Journal Description
Energies
Energies
is a peer-reviewed, open access journal of related scientific research, technology development, engineering policy, and management studies related to the general field of energy, from technologies of energy supply, conversion, dispatch, and final use to the physical and chemical processes behind such technologies. Energies is published semimonthly online by MDPI. The European Biomass Industry Association (EUBIA), Association of European Renewable Energy Research Centres (EUREC), Institute of Energy and Fuel Processing Technology (ITPE), International Society for Porous Media (InterPore), CYTED and others are affiliated with Energies and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Ei Compendex, RePEc, Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: CiteScore - Q1 (Engineering (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.1 days after submission; acceptance to publication is undertaken in 3.3 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Sections: published in 41 topical sections.
- Testimonials: See what our editors and authors say about Energies.
- Companion journals for Energies include: Fuels, Gases, Nanoenergy Advances and Solar.
Impact Factor:
3.2 (2022);
5-Year Impact Factor:
3.3 (2022)
Latest Articles
Optimization of Frequency Modulation Energy Storage Configuration in Power Grid Based on Equivalent Full Cycle Model
Energies 2024, 17(9), 2120; https://doi.org/10.3390/en17092120 (registering DOI) - 29 Apr 2024
Abstract
This paper aims to meet the challenges of large-scale access to renewable energy and increasingly complex power grid structure, and deeply discusses the application value of energy storage configuration optimization scheme in power grid frequency modulation. Based on the equivalent full cycle model
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This paper aims to meet the challenges of large-scale access to renewable energy and increasingly complex power grid structure, and deeply discusses the application value of energy storage configuration optimization scheme in power grid frequency modulation. Based on the equivalent full cycle model and a large number of actual operation data, various energy storage technologies are technically analyzed, and the economic and environmental performance of different energy storage configuration schemes are comprehensively evaluated. On this basis, this paper puts forward a set of efficient and economical energy storage configuration optimization strategies to meet the demand of power grid frequency modulation and promote the wide application of energy storage technology. After an in-depth analysis, it is found that the optimized energy storage configuration scheme is excellent in technology, economy, and environmental protection. Specifically, in terms of technical performance, the optimization scheme has significantly improved key indicators such as energy storage efficiency, capacity and power, and response speed, which can better meet the requirements of power grid frequency modulation. Through the verification of actual operation data, it is found that the overall efficiency of the optimized energy storage configuration scheme is above 55%, which is helpful to the stability and efficiency of power grid frequency modulation. In terms of economic performance, although the initial investment cost of the optimization scheme may be high, it is found that it has good economy through the evaluation of long-term operation benefits. Considering that the energy storage system can reduce the operating cost of the power grid, improve the energy utilization rate, and achieve the optimization of cost-effectiveness in the long run, this scheme is economically feasible and attractive. In terms of environmental performance, the optimization scheme effectively reduces the negative impact on the environment by improving energy storage efficiency, reducing emissions, and optimizing resource utilization. This is not only conducive to the sustainable development of the power grid but also in line with the current global trend of promoting green and low-carbon transformation. To sum up, this paper not only provides an efficient and economical energy storage allocation optimization strategy for power grid frequency modulation but also provides a scientific basis for relevant decision-making departments. By promoting the practical application and development of energy storage technology, this paper is helpful to improve the frequency modulation ability of power grid, optimize energy structure, and reduce environmental pollution, and thus achieve the goal of sustainable energy development. The data results and in-depth analysis of this paper provide strong support for the practical application of energy storage configuration optimization scheme and also provide important reference for the further innovation and development of energy storage technology.
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(This article belongs to the Special Issue Advanced Energy Storage Technologies and Applications (AESAs))
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Optimal Scheduling of Electricity and Carbon in Multi-Park Integrated Energy Systems
by
Kun Li, Yulong Ying, Xiangyu Yu and Jingchao Li
Energies 2024, 17(9), 2119; https://doi.org/10.3390/en17092119 (registering DOI) - 29 Apr 2024
Abstract
In order to maximize the utilization efficiency of renewable energy resources and reduce carbon costs in multi-park integrated energy systems (MIESs), this paper proposes an electricity–carbon energy scheduling method for MIESs, where a electricity–carbon joint trading market is established to allow energy interactions
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In order to maximize the utilization efficiency of renewable energy resources and reduce carbon costs in multi-park integrated energy systems (MIESs), this paper proposes an electricity–carbon energy scheduling method for MIESs, where a electricity–carbon joint trading market is established to allow energy interactions between IESs so as to satisfy their energy deficiencies and surpluses. Simultaneously, through leveraging differences in carbon prices among regions, carbon quotas are shared between all IESs, thereby reducing the overall carbon trading costs within the region. The paper also suggests that to encourage carbon cooperation between IESs, incentive measures such as government subsidies could be provided to foster collaboration. The simulation results demonstrate that the proposed electricity–carbon energy scheduling method for MIESs can effectively improve the utilization flexibility of various energy resources and obtain the higher economic benefits, compared with the traditional method where each IES operates independently.
