Topic Editors

Prof. Dr. Alon Kuperman
Applied Energy Laboratory, School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
Dr. Alessandro Lampasi
National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), 00044 Frascati, Italy

Energy Storage and Conversion Systems

Abstract submission deadline
closed (15 July 2022)
Manuscript submission deadline
15 October 2022
Viewed by
24856

Topic Information

Dear Colleagues,

Energy storage and conversion are crucial topics for research and industry, especially in the perspective of a sustainable development. Scientific and technological progresses in these fields may improve the potential capabilities and the efficiency in the use of energy both traditional, renewable and unconventional sources.

Energy storage technologies, such as batteries, fuel cells, supercapacitors (ultracapacitors), superconducting magnetic energy storage (SMES), combined with reductions in costs, are creating new scenarios and opportunities in the development and the market of energy generation, grids, industrial plants, complex systems and consumer electronics.

We would like to invite submissions to this Topic to collect the latest developments and applications in these interdisciplinary fields and to provide a common framework to authors from different research areas.

The Topics of interest for publication include, but are not limited to, the following:

  • Energy storage theory and applications;
  • Energy conversion theory and applications;
  • Power electronics and converters for smart grids, microgrids and electrical/hybrid vehicles;
  • Power converters for renewable sources, such as solar, wind, hydro and marine power;
  • High-voltage direct current (HVDC) grids and conversion systems;
  • Experimental techniques for characterization and diagnosis of energy storage and conversion systems;
  • Approaches and tools for modeling and simulation;
  • Batteries technologies, processes, materials, test and modeling;
  • Fuel cells and hydrogen-based systems;
  • Supercapacitors (ultracapacitors) and lithium-ion capacitors;
  • Superconducting magnetic energy storage (SMES);
  • Thermal energy storage, cogeneration and thermal management;
  • Combination and integration of several energy sources and storage solutions;
  • Control algorithms, including artificial intelligence tools;
  • Management systems, such as battery management systems (BMS);
  • Power quality, load management, peak shaving and back-up issues;
  • Energy harvesting and recovery;
  • Reliability, resilience and safety of complex systems and grids;
  • Technical-economical evaluations and market analyses.

Prof. Dr. Alon Kuperman
Dr. Alessandro Lampasi
Topic Editors

Keywords

  • energy storage
  • energy conversion
  • renewable energy
  • power generation
  • energy management
  • power systems
  • power electronics
  • power converters
  • smart grids
  • electrical vehicles
  • batteries
  • supercapacitors
  • fuel cells
  • electrical machines and drives
  • testing and modeling

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Energies
energies
3.252 5.0 2008 16.2 Days 2200 CHF Submit
Electronics
electronics
2.690 3.7 2012 16.6 Days 2000 CHF Submit
Processes
processes
3.352 3.5 2013 13 Days 2000 CHF Submit
Electricity
electricity
- - 2020 24 Days 1000 CHF Submit
Solar
solar
- - 2021 15.0 days * 1000 CHF Submit

* Median value for all MDPI journals in the first half of 2022.


Preprints is a platform dedicated to making early versions of research outputs permanently available and citable. MDPI journals allow posting on preprint servers such as Preprints.org prior to publication. For more details about reprints, please visit https://www.preprints.org.

Published Papers (38 papers)

