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Volume 13
Issue 22
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Energies, Volume 13, Issue 22 (November-2 2020) – 304 articles

Cover Story (view full-size image): Reducing CO2 emissions is of significant importance to the aviation industry. Switching to natural gas could be both environmentally and economically beneficial, however, its implementation has technical challenges. This feasibility study addresses aircraft integration aspects and showcases that using liquefied natural gas can potentially reduce in-flight CO2 emissions by at least 15%. View this paper.
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15 pages, 3975 KiB  
Article
Radiation-Thermodynamic Modelling and Simulating the Core of a Thermophotovoltaic System
by Chukwuma Ogbonnaya, Chamil Abeykoon, Adel Nasser and Ali Turan
Energies 2020, 13(22), 6157; https://doi.org/10.3390/en13226157 - 23 Nov 2020
Cited by 7 | Viewed by 2514
Abstract
Thermophotovoltaic (TPV) systems generate electricity without the limitations of radiation intermittency, which is the case in solar photovoltaic systems. As energy demands steadily increase, there is a need to improve the conversion dynamics of TPV systems. Consequently, this study proposes a novel radiation-thermodynamic [...] Read more.
Thermophotovoltaic (TPV) systems generate electricity without the limitations of radiation intermittency, which is the case in solar photovoltaic systems. As energy demands steadily increase, there is a need to improve the conversion dynamics of TPV systems. Consequently, this study proposes a novel radiation-thermodynamic model to gain insights into the thermodynamics of TPV systems. After validating the model, parametric studies were performed to study the dependence of power generation attributes on the radiator and PV cell temperatures. Our results indicated that a silicon-based photovoltaic (PV) module could produce a power density output, thermal losses, and maximum voltage of 115.68 W cm−2, 18.14 W cm−2, and 36 V, respectively, at a radiator and PV cell temperature of 1800 K and 300 K. Power density output increased when the radiator temperature increased; however, the open circuit voltage degraded when the temperature of the TPV cells increased. Overall, for an 80 W PV module, there was a potential for improving the power generation capacity by 45% if the TPV system operated at a radiator and PV cell temperature of 1800 K and 300 K, respectively. The thermal efficiency of the TPV system varied with the temperature of the PV cell and radiator. Full article
(This article belongs to the Section J: Thermal Management)
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19 pages, 9287 KiB  
Article
Evaluation of Clearance to Stop Requirements in A Seismically Isolated Nuclear Power Plant
by Gyeonghee An, Minkyu Kim, Jae-Wook Jung, Gilberto Mosqueda and Joaquin Fabian Marquez
Energies 2020, 13(22), 6156; https://doi.org/10.3390/en13226156 - 23 Nov 2020
Cited by 6 | Viewed by 2172
Abstract
Seismically isolated nuclear power plants (NPPs) can provide substantial benefits towards reducing the failure probability of NPPs, especially for beyond design basis earthquake shaking. One risk posed by seismic isolation is the potential for pounding to a stop or moat wall, with currently [...] Read more.
Seismically isolated nuclear power plants (NPPs) can provide substantial benefits towards reducing the failure probability of NPPs, especially for beyond design basis earthquake shaking. One risk posed by seismic isolation is the potential for pounding to a stop or moat wall, with currently little guidance provided by design standards on how to address this concern. In this paper, a structural model of an isolated NPP based on the Advanced Power Reactor 1400 MW is enveloped with moat walls and advanced bearing models. The bearing models account for large strain behavior through failure based on full-scale experiments with lead rubber bearings (LRBs). Using these analytical models and a measured ultimate property diagram from LRB failure tests, the range of clearance to the stop considering the performance criteria for the NPP is investigated. Although the analysis results are dependent on the particular models, ground motions, and criteria employed, this research provides an overview of the seismic response and performance criteria of an isolated NPP considering the clearance to the stop. Full article
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21 pages, 4936 KiB  
Article
An Economic Penalty Scheme for Optimal Parking Lot Utilization with EV Charging Requirements
by Ruifeng Shi, Jie Zhang, Hao Su, Zihang Liang and Kwang Y. Lee
Energies 2020, 13(22), 6155; https://doi.org/10.3390/en13226155 - 23 Nov 2020
Cited by 8 | Viewed by 2817
Abstract
In the parking lots of public commercial areas, such as shopping malls, hospitals, and scenic spots, the parking spaces with electric vehicle (EV) charging facilities are often occupied by ordinary cars. How to regulate the parking order in the parking lot is a [...] Read more.
In the parking lots of public commercial areas, such as shopping malls, hospitals, and scenic spots, the parking spaces with electric vehicle (EV) charging facilities are often occupied by ordinary cars. How to regulate the parking order in the parking lot is a key issue in the operation and management of the parking facilities. In this paper, a method of assessing parking fees for vehicles parked at the charging facilities is proposed based on an economic penalty strategy, including fixed-penalty and dynamic-penalty strategies. First, a traffic flow model of the parking lot in public area is established. Then, a price and consumption model of parking fees and parking lot utilization is established, along with different penalty strategies. Finally, taking the parking lot of a shopping mall as an example, the penalty strategies are optimized through particle swarm optimization (PSO) algorithm. The simulation results show that the method proposed can help to improve the utilization of EV charging facilities in parking lots and guide the orderly parking and charging of EVs at the same time. Full article
(This article belongs to the Special Issue Electric Vehicle Charging: Social and Technical Issues)
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13 pages, 1405 KiB  
Article
Deep Learning Approach to Power Demand Forecasting in Polish Power System
by Tomasz Ciechulski and Stanisław Osowski
Energies 2020, 13(22), 6154; https://doi.org/10.3390/en13226154 - 23 Nov 2020
Cited by 8 | Viewed by 2236
Abstract
The paper presents a new approach to predicting the 24-h electricity power demand in the Polish Power System (PPS, or Krajowy System Elektroenergetyczny—KSE) using the deep learning approach. The prediction system uses a deep multilayer autoencoder to generate diagnostic features and an ensemble [...] Read more.