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(This article belongs to the Section C: Energy Economics and Policy)
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Mean Field Game-Based Algorithms for Charging in Solar-Powered Parking Lots and Discharging into Homes a Large Population of Heterogeneous Electric Vehicles
by
Samuel M. Muhindo
Energies 2024, 17(9), 2118; https://doi.org/10.3390/en17092118 (registering DOI) - 29 Apr 2024
Abstract
An optimal daily scheme is presented to coordinate a large population of heterogeneous battery electric vehicles when charging in daytime work solar-powered parking lots and discharging into homes during evening peak-demand hours. First, we develop a grid-to-vehicle strategy to share the solar energy
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An optimal daily scheme is presented to coordinate a large population of heterogeneous battery electric vehicles when charging in daytime work solar-powered parking lots and discharging into homes during evening peak-demand hours. First, we develop a grid-to-vehicle strategy to share the solar energy available in a parking lot between vehicles where the statistics of their arrival states of charge are dictated by an aggregator. Then, we develop a vehicle-to-grid strategy so that vehicle owners with a satisfactory level of energy in their batteries could help to decongest the grid when they return by providing backup power to their homes at an aggregate level per vehicle based on a duration proposed by an aggregator. Both strategies, with concepts from Mean Field Games, would be implemented to reduce the standard deviation in the states of charge of batteries at the end of charging/discharging vehicles while maintaining some fairness and decentralization criteria. Realistic numerical results, based on deterministic data while considering the physical constraints of vehicle batteries, show, first, in the case of charging in a parking lot, a strong to slight decrease in the standard deviation in the states of charge at the end, respectively, for the sunniest day, an average day, and the cloudiest day; then, in the case of discharging into the grid, over three days, we observe at the end the same strong decrease in the standard deviation in the states of charge.
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(This article belongs to the Special Issue Energy Management Systems of Electric Vehicles: New Trends and Dynamic Futures)
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Combined Effects of Thermal Buoyancy, Wind Action, and State of the First-Floor Lobby Entrance on the Pressure Difference in a High-Rise Building
by
Haiwei Xu, Lingfeng Su, Wenjuan Lou and Hongyang Shan
Energies 2024, 17(9), 2117; https://doi.org/10.3390/en17092117 (registering DOI) - 29 Apr 2024
Abstract
The stack effect in high-rise buildings, stemming from an inside/outside temperature difference, may produce a significant pressure difference on the elevator doors, potentially causing elevator malfunctions. This effect can also be influenced by wind action and human behaviors, e.g., opening/closing of building entrances.
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The stack effect in high-rise buildings, stemming from an inside/outside temperature difference, may produce a significant pressure difference on the elevator doors, potentially causing elevator malfunctions. This effect can also be influenced by wind action and human behaviors, e.g., opening/closing of building entrances. In this study, a wind tunnel test was conducted to determine the real wind pressure distribution on a high-rise building in northern China. A numerical simulation utilizing the Conjunction of Multizone Infiltration Specialists software (COMIS) was carried out to investigate the pressure difference of elevator doors under the effects of thermal buoyancy, wind action, and opening/closing of the first-floor lobby entrance. An alternative solution of a locally strengthened envelope is proposed and validated for the studied building zone. The study reveals that the opening of the first-floor lobby entrance increases the pressure difference regardless of the environmental conditions, and the increase of wind speed tends to increase the pressure difference in winter but decrease it in summer. The proposed countermeasure combination, involving using revolving doors instead of swing doors, increasing additional partitions, and strengthening the local building envelope, was found to be synergistic and effective in reducing the pressure difference inside the building. The research findings offer practical engineering solutions for mitigating elevator door pressure challenges in high-rise buildings.