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Article
Optimization of Micro-CAES and TES Systems for Trigeneration
Energies 2022, 15(17), 6232; https://doi.org/10.3390/en15176232 - 26 Aug 2022
Abstract
Energy storage makes energy continuously available, programmable, and at power levels different from the original intensity. This study investigates the feasibility of compressed-air energy storage (CAES) systems on a small scale. In addition to the CAES systems, there are two TES (thermal energy [...] Read more.
Energy storage makes energy continuously available, programmable, and at power levels different from the original intensity. This study investigates the feasibility of compressed-air energy storage (CAES) systems on a small scale. In addition to the CAES systems, there are two TES (thermal energy storage) systems for the recovery of calories and frigories. The micro-CAES + TES system is designed for a single-family residential building equipped with a photovoltaic system with a nominal power of 3 kW. The system is optimized as a potential alternative to battery storage for a typical domestic photovoltaic system. The multi-objective optimization analysis is carried out with the modeFRONTIER software. Once the best configuration of the micro-CAES + TES system is identified, it is compared with electrochemical storage systems, considering costs, durability, and performance. The efficiency of CAES (8.4%) is almost one-tenth of the efficiency of the most efficient batteries on the market (70–90%). Its discharge times are also extremely short. It is shown that the advantages offered by the application of mechanical accumulation on a small scale are mainly related to the exploitation of the thermal waste of the process and the estimated useful life compared to the batteries currently on the market. The studied system proves to be non-competitive compared to batteries because of its minimal efficiency and high cost. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Communication
Expanded K0.37Fe0.04Al0.07Mn0.89O2 Layered Material as a High-Performance Cathode in Sodium-Ion Batteries
Energies 2022, 15(15), 5659; https://doi.org/10.3390/en15155659 - 04 Aug 2022
Abstract
Due to a high operating voltage and theoretical capacity, P2-type layered Mn-based metal oxides are considered to be promising cathodes in sodium-ion batteries, but their poor structural stability in the process of Na+ insertion/deinsertion severely hinders their practical application. Here, an interesting [...] Read more.
Due to a high operating voltage and theoretical capacity, P2-type layered Mn-based metal oxides are considered to be promising cathodes in sodium-ion batteries, but their poor structural stability in the process of Na+ insertion/deinsertion severely hinders their practical application. Here, an interesting K+ pre-intercalation is used to expand the interlayer distance and enhance the electrochemical reversibility of KsFexAlyMnzO2. With a suitable K+ content, the optimized electrode shows a high specific capacity of 135 mAh g−1 at 0.1 C, a good rate capability of 80 mAh g−1 at 5 C and an excellent cycling performance of 76.4% capacity retention after 200 cycles at a high rate of 5 C. This work proves the feasibility of a K+ pre-intercalation strategy in a P2-type layered cathode. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Energy Consumption Estimation for Electric Buses Based on a Physical and Data-Driven Fusion Model
Energies 2022, 15(11), 4160; https://doi.org/10.3390/en15114160 - 06 Jun 2022
Cited by 2
Abstract
The energy consumption of electric vehicles is closely related to the problems of charging station planning and vehicle route optimization. However, due to various factors, such as vehicle performance, driving habits and environmental conditions, it is difficult to estimate vehicle energy consumption accurately. [...] Read more.
The energy consumption of electric vehicles is closely related to the problems of charging station planning and vehicle route optimization. However, due to various factors, such as vehicle performance, driving habits and environmental conditions, it is difficult to estimate vehicle energy consumption accurately. In this work, a physical and data-driven fusion model was designed for electric bus energy consumption estimation. The basic energy consumption of the electric bus was modeled by a simplified physical model. The effects of rolling drag, brake consumption and air-conditioning consumption are considered in the model. Taking into account the fluctuation in energy consumption caused by multiple factors, a CatBoost decision tree model was constructed. Finally, a fusion model was built. Based on the analysis of electric bus data on the big data platform, the performance of the energy consumption model was verified. The results show that the model has high accuracy with an average relative error of 6.1%. The fusion model provides a powerful tool for the optimization of the energy consumption of electric buses, vehicle scheduling and the rational layout of charging facilities. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Preparation of a Honeycomb-like FeNi(OH/P) Nanosheet Array as a High-Performance Cathode for Hybrid Supercapacitors
Energies 2022, 15(11), 3877; https://doi.org/10.3390/en15113877 - 24 May 2022
Abstract
Polymetallic transition metal phosphides (TMPs) exhibit quasi-metallic properties and a high electrical conductivity, making them attractive for high-performance hybrid supercapacitors (HSCs). Herein, a nanohoneycomb (NHC)-like FeNi layered double hydroxide (LDH) array was grown in situ on 3D current collector nickel foam (NF), which [...] Read more.
Polymetallic transition metal phosphides (TMPs) exhibit quasi-metallic properties and a high electrical conductivity, making them attractive for high-performance hybrid supercapacitors (HSCs). Herein, a nanohoneycomb (NHC)-like FeNi layered double hydroxide (LDH) array was grown in situ on 3D current collector nickel foam (NF), which is also the nickel source during the hydrothermal process. By adjusting the amount of NaH2PO2, an incomplete phosphated FeNi(OH/P) nanosheet array was obtained. The optimized FeNi(OH/P) nanosheet array exhibited a high capacity up to 3.6 C cm−2 (408.3 mAh g−1) and an excellent long-term cycle performance (72.0% after 10,000 cycles), which was much better than FeNi LDH’s precursor. In addition, the hybrid supercapacitor (HSC) assembled with FeNi(OH/P) (cathode) and polypyrrole (PPy/C, anode) achieved an ultra-high energy density of 45 W h kg−1 at a power density of 581 W kg−1 and an excellent cycle stability (118.5%, 2000 cycles), indicating its great potential as an HSC with a high electrochemical performance. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Depositional Environment Changes during the Cenozoic in the Northeastern Margin of the Qinghai–Tibet Plateau
Processes 2022, 10(5), 1000; https://doi.org/10.3390/pr10051000 - 18 May 2022
Abstract
The uplift of the Tibetan Plateau (TP) during the late Cenozoic is thought to be one of the crucial factors controlling the Asian climate. However, the complex interaction between tectonics and climate change remains unclear. The carbon and oxygen isotopes and elementary geochemistry [...] Read more.
The uplift of the Tibetan Plateau (TP) during the late Cenozoic is thought to be one of the crucial factors controlling the Asian climate. However, the complex interaction between tectonics and climate change remains unclear. The carbon and oxygen isotopes and elementary geochemistry of rocks from the early Eocene Lulehe Formation to the Miocene Youshashan Formation in the northern margin of Qaidam Basin, shows important variations in the Rb/Sr, MgO/CaO, Sr/Cu, and V/Cr ratios, together with CMI and CIA, which are interpreted as reflecting relevant regional climate and environmental changes. Combining the above mentioned parameters, we reconstructed the evolution of the sedimentary environment in the Qaidam Basin. The climate is roughly divided into four stages: (1) warm and humid; (2) cold and dry; (3) alternations of cold and dry with warm and humid; and (4) cold and arid. At the same time, there are also minor short-term changes of dry, wet, cold, and warm in each stage. The early Eocene to Miocene climate changes in the Qaidam Basin were mainly affected by global climate changes, the uplift of the Qinghai Tibet Plateau, and the long-lasting plate collision, but there was no continuous drought due to the uplift of the Qinghai Tibet Plateau. From the early Eocene to the late Miocene, the climate of the Qaidam Basin became warm and humid. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Valve Regulated Lead Acid Battery Evaluation under Peak Shaving and Frequency Regulation Duty Cycles
Energies 2022, 15(9), 3389; https://doi.org/10.3390/en15093389 - 06 May 2022
Abstract
This work highlights the performance metrics and the fundamental degradation mechanisms of lead-acid battery technology and maps these mechanisms to generic duty cycles for peak shaving and frequency regulation grid services. Four valve regulated lead acid batteries have been tested for two peak [...] Read more.
This work highlights the performance metrics and the fundamental degradation mechanisms of lead-acid battery technology and maps these mechanisms to generic duty cycles for peak shaving and frequency regulation grid services. Four valve regulated lead acid batteries have been tested for two peak shaving cycles at different discharge rates and two frequency regulation duty cycles at different SOC ranges. Reference performance and pulse resistance tests are done periodically to evaluate battery degradation over time. The results of the studies are expected to provide a valuable understanding of lead acid battery technology suitability for grid energy storage applications. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Energy and Exergy Analysis of an Ammonia Fuel Cell Integrated System for Marine Vessels
Energies 2022, 15(9), 3331; https://doi.org/10.3390/en15093331 - 03 May 2022
Abstract
In this paper, a new integrated system of solid oxide fuel cell (SOFC)–gas turbine (GT)–steam Rankine cycle (SRC)–exhaust gas boiler (EGB) is presented, in which ammonia is introduced as a promising fuel source to meet shipping decarbonization targets. For this purpose, an SOFC [...] Read more.
