14 pages, 14783 KiB  
Article
Low-Cost Solar Electricity Using Stationary Solar Fields; Technology Potential and Practical Implementation Challenges to Be Overcome. Outcomes from H2020 MOSAIC Project
by Cristóbal Villasante 1,*, Saioa Herrero 1, Marcelino Sánchez 2, Iñigo Pagola 2, Adrian Peña 2, David Olasolo 1 and Ana Bernardos 2
1 Fundacion Tekniker, Polo Tecnológico de Eibar, Calle Iñaki Goenaga 5, 20600 Gipuzkoa, Spain
2 CENER (National Renewable Energy Centre of Spain), Ciudad de la Innovación 7, 31621 Navarra, Spain
Energies 2020, 13(7), 1816; https://doi.org/10.3390/en13071816 - 10 Apr 2020
Cited by 7 | Viewed by 6046
Abstract
At any time of the day, a spherical mirror reflects the rays coming from the sun along a line that points to the sun through the center of the sphere. This makes it possible to build concentrated solar power(CSP) plants with fixed solar [...] Read more.
At any time of the day, a spherical mirror reflects the rays coming from the sun along a line that points to the sun through the center of the sphere. This makes it possible to build concentrated solar power(CSP) plants with fixed solar fields and mobile receivers; that is, solar fields can be significantly cheaper and simpler, but challenging tracking systems for the mobile receiver need to be implemented. The cost-cutting possibilities for this technology have been under-researched. This article describes the MOSAIC concept, which aims to achieve low-cost solar energy by boosting the benefits of spherical reflectors while addressing their challenges. This new concept proposes to build large modular plants from semi-Fresnel solar bowls. One of these modules has been designed and is under construction in Spain. This article reports the main lessons learned during the design phase, describes the advantages and challenges of the concept, details the proposed routes to overcome them, and identifies the steps needed to develop a fully competitive industrial solution. Full article
(This article belongs to the Special Issue Research on Solar Collector)
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15 pages, 3750 KiB  
Article
Advances in the Definition of Needs and Specifications for a Climate Service Tool Aimed at Small Hydropower Plants’ Operation and Management
by Eva Contreras 1,*, Javier Herrero 1, Louise Crochemore 2, Ilias Pechlivanidis 2, Christiana Photiadou 2, Cristina Aguilar 1 and María José Polo 1
1 Fluvial Dynamics and Hydrology Research Group, Andalusian Institute for Earth System Research, University of Cordoba, 14071 Cordoba, Spain
2 Hydrology Research Unit, Swedish Meteorological and Hydrological Institute, SE-601 76 Norrköping, Sweden
Energies 2020, 13(7), 1827; https://doi.org/10.3390/en13071827 - 9 Apr 2020
Cited by 14 | Viewed by 3889
Abstract
The operation feasibility of small hydropower plants in mountainous sites is subjected to the run-of-river flow, which is also dependent on a high variability in precipitation and snow cover. Moreover, the management of this kind of system has to be performed with some [...] Read more.
The operation feasibility of small hydropower plants in mountainous sites is subjected to the run-of-river flow, which is also dependent on a high variability in precipitation and snow cover. Moreover, the management of this kind of system has to be performed with some particular operation conditions of the plant (e.g., turbine minimum and maximum discharge) but also some environmental flow requirements. In this context, a technological climate service is conceived in a tight connection with end users, perfectly answering the needs of the management of small hydropower systems in a pilot area, and providing a forecast of the river streamflow together with other operation data. This paper presents an overview of the service but also a set of lessons learnt related to the features, requirements, and considerations to bear in mind from the point of view of climate service developers. In addition, the outcomes give insight into how this kind of service could change the traditional management (normally based on past experience), providing a probability range of the future river flow based on future weather scenarios according to the range of future weather possibilities. This highlights the utility of the co-generation process to implement climate services for water and energy fields but also that seasonal climate forecasting could improve the business as usual of this kind of facility. Full article
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18 pages, 4538 KiB  
Article
An Experimental Investigation of the External Wind Effects on the Ceiling Temperature Distribution of Fire-Induced Thermal Flow in a Corridor Connected to a Compartment
by Bei Cao, Xiaodong Zhou, Yubiao Huang, Yuan Zheng, Kai Ye, Hong Liu and Lizhong Yang *
State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China
Energies 2020, 13(7), 1826; https://doi.org/10.3390/en13071826 - 9 Apr 2020
Cited by 2 | Viewed by 2263
Abstract
Fire-induced thermal flow is the greatest threat to trapped people and the heat-resistant quality of building structures. This paper presents an experimental investigation of the effects of external wind on the ceiling temperature distribution of fire-induced thermal flow in a one-sixth scale corridor [...] Read more.