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(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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Development and Validation of a Novel Zero-Dimensional Heat Rejection Model for High-Efficiency Engines
by
Francesca Furia, Vittorio Ravaglioli, Alberto Cerofolini and Carlo Bussi
Energies 2024, 17(9), 2116; https://doi.org/10.3390/en17092116 (registering DOI) - 29 Apr 2024
Abstract
In recent years, the trend towards the performance maximization of modern internal combustion engines has led to the creation of accurate simulation models to optimize the engine design and operating conditions. Temperature management is crucial to achieve the performance goals of an internal
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In recent years, the trend towards the performance maximization of modern internal combustion engines has led to the creation of accurate simulation models to optimize the engine design and operating conditions. Temperature management is crucial to achieve the performance goals of an internal combustion engine without affecting the component’s reliability. Formula 1 mandates that only a limited number of experimental tests can be performed, which leads to the necessity of simulators capable of substituting empirical tests. Furthermore, the requirement of adapting the vehicle setup before each race weekend to maximize the performance on each circuit layout necessitates short computational time. To address this, the development of a zero-dimensional model of the thermal flows within an engine is presented in this paper. This model allows to precisely compute the dynamic variations of all the heat flows inside the combustion engine, excluding only the radiative ones and the engine components’ temperatures. The new simulation approach has been developed and validated on a Formula 1 engine and shown to be precise and fast. The results demonstrate the value of the proposed model with an average engine fluid temperature error of less than 1 °C for a computational cost comparable with on-board applications.
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(This article belongs to the Special Issue Internal Combustion Engine: Research and Application—2nd Edition)
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Online Estimation of Three-Phase Induction Motor Parameters Using an Extended Kalman Filter for Energy Saving
by
Sasiya Udomsuk, Kongpol Areerak, Tidarut Areerak and Kongpan Areerak
Energies 2024, 17(9), 2115; https://doi.org/10.3390/en17092115 (registering DOI) - 28 Apr 2024
Abstract
In this paper, the online estimation of three-phase induction motor parameters using an extended Kalman filter for energy saving is proposed. The optimal value of the stator current on the d-axis is calculated to obtain the minimum power loss. Accurate motor parameters
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In this paper, the online estimation of three-phase induction motor parameters using an extended Kalman filter for energy saving is proposed. The optimal value of the stator current on the d-axis is calculated to obtain the minimum power loss. Accurate motor parameters are required to calculate the optimal stator current value for energy saving. Hence, to estimate motor parameters in real time, an online estimator known as the extended Kalman filter is applied. The energy consumption results for the motor using the proposed approach (estimated parameters with extended Kalman filter) are compared with those obtained using the conventional approach and energy saving (fixed parameters without parameter estimation) approach. As revealed by the comparison results from implementation in a laboratory, the proposed approach can provide minimum power losses for the three-phase induction motor drive, and the maximum energy-saving percentage is 60.18% compared with using the conventional drive approach.
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(This article belongs to the Section F: Electrical Engineering)
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Charge Carrier Formation following Energy Gap Law in Photo-Activated Organic Materials for Efficient Solar Cells
by
Aniket Rana, Nikita Vashistha, Amit Kumar, Mahesh Kumar and Rajiv K. Singh
Energies 2024, 17(9), 2114; https://doi.org/10.3390/en17092114 (registering DOI) - 28 Apr 2024
Abstract
The charge carrier formation and transport in the pristine polymers as well as in the polymer–fullerene blend is still a hot topic of discussion for the scientific community. In the present work, the carrier generation in some prominent organic molecules has been studied
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The charge carrier formation and transport in the pristine polymers as well as in the polymer–fullerene blend is still a hot topic of discussion for the scientific community. In the present work, the carrier generation in some prominent organic molecules has been studied through ultrafast transient absorption spectroscopy. The identification of the exciton and polaron lifetimes of these polymers has led to device performance-related understanding. In the Energy Gap Law, the slope of the linear fit gradient (γ) of lifetimes vs. bandgap are subjected to the geometrical rearrangements experienced by the polymers during the non-radiative decay from the excited state to the ground state. The value of gradient (γ) for excitons and polarons is found to be −1.1 eV−1 and 1.14 eV−1, respectively. It suggests that the exciton decay to the ground state is likely to involve a high distortion in polymer equilibrium geometry. This observation supports the basis of Stokes shift found in the conjugated polymers due to the high disorder. It provides the possible reasons for the substantial variation in the exciton lifetime. As the bandgap becomes larger, exciton decay rate tends to reduce due to the weak attraction between the holes in the HUMO and electron in the LUMO. The precise inverse action is observed for the polymer–fullerene blend, as the decay of polaron tends to increase as the bandgap of polymer increases.