In this paper, a new integrated system of solid oxide fuel cell (SOFC)–gas turbine (GT)–steam Rankine cycle (SRC)–exhaust gas boiler (EGB) is presented, in which ammonia is introduced as a promising fuel source to meet shipping decarbonization targets. For this purpose, an SOFC is presented as the main power-generation source for a specific marine propulsion plant; the GT and SRC provide auxiliary power for machinery and accommodation lighting, and steam from the waste heat boiler is used for heating seafarer accommodation. The combined system minimizes waste heat and converts it into useful work and power. Energy and exergy analyses are performed based on the first and second laws of thermodynamics. A parametric study of the effects of the variation in the SOFC current density, fuel utilization factor, superheat temperature, and SRC evaporation pressure is conducted to define the optimal operating parameters for the proposed system. In the present study, the energy and exergy efficiencies of the integrated system are 64.49% and 61.10%, respectively. These results serve as strong motivation for employing an EGB and SRC for waste heat recovery and increasing the overall energy-conversion efficiency of the system. The SRC energy and exergy efficiencies are 25.58% and 41.21%, respectively. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Topology Optimization Combined with a Parametric Algorithm for Industrial Synchronous Reluctance Motor Design
Processes 2022, 10(4), 746; https://doi.org/10.3390/pr10040746 - 12 Apr 2022
Abstract
In this paper, we propose combining topology optimization with a parametric algorithm (TOCPA) to design an industrial synchronous reluctance motor (SynRM) that satisfies super-premium efficiency (IE4). TOCPA consists of two main processes. An improved niching algorithm is proposed as an existing parametric algorithm, [...] Read more.
In this paper, we propose combining topology optimization with a parametric algorithm (TOCPA) to design an industrial synchronous reluctance motor (SynRM) that satisfies super-premium efficiency (IE4). TOCPA consists of two main processes. An improved niching algorithm is proposed as an existing parametric algorithm, and multiple optimal points were identified quickly and effectively within the design range specified by the user. Existing parametric algorithms lack the ability to find unpredictable new optimal shapes; therefore, topology optimization has been added. TOCPA converges the two optimization methods to compensate for the shortcomings of each and maximizes the advantages. In addition, the boundary surface ON–OFF method is applied to accelerate the topology optimization process. Subsequent ratio-based smoothing techniques smooth out discontinuous interfaces and remove clusters to improve the torque characteristics and reduce the manufacturing difficulty. Finally, the torque ripple was reduced using the skew technique, and mechanical stability was confirmed using a stress analysis. An IE4 industrial SynRM was successfully designed using TOCPA. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Determining the Composition of Carbonate Solvent Systems Used in Lithium-Ion Batteries without Salt Removal
Energies 2022, 15(8), 2805; https://doi.org/10.3390/en15082805 - 12 Apr 2022
Abstract
In this work, two methods were investigated for determining the composition of carbonate solvent systems used in lithium-ion (Li-ion) battery electrolytes. One method was based on comprehensive two-dimensional gas chromatography with electron ionization time-of-flight mass spectrometry (GC×GC/EI TOF MS), which often enables unknown [...] Read more.
In this work, two methods were investigated for determining the composition of carbonate solvent systems used in lithium-ion (Li-ion) battery electrolytes. One method was based on comprehensive two-dimensional gas chromatography with electron ionization time-of-flight mass spectrometry (GC×GC/EI TOF MS), which often enables unknown compound identification by their electron ionization (EI) mass spectra. The other method was based on comprehensive two-dimensional gas chromatography with flame ionization detection (GC×GC/FID). Both methods were used to determine the concentrations of six different commonly used carbonates in Li-ion battery electrolytes (i.e., ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and vinylene carbonate (VC) in model compound mixtures (MCMs), single-blind samples (SBS), and a commercially obtained electrolyte solution (COES). Both methods were found to be precise (uncertainty < 5%), accurate (error < 5%), and sensitive (limit of detection <0.12 ppm for FID and <2.7 ppm for MS). Furthermore, unlike the previously reported methods, these methods do not require removing lithium hexafluorophosphate salt (LiPF6) from the sample prior to analysis. Removal of the lithium salt was avoided by diluting the electrolyte solutions prior to analysis (1000-fold dilution) and using minimal sample volumes (0.1 µL) for analysis. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Novel Terahertz Spectroscopy Analysis for the Electrode with Carbon Nanotubes (CNTs) in Lithium-Ion Batteries
Energies 2022, 15(7), 2665; https://doi.org/10.3390/en15072665 - 05 Apr 2022
Abstract
In this study, to use carbon nanotubes (CNTs) as a conductive material instead of carbon black in cathode electrodes, their dispersions were prepared in 1-Methyl-2-pyrrolidinone (NMP) solvent by using an ultrasonic horn, and their dispersion stability was analyzed using CNTs on the formation [...] Read more.
In this study, to use carbon nanotubes (CNTs) as a conductive material instead of carbon black in cathode electrodes, their dispersions were prepared in 1-Methyl-2-pyrrolidinone (NMP) solvent by using an ultrasonic horn, and their dispersion stability was analyzed using CNTs on the formation of the network between cathode electrode constituent materials comprised of cathode material, CNTs, and current collectors, and their correlation with electrochemical performance results were investigated using various analytical techniques. Particularly, in the analysis, terahertz time domain spectroscopy (THz-TDS), a new non-destructive analysis method, was used to analyze and compare the various optical properties of the cathode’s slurries that co-existed with CNTs and cathode material, suggesting the suitability of its analytical use in the field of materials dispersion and the slurry manufacturing process for lithium-ion batteries (LIBs). In the investigated results, the sample with the highest dispersion stability of CNTs uniformly formed the networks of CNTs and cathode material in the electrode, which results in the highest electrical conductivity among all samples, and as a result, the best performance in electrochemical evaluations. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
A Techno-Economic Assessment of Fischer–Tropsch Fuels Based on Syngas from Co-Electrolysis
Processes 2022, 10(4), 699; https://doi.org/10.3390/pr10040699 - 04 Apr 2022
Cited by 1
Abstract
As a part of the worldwide efforts to substantially reduce CO2 emissions, power-to-fuel technologies offer a promising path to make the transport sector CO2-free, complementing the electrification of vehicles. This study focused on the coupling of Fischer–Tropsch synthesis for the [...] Read more.
As a part of the worldwide efforts to substantially reduce CO2 emissions, power-to-fuel technologies offer a promising path to make the transport sector CO2-free, complementing the electrification of vehicles. This study focused on the coupling of Fischer–Tropsch synthesis for the production of synthetic diesel and kerosene with a high-temperature electrolysis unit. For this purpose, a process model was set up consisting of several modules including a high-temperature co-electrolyzer and a steam electrolyzer, both of which were based on solid oxide electrolysis cell technology, Fischer–Tropsch synthesis, a hydrocracker, and a carrier steam distillation. The integration of the fuel synthesis reduced the electrical energy demand of the co-electrolysis process by more than 20%. The results from the process simulations indicated a power-to-fuel efficiency that varied between 46% and 67%, with a decisive share of the energy consumption of the co-electrolysis process within the energy balance. Moreover, the utilization of excess heat can substantially to completely cover the energy demand for CO2 separation. The economic analysis suggests production costs of 1.85 €/lDE for the base case and the potential to cut the costs to 0.94 €/lDE in the best case scenario. These results underline the huge potential of the developed power-to-fuel technology. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Solidified-Air Energy Storage: Conceptualization and Thermodynamic Analysis
Energies 2022, 15(6), 2159; https://doi.org/10.3390/en15062159 - 16 Mar 2022
Abstract
Grid-scale electrical energy storage (EES) is a key component in cost-effective transition scenarios to renewable energy sources. The requirement of scalability favors EES approaches such as pumped-storage hydroelectricity (PSH) or compressed-air energy storage (CAES), which utilize the cheap and abundant storage materials water [...] Read more.
Grid-scale electrical energy storage (EES) is a key component in cost-effective transition scenarios to renewable energy sources. The requirement of scalability favors EES approaches such as pumped-storage hydroelectricity (PSH) or compressed-air energy storage (CAES), which utilize the cheap and abundant storage materials water and air, respectively. To overcome the site restriction and low volumetric energy densities attributed to PSH and CAES, liquid-air energy storage (LAES) has been devised; however, it suffers from a rather small round-trip efficiency (RTE) and challenging storage conditions. Aiming to overcome these drawbacks, a novel system for EES is developed using solidified air (i.e., clathrate hydrate of air) as the storable phase of air. A reference plant for solidified-air energy storage (SAES) is conceptualized and modeled thermodynamically using the software CoolProp for water and air as well as empirical data and first-order approximations for the solidified air (SA). The reference plant exhibits a RTE of 52% and a volumetric storage density of 47 kWh per m3 of SA. While this energy density relates to only one half of that in LAES plants, the modeled RTE of SAES is comparable already. Since improved thermal management and the use of thermodynamic promoters can further increase the RTEs in SAES, the technical potential of SAES is in place already. Yet, for a successful implementation of the concept—in addition to economic aspects—questions regarding the stability of SA must be first clarified and challenges related to the processing of SA resolved. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Analysis of a Wind-Driven Air Compression System Utilising Underwater Compressed Air Energy Storage