The paper presents a new approach to predicting the 24-h electricity power demand in the Polish Power System (PPS, or Krajowy System Elektroenergetyczny—KSE) using the deep learning approach. The prediction system uses a deep multilayer autoencoder to generate diagnostic features and an ensemble of two neural networks: multilayer perceptron and radial basis function network and support vector machine in regression model, for final 24-h forecast one-week advance. The period of the data that is the subject of the experiments is 2014–2019, which has been divided into two parts: Learning data (2014–2018), and test data (2019). The numerical experiments have shown the advantage of deep learning over classical approaches of neural networks for the problem of power demand prediction. Full article
(This article belongs to the Special Issue Computational Intelligence and Load Forecasting in Power Systems)
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16 pages, 2300 KiB  
Article
Optimizing Resource Utilization in Biomass Supply Chains by Creating Integrated Biomass Logistics Centers
by Xuezhen Guo, Juliën Voogt, Bert Annevelink, Joost Snels and Argyris Kanellopoulos
Energies 2020, 13(22), 6153; https://doi.org/10.3390/en13226153 - 23 Nov 2020
Cited by 22 | Viewed by 3307
Abstract
Bio-based supply chains are by nature complex to optimize. The new logistic concept of integrated biomass logistical center (IBLC) provides us the opportunity to make full use of the idle capacity for a food/feed plant to produce biobased products so that the entire [...] Read more.
Bio-based supply chains are by nature complex to optimize. The new logistic concept of integrated biomass logistical center (IBLC) provides us the opportunity to make full use of the idle capacity for a food/feed plant to produce biobased products so that the entire chain efficiency can be improved. Although research has been conducted to analyze the IBLC concept, is yet to be an optimization model that can optimally arrange the activities in the supply chain where an IBLC stands in the middle. To fill the knowledge gap in the literature, this paper makes the first step to develop a MILP model that enables biobased supply chain optimization with the IBLC concept, which supports logistic and processing decisions in the chain. The model is applied in a case study for a feed and fodder plant in Spain where managerial insights have been derived for transferring the plant to a profitable IBLC. Full article
(This article belongs to the Special Issue Renewable Energy Production from Energy Crops and Agricultural Residues)
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12 pages, 6936 KiB  
Article
Performance Improvement of Condensation Reduction and Removal in Heat Recovery Ventilators Using Purge Methods
by Kwiyoung Park, Dongchan Lee, Hyun Joon Chung and Yongchan Kim
Energies 2020, 13(22), 6152; https://doi.org/10.3390/en13226152 - 23 Nov 2020
Cited by 3 | Viewed by 1936
Abstract
In this study, several purge and ventilation methods are proposed to reduce and remove condensation in a heat recovery ventilator for commercial and household buildings. The effects of the airflow rate, duration of ventilation, purge interval, and return air temperature on the quantities [...] Read more.
In this study, several purge and ventilation methods are proposed to reduce and remove condensation in a heat recovery ventilator for commercial and household buildings. The effects of the airflow rate, duration of ventilation, purge interval, and return air temperature on the quantities of condensation and condensation removal in the heat recovery ventilator are analyzed. The increase in the air flow rate and return air temperature increases the condensation removal rate owing to the enhanced evaporation of the condensate. Furthermore, the reductions in the duration of ventilation and purge interval decreased the accumulation of condensate on the heat exchanger element. Based on the experimental results, optimum ventilation and purge strategies are proposed according to the outdoor temperature. The operation of the heat recovery ventilator with the proposed ventilation and purge strategies shows at least a 33% and up to an 80% reduction in the quantity of condensate compared with a given operation method. Accordingly, the proposed operation strategies can significantly reduce the growth of microorganisms and fungi and also increase the efficiency of a heat recovery ventilator. However, further investigation on the detailed performance according to the outdoor humidity and overall energy analysis is necessary to supplement the limitations of this study. Full article
(This article belongs to the Special Issue Ventilation and Building Energy Systems)
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18 pages, 9832 KiB  
Article
Numerical Analysis for Hydrogen Flame Acceleration during a Severe Accident in the APR1400 Containment Using a Multi-Dimensional Hydrogen Analysis System
by Hyung Seok Kang, Jongtae Kim, Seong Wan Hong and Sang Baik Kim
Energies 2020, 13(22), 6151; https://doi.org/10.3390/en13226151 - 23 Nov 2020
Cited by 7 | Viewed by 2315
Abstract
Korea Atomic Energy Research Institute (KAERI) established a multi-dimensional hydrogen analysis system to evaluate hydrogen release, distribution, and combustion in the containment of a Nuclear Power Plant (NPP), using MAAP, GASFLOW, and COM3D. In particular, KAERI developed an analysis methodology for a hydrogen [...] Read more.
Korea Atomic Energy Research Institute (KAERI) established a multi-dimensional hydrogen analysis system to evaluate hydrogen release, distribution, and combustion in the containment of a Nuclear Power Plant (NPP), using MAAP, GASFLOW, and COM3D. In particular, KAERI developed an analysis methodology for a hydrogen flame acceleration, on the basis of the COM3D validation results against measured data of the hydrogen combustion tests in the ENACCEF and THAI facilities. The proposed analysis methodology accurately predicted the peak overpressure with an error range of approximately ±10%, using the Kawanabe model used for a turbulent flame speed in the COM3D. KAERI performed a hydrogen flame acceleration analysis using the multi-dimensional hydrogen analysis system for a severe accident initiated by a station blackout (SBO), under the assumption of 100% metal–water reaction in the Reactor Pressure Vessel (RPV), to evaluate an overpressure buildup in the containment of the Advanced Power Reactor 1400 MWe (APR1400). The magnitude of the overpressure buildup in the APR1400 containment might be used as a criterion to judge whether the containment integrity is maintained or not, when the hydrogen combustion occurs during a severe accident. The COM3D calculation results using the established analysis methodology showed that the calculated peak pressure in the containment was lower than the fracture pressure of the APR1400 containment. This calculation result might have resulted from a large air volume of the containment, a reduced hydrogen concentration owing to passive auto-catalytic recombiners installed in the containment during the hydrogen release from the RPV, and a lot of stem presence during the hydrogen combustion period in the containment. Therefore, we found that the current design of the APR1400 containment maintained its integrity when the flame acceleration occurred during the severe accident initiated by the SBO accident. Full article
(This article belongs to the Special Issue Advances in Hydrogen Safety)
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22 pages, 2821 KiB  
Article
Floating Offshore Renewable Energy Farms. A Life-Cycle Cost Analysis at Brindisi, Italy
by Daniela Pantusa, Antonio Francone and Giuseppe Roberto Tomasicchio
Energies 2020, 13(22), 6150; https://doi.org/10.3390/en13226150 - 23 Nov 2020
Cited by 12 | Viewed by 3043
Abstract
The present paper deals with the Life-Cycle Cost (LCC) of an offshore renewable energy farm that is currently a topic of interest for operators and investors. The LCC analysis refers to the Cost Breakdown Structure (CBS) considering all the phases of life span, [...] Read more.