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(This article belongs to the Special Issue New Insights into Solar Cells)
Open AccessArticle
Improved Error-Based Ensemble Learning Model for Compressor Performance Parameter Prediction
by
Xinguo Miao, Lei Liu, Zhiyong Wang and Xiaoming Chen
Energies 2024, 17(9), 2113; https://doi.org/10.3390/en17092113 (registering DOI) - 28 Apr 2024
Abstract
Large compressors have complex structures and constantly changing operating conditions. It is challenging to build physical models of compressors to analyse their performance parameters. An improved error-based stacked ensemble learning prediction model is proposed in this work. This model simplifies the modelling steps
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Large compressors have complex structures and constantly changing operating conditions. It is challenging to build physical models of compressors to analyse their performance parameters. An improved error-based stacked ensemble learning prediction model is proposed in this work. This model simplifies the modelling steps in a data-driven manner and obtains accurate prediction results. An enhanced integrated model employs K-fold cross-validation to assign dataset weights based on validation set errors, achieving a 12.4% reduction in average output error. Additionally, the output error of the meta-model undergoes a Box–Cox transformation for error compensation, decreasing the average output error by 14.0%. The Stacking model, combining the above improvements, notably reduces the root-mean-square errors for power, surge, and blocking boundaries by 24.2%, 20.6%, and 23.3%, respectively. This integration significantly boosts prediction accuracy.
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(This article belongs to the Section F5: Artificial Intelligence and Smart Energy)
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Enhancing the Efficiency of Rotary Thermal Propulsion Systems
by
Xuankun Shen and Aaron W. Costall
Energies 2024, 17(9), 2112; https://doi.org/10.3390/en17092112 (registering DOI) - 28 Apr 2024
Abstract
Transport electrification is essential for reducing CO2 emissions, and technologies such as hybrid and range-extended electric vehicles will play a crucial transitional role. Such vehicles employ an internal combustion engine for on-board chemical energy conversion. The Wankel rotary engine should be an
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Transport electrification is essential for reducing CO2 emissions, and technologies such as hybrid and range-extended electric vehicles will play a crucial transitional role. Such vehicles employ an internal combustion engine for on-board chemical energy conversion. The Wankel rotary engine should be an excellent candidate for this purpose, offering a high power-to-weight ratio, simplicity, compactness, perfect balance, and low cost. Until recently, however, it has not been in production in the automotive market, due, in part, to relatively low combustion efficiency and high fuel consumption and unburnt hydrocarbon emissions, which can be traced to constraints on flame speed, an elongated combustion chamber, and relatively low compression ratios. This work used large eddy simulations to study the in-chamber flow in a peripherally ported 225cc Wankel rotary engine, providing insight into these limitations. Flow structures created during the intake phase play a key role in turbulence production but the presence of the pinch point inherent to Wankel engine combustion chambers inhibits flame propagation. Two efficiency-enhancement technologies are introduced as disruptive solutions: (i) pre-chamber jet ignition and (ii) a two-stage rotary engine. These concepts overcome the traditional efficiency limitations and show that the Wankel rotary engine design can be further enhanced for its role as a range extender in electrified vehicles.
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(This article belongs to the Special Issue Disruptive Solutions for Innovative Internal Combustion Engines and Advanced Combustion)
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Energy Management Strategy for a Net Zero Emission Islanded Photovoltaic Microgrid-Based Green Hydrogen System
by
Nisrine Naseri, Soumia El Hani, Mohamed Machmoum, Elhoussin Elbouchikhi and Amina Daghouri
Energies 2024, 17(9), 2111; https://doi.org/10.3390/en17092111 (registering DOI) - 28 Apr 2024
Abstract
Investing in green hydrogen systems has become a global objective to achieve the net-zero emission goal. Therefore, it is seen as the primary force behind efforts to restructure the world’s energy, lessen our reliance on gas, attain carbon neutrality, and combat climate change.
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Investing in green hydrogen systems has become a global objective to achieve the net-zero emission goal. Therefore, it is seen as the primary force behind efforts to restructure the world’s energy, lessen our reliance on gas, attain carbon neutrality, and combat climate change. This paper proposes a power management for a net zero emission PV microgrid-based decentralized green hydrogen system. The hybrid microgrid combines a fuel cell, battery, PV, electrolyzer, and compressed hydrogen storage (CHSU) unit aimed at power sharing between the total components of the islanded DC microgrid and minimizing the equivalent hydrogen consumption (EHC) by the fuel cell and the battery. In order to minimize the EHC and maintain the battery SOC, an optimization-based approach known as the Equivalent Consumption Minimization Strategy (ECMS) is used. A rule-based management is used to manage the power consumed by the electrolyzer and the CHSU by the PV system in case of excess power. The battery is controlled by an inverse droop control to regulate the dc bus voltage and the output power of the PV system is maximized by the fuzzy logic controller-based MPPT. As the hybrid microgrid works in the islanded mode, a two-level hierarchical control is applied in order to generate the voltage and the frequency references. The suggested energy management approach establishes the operating point for each system component in order to enhance the system’s efficiency. It allows the hybrid system to use less hydrogen while managing energy more efficiently.