Fire-induced thermal flow is the greatest threat to trapped people and the heat-resistant quality of building structures. This paper presents an experimental investigation of the effects of external wind on the ceiling temperature distribution of fire-induced thermal flow in a one-sixth scale corridor connected to a compartment. In the experiments, the fire source was placed in the compartment with hot thermal flow spilled into the connected corridor. The heat release rate (HRR) was changed from 10 to 20 kW and the external wind velocity was changed from 0 to 2.09 m/s. The ends of the corridor could be adjusted to be fully or partially open to the environment with dam-boards arranged at the ends of the corridor. An effective corridor HRR, Qcorridor, was defined to account for the amount of the spilled plume into the corridor. Results show that the temperature under the ceiling changed in a non-monotonic way with wind velocity: it first increased and then decreased with wind velocity. It was revealed that the dam-boards at the corridor opening had an evidently shielding effect, leading to higher temperature compared to the fully open environment. Finally, uniform correlations are proposed for predicting the attenuation law of ceiling temperature profiles in corridors for different wind conditions. Full article
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12 pages, 2113 KiB  
Article
The Effect of the Addition of a Fat Emulsifier on the Amount and Quality of the Obtained Biogas
by Jakub Sikora 1,*, Marcin Niemiec 2, Anna Szeląg-Sikora 1, Zofia Gródek-Szostak 3, Maciej Kuboń 1 and Monika Komorowska 4
1 Faculty of Production and Power Engineering, University of Agriculture in Krakow, ul. Balicka 116B, 30-149 Kraków, Poland
2 Faculty of Faculty of Agriculture and Economics, University of Agriculture in Krakow, ul. Mickiewicza 21, 31-121 Kraków, Poland
3 Department of Economics and Enterprise Organization, Cracow University of Economics, ul. Rakowicka 27, 31-510 Krakow, Poland
4 Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, al. Mickiewicza 21, 31-121 Kraków, Poland
Energies 2020, 13(7), 1825; https://doi.org/10.3390/en13071825 - 9 Apr 2020
Cited by 19 | Viewed by 2675
Abstract
Slaughterhouse waste management is an important technological, economic, and environmental challenge. Recently, more and more attention has been paid to the possibility of obtaining biogas from waste generated by slaughterhouses. The aim of the paper was to examine the effect of an emulsifier [...] Read more.
Slaughterhouse waste management is an important technological, economic, and environmental challenge. Recently, more and more attention has been paid to the possibility of obtaining biogas from waste generated by slaughterhouses. The aim of the paper was to examine the effect of an emulsifier addition in the form of a carboxymethyl cellulose solution to create animal waste fermentation media based on the quantity and quality of the generated biogas. The adopted research goal was achieved based on a laboratory experiment of methane fermenting poultry processing waste. The waste was divided into two fractions: soft (tissue) and hard (bone). A fat emulsifier in a concentration of 1%, 2.5%, 5%, and 10% of fresh weight of the substrate was added to each substrate sample made from the above fractions. The emulsifier used was a 55% carboxymethyl cellulose solution, since this emulsifier is most commonly used in food production. The experiment was conducted in order to determine how the addition of an emulsifier (55% carboxymethylcellulose solution) affects the hydration of fats during methane fermentation, as demonstrated on poultry slaughterhouse waste. The samples were subjected to static methane fermentation, according to the methodology of DIM DIN 38414(DIN Deutches Institut für Normung). The experiment lasted 30 days. The total amount of biogas obtained after fermentation was 398 mL·g−1 for the soft fraction and 402 mL·g−1 for the hard fraction. In the case of the soft waste fraction, the addition of carboxymethylcellulose at 1% of the mass to the biogas process increased the amount of obtained biogas by 16%. In the case of the hard fraction, no effect of the addition of emulsifier on the total amount of biogas obtained was identified. In each case, the biogas from substrates with added emulsifier contained less methane and slightly more carbon. The emulsifier added to the soft fraction of slaughterhouse waste from poultry processing allowed cutting the process of methanogenesis by over 50% while maintaining the efficiency of biogas production. In the case of biogasification of bone tissue, no unambiguous effect of the addition of emulsifier on the improvement of process efficiency was identified. Full article
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14 pages, 3355 KiB  
Article
Improvement of Fusel Oil Features and Effect of Its Use in Different Compression Ratios for an SI Engine on Performance and Emission
by Süleyman Şimşek 1,*, Hasan Saygın 1 and Bülent Özdalyan 2
1 Department of Mechanical Engineering, Istanbul Aydın University, 34295 Istanbul, Turkey
2 Department of Mechanical Engineering, Karabuk University, 78050 Karabuk, Turkey
Energies 2020