation and application of SAGD rapid preheating technology effectively solve the problem of the long preheating cycle in the SAGD steam cycle. The thermal properties of reservoir rocks are an important factor affecting the heat transfer law governing their formation during the [...] Read more.
The incorporation and application of SAGD rapid preheating technology effectively solve the problem of the long preheating cycle in the SAGD steam cycle. The thermal properties of reservoir rocks are an important factor affecting the heat transfer law governing their formation during the rapid preheating process of SAGD. During the rapid preheating process of SAGD, the expansion of the reservoir and the steam cycle process will cause changes in the pore permeability, oil-water saturation, and temperature of the reservoir rocks, which will inevitably lead to differences in the changes that occur in the thermal properties of the reservoir rocks, compared to those under the influence of a single factor. In this study, experiments were conducted to determine the thermal properties of reservoir rocks under the combined influence of pore permeability, oil-water saturation, and temperature, quantitatively characterizing the changes in the thermal properties of reservoir rocks. Using the orthogonal method to design and carry out experiments for determining the thermal properties of reservoir rocks, the main factors affecting the thermal properties of reservoir rocks and the significance of each factor’s impact on the thermal properties of reservoir rocks were determined through intuitive analysis and variance analysis of the experimental results. Finally, a regression equation that can characterize changes in the thermal properties of reservoir rocks under the influence of multiple factors was obtained through multiple nonlinear regressions of the experimental results. Full article
(This article belongs to the Special Issue New Advances in Oil, Gas and Geothermal Reservoirs: 2nd Edition)
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19 pages, 13896 KiB  
Article
Numerical Study on Auxiliary Propulsion Performance of Foldable Three-Element Wingsail Utilizing Wind Energy
by Yongxu Jiang, Chenze Cao, Ting Cui, Hao Yang and Zhengjun Tian
Energies 2024, 17(15), 3833; https://doi.org/10.3390/en17153833 - 3 Aug 2024
Viewed by 456
Abstract
Sail-assisted propulsion is an important energy-saving technology in the shipping industry, and the development of foldable wingsails has recently become a hot topic. This type of sail is usually composed of multiple elements, and its performance at different folding configurations is very sensitive [...] Read more.
Sail-assisted propulsion is an important energy-saving technology in the shipping industry, and the development of foldable wingsails has recently become a hot topic. This type of sail is usually composed of multiple elements, and its performance at different folding configurations is very sensitive to changes in incoming airflow, which result in practical operational challenges. Therefore, original and optimized three-element wingsails (bare and concave) are modeled and simulated using the unsteady RANS method with the k-ω SST turbulence model. Next, certain key design and structural parameters (such as angle of attack, apparent wind angle, and camber) are employed to characterize the auxiliary propulsion performance, and the differences are explained in combination with the flow field details. The results show that, in the unfolded state, the aerodynamic performance of the concave wingsail is better than that of the bare wingsail, exhibiting higher lift coefficients, lower drag coefficients, and a more stable surface flow. In the fully folded state, wherein both the nose and flap are rotated, the thrust performance of the concave wingsail remains superior. Specifically, at an angle of attack of 8 degrees, the thrust coefficient of the concave wingsail is approximately 23.5% higher than that of the bare wingsail, indicating improved wind energy utilization. The research results are of great significance for engineering applications and subsequent optimization design. Full article
(This article belongs to the Special Issue Wind and Wave Energy Resource Assessment and Combined Utilization)
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