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(This article belongs to the Section A1: Smart Grids and Microgrids)
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Simulation-Based Evaluation of the Impact of an Electrochromic Glazing on the Energy Use and Indoor Comfort of an Office Room
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Henriqueta Teixeira, A. Moret Rodrigues, Daniel Aelenei and M. Glória Gomes
Energies 2024, 17(9), 2110; https://doi.org/10.3390/en17092110 (registering DOI) - 28 Apr 2024
Abstract
Electrochromic glazing alters its optical properties in the absence/presence of an electrical charge, varying from clear to dark to control daylighting and solar heat gains. This study aims to evaluate the impact of an electrochromic glazing, with indoor glare or temperature control, on
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Electrochromic glazing alters its optical properties in the absence/presence of an electrical charge, varying from clear to dark to control daylighting and solar heat gains. This study aims to evaluate the impact of an electrochromic glazing, with indoor glare or temperature control, on the energy performance and thermal and visual comfort of an office room under three European climates, using a calibrated simulation model. The novelty of the paper lies in its combined performance assessment, using different standards and metrics. The results showed reduced climatization energy requirements with temperature control, but significantly increased artificial lighting energy use. Glare control achieved useful illuminance levels during 74–80% of working hours. Concerning temperature control, working hours within thermal comfort increased (21–43%) under a free-float regime. Moreover, the performance of this glazing was compared to that of a clear glazing with/without a reflective film and a thermochromic glazing for different solar orientations. The electrochromic glazing with glare control showed the highest energy savings (14–36%) for a western orientation, and the lowest negative impact on daylighting for a northern orientation. The best glare reduction was achieved with the reflective film. Considering the free-float regime, the electrochromic glazing, with temperature control, showed the highest increase in working hours within thermal comfort (6–9%) for a western orientation.
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(This article belongs to the Special Issue Advanced Energy Systems in Energy Resilient, Zero/Positive Energy Buildings, Communities and Districts)
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Experimental Study on Ultra-Low Concentration Methane Regenerative Thermal Oxidation
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Junhui Yang, Liguo Yang, Jida Zhang, Xiaoxu Fan, Sheng Li, Luyao Zhang and Weijie Zhang
Energies 2024, 17(9), 2109; https://doi.org/10.3390/en17092109 (registering DOI) - 28 Apr 2024
Abstract
As a major coal country, China faces the issue of significant gas emissions during the coal mining process. This study aims to improve the utilization efficiency of mine gas, reduce greenhouse gas emissions, and promote the low-carbon and green transformation of the coal
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As a major coal country, China faces the issue of significant gas emissions during the coal mining process. This study aims to improve the utilization efficiency of mine gas, reduce greenhouse gas emissions, and promote the low-carbon and green transformation of the coal industry. A 10 kW gas regenerative thermal oxidizer (RTO) experimental system was constructed. The effects of initial methane concentration, low-temperature flue gas proportion, and operating load on combustion temperature, methane oxidation rate, high-temperature flue gas energy, and system thermal efficiency were studied. The results show that when the combustion temperature is below 600 °C, the CH4 combustion reaction cannot proceed effectively, and the system temperature continuously decreases and cannot be maintained stably. The experiment determines the stable operating methane concentration range of the RTO. In this experimental system, the lower limit of the initial methane concentration is 0.28%, corresponding to an 86% methane oxidation rate. As the initial methane concentration decreases, the combustion temperature also decreases, and the methane oxidation rate follows suit. The higher the low-temperature flue gas proportion, the higher the combustion temperature, and the system’s thermal efficiency and output heat decrease with the increase in the low-temperature flue gas proportion. This experiment explores multiple factors affecting regenerative thermal oxidation, providing a basis for ensuring the safe and stable operation of the system and its optimization. Improving the thermal insulation and heat exchange performance of the storage body can expand the lower limit of the initial methane concentration, thereby increasing the stability and thermal efficiency of the system.