Energies 2022, 15(6), 2142; https://doi.org/10.3390/en15062142 - 15 Mar 2022
Cited by 1
Abstract
The increasing push for renewable penetration into electricity grids will inevitably lead to an increased requirement for grid-scale energy storage at multiple time scales. It will, necessarily, lead to a higher proportion of the total energy consumed having been passed through storage. Offshore [...] Read more.
The increasing push for renewable penetration into electricity grids will inevitably lead to an increased requirement for grid-scale energy storage at multiple time scales. It will, necessarily, lead to a higher proportion of the total energy consumed having been passed through storage. Offshore wind is a key technology for renewable penetration, and the co-location of energy storage with this wind power provides significant benefits. A novel generation-integrated energy storage system is described here in the form of a wind-driven air compressor feeding underwater compressed air energy storage. A direct drive compressor would require very high intake swept volumes. To overcome this difficulty, some prior compression is introduced. This paper discusses the constituent technologies for this concept, as well as the various configurations that it might take and the logic behind operating it. Special consideration has been given to the differences resulting from utilising a near-isothermal wind-driven compressor versus a near-adiabatic one. Multiple iterations of the system have been simulated. This has been done using a price-matching algorithm to optimise the system operation and using volumetric air flow rates to calculate exergy flow. Simulated operation has been performed for a year of real wind and electricity price data. This work has been performed in order to clarify the relationships between several key parameters in the system, including pressure and work ratios, volumetric flowrates, storage costs and profit rates. An additional objective of this paper was to determine whether the system has the potential for economic viability in some future energy grid, especially when compared with alternative wind and energy storage solutions. The results of the simulation indicated that, with proper sizing, the system might perform competitively with these alternatives. Maximum one-year return on investment values of 9.8% for the isothermal case and 13% for the adiabatic case were found. These maxima were reached with ~15–20 h of output storage. In all cases, it was found that maximising the power of the wind-driven compressor compared with the initial compressor was favourable. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
A Robust Algorithm for State-of-Charge Estimation under Model Uncertainty and Voltage Sensor Bias
Energies 2022, 15(4), 1537; https://doi.org/10.3390/en15041537 - 19 Feb 2022
Cited by 1
Abstract
Accurate estimation of the state of charge (SOC) of zinc–nickel single-flow batteries (ZNBs) is an important problem in battery management systems (BMSs). A nonideal electromagnetic environment will usually cause the measured signal to contain nonnegligible noise and bias. At the same time, due [...] Read more.
Accurate estimation of the state of charge (SOC) of zinc–nickel single-flow batteries (ZNBs) is an important problem in battery management systems (BMSs). A nonideal electromagnetic environment will usually cause the measured signal to contain nonnegligible noise and bias. At the same time, due to the influence of battery ageing, environmental temperature changes, and a complex reaction mechanism, it is difficult to establish a very accurate system model that can be applied to various complex working conditions. The unscented Kalman filter (UKF) is a widely used SOC estimation algorithm, but the UKF will reduce the estimation accuracy and divergence under the influence of inaccurate model and sensor errors. To improve the performance of the UKF, a robust desensitized unscented Kalman filter (RDUKF) is proposed to realize an accurate SOC estimation of batteries in the context of different disturbances. Then, the proposed method is applied to cases of error interference, such as Gaussian noise, voltage sensor drift, an unknown initial state, and inaccurate model parameters. The simulation and experimental results show that compared with the standard UKF algorithm, the proposed estimation algorithm can effectively suppress the influence of various errors and disturbances and achieve higher accuracy and robustness. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
State of Charge Dual Estimation of a Li-ion Battery Based on Variable Forgetting Factor Recursive Least Square and Multi-Innovation Unscented Kalman Filter Algorithm
Energies 2022, 15(4), 1529; https://doi.org/10.3390/en15041529 - 18 Feb 2022
Cited by 1
Abstract
Battery management is the key technical link for electric vehicles. A good battery management system can realize the balanced charge and discharge of batteries, reducing the capacity degradation and the loss of health caused by battery overcharge and discharge, which all depend on [...] Read more.
Battery management is the key technical link for electric vehicles. A good battery management system can realize the balanced charge and discharge of batteries, reducing the capacity degradation and the loss of health caused by battery overcharge and discharge, which all depend on the real-time and accurate estimation of the battery’s state of charge (SOC). However, the battery’s SOC has highly complex nonlinear time-varying characteristics related to the complex chemical and physical state and dynamic environmental conditions, which are difficult to measure directly, and this has become a difficulty in design and research. According to the characteristics of ternary lithium-ion batteries of electric vehicles, a battery SOC dual estimation algorithm based on the Variable Forgetting Factor Recursive Least Square (VFFRLS) and Multi-Innovation Unscented Kalman Filter (MIUKF) is proposed in this paper. The VFFRLS algorithm is used to estimate battery model parameters, and the MIUKF algorithm is used to estimate the battery’s SOC in real time. The two algorithms are coupled to update battery model parameters and estimate the SOC. The experiment results show that the algorithm has high accuracy and stability. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Study on Heat Transfer Process and Fresh Water Output Performance of Phase Change Heat Storage Dehumidifier
Energies 2022, 15(4), 1504; https://doi.org/10.3390/en15041504 - 17 Feb 2022
Abstract
In the humidification-dehumidification solar desalination process, using phase change materials to recover water vapor condensation latent heat in the dehumidification can improve heat utilization and water production performances. When sodium thiosulfate pentahydrate and paraffin were used as phase change materials respectively in the [...] Read more.
In the humidification-dehumidification solar desalination process, using phase change materials to recover water vapor condensation latent heat in the dehumidification can improve heat utilization and water production performances. When sodium thiosulfate pentahydrate and paraffin were used as phase change materials respectively in the phase change heat storage dehumidifier, by means of numerical simulation and experiment, the heat transfer process, entropy generation, and water production performances of heat pipes and copper wire meshes coupled phase change materials in the dehumidifier were studied. The results showed that sodium thiosulfate pentahydrate has stronger heat transfer ability, higher thermal entropy generation, and heat storage capacity than paraffin; adding copper wire meshes into the phase change material can accelerate heat transfer and shorten the time required for monitoring points to reach phase change temperature; increasing the wet air temperature at inlet of phase change heat storage dehumidifier, using copper wire meshes in the phase change material, increasing the diameter of copper wire mesh, and using a passive basin desalinator for secondary water production can improve water production performances. In brief, the use of sodium thiosulfate pentahydrate and copper wire meshes in the phase change heat storage dehumidifier leads to better heat storage and heat transfer effects. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Improvement in the Electrochemical Properties of Lithium Metal by Heat Treatment: Changes in the Chemical Composition of Native and Solid Electrolyte Interphase Films
Energies 2022, 15(4), 1419; https://doi.org/10.3390/en15041419 - 15 Feb 2022
Abstract
This study aims to improve the electrochemical properties of lithium metal for application as a negative electrode in high-energy-density batteries. Lithium metal was heat-treated at varying temperatures to modify the native and solid electrolyte interphase (SEI) films, which decreased the interfacial resistance between [...] Read more.
This study aims to improve the electrochemical properties of lithium metal for application as a negative electrode in high-energy-density batteries. Lithium metal was heat-treated at varying temperatures to modify the native and solid electrolyte interphase (SEI) films, which decreased the interfacial resistance between the lithium electrode and electrolyte, thereby improving the cycling performance. Moreover, the influence of the native and SEI films on lithium metals depended on the heat-treatment temperature. Accordingly, X-ray photoelectron spectroscopy (XPS) was performed to investigate the chemical composition of the native and SEI films on the heat-treated lithium metals before and after immersion in an organic electrolyte solution. The XPS results revealed the high dependence of the chemical composition of the outer layer of the native and SEI films on the heat-treatment temperature, implying that the native and SEI films can be effectively modified by heat treatment. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Modeling and Design of High-Power Enhanced Leakage-Inductance-Integrated Medium-Frequency Transformers for DAB Converters