The present paper deals with the Life-Cycle Cost (LCC) of an offshore renewable energy farm that is currently a topic of interest for operators and investors. The LCC analysis refers to the Cost Breakdown Structure (CBS) considering all the phases of life span, and it has been carried out for floating offshore wind farms (FOWFs) and hybrid wind-wave farms (HWWFs). For HWWFs, this paper proposes a hybrid wind-wave energy system (HWWES), which provides the coupling of wave energy converter (WEC) with Tension Leg Platform (TLP) or Spar Buoy platform (SB). The LCC analysis has been carried out considering: (i) FOWF consisting of TLP floating platforms; (ii) FOWF consisting of a SB floating platforms; (iii) HWWF realized with the conceived hybrid system coupling the WEC with the TLP platform; (iv) HWWF realized with the conceived hybrid system coupling the WEC with SB platform. In addition to the LCC evaluation, the Levelized Cost of Energy (LCOE) analysis has also been carried out. The site chosen for the study is off the port of Brindisi, southern Italy. This work’s interest lies in having performed a LCC analysis for FOWF and HWWF in the Mediterranean that is an area of growing interest for offshore renewable energy, and obtained results have allowed making assessments on costs for offshore energy farms. Full article
(This article belongs to the Special Issue Offshore Wind Energy Technology and System Integration)
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22 pages, 6746 KiB  
Article
Impact of Current Density and Cooling on the Weight Balance of Electrical Propulsion Drives for Aviation
by Jan Hoffmann, Wolf-Rüdiger Canders and Markus Henke
Energies 2020, 13(22), 6149; https://doi.org/10.3390/en13226149 - 23 Nov 2020
Cited by 6 | Viewed by 3520
Abstract
Through applying an exemplary design study, the dependencies between current density, temperatures, and weight in an electrical drive system for a small range aircraft with conventional electrical fan or propeller drives are evaluated. This study applies a combined numerical (Finite Element Method FEM) [...] Read more.
Through applying an exemplary design study, the dependencies between current density, temperatures, and weight in an electrical drive system for a small range aircraft with conventional electrical fan or propeller drives are evaluated. This study applies a combined numerical (Finite Element Method FEM) and analytical approach to the machine design, calculation of temperatures, and cooling system design (cooler, pumps, piping). A design scenario was defined using start and climb flight in a warm tropical surrounding as the worst load case. The design has to move between two fixed temperature limits: The maximum allowable temperature in the machine insulation and the ambient temperature. The implemented method facilitates a comparatively fast-medium depth design of the drive system. The derived results show, in fact, a minimum of weight at a certain current density, which is one of the key interests for the designers of the electrical machine. The main influences on this minimum are the temperature drops in the machine, the heat transfer to the cooling fluid, the heat transfer to the cooler wall, and the remaining heat rejection to the ambient. Method and results are transferable to other types of airplanes with different ratings. Full article
(This article belongs to the Special Issue Electrical Machine Design 2020)
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17 pages, 69623 KiB  
Article
Pore-Structural Characteristics of Tight Fractured-Vuggy Carbonates and Its Effects on the P- and S-Wave Velocity: A Micro-CT Study on Full-Diameter Cores
by Wei Li, Xiangjun Liu, Lixi Liang, Yinan Zhang, Xiansheng Li and Jian Xiong
Energies 2020, 13(22), 6148; https://doi.org/10.3390/en13226148 - 23 Nov 2020
Cited by 3 | Viewed by 2334
Abstract
Pore structure has been widely observed to affect the seismic wave velocity of rocks. Although taking lab measurements on 1.0-inch core plugs is popular, it is not representative of the fractured-vuggy carbonates because many fractures and vugs are on a scale up to [...] Read more.
Pore structure has been widely observed to affect the seismic wave velocity of rocks. Although taking lab measurements on 1.0-inch core plugs is popular, it is not representative of the fractured-vuggy carbonates because many fractures and vugs are on a scale up to several hundred microns (and greater) and are spatially heterogeneous. To overcome this shortage, we carried out the lab measurements on full-diameter cores (about 6.5–7.5 cm in diameter). The micro-CT (micro computed tomography) scanning technique is used to characterize the pore space of the carbonates and image processing methods are applied to filter the noise and enhance the responses of the fractures so that the constructed pore spaces are reliable. The wave velocities of P- and S-waves are determined then and the effects of the pore structure on the velocity are analyzed. The results show that the proposed image processing method is effective in constructing and quantitatively characterizing the pore space of the full-diameter fractured-vuggy carbonates. The porosity of all the collected tight carbonate samples is less than 4%. Fractures and vugs are well-developed and the spatial distributions of them are heterogeneous causing, even the samples having similar porosity, the pore structure characteristics of the samples being significantly different. The pores and vugs mainly contribute to the porosity of the samples and the fractures contribute to the change in the wave velocities more than pores and vugs. Full article
(This article belongs to the Special Issue Development of Unconventional Reservoirs 2020)
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19 pages, 9954 KiB  
Article
A Comparative CFD Study of Two Air Distribution Systems with Hot Aisle Containment in High-Density Data Centers
by Jinkyun Cho, Jesang Woo, Beungyong Park and Taesub Lim
Energies 2020, 13(22), 6147; https://doi.org/10.3390/en13226147 - 23 Nov 2020
Cited by 6 | Viewed by 3594
Abstract
Removing heat from high-density information technology (IT) equipment is essential for data centers. Maintaining the proper operating environment for IT equipment can be expensive. Rising energy cost and energy consumption has prompted data centers to consider hot aisle and cold aisle containment strategies, [...] Read more.
Removing heat from high-density information technology (IT) equipment is essential for data centers. Maintaining the proper operating environment for IT equipment can be expensive. Rising energy cost and energy consumption has prompted data centers to consider hot aisle and cold aisle containment strategies, which can improve the energy efficiency and maintain the recommended level of inlet air temperature to IT equipment. It can also resolve hot spots in traditional uncontained data centers to some degree. This study analyzes the IT environment of the hot aisle containment (HAC) system, which has been considered an essential solution for high-density data centers. The thermal performance was analyzed for an IT server room with HAC in a reference data center. Computational fluid dynamics analysis was conducted to compare the operating performances of the cooling air distribution systems applied to the raised and hard floors and to examine the difference in the IT environment between the server rooms. Regarding operating conditions, the thermal performances in a state wherein the cooling system operated normally and another wherein one unit had failed were compared. The thermal performance of each alternative was evaluated by comparing the temperature distribution, airflow distribution, inlet air temperatures of the server racks, and recirculation ratio from the outlet to the inlet. In conclusion, the HAC system with a raised floor has higher cooling efficiency than that with a hard floor. The HAC with a raised floor over a hard floor can improve the air distribution efficiency by 28%. This corresponds to 40% reduction in the recirculation ratio for more than 20% of the normal cooling conditions. The main contribution of this paper is that it realistically implements the effectiveness of the existing theoretical comparison of the HAC system by developing an accurate numerical model of a data center with a high-density fifth-generation (5G) environment and applying the operating conditions. Full article
(This article belongs to the Section G: Energy and Buildings)
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20 pages, 4728 KiB  
Article
Techno-Economic Feasibility Analysis through Optimization Strategies and Load Shifting in Isolated Hybrid Microgrids with Renewable Energy for the Non-Interconnected Zone (NIZ) of Colombia
by Yimy E. García-Vera, Rodolfo Dufo-López and José L. Bernal-Agustín
Energies 2020, 13(22), 6146; https://doi.org/10.3390/en13226146 - 23 Nov 2020
Cited by 12 | Viewed by 2732
Abstract
In developing countries, electrification in remote areas, where access to energy is limited or null, has been one of the biggest challenges in recent years. Isolated microgrids with renewable generation are an efficient alternative for the energy supply in these areas. The objective [...] Read more.