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(This article belongs to the Topic Mining Safety and Sustainability, 2nd Volume)
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Advances in Numerical Heat Transfer and Fluid Flow
by
Artur S. Bartosik
Energies 2024, 17(9), 2108; https://doi.org/10.3390/en17092108 (registering DOI) - 28 Apr 2024
Abstract
Scientists continuously are looking for new methods that allow them to better understand the flow and heat transfer phenomena [...]
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(This article belongs to the Special Issue Numerical Heat Transfer and Fluid Flow 2023)
Open AccessArticle
Influence of Organic Matter Thermal Maturity on Rare Earth Element Distribution: A Study of Middle Devonian Black Shales from the Appalachian Basin, USA
by
Shailee Bhattacharya, Shikha Sharma, Vikas Agrawal, Michael C. Dix, Giovanni Zanoni, Justin E. Birdwell, Albert S. Wylie, Jr. and Tom Wagner
Energies 2024, 17(9), 2107; https://doi.org/10.3390/en17092107 (registering DOI) - 28 Apr 2024
Abstract
This study focuses on understanding the association of rare earth elements (REE; lanthanides + yttrium + scandium) with organic matter from the Middle Devonian black shales of the Appalachian Basin. Developing a better understanding of the role of organic matter (OM) and thermal
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This study focuses on understanding the association of rare earth elements (REE; lanthanides + yttrium + scandium) with organic matter from the Middle Devonian black shales of the Appalachian Basin. Developing a better understanding of the role of organic matter (OM) and thermal maturity in REE partitioning may help improve current geochemical models of REE enrichment in a wide range of black shales. We studied relationships between whole rock REE content and total organic carbon (TOC) and compared the correlations with a suite of global oil shales that contain TOC as high as 60 wt.%. The sequential leaching of the Appalachian shale samples was conducted to evaluate the REE content associated with carbonates, Fe–Mn oxyhydroxides, sulfides, and organics. Finally, the residue from the leaching experiment was analyzed to assess the mineralogical changes and REE extraction efficiency. Our results show that heavier REE (HREE) have a positive correlation with TOC in our Appalachian core samples. However, data from the global oil shales display an opposite trend. We propose that although TOC controls REE enrichment, thermal maturation likely plays a critical role in HREE partitioning into refractory organic phases, such as pyrobitumen. The REE inventory from a core in the Appalachian Basin shows that (1) the total REE ranges between 180 and 270 ppm and the OM-rich samples tend to contain more REE than the calcareous shales; (2) there is a relatively higher abundance of middle REE (MREE) to HREE than lighter REE (LREE); (3) there is a disproportionate increase in Y and Tb with TOC likely due to the rocks being over-mature; and (4) the REE extraction demonstrates that although the OM has higher HREE concentration, the organic leachates contain more LREE, suggesting it is more challenging to extract HREE from OM than using traditional leaching techniques.
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(This article belongs to the Special Issue Exploration and Development of Unconventional Oil and Gas Resources: Latest Advances and Prospects)
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Research on Optimal Operation of Power Generation and Consumption for Enterprises with Captive Power Plants Participating in Power Grid Supply–Demand Regulation
by
Hangming Liu, Huirong Zhao, Jincheng Yang and Daogang Peng
Energies 2024, 17(9), 2106; https://doi.org/10.3390/en17092106 (registering DOI) - 28 Apr 2024
Abstract
Wind and solar power curtailment and the difficulty of peak regulation are issues that urgently need to be addressed in the process of China’s new electric power system. Enterprises with captive power plants (ECPPs) are large-capacity power consumers and producers, with significant optimization
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Wind and solar power curtailment and the difficulty of peak regulation are issues that urgently need to be addressed in the process of China’s new electric power system. Enterprises with captive power plants (ECPPs) are large-capacity power consumers and producers, with significant optimization and adjustment potential on both the supply and demand sides. This paper aims to promote the active participation of ECPPs in grid supply–demand regulation and proposes an optimization model for the power generation and consumption of ECPPs based on a day-ahead, intra-day two-stage dispatching model. First, targeting demand response scenarios, mathematical models for analyzing the potential of ECPPs to participate in power grid supply–demand regulation are proposed. Then, an optimization model for ECPP generation and consumption with load regulation is established, and a two-stage dispatching model is proposed to fully mobilize the regulation flexibility of ECPPs. Finally, a robust dispatching model considering price uncertainty is established based on information gap decision theory. The case results show that ECPPs can reduce the curtailment rate in a region by approximately 9%, alleviate the peak pressure of the power grid, reduce carbon emissions by 1373.55 tons, and promote low-carbon development for themselves. Meanwhile, considering price uncertainty strengthens the risk resistance capability of ECPPs and provides a basis for their willingness to participate in supply–demand regulation.