Energies 2022, 15(4), 1361; https://doi.org/10.3390/en15041361 - 14 Feb 2022
Cited by 1
Abstract
For dual active bridge (DAB) converters, integrating the phase-shifting inductance (PSI) in the medium-frequency transformer (MFT) is an effective way to improve the overall power density. Different from the existing leakage-inductance-integrated (LII) structure, a concentric-winding (CW) enhanced leakage-inductance-integrated (ELII) structure, which includes an [...] Read more.
For dual active bridge (DAB) converters, integrating the phase-shifting inductance (PSI) in the medium-frequency transformer (MFT) is an effective way to improve the overall power density. Different from the existing leakage-inductance-integrated (LII) structure, a concentric-winding (CW) enhanced leakage-inductance-integrated (ELII) structure, which includes an additional core, is proposed in this paper. In order to explain the operating mode of CW ELII MFT, a magnetic circuit model is established, and the analysis is carried out under the typical DAB excitation. The total leakage inductance of CW ELII MFT is divided into the winding leakage inductance and the additional leakage inductance for calculation. The integrated structure makes the heat dissipation of the MFT challenging. Therefore, the air–water combined cooling method is adopted in the design. A thermal resistance model is built for the winding air channel under forced convection. On this basis, MFT designs with different integration structures for different leakage inductance requirements are compared. Finally, a 200 kW/4 kHz/200 μH MFT prototype was designed and manufactured, which achieved the power density of 5.16 kW/dm3 and the efficiency of 99.30%. The prototype was tested in a DAB converter, which is a module of a 2 MW modular multilevel converter-bidirectional DC–DC converter (MMC-BDC). Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Stress Coupling Analysis and Failure Damage Evaluation of Wind Turbine Blades during Strong Winds
Energies 2022, 15(4), 1339; https://doi.org/10.3390/en15041339 - 12 Feb 2022
Cited by 1
Abstract
Blades in strong wind conditions are prone to various failures and damage that is due to the action of random variable amplitude loads. In this study, we analyze the failure of 1.5 MW horizontal axis wind turbine blades. The computational fluid dynamics unsteady [...] Read more.
Blades in strong wind conditions are prone to various failures and damage that is due to the action of random variable amplitude loads. In this study, we analyze the failure of 1.5 MW horizontal axis wind turbine blades. The computational fluid dynamics unsteady calculation method is used to simulate the aerodynamic load distribution on the blade. Fluid–structure coupling methods are applied to calculate the blade stress. The results show that the equivalent stress of the blade is the largest when the azimuth angle is 30°, and the maximum equivalent stress is 20.60 MPa. There are obvious stress peaks in six sections, such as r/R = 0.10 (the span length of blade/the full length of the blade = 0.10). The frequency of damage that is caused by the stress in each area of the blade is determined based on the blade damage. The frequency of gel coat cracking in the blade tips and leaves is 77.78% and 22.22%, respectively, and the frequency of crack occurrence is 87.75%, 10.20% and 2.05%, respectively. By combining the stress concentration area and the damage results, the cause of blade damage is determined, which can replace the traditional inspection methods and improve the inspection efficiency. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Polarization Voltage Characterization of Lithium-Ion Batteries Based on a Lumped Diffusion Model and Joint Parameter Estimation Algorithm
Energies 2022, 15(3), 1150; https://doi.org/10.3390/en15031150 - 04 Feb 2022
Cited by 2
Abstract
Polarization is a universal phenomenon that occurs inside lithium-ion batteries especially during operation, and whether it can be accurately characterized affects the accuracy of the battery management system. Model-based approaches are commonly adopted in studies of the characterization of polarization. Towards the application [...] Read more.
Polarization is a universal phenomenon that occurs inside lithium-ion batteries especially during operation, and whether it can be accurately characterized affects the accuracy of the battery management system. Model-based approaches are commonly adopted in studies of the characterization of polarization. Towards the application of the battery management system, a lumped diffusion model with three parameters was adopted. In addition, a joint algorithm composed of the Particle Swarm Optimization algorithm and the Levenberg-Marquardt method is proposed to identify model parameters. Verification experiments showed that this proposed algorithm can significantly improve the accuracy of model output voltages compared to the Particle Swarm Optimization algorithm alone and the Levenberg-Marquardt method alone. Furthermore, to verify the real-time performance of the proposed method, a hardware implementation platform was built, and this system’s performance was tested under actual operating conditions. Results show that the hardware platform is capable of realizing the basic function of quantitative polarization voltage characterization, and the updating frequency of relevant parameters can reach 1 Hz, showing good real-time performance. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Numerical Study on Pool Film Boiling of Liquid Hydrogen over Horizontal Cylinders
Energies 2022, 15(3), 1044; https://doi.org/10.3390/en15031044 - 30 Jan 2022
Cited by 1
Abstract
Due to the low boiling point of hydrogen, the boiling phenomenon is usually encountered in the applications of liquid hydrogen. The underlying mechanism as well as the physical performance of film boiling over horizontal cylinders are not yet fully understood, especially for the [...] Read more.
Due to the low boiling point of hydrogen, the boiling phenomenon is usually encountered in the applications of liquid hydrogen. The underlying mechanism as well as the physical performance of film boiling over horizontal cylinders are not yet fully understood, especially for the various diameters. In this paper, pool film boiling of hydrogen over horizontal cylinders with diameters ranging from 0.2 to 30 mm is investigated based on the volume-of-fluid method. By the analysis of the gas–liquid interface evolution and the heat transfer mechanism, the cylinders are divided into wire heaters, transition heaters, and tube heaters. The results show that the heat transfer of the wire is affected by the evolution of a single bubble, while the heat transfer of the tube is mainly affected by the movement of multiple crescent-shaped gas structures along the surface. Besides, with the increase in cylinder diameter, the bubble detachment diameter increases, the heat flux decreases correspondingly, and the bubble growth period experiences a complicated principle. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Thermal Performance Improvement for Different Strategies of Battery Thermal Management Systems Combined with Jute—A Comparison Study
Energies 2022, 15(3), 873; https://doi.org/10.3390/en15030873 - 25 Jan 2022
Cited by 3
Abstract
Jute is a cheap, eco-friendly, widely available material well-known for its cooling properties. In electric vehicles (EVs), dissipating a huge amount of the heat generated from lithium-ion batteries with an efficient, light, and low-power consumption battery thermal management system (BTMS) is required. In [...] Read more.
Jute is a cheap, eco-friendly, widely available material well-known for its cooling properties. In electric vehicles (EVs), dissipating a huge amount of the heat generated from lithium-ion batteries with an efficient, light, and low-power consumption battery thermal management system (BTMS) is required. In our previous study, jute fibers were proposed and investigated as a novel medium to enhance the cooling efficiency of air-based battery thermal management systems. In this paper, as the first attempt, jute was integrated with a phase change material (PCM) passive cooling system, and the thermal performance of a 50 Ah prismatic battery was studied. Temperature evolution, uniformity, and cooling efficiency were investigated. A comparison between the thermal behavior of the air-based BTMS and PCM-assisted cooling system was performed. The results indicated that adding jute to the BTMS increased the cooling efficiency and especially decreased the temperature development. Furthermore, the temperature difference (ΔT) efficiency was enhanced by 60% when integrating jute with PCM, and temperature uniformity improved by 3% when integrating jute with air-based BTMS. This article compared the integration of jute with active cooling and passive cooling; thus, it shed light on the importance of jute as a novel, eco-friendly, lightweight, cheap, available, and nontoxic material added to two strategies of BTMS. The setup was physically made and experimentally studied for the purpose of BTMS optimization. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Planning Method and Principles of the Cloud Energy Storage Applied in the Power Grid Based on Charging and Discharging Load Model for Distributed Energy Storage Devices
Processes 2022, 10(2), 194; https://doi.org/10.3390/pr10020194 - 20 Jan 2022
Abstract
The cloud energy storage system (CES) is a shared distributed energy storage resource. The random disordered charging and discharging of large-scale distributed energy storage equipment has a great impact on the power grid. This paper solves two problems. On one hand, to present [...] Read more.