In developing countries, electrification in remote areas, where access to energy is limited or null, has been one of the biggest challenges in recent years. Isolated microgrids with renewable generation are an efficient alternative for the energy supply in these areas. The objective of this work was to analyse the techno-economic viability of 6 isolated microgrids in different locations in the non-interconnected zone of Colombia, considering different climatic conditions, the availability of renewable resources, the current consumption profile, and a modified profile applying demand-side management. Modelling and simulation were performed considering storage systems based on lithium and lead-acid batteries. The resulting simulations provide the optimal system cost, emissions levels, electricity cost and battery lifetime. This study demonstrates that isolated hybrid microgrids with renewable energy are a feasible alternative to solve access to energy problems, reducing the need for diesel generators and optimizing the use of renewable energies and battery-based storage systems. Full article
(This article belongs to the Section A1: Smart Grids and Microgrids)
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18 pages, 8776 KiB  
Article
Numerical Simulation of the Air Cooling System for Scientific Payload Rack on a Space Station
by Yuan-Yuan Lou, Ben-Yuan Cai, Yun-Ze Li, Jia-Xin Li and En-Hui Li
Energies 2020, 13(22), 6145; https://doi.org/10.3390/en13226145 - 23 Nov 2020
Cited by 4 | Viewed by 2540
Abstract
The space scientific payload rack is a multifunctional experimental platform, and the requirements of the environmental temperature index are different for diversified experimental modules inside. The air cooling system is an important part of the rack thermal control system. A new type of [...] Read more.
The space scientific payload rack is a multifunctional experimental platform, and the requirements of the environmental temperature index are different for diversified experimental modules inside. The air cooling system is an important part of the rack thermal control system. A new type of air cooling system with small size and flexible arrangement is proposed in this paper, that is, micro air ducts with pinhole-sized air vents. The rack physical models of new and traditional air cooling modes are established, respectively. The numerical simulation of the inner air flow is carried out by Ansys Fluent CFD software (Ansys Inc., Canonsburg, PA, USA), which verifies that compared with the traditional method, the temperature field and flow field of the new air cooling method are more uniform, and the heat sources located at the edge of the rack can also be cooled better. Full article
(This article belongs to the Section J: Thermal Management)
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24 pages, 4363 KiB  
Article
Energy-Based Novel Quantifiable Sustainability Value Assessment Method for Machining Processes
by Aqib Mashood Khan, Saqib Anwar, Munish Kumar Gupta, Abdullah Alfaify, Saqib Hasnain, Muhammad Jamil, Mozammel Mia and Danil Yurievich Pimenov
Energies 2020, 13(22), 6144; https://doi.org/10.3390/en13226144 - 23 Nov 2020
Cited by 9 | Viewed by 2315
Abstract
Sustainability assessments of cooling/lubrication-assisted advanced machining processes has been demanded by environment control agencies because it is an effective management tool for improving process sustainability. To achieve an effective and efficient sustainability evolution of machining processes, there is a need to develop a [...] Read more.
Sustainability assessments of cooling/lubrication-assisted advanced machining processes has been demanded by environment control agencies because it is an effective management tool for improving process sustainability. To achieve an effective and efficient sustainability evolution of machining processes, there is a need to develop a new method that can incorporate qualitative indicators to create a quantifiable value. In the present research work, a novel quantifiable sustainability value assessment method was proposed to provide performance quantification of the existing sustainability assessment methods. The proposed method consists of three steps: establishing sustainable guidelines and identifying new indicators, data acquisition, and developing an algorithm, which creates the Overall Performance Assessment Indicator (OPAI) from the sustainability assessment method. In the proposed algorithm, initially, both quantitative and qualitative sustainability indicators are normalized. After weight assignment and aggregation, the OPAI is obtained. The developed algorithm was validated from three literature case studies, and optimal cutting parameters were obtained. The present methodology provides effective guidelines for a machinist to enhance process performance and achieve process optimization. The study also offers a relationship between sustainable and machining metrics for the support of industrial sustainability. Full article
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31 pages, 7807 KiB  
Article
Optimization of a PV-Wind Hybrid Power Supply Structure with Electrochemical Storage Intended for Supplying a Load with Known Characteristics
by Leszek Kasprzyk, Andrzej Tomczewski, Robert Pietracho, Agata Mielcarek, Zbigniew Nadolny, Krzysztof Tomczewski, Grzegorz Trzmiel and Juan Alemany
Energies 2020, 13(22), 6143; https://doi.org/10.3390/en13226143 - 23 Nov 2020
Cited by 11 | Viewed by 2466
Abstract
An important aspect of the off-grid utilization of hybrid generation systems is the integration of energy storage facilities into their structures, which allows for improved power supply reliability. However, this results in a significant increase in the cost of such systems. Therefore, it [...] Read more.