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(This article belongs to the Section F2: Distributed Energy System)
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A New Approach to the Economic Evaluation of Thermomodernization: Annual Assessment Based on the Example of Production Space
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Orest Voznyak, Edyta Dudkiewicz, Marta Laska, Ievgen Antypov, Nadiia Spodyniuk, Iryna Sukholova and Olena Savchenko
Energies 2024, 17(9), 2105; https://doi.org/10.3390/en17092105 (registering DOI) - 28 Apr 2024
Abstract
Energy and economic assessments are of great relevance in the context of decision processes for the most optimal solutions for building renovations. Following the method recommended by UNIDO, economic analyses of thermal modernization options are carried out based on the Simple Payback Time
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Energy and economic assessments are of great relevance in the context of decision processes for the most optimal solutions for building renovations. Following the method recommended by UNIDO, economic analyses of thermal modernization options are carried out based on the Simple Payback Time (SPBT), Net Present Value Ratio (NPVR) and Internal Rate of Return (IRR) indices. Incorporating these indicators and a new approach that involves aggregating thermomodernization activities not only in the cold and warm seasons separately, but throughout the whole year, an economic evaluation of the thermomodernization of a production space was carried out. In this case study, the renovation options included wall insulation, window replacement, the installation of infrared heater, a two-flow air diffuser (TFAD) and variable air volume. The economic effect indicated by the highest NPVR over a normative period of 15 years was obtained for the installation of an infrared heater and a TFAD with a variable mode ventilation system. The SPBT for this case was also the lowest.
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(This article belongs to the Special Issue Internal Environment and Thermal Performance of Buildings)
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Dynamics Power Quality Cost Assessment Based on a Gradient Descent Method
by
Jingyi Zhang, Tongtian Sheng, Pan Gu, Miao Yu, Jiaxin Yan, Jianqun Sun and Shanhe Liu
Energies 2024, 17(9), 2104; https://doi.org/10.3390/en17092104 (registering DOI) - 28 Apr 2024
Abstract
The escalating demand for power load is increasingly prone to triggering power quality (PQ) issues, leading to severe economic losses. Aiming at reducing the economic losses, this paper focuses on the coordinated relationship between PQ and economic costs. Firstly, a multilayer multiple linear
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The escalating demand for power load is increasingly prone to triggering power quality (PQ) issues, leading to severe economic losses. Aiming at reducing the economic losses, this paper focuses on the coordinated relationship between PQ and economic costs. Firstly, a multilayer multiple linear stepwise regression method is employed to screen PQ indicators, identifying harmonic and voltage deviation as the primary influencing factors of PQ. Secondly, a gradient descent optimization algorithm based on the Least Absolute Shrinkage and Selection Operator (LASSO) is proposed, enabling rapid computation of the minimum PQ cost. Finally, through validations of two case studies, the results confirm that the proposed method can rapidly calculate the minimum PQ cost based on real-time load demands, enabling the dynamic adjustment of PQ cost to meet the evolving needs of power system development.
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(This article belongs to the Special Issue Intelligent Analysis and Control of Modern Power Systems)
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Open AccessArticle
A Novel PETG Microchannel Reactor for Microwave-Powered Biodiesel Production
by
Koguleshun Subramaniam, Kang Yao Wong, Kok Hoe Wong, Cheng Tung Chong and Jo-Han Ng
Energies 2024, 17(9), 2103; https://doi.org/10.3390/en17092103 (registering DOI) - 28 Apr 2024
Abstract
Biodiesel stands at the forefront as a replacement for fossil diesel in compression ignition engines, particularly in the transportation sector where diesel engines are the primary movers. However, biodiesel production is hampered by poor heat and mass transfer during the transesterification reaction, leading
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Biodiesel stands at the forefront as a replacement for fossil diesel in compression ignition engines, particularly in the transportation sector where diesel engines are the primary movers. However, biodiesel production is hampered by poor heat and mass transfer during the transesterification reaction, leading to long production times and high costs due to inefficient energy utilisation. This study targets heat and mass transfer issues during the production of biodiesel via a synergic approach that combines microwave-assisted heating and microfluidics via a polyethylene terephthalate glycol (PETG) microchannel reactor. The transesterification reaction of palm oil and methanol was investigated using a full factorial design of experiments (DOE) method. Biodiesel yield was quantified via gas chromatographic analysis, and the results were optimised using statistical analysis. Optical analysis of slug quantification within the microchannel revealed that small slugs, smaller than 1 mm, accelerated the transesterification reaction. The composite-optimised experimental results, aimed at minimising energy costs and environmental impacts while maximising fatty acid methyl ester (FAME) yield, indicate a reaction temperature of 50 °C, a catalyst loading of 1.0 wt.%, and a 3:1 methanol to oil molar ratio. Regression analysis revealed that the reaction temperature was statistically insignificant when utilising the PETG microchannel reactor. This key finding positively impacts biodiesel production as it relates to significantly reduced energy intensity, costs, and emissions. Overall, this research work paves a pathway toward an energy-efficient and sub-minute rapid transesterification reaction, highlighting the effectiveness of microwave heat delivery and effects of microfluidics via the PETG microchannel reactor in overcoming heat and mass transfer barriers in biodiesel production.