The cloud energy storage system (CES) is a shared distributed energy storage resource. The random disordered charging and discharging of large-scale distributed energy storage equipment has a great impact on the power grid. This paper solves two problems. On one hand, to present detailed plans for designing an orderly controlled CES system in a realistic power system. On the other hand, Monte Carlo simulation (MCS) is used for analyzing the load curves of five types of distributed energy storage systems to manage and operate the CES system. A method of its planning and the principles of CES for applied in a power grid, are presented by analyzing the impact based on five load curves including the electric vehicle (EV), the ice storage system, the demand response, the heat storage system, and the decentralized electrochemical energy storage system. The MCS simulates the random charging and discharging of the system over a five-year planned scaling of distributed energy storage from 2021 through 2025. The influence of distributed energy storage systems on power grid capacity, load characteristics, and safety margins is researched to summarize the applicable fields of CES in supporting large power grids. Finally, important conclusions are summarized and other research possibilities in this field are presented. This paper represents a significant reference for planners. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Grid and PV Fed Uninterruptible Induction Motor Drive Implementation and Measurements
Energies 2022, 15(3), 708; https://doi.org/10.3390/en15030708 - 19 Jan 2022
Cited by 2
Abstract
Motors powered directly from solar panels are becoming more and more popular in pump applications. However, solar panels can be the source of operational issues due to varying irradiance, ambient temperature, weather. This paper shows how it is worth expanding a solar induction [...] Read more.
Motors powered directly from solar panels are becoming more and more popular in pump applications. However, solar panels can be the source of operational issues due to varying irradiance, ambient temperature, weather. This paper shows how it is worth expanding a solar induction motor drive to provide an uninterrupted flow of electricity to the motor. In addition, the main components of the uninterruptible induction motor drive are presented, including the LLC (inductor-inductor-capacitor) converter, the three-phase inverter, and the three-phase rectifier. LLC converters that can increase the voltage from 25–40 V to 330 V cannot be bought directly from manufacturers. Therefore, a custom LLC converter was made for the research. It was necessary to build a custom converter to avoid the use of solar panel strings. This way, solar panels connected in parallel can be used. A low-voltage (25–40 V) supply was implemented from the solar side, while the induction motor requires 230 V AC three-phase voltage in delta connection. For this reason, a voltage boost is required from the low voltage side. The grid feeds the universal DC link through the three-phase rectifier. This allows the motor to consume varying amounts of electricity from the grid or the solar panel. The study also presents in detail the LLC converter that performs the voltage boost. Measuring the entire motor drive, switching transients and efficiencies can be observed at different input voltages for different supplies as well as loads. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Review
Review of Carnot Battery Technology Commercial Development
Energies 2022, 15(2), 647; https://doi.org/10.3390/en15020647 - 17 Jan 2022
Cited by 6
Abstract
Carnot batteries are a quickly developing group of technologies for medium and long duration electricity storage. It covers a large range of concepts which share processes of a conversion of power to heat, thermal energy storage (i.e., storing thermal exergy) and in times [...] Read more.
Carnot batteries are a quickly developing group of technologies for medium and long duration electricity storage. It covers a large range of concepts which share processes of a conversion of power to heat, thermal energy storage (i.e., storing thermal exergy) and in times of need conversion of the heat back to (electric) power. Even though these systems were already proposed in the 19th century, it is only in the recent years that this field experiences a rapid development, which is associated mostly with the increasing penetration of intermittent cheap renewables in power grids and the requirement of electricity storage in unprecedented capacities. Compared to the more established storage options, such as pumped hydro and electrochemical batteries, the efficiency is generally much lower, but the low cost of thermal energy storage in large scale and long lifespans comparable with thermal power plants make this technology especially feasible for storing surpluses of cheap renewable electricity over typically dozens of hours and up to days. Within the increasingly extensive scientific research of the Carnot Battery technologies, commercial development plays the major role in technology implementation. This review addresses the gap between academia and industry in the mapping of the technologies under commercial development and puts them in the perspective of related scientific works. Technologies ranging from kW to hundreds of MW scale are at various levels of development. Some are still in the stage of concepts, whilst others are in the experimental and pilot operations, up to a few commercial installations. As a comprehensive technology review, this paper addresses the needs of both academics and industry practitioners. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Analysis of Stand-Alone Photovoltaic—Marine Current Hybrid System and the Influence on Daily and Seasonal Energy Storage
Energies 2022, 15(2), 468; https://doi.org/10.3390/en15020468 - 10 Jan 2022
Abstract
Stand-alone systems in remote regions require the utilization of renewable resources; however, their natural intermittence requires the implementation of energy-storage systems that allow a continuous power supply. More than one renewable source is usually available at the same site. Thus, the choice of [...] Read more.
Stand-alone systems in remote regions require the utilization of renewable resources; however, their natural intermittence requires the implementation of energy-storage systems that allow a continuous power supply. More than one renewable source is usually available at the same site. Thus, the choice of a hybrid system seems viable. It is relevant to study hybrid systems as they could reduce energy storage; however, sizing the hybrid system might have several implications, not only for the available daily energy, but also for the required daily energy storage and surplus seasonal energy. In this work, we present a case study of a stand-alone, conventional household powered by photovoltaic and marine-current-energy systems in Cozumel, Mexico. The analysis of different hybridization degrees serves as a guidance tool to decide whether hybrid systems are required for a specific situation; in contrast to previous approaches, where ideal consumption and generation profiles have been utilized, yearlong profiles were utilized here. The renewable potential data were obtained on site at an hourly resolution; requirements such as size of and cycles in the daily and seasonal energy storage were analyzed according to the degree of participation or hybridization of the proposed renewable systems through an algorithm that evaluates power generation and daily consumption throughout the year. A further analysis indicated that marine-current-energy implementation reduces the size of the daily energy-storage system by 79% in comparison to the use of only a photovoltaic system due to the similarity between the energy-demand profile and the marine-current-energy production profile. The results indicate that a greater participation of marine currents can help decrease daily storage while increasing seasonal storage by 16% compared to using only solar energy. On the other hand, hybridization enabled a reduction in the number of daily charge and discharge cycles at 0.2 hybridization degrees. It also allowed us to reduce the seasonal energy storage by 38% at 0.6 hybridization degrees with respect to only using energy from marine currents. Afterwards, energy-storage technologies were evaluated using the TOPSIS Multi-Criteria Decision Analysis to validate the best-suited technology for the energy-storage system. The evaluation considered the characteristics of the technology and the periods of energy storage. In this work, hybrid storage systems were mandatory since, for daily storage, lithium-ion batteries are better suited, while for seasonal storage, hydrogen-producing systems are more suitable to manage the amount of energy and the storage duration due to the high seasonal renewable-energy variations. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Heat Transfer Enhancement by Perforated and Louvred Fin Heat Exchangers
Energies 2022, 15(2), 400; https://doi.org/10.3390/en15020400 - 06 Jan 2022
Cited by 1
Abstract
Multi-tube multi-fin heat exchangers are extensively used in various industries. In the current work, detailed experimental investigations were carried out to establish the flow/heat transfer characteristics in three distinct heat exchanger geometries. A novel perforated plain fin design was developed, and its performance [...] Read more.
Multi-tube multi-fin heat exchangers are extensively used in various industries. In the current work, detailed experimental investigations were carried out to establish the flow/heat transfer characteristics in three distinct heat exchanger geometries. A novel perforated plain fin design was developed, and its performance was evaluated against standard plain and louvred fins designs. Experimental setups were designed, and the tests were carefully carried out which enabled quantification of the heat transfer and pressure drop characteristics. In the experiments the average velocity of air was varied in the range of 0.7 m/s to 4 m/s corresponding to Reynolds numbers of 600 to 2650. The water side flow rates in the tubes were kept at 0.12, 0.18, 0.24, 0.3, and 0.36 m3/h corresponding to Reynolds numbers between 6000 and 30,000. It was found that the louvred fins produced the highest heat transfer rate due to the availability of higher surface area, but it also produced the highest pressure drops. Conversely, while the new perforated design produced a slightly higher pressure drop than the plain fin design, it gave a higher value of heat transfer rate than the plain fin especially at the lower liquid flow rates. Specifically, the louvred fin gave consistently high pressure drops, up to 3 to 4 times more than the plain and perforated models at 4 m/s air flow, however, the heat transfer enhancement was only about 11% and 13% over the perforated and plain fin models, respectively. The mean heat transfer rate and pressure drops were used to calculate the Colburn and Fanning friction factors. Two novel semiempirical relationships were derived for the heat exchanger’s Fanning and Colburn factors as functions of the non-dimensional fin surface area and the Reynolds number. It was demonstrated that the Colburn and Fanning factors were predicted by the new correlations to within ±15% of the experiments. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