An important aspect of the off-grid utilization of hybrid generation systems is the integration of energy storage facilities into their structures, which allows for improved power supply reliability. However, this results in a significant increase in the cost of such systems. Therefore, it is justified to use optimization resulting in the minimization of the selected economic indicator taking into account the most important technical constraints. For this reason, this work proposes an algorithm to optimize the structure of a hybrid off-grid power distribution system (with electrochemical energy storage), designed to supply a load with known daily energy demand. The authors recommend genetic algorithm utilization as well as a modified criterion for evaluating the quality of solutions based on the Levelized Cost of Energy (LCOE) index. Several technical and economic analyses were presented, including unit costs, power distribution of the wind and solar sections, nominal battery capacity, SSSI index (System Self-Sufficiency Index), etc. The model of the system includes durability of the elements which have a significant impact on the periodic battery replacement. The tests were carried out for two types of loads and two types of electrochemical batteries (NMC—Lithium Nickel Manganese Cobalt Oxide; and PbO2—Lead-Acid Battery), taking into account the forecast of an increased lifetime of NMC type batteries and decreasing their price within five years. The proposed synthesis method of photovoltaic-wind (PV-wind) hybrid off-line systems leads to limiting the energy capacity of electrochemical storages. Based on the analyses, the authors proposed recommended methods to improve (reduce) the value of the criterion index (LCOE) for PV-wind off-grid systems while maintaining the assumed level of power supply reliability. Full article
(This article belongs to the Special Issue Stationary and Mobile Electric Energy Storage System as a Flexibility Option to Integrate Volatile Renewable Energy Sources)
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24 pages, 22163 KiB  
Article
Conversion and Testing of a Solar Thermal Parabolic Trough Collector for CPV-T Application
by Richard Felsberger, Armin Buchroithner, Bernhard Gerl and Hannes Wegleiter
Energies 2020, 13(22), 6142; https://doi.org/10.3390/en13226142 - 23 Nov 2020
Cited by 23 | Viewed by 3384
Abstract
In the field of solar power generation, concentrator systems, such as concentrator photovoltaics (CPV) or concentrated solar power (CSP), are subject of intensive research activity, due to high efficiencies in electrical power generation compared to conventional photovoltaics (PV) and low-cost energy storage on [...] Read more.
In the field of solar power generation, concentrator systems, such as concentrator photovoltaics (CPV) or concentrated solar power (CSP), are subject of intensive research activity, due to high efficiencies in electrical power generation compared to conventional photovoltaics (PV) and low-cost energy storage on the thermal side. Even though the idea of combining the thermal and electrical part in one absorber is obvious, very few hybrid systems (i.e., concentrator photovoltaics-thermal systems (CPV-T)) are either described in literature or commercially available. This paper features the conversion of a commercial thermal parabolic trough collector to a CPV-T hybrid system using multi-junction PV cells. The design process is described in detail starting with the selection of suitable PV cells, elaborating optical and mechanical system requirements, heat sink design and final assembly. Feasibility is proven by practical tests involving maximum power point tracking as well as empirical determination of heat generation and measurement results are presented. Full article
(This article belongs to the Special Issue Solar Hybrid Power Systems)
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18 pages, 3949 KiB  
Article
Numerical and Experimental Analysis of Heat Transfer for Solid Fuels Combustion in Fixed Bed Conditions
by Wojciech Judt
Energies 2020, 13(22), 6141; https://doi.org/10.3390/en13226141 - 23 Nov 2020
Cited by 9 | Viewed by 2274
Abstract
The paper concerns the analysis of the heat transfer process that occurred during solid fuel burning in fixed bed conditions. The subject of the analysis is a cylindrical combustion chamber with an output of 12 kW heating power equipped with a retort burner [...] Read more.
The paper concerns the analysis of the heat transfer process that occurred during solid fuel burning in fixed bed conditions. The subject of the analysis is a cylindrical combustion chamber with an output of 12 kW heating power equipped with a retort burner for hard coal and biomass combustion. During the research, a numerical and experimental study is performed. The analysis is prepared for various heat load of the combustion chamber, which allowed for the reconstruction of real working conditions for heating devices working with solid fuels combustion. The temperature distribution obtained by the experimental way is compared with results of the numerical modeling. Local distribution of principal heat transfer magnitudes like a heat flux density and a heat transfer coefficient that occurred on the sidewall of the combustion chamber is analyzed. The analysis showed, that the participation of convection and radiation in the overall heat transfer process has resulted from the heat load of the heating device. Research results may be used for improving an analytical approach of design process taking place for domestic and industrial combustion chambers. Full article
(This article belongs to the Special Issue Computational Thermal, Energy, and Environmental Engineering)
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28 pages, 4123 KiB  
Article
Fog Forecast Using WRF Model Output for Solar Energy Applications
by Saverio Teodosio Nilo, Domenico Cimini, Francesco Di Paola, Donatello Gallucci, Sabrina Gentile, Edoardo Geraldi, Salvatore Larosa, Elisabetta Ricciardelli, Ermann Ripepi, Mariassunta Viggiano and Filomena Romano
Energies 2020, 13(22), 6140; https://doi.org/10.3390/en13226140 - 23 Nov 2020
Cited by 4 | Viewed by 3529
Abstract
The occurrence of fog often causes errors in the prediction of the incident solar radiation and the power produced by photovoltaic cells. An accurate fog forecast would benefit solar energy producers and grid operators, who could take coordinated actions to reduce the impact [...] Read more.
The occurrence of fog often causes errors in the prediction of the incident solar radiation and the power produced by photovoltaic cells. An accurate fog forecast would benefit solar energy producers and grid operators, who could take coordinated actions to reduce the impact of discontinuity, the main drawback of renewable energy sources. Considering that information on discontinuity is crucial to optimize power production estimation and plant management efficiency, in this work, a fog forecast method based on the output of the Weather Research and Forecasting (WRF) numerical model is presented. The areal extension and temporal duration of a fog event are not easy to predict. In fact, there are many physical processes and boundary conditions that cause fog development, such as the synoptic situation, air stability, wind speed, season, aerosol load, orographic influence, humidity and temperature. These make fog formation a complex and rather localized event. Thus, the results of a fog forecast method based on the output variables of the high spatial resolution WRF model strongly depend on the specific site under investigation. In this work, the thresholds are site-specifically designed so that the implemented method can be generalized to other sites after a preliminary meteorological and climatological study. The proposed method is able to predict fog in the 6–30 h interval after the model run start time; it has been evaluated against METeorological Aerodrome Report data relative to seven selected sites, obtaining an average accuracy of 0.96, probability of detection of 0.83, probability of false detection equal to 0.03 and probability of false alarm of 0.18. The output of the proposed fog forecast method can activate (or not) a specific fog postprocessing layer designed to correct the global horizontal irradiance forecasted by the WRF model in order to optimize the forecast of the irradiance reaching the photovoltaic panels surface. Full article
(This article belongs to the Special Issue Solar Radiation Forecasting and Photovoltaic Systems Performance Modeling)
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25 pages, 20640 KiB  
Article
Emergy Based Decoupling Analysis of Ecosystem Services on Urbanization: A Case of Shanghai, China
by Hengyu Pan, Yong Geng, Ji Han, Cheng Huang, Wenyi Han and Zhuang Miao
Energies 2020, 13(22), 6139; https://doi.org/10.3390/en13226139 - 23 Nov 2020
Cited by 3 | Viewed by 2639
Abstract
In order to respond to rapid urbanization, understanding the relationships between urbanization and ecosystem services (ESs) is of practical importance to move toward sustainable urban development. In this study, an emergy-GIS based method is proposed to evaluate ESs. Spatiotemporal emergy values of water [...] Read more.
In order to respond to rapid urbanization, understanding the relationships between urbanization and ecosystem services (ESs) is of practical importance to move toward sustainable urban development. In this study, an emergy-GIS based method is proposed to evaluate ESs. Spatiotemporal emergy values of water retention (WR), air purification (AP), carbon sequestration (CS), soil conservation (SC), and biodiversity conservation (BC) were quantified and relationships among these ESs were analyzed by taking China’s largest city, Shanghai, as a case. The decoupling analysis was conducted to study the relationship between urbanization and ESs. Results show that the total value of regulating ESs had declined by 8.24% from 2005 to 2010. Chongming had the largest value of ESs, followed by Pudong. There is a synergetic relationship among AP, CS, and SC, while a tradeoff appears between WR and other services. Irregular “U” shape relationships between the decrease of ESs and urbanization indicators were observed. Results from decoupling analysis show that ESs experienced weak decoupling from urbanization in most districts. Finally, policy implications were raised based on the study results. Full article
(This article belongs to the Collection Feature Papers in Energy, Environment and Well-Being)
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19 pages, 3765 KiB  
Article
Real-Time Pricing Scheme in Smart Grid Considering Time Preference: Game Theoretic Approach
by Ri Piao, Deok-Joo Lee and Taegu Kim
Energies 2020, 13(22), 6138; https://doi.org/10.3390/en13226138 - 23 Nov 2020
Cited by 1 | Viewed by 2441
Abstract
Unbalanced power demand across time slots causes overload in a specific time zone. Various studies have proved that this can be mitigated through smart grid and price policy, but research on time preference is insufficient. This study proposed a real-time pricing model on [...] Read more.
Unbalanced power demand across time slots causes overload in a specific time zone. Various studies have proved that this can be mitigated through smart grid and price policy, but research on time preference is insufficient. This study proposed a real-time pricing model on a smart grid through a two-stage Stackelberg game model based on a utility function that reflects the user’s time preference. In the first step, the suppliers determine the profit-maximizing price, and then, the users decide the electricity usage schedule according to the given price. Nash equilibrium and comparative analysis of the proposed game explain the relationship between time preference, price, and usage. Additionally, a Monte Carlo simulation demonstrated the effect of the change in time preference distribution. The experimental results confirmed that the proposed real-time pricing method lowers peak-to-average ratio (PAR) and increases overall social welfare. This study is meaningful in that it presents a pricing method that considers both users’ and suppliers’ strategies with time preference. It is expected that the proposed method would contribute to a reduction in the need for additional power generation facilities through efficient operation of the smart grid. Full article
(This article belongs to the Special Issue Economic Analysis of Technological Energy Systems)
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28 pages, 4804 KiB  
Article
Energy Allocation Strategies for Common Property Load Connected to Shared Solar and Battery Storage Systems in Strata Apartments
by Moiz Masood Syed, Gregory M. Morrison and James Darbyshire
Energies 2020, 13(22), 6137; https://doi.org/10.3390/en13226137 - 23 Nov 2020
Cited by 6 | Viewed by 2681
Abstract
Common property (CP) is a significant consumer of electricity in apartment buildings. Although some apartments in Australia have adopted shared microgrid configurations to offset grid consumption, the characteristics and load patterns of CP are rarely discussed due to lack of available data. As [...] Read more.
Common property (CP) is a significant consumer of electricity in apartment buildings. Although some apartments in Australia have adopted shared microgrid configurations to offset grid consumption, the characteristics and load patterns of CP are rarely discussed due to lack of available data. As common areas normally constitute part of owner corporations, energy distribution in these premises requires attention. This paper presents empirical analysis of the CP load connected to shared solar and battery storage for three apartment complexes located in Perth Australia. Load patterns for CP over a defined dataset period were analyzed, and grid usage reduction was examined by implementing and comparing three energy allocation strategies based on surplus energy utilization. The findings indicated significant grid usage reduction for CP load in different apartments after implementation of three strategies. Instantaneous consumption decreased 72%, and surplus allocation strategy reduced 91%, while consumption-based allocation reduced 76%, of grid electricity. Moreover, consumption-based allocation offered improved cost benefits compared to the other two strategies. The results further revealed the usefulness of energy allocation and effectiveness of surplus energy utilization. Based on outcomes, the strategies provide consolidation with conventional energy trading mechanisms and broadly link to the virtual power plant concept for coordinating energy flows between multiple generators. Full article
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20 pages, 12352 KiB  
Article
Reduction of Entrained Vortices in Submersible Pump Suction Lines Using Numerical Simulations
by Virgel M. Arocena, Binoe E. Abuan, Joseph Gerard T. Reyes, Paul L. Rodgers and Louis Angelo M. Danao
Energies 2020, 13(22), 6136; https://doi.org/10.3390/en13226136 - 23 Nov 2020
Cited by 13 | Viewed by 3718
Abstract
Pump intake structure design is one area where physical models still remain as the only acceptable method that can provide reliable engineering results. Ensuring the amount of turbulence, entrained air vortices, and swirl are kept within acceptable limits requires site-specific, expensive, and time-consuming [...] Read more.
Pump intake structure design is one area where physical models still remain as the only acceptable method that can provide reliable engineering results. Ensuring the amount of turbulence, entrained air vortices, and swirl are kept within acceptable limits requires site-specific, expensive, and time-consuming physical model studies. This study aims to investigate the viability of Computational Fluid Dynamics (CFD) as an alternative tool for pump intake design thus reducing the need for extensive physical experiments. In this study, a transient multiphase simulation of a 530 mm wide rectangular intake sump housing a 116 m3/h pump is presented. The flow conditions, vortex formation and inlet swirl are compared to an existing 1:10 reduced scaled physical model test. For the baseline test, the predicted surface and submerged vortices agreed well with those observed in the physical model. Both the physical model test and the numerical model showed that the initial geometry of the pump sump is unacceptable as per ANSI/HI 9.8 criteria. Strong type 2 to type 3 submerged vortices were observed at the floor of the pump and behind the pump. Consequently, numerical simulations of proposed sump design modification are further investigated. Two CFD models with different fillet-splitter designs are evaluated and compared based on the vortex formation and swirl. In the study, it was seen that a trident-shaped splitter design was able to prevent flow separation and vortex suppression as compared to a cross-baffle design based on ANSI/HI 9.8. CFD results for the cross-baffle design showed that backwall and floor vortices were still present and additional turbulence was observed due to the cross-flow caused by the geometry. Conversely, CFD results for the trident-shaped fillet-splitter design showed stable flow and minimized the floor and wall vortices previously observed in the first two models. Full article
(This article belongs to the Special Issue Mathematical Modelling of Energy Systems and Fluid Machinery)
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15 pages, 7527 KiB  
Article
Flexible Kinetic Energy Release Controllers for a Wind Farm in an Islanding System
by Yi-Wei Chen and Yuan-Yih Hsu
Energies 2020, 13(22), 6135; https://doi.org/10.3390/en13226135 - 23 Nov 2020
Cited by 1 | Viewed by 1582
Abstract
To improve frequency nadir following a disturbance and avoid under-frequency load shedding, two types of flexible kinetic energy release controllers for the doubly fed induction generator (DFIG) are proposed. The basic idea is to release only a small amount of kinetic energy stored [...] Read more.
To improve frequency nadir following a disturbance and avoid under-frequency load shedding, two types of flexible kinetic energy release controllers for the doubly fed induction generator (DFIG) are proposed. The basic idea is to release only a small amount of kinetic energy stored at the DFIG in the initial transient period (1–3 s after the disturbance). When the frequency dip exceeds a preset threshold, the amount of kinetic energy released is increased to improve the frequency nadir. To achieve the goal of flexible kinetic energy release, a deactivation function based integral controller is first presented. To further improve the dynamic frequency response under parameter uncertainties and external disturbances, a second flexible kinetic energy release controller is designed using a proportional-integral controller, with the gains being adapted in real-time with the particle swarm optimization algorithm. Based on the MATLAB/SIMULINK simulation results for a local power system, it is concluded that the frequency nadir can be maintained around the under-frequency load shedding threshold of 59.6 Hz using the proposed controllers. Full article
(This article belongs to the Special Issue Wind Power Integration into Power Systems: Stability and Control Aspects)
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11 pages, 358 KiB  
Article
Operational Costs of He3 Separation Using the Superfluidity of He4
by Jakub Niechciał, Piotr Banat, Wojciech Kempiński, Zbigniew Trybuła, Maciej Chorowski, Jarosław Poliński, Katarzyna Chołast and Andrzej Kociemba
Energies 2020, 13(22), 6134; https://doi.org/10.3390/en13226134 - 23 Nov 2020
Cited by 7 | Viewed by 8217
Abstract
Helium is the second most abundant element in the Universe after hydrogen. Considerable resources of helium-3 isotope (He3) are located mostly outside the Earth. He3 is very important for science and industry, especially for airport neutron detectors, lung tomography and helium dilution refrigerators. [...] Read more.
Helium is the second most abundant element in the Universe after hydrogen. Considerable resources of helium-3 isotope (He3) are located mostly outside the Earth. He3 is very important for science and industry, especially for airport neutron detectors, lung tomography and helium dilution refrigerators. Besides, global warming is forcing the industry and governments to search for alternative energy sources, and He3 has the potential to be used as fuel in future nuclear fusion power plants. Unfortunately, the price of gaseous He3 has recently increased from $200 per liter to over $2750. The expected further increase in price and demands led us to present an analysis of the economic profitability for He3 separation process, which utilizes the properties of superfluid helium. This paper shows the arguments supporting the idea that extraction from natural sources is the only economically viable way of obtaining He3 isotope nowadays. The method could be relatively easily implemented into the production cycles of the low temperature natural gas purification plant. Full article
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26 pages, 637 KiB  
Article
Using Agent-Based Models to Generate Transformation Knowledge for the German Energiewende—Potentials and Challenges Derived from Four Case Studies
by Georg Holtz, Christian Schnülle, Malcolm Yadack, Jonas Friege, Thorben Jensen, Pablo Thier, Peter Viebahn and Émile J. L. Chappin
Energies 2020, 13(22), 6133; https://doi.org/10.3390/en13226133 - 23 Nov 2020
Cited by 1 | Viewed by 2453
Abstract
The German Energiewende is a deliberate transformation of an established industrial economy towards a nearly CO2-free energy system accompanied by a phase out of nuclear energy. Its governance requires knowledge on how to steer the transition from the existing status quo [...] Read more.
The German Energiewende is a deliberate transformation of an established industrial economy towards a nearly CO2-free energy system accompanied by a phase out of nuclear energy. Its governance requires knowledge on how to steer the transition from the existing status quo to the target situation (transformation knowledge). The energy system is, however, a complex socio-technical system whose dynamics are influenced by behavioural and institutional aspects, which are badly represented by the dominant techno-economic scenario studies. In this paper, we therefore investigate and identify characteristics of model studies that make agent-based modelling supportive for the generation of transformation knowledge for the Energiewende. This is done by reflecting on the experiences gained from four different applications of agent-based models. In particular, we analyse whether the studies have improved our understanding of policies’ impacts on the energy system, whether the knowledge derived is useful for practitioners, how valid understanding derived by the studies is, and whether the insights can be used beyond the initial case-studies. We conclude that agent-based modelling has a high potential to generate transformation knowledge, but that the design of projects in which the models are developed and used is of major importance to reap this potential. Well-informed and goal-oriented stakeholder involvement and a strong collaboration between data collection and model development are crucial. Full article
(This article belongs to the Special Issue Agent-Based Modeling of Socioeconomic Challenges of Energy Transition)
27 pages, 3867 KiB  
Article
Hydrogen Fuel Cell Road Vehicles and Their Infrastructure: An Option towards an Environmentally Friendly Energy Transition
by Olivier Bethoux
Energies 2020, 13(22), 6132; https://doi.org/10.3390/en13226132 - 23 Nov 2020
Cited by 65 | Viewed by 7949
Abstract
The latest pre-production vehicles on the market show that the major technical challenges posed by integrating a fuel cell system (FCS) within a vehicle—compactness, safety, autonomy, reliability, cold starting—have been met. Regarding the ongoing maturity of fuel cell systems dedicated to road transport, [...] Read more.
The latest pre-production vehicles on the market show that the major technical challenges posed by integrating a fuel cell system (FCS) within a vehicle—compactness, safety, autonomy, reliability, cold starting—have been met. Regarding the ongoing maturity of fuel cell systems dedicated to road transport, the present article examines the advances still needed to move from a functional but niche product to a mainstream consumer product. It seeks to address difficulties not covered by more traditional innovation approaches. At least in long-distance heavy-duty vehicles, fuel cell vehicles (FCVs) are going to play a key role in the path to zero-emissions in one or two decades. Hence the present study also addresses the structuring elements of the complete chain: the latter includes the production, storage and distribution of hydrogen. Green hydrogen appears to be one of the potential uses of renewable energies. The greener the electricity is, the greater the advantage for hydrogen since it permits to economically store large energy quantities on seasonal rhythms. Moreover, natural hydrogen might also become an economic reality pushing the fuel cell vehicle to be a competitive and environmentally friendly alternative to the battery electric vehicle. Based on its own functional benefits for on board systems, hydrogen in combination with the fuel cell will achieve a large-scale use of hydrogen in road transport, as soon as renewable energies become more widespread. Its market will expand from large driving range and heavy load vehicles. Full article
(This article belongs to the Special Issue Design, Diagnosis and Control and Social Acceptance of Battery, Solar Cell and Fuel Cell System)
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21 pages, 3415 KiB  
Article
Robust Optimal Operation Strategy for a Hybrid Energy System Based on Gas-Fired Unit, Power-to-Gas Facility and Wind Power in Energy Markets
by Masoud Agabalaye-Rahvar, Amin Mansour-Saatloo, Mohammad Amin Mirzaei, Behnam Mohammadi-Ivatloo, Kazem Zare and Amjad Anvari-Moghaddam
Energies 2020, 13(22), 6131; https://doi.org/10.3390/en13226131 - 23 Nov 2020
Cited by 22 | Viewed by 3037
Abstract
Gas-fired power units (GFUs) are the best technology in recent years due to lower natural gas prices, higher energy transformation performance, and lower CO2 emission, as compared to the conventional power units (CPUs). A permanent storage facility called power-to-gas (P2G) technology can [...] Read more.
Gas-fired power units (GFUs) are the best technology in recent years due to lower natural gas prices, higher energy transformation performance, and lower CO2 emission, as compared to the conventional power units (CPUs). A permanent storage facility called power-to-gas (P2G) technology can provide adaptation of ever-increasing renewable energy sources (RESs) fluctuations in power system operations, as well as reduce dependency to buy natural gas from the gas network. High investment and utilization expenditures of state-of-the-art P2G technology do not lead to economically effective operation individually. Therefore, in the present paper, an integrated GFUs-P2G-wind power unit (WPU) system is proposed to determine its optimal bidding strategy in the day-ahead energy market. A robust optimization approach is also taken into account to accommodate the proposed bidding strategy within the electricity price uncertainty environment. This problem was studied by using a case study that included a P2G facility, GFU, and WPUs to investigate the effectiveness and capability of the proposed robust bidding strategy in the day-ahead energy market. Simulation results indicate that the obtained profit increase by introducing the integrated energy system, and the P2G facility has a significant effect on participating GFUs, which have gas-consumption limitations in order to achieve maximum profit. Moreover, as it can be said, the amount of purchased natural gas is decreased in the situations, which do not have any gas-consumption limitations. Furthermore, the proposed system’s operation in the robust environment provides more robustness against electricity price deviations, although it leads to lower profit. In addition, deploying P2G technology causes about 1% incrementation in the introduced system profit. Full article
(This article belongs to the Special Issue Intelligent Energy Systems and Energy Policy)
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17 pages, 3130 KiB  
Article
Influence of MOSFET Parasitic Capacitance on the Operation of Interleaved ZVS Boost Converters
by Piotr Zimoch, Marcin Kasprzak and Kamil Kierepka
Energies 2020, 13(22), 6130; https://doi.org/10.3390/en13226130 - 23 Nov 2020
Cited by 2 | Viewed by 1952
Abstract
Interleaved zero-voltage switching boost converters have been known for over 20 years. However, the influence of parasitic capacitance of transistors has not been described. In this paper the converter is analyzed and the equation for voltage ratio is derived for any number of [...] Read more.
Interleaved zero-voltage switching boost converters have been known for over 20 years. However, the influence of parasitic capacitance of transistors has not been described. In this paper the converter is analyzed and the equation for voltage ratio is derived for any number of converter phases. First a general description of the topology, including main voltage and current waveforms, is provided. Subsequently the converter is analyzed and conditions for soft switching are derived. Next the analysis results are compared to measurements of an experimental converter setup. Discrepancies are identified and the influence of parasitic capacitance is analyzed. By considering the parasitic capacitance the difference between experimental and analytical results of voltage ratio is reduced from 0.2 to less than 0.05. Full article
(This article belongs to the Section A1: Smart Grids and Microgrids)
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14 pages, 3886 KiB  
Article
Study on Heat Transfer Performance of Antifreeze-R134a Heat Exchanger (ARHEx)
by Liping Pang, Kun Luo, Shizhao Yu, Desheng Ma, Miao Zhao and Xiaodong Mao
Energies 2020, 13(22), 6129; https://doi.org/10.3390/en13226129 - 23 Nov 2020
Cited by 1 | Viewed by 1966
Abstract
In this paper, the liquid cooling and vapor compression refrigeration system based on an Antifreeze-R134a Heat Exchanger (ARHEx) was applied to the thermal management system for high-power avionics in helicopters. The heat transfer performance of the ARHEx was studied. An experimental prototype of [...] Read more.
In this paper, the liquid cooling and vapor compression refrigeration system based on an Antifreeze-R134a Heat Exchanger (ARHEx) was applied to the thermal management system for high-power avionics in helicopters. The heat transfer performance of the ARHEx was studied. An experimental prototype of ARHEx was designed and established. A series of experiments was carried out with a ground experimental condition. A heat transfer formula for the antifreeze side in the ARHEx was obtained by means of the coefficient of Nusselt number with experimental analysis. The performance of heat transfer and pressure drop for the refrigerant side of the ARHEx was deduced for the given condition. Full article
(This article belongs to the Collection Advances in Heat Transfer Enhancement)
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7 pages, 184 KiB  
Editorial
Carbon Emission Reduction—Carbon Tax, Carbon Trading, and Carbon Offset
by Wen-Hsien Tsai
Energies 2020, 13(22), 6128; https://doi.org/10.3390/en13226128 - 23 Nov 2020
Cited by 22 | Viewed by 10261
Abstract
The Paris Agreement was signed by 195 nations in December 2015 to strengthen the global response to the threat of climate change following the 1992 United Nations Framework Convention on Climate Change (UNFCC) and the 1997 Kyoto Protocol [...] Full article
(This article belongs to the Special Issue Carbon Emission Reduction—Carbon Tax, Carbon Trading, and Carbon Offset)
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