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(This article belongs to the Section A4: Bio-Energy)
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Open AccessArticle
Electromagnetic Performance Analysis of Dual-Three-Phase Dual-Rotor Flux-Switching Permanent Magnet Machines
by
Yizhi Chen, Guishu Zhao, Zhengliang Li, Zhe Chang, Shuye Ding and Yuheng Zhou
Energies 2024, 17(9), 2102; https://doi.org/10.3390/en17092102 (registering DOI) - 28 Apr 2024
Abstract
In this paper, a novel dual-three-phase dual-rotor flux-switching permanent magnet (PM) (DRFSPM) machine, building upon conventional FSPM machines, is proposed, where the stator is equipped with dual PMs and dual armature windings, enabling it to operate in various working modes and provide fault
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In this paper, a novel dual-three-phase dual-rotor flux-switching permanent magnet (PM) (DRFSPM) machine, building upon conventional FSPM machines, is proposed, where the stator is equipped with dual PMs and dual armature windings, enabling it to operate in various working modes and provide fault tolerance in the event of PM or armature winding faults. Depending on the magnetization directions of the PMs, the proposed DRFSPM machine’s structure can be categorized as 6N-DRFSPM or NS-DRFSPM. In order to assess the electromagnetic performance of the proposed DRFSPM machines with two different magnetizing modes, the topology and operating principle of the two DRFSPM machines are introduced first. Then, the no-load air-gap flux density of the two proposed machines is investigated for a more optimized and purposeful design. Finally, a comparison of the electromagnetic performance between the two proposed DRFSPM machines is conducted by finite-element analysis (FEA), and the FEA-predicted results indicate that the proposed 6N-DRFSPM machine outperforms the NS-DRFSPM machine, as it exhibits a larger back-EMF and average torque and a smaller cogging torque and torque ripple.
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(This article belongs to the Special Issue Analysis and Design of High-Energy-Efficiency Permanent Magnet Machines)
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Open AccessArticle
Design and Analysis of a Controllable Reactor Solid-State Circuit Breaker for Enhanced Fault Current Interruption in AC/DC Microgrids
by
Ali Bakhshi, Ali Moghim and Mojgan Hojabri
Energies 2024, 17(9), 2101; https://doi.org/10.3390/en17092101 (registering DOI) - 28 Apr 2024
Abstract
The occurrence of short-circuit faults in AC/DC microgrids gives rise to exceptionally high currents with rapid escalation, particularly in DC feeders where current zero-crossing is absent. This study introduces a comprehensive design procedure for a solid-state breaker tailored to address this challenge. A
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The occurrence of short-circuit faults in AC/DC microgrids gives rise to exceptionally high currents with rapid escalation, particularly in DC feeders where current zero-crossing is absent. This study introduces a comprehensive design procedure for a solid-state breaker tailored to address this challenge. A key innovation of the proposed solid-state circuit breaker lies in the incorporation of a current limiter reactor, which effectively constrains the current flow in both the load commutation switch and main breakers. Additionally, the inclusion of a resistive branch diminishes energy dissipation in the main breakers, safeguarding them against voltage stress. Consequently, the operational efficiency of the breaker is significantly enhanced, ensuring swift and efficient fault current interruption in vulnerable AC/DC microgrid scenarios. The efficacy of the proposed solid-state breaker was rigorously examined through analytical studies, and the results were validated using MATLAB/Simulink simulations. This breakthrough design represents a promising advancement in the realm of microgrid protection, offering a robust solution for mitigating the impact of short-circuit faults in AC/DC systems.
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(This article belongs to the Section F: Electrical Engineering)
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