The Bi-Level Optimization Model Research for Energy-Intensive Load and Energy Storage System Considering Congested Wind Power Consumption
Processes 2022, 10(1), 51; https://doi.org/10.3390/pr10010051 - 27 Dec 2021
Abstract
Due to the uncertainty of wind power output, the congestion of wind power has become prominent. Exactly how to improve the capacity of wind power consumption has become a problem that needs to be studied urgently. In this paper, an energy storage system [...] Read more.
Due to the uncertainty of wind power output, the congestion of wind power has become prominent. Exactly how to improve the capacity of wind power consumption has become a problem that needs to be studied urgently. In this paper, an energy storage system and energy-extensive load with adjustable characteristics are used as an important means of consuming wind power. Firstly, we analyze the reasons for the congestion according to the characteristics of wind power output, and establish a model of the grid’s ability to integrate wind power based on the concept of a wind power admissible interval. Secondly, we analyze the energy-extensive load regulation characteristics and establish an energy-extensive load dispatch model. Thirdly, on the basis of considering the energy-extensive load and energy storage system adjustment constraints, a bi-level optimization model is established. The upper level determines the configured capacity of the energy storage system with the goal of minimizing the total economic investment of the energy storage system, and the lower level coordinates the dispatching with the goal of maximizing wind power consumption and minimizing system operating costs. Finally, a certain region is taken as an example to verify the validity of the proposed method. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Flow Stability in a Miniature Centrifugal Pump under the Periodic Pulse Flow
Energies 2021, 14(24), 8338; https://doi.org/10.3390/en14248338 - 10 Dec 2021
Abstract
The flow behavior inside a miniature centrifugal pump, under a periodic pulse flow rate, was studied by means of numerical simulation. For a given incoming periodic pulse flow with a sine wave, the performance of the centrifugal pump was investigated in the section [...] Read more.
The flow behavior inside a miniature centrifugal pump, under a periodic pulse flow rate, was studied by means of numerical simulation. For a given incoming periodic pulse flow with a sine wave, the performance of the centrifugal pump was investigated in the section with increasing flow and the section with decreasing flow, and the special points of the flow rate and the periodic flow were identified. Further, the energy gradient method and the Q-criterion were adopted to analyze the internal vertical structure and flow stability. It was found that the regions with large variations in velocity and total pressure were mainly located at the leading edge of the suction surface and the middle area of the pressure surface of the blades. Irregular pressure fluctuation frequency under the periodic pulse flow was shown; this was mainly concentrated in the low-frequency zones close to the impeller’s rotational frequency. In addition, for the same flow rate in the periodic pulse flow, the pressure frequency fluctuation for the increasing flow rate section was higher than that observed for the decreasing flow rate section. It was found that the most unstable sections appeared in the first half-period of the flow rate variation (large flow rate), according to the distributions of the Q criteria of the vortex and the energy gradient function K. In this section, motions of strong vortices led to large gradients of the mechanical energy. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Distributed Control Strategy of Single-Phase Battery Systems for Compensation of Unbalanced Active Powers in a Three-Phase Four-Wire Microgrid
Energies 2021, 14(24), 8287; https://doi.org/10.3390/en14248287 - 09 Dec 2021
Abstract
Unbalanced active powers can affect power quality and system reliability due to high penetration and uneven allocation of single-phase photovoltaic (PV) rooftop systems and load demands in a three-phase four-wire microgrid. This paper proposes a distributed control strategy to alleviate the unbalanced active [...] Read more.
Unbalanced active powers can affect power quality and system reliability due to high penetration and uneven allocation of single-phase photovoltaic (PV) rooftop systems and load demands in a three-phase four-wire microgrid. This paper proposes a distributed control strategy to alleviate the unbalanced active powers using distributed single-phase battery storage systems. In order to balance the unbalanced active powers at the point of common coupling (PCC) in a distributed manner, the agents (households’ single-phase battery storage systems) must have information on the active powers and phases. Inspired by supervised learning, a clustering approach was developed to use labels in order to match the three-phase active powers at the PCC with the agents’ phases. This enables the agent to select the correct active power data from the three-phase active powers. Then, a distributed power balancing control strategy is applied by all agents to compensate the unbalanced active powers. Each agent calculates the average grid power based on information received from its neighbours so that all agents can then cooperatively operate in either charging or discharging modes to achieve the compensation. As an advantage, the proposed distributed control strategy offers the battery owners flexibility to participate in the strategy. Case studies comparing performance of local, centralized, and the proposed distributed strategy on a modified IEEE-13-bus test system with real household PV powers and load demands are provided. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Flexible Films as Anode Materials Based on rGO and TiO2/MnO2 in Li-Ion Batteries Free of Non-Active Agents
Energies 2021, 14(23), 8168; https://doi.org/10.3390/en14238168 - 06 Dec 2021
Abstract
Recently, to meet the growing demand for stable and flexible batteries, anodes in the form of thin films have drawn the attention of researchers. It is clear that mass production of such batteries would bring the worldwide distribution of flexible devices and wearable [...] Read more.
Recently, to meet the growing demand for stable and flexible batteries, anodes in the form of thin films have drawn the attention of researchers. It is clear that mass production of such batteries would bring the worldwide distribution of flexible devices and wearable electronics closer. Currently, electrodes are deposited on a flexible substrate and consist of conductive and binding agents that increase the volume/weight of the electrode. Here, we propose free-standing and non-active-material-free thin films based on reduced graphene oxide (rGO), titanium dioxide (TiO2) and manganese dioxide (MnO2) as working electrodes in lithium-ion half-cells prepared via the vacuum-assisted filtration method. The electrochemical performance of the assembled half-cells exhibited good cyclic stability and a reversible capacity at lower current densities. The addition of TiO2 and MnO2 improved the capacity of the rGO film, while rGO itself provided a stable rate performance. rGO/TiO2/MnO2 film showed the highest discharge capacity (483 mAh/g at 50 mA/g). In addition, all assembled cells displayed excellent repeatability and reversibility in cyclic voltammetry measurements and good lithium-ion diffusion through the electrolyte, SEI layer and the active material itself. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Review
A Review on the Challenges of Using Zeolite 13X as Heat Storage Systems for the Residential Sector
Energies 2021, 14(23), 8062; https://doi.org/10.3390/en14238062 - 02 Dec 2021
Abstract
In recent years, several attempts have been made to promote renewable energy in the residential sector to help reducing its CO2 emissions. Among existing approaches utilizing substances capable of directly storing and transporting thermal energy has recently become a point of interest. [...] Read more.
In recent years, several attempts have been made to promote renewable energy in the residential sector to help reducing its CO2 emissions. Among existing approaches utilizing substances capable of directly storing and transporting thermal energy has recently become a point of interest. Zeolite 13X with exceptional capacity to safely store thermal energy for long periods and release heat due to its unique molecular structure is known to be one of the best options serving this purpose. However, the application of this ceramic as a heat storage material in the residential sector is associated with significant challenges dictated by the limitations of the sector, such as space restrictions and affordability. The current review attempts to explore the extent of these challenges, mainly related to design and efficiency from different perspectives. The main aim here is to provide a clear vision for a better understanding of the state of the art of this technology and to help to identify possible solutions fostering the adaptation of this technology to the residential sector. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Development of a Smart Supercapacitor Energy Storage System for Aircraft Electric Power Systems
Energies 2021, 14(23), 8056; https://doi.org/10.3390/en14238056 - 02 Dec 2021
Cited by 3
Abstract
This paper presents the development of a supercapacitor energy storage system (ESS) aimed to minimize weight, which is very important for aerospace applications, whilst integrating smart functionalities like voltage monitoring, equalization, and overvoltage protection for the cells. The methodology for selecting the supercapacitor [...] Read more.
This paper presents the development of a supercapacitor energy storage system (ESS) aimed to minimize weight, which is very important for aerospace applications, whilst integrating smart functionalities like voltage monitoring, equalization, and overvoltage protection for the cells. The methodology for selecting the supercapacitor cells type/size is detailed to achieve the safest and most energy-dense ESS. Additionally, the development of the interface electronics for cells’ voltage monitoring and overvoltage protection is presented. The proposed design implements a modular distributed architecture coordinated using communication buses to minimize the wirings and associated complexity and to enable system reconfiguration and expansions, as well as fault diagnoses. Validating the proposed ESS functionalities has been done via experimental testing and the results are presented and discussed. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Effects of Chemical Properties and Inherent Mineral Matters on Pyrolysis Kinetics of Low-Rank Coals
Processes 2021, 9(12), 2111; https://doi.org/10.3390/pr9122111 - 24 Nov 2021
Abstract
The kinetics during the pyrolysis process depend on both chemical structure and inherent mineral matters in coal, but normally, only one of these components is investigated in literature. In the present work, four low-rank coals were pyrolyzed in a thermogravimetric analyzer at a [...] Read more.
The kinetics during the pyrolysis process depend on both chemical structure and inherent mineral matters in coal, but normally, only one of these components is investigated in literature. In the present work, four low-rank coals were pyrolyzed in a thermogravimetric analyzer at a heating rate of 10 K/min in a constant nitrogen stream at a temperature up to 900 °C to study the pyrolysis behavior and kinetics. Two of the samples were raw coal (R-YL) and clean coal (C-YL) obtained through the washing process. The results showed that the coal-washing process mainly affected the inorganic part (mineral matters) and structure in coal, which did not largely change the chemical properties. The pyrolysis behavior in primary stage (before 550 °C) was mainly affected by the chemical properties of coal, while the pyrolysis behavior in higher temperature also depended on inherent mineral matters. The kinetics of four coals were obtained using the Coats–Redfern (CR) method with five theoretical models. The difference of E value was almost negligible for R-YL and C-YL, also showing that the coal-washing process did not largely change the chemical properties. The higher frequency factor A for clean coal C-YL showed a more porous structure due to the coal-washing process. The apparent activation energy E in the third stage was affected by the thermodynamic property of inherent minerals. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Communication
Towards High Efficiency CO2 Utilization by Glow Discharge Plasma
Processes 2021, 9(11), 2063; https://doi.org/10.3390/pr9112063 - 18 Nov 2021
Cited by 1
Abstract
Plasma technology reaches rapidly increasing efficiency in catalytic applications. One such application is the splitting reaction of CO2 to oxygen and carbon monoxide. This reaction could be a cornerstone of power-to-X processes that utilize electricity to produce value-added compounds such as chemicals [...] Read more.
Plasma technology reaches rapidly increasing efficiency in catalytic applications. One such application is the splitting reaction of CO2 to oxygen and carbon monoxide. This reaction could be a cornerstone of power-to-X processes that utilize electricity to produce value-added compounds such as chemicals and fuels. However, it poses problems in practice due to its highly endothermal nature and challenging selectivity. In this communication a glow discharge plasma reactor is presented that achieves high energy efficiency in the CO2 splitting reaction. To achieve this, a magnetic field is used to increase the discharge volume. Combined with laminar gas flow, this leads to even energy distribution in the working gas. Thus, the reactor achieves very high energy efficiency of up to 45% while also reaching high CO2 conversion efficiency. These results are briefly explained and then compared to other plasma technologies. Lastly, cutting edge energy efficiencies of competing technologies such as CO2 electrolysis are discussed in comparison. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Synthesis of Cost-Optimal Heat Exchanger Networks Using a Novel Stochastic Algorithm and a Modified Stage-Wised Superstructure
Processes 2021, 9(11), 2060; https://doi.org/10.3390/pr9112060 - 17 Nov 2021
Abstract
Facing the current energy structure urgently needs to be transformed, heat exchanger network (HEN) can implement heat recovery and cost reduction by the arrangement for heat exchanges between cold and hot streams. The plenty of integer and continuous variables involved in HEN synthesis [...] Read more.
Facing the current energy structure urgently needs to be transformed, heat exchanger network (HEN) can implement heat recovery and cost reduction by the arrangement for heat exchanges between cold and hot streams. The plenty of integer and continuous variables involved in HEN synthesis cause the results to be easily trapped in local optima. To avoid this situation, the mechanism of accepting imperfect solutions is added in a novel algorithm called Random Walk Algorithm with Compulsive Evolution. However, several potential solutions maybe abandoned by accepting imperfect solutions. To maintain the global searching ability, and at the same time, protecting the potential solutions during the optimization process, the limitations of accepting imperfect solutions are investigated in this work, then a back substitution strategy and elite optimization strategy based on algorithm are proposed. The former is to identify and adjust the inferior individuals in long-term stagnation while the latter is to keep and perform a fine search for the better solutions. Furthermore, a modified stage-wised superstructure is also developed to implement the flexible placement of utilities, which efficiently enlarges the solution domain. The validation of strategies and model is implemented by three cases, the results are lower, with 2219 $/year, 1280 $/year, and 2M $/year than the best published result, revealing the strong abilities of the proposed method in designing more economical HENs. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Magnetic Field Saturation of Non-Insulation High-Temperature Superconducting Coils during Overcurrent
Electronics 2021, 10(22), 2789; https://doi.org/10.3390/electronics10222789 - 14 Nov 2021
Abstract
Non-insulation high-temperature superconducting coils provide a much lower risk of burnout in fault/abnormal conditions, such as hot-spot quench and overcurrent. This study employs an equivalent circuit grid model, coupled with magnetic field calculation and the EJ power law of superconductors, to [...] Read more.
Non-insulation high-temperature superconducting coils provide a much lower risk of burnout in fault/abnormal conditions, such as hot-spot quench and overcurrent. This study employs an equivalent circuit grid model, coupled with magnetic field calculation and the EJ power law of superconductors, to deeply and systematically investigate the overcurrent charging process in a double-pancake non-insulation coil. An evident saturation of the magnetic field in the axial direction of the coil was observed and verified by experiments. Experimentally, the entire process, including the behavior of the magnetic field, was consistent with the numerical results. Based on the verified model, two main points were addressed: (1) Transient current distribution inside the coil during overcurrent charging was studied. Potential quenching risks were found to be at the innermost and outermost turn near the electrodes, as well as the pancake-to-pancake connection part. (2) Magnetic field saturation, which is a unique phenomenon in non-insulation superconducting coils during overcurrent charging, was studied in detail and first quantitatively defined by a new concept “converged load factor”. Its relationship with turn-to-turn resistivity was revealed. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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Article
Sodium-Potassium Alloy Heat Pipe under Geyser Boiling Experimental Study: Heat Transfer Analysis
Energies 2021, 14(22), 7582; https://doi.org/10.3390/en14227582 - 12 Nov 2021
Cited by 4
Abstract
In the geyser boiling mode, the working fluid state is divided into a boiling process and a quiet process, and the sodium-potassium (Na-K) alloy heat pipe can discontinuously transfer heat at each boiling. The overheating of the liquid working fluid at the bottom [...] Read more.
In the geyser boiling mode, the working fluid state is divided into a boiling process and a quiet process, and the sodium-potassium (Na-K) alloy heat pipe can discontinuously transfer heat at each boiling. The overheating of the liquid working fluid at the bottom causes short-term boiling and forms slug bubble, the strong condensing ability quickly conducts heat from the evaporator section. And geyser boiling can occur before the working fluid forms continuous flow, so it transfers more heat at lower temperatures than natural convection cooling. In this study, the heat transfer process of a Na-K alloy heat pipe with forced convection cooling under different heating power was experimental studied. The geyser boiling mode can make the Na-K alloy heat pipe work below 650 °C and reduce the start-up time. In the process of geyser boiling, the heat transfer quantity was increased by the boiling frequency and the amount of vapor produced in a single boiling. The boiling temperature had no obvious change with the increased of heating power, and the condenser section temperature increased with the heating power. Full article
(This article belongs to the Topic Energy Storage and Conversion Systems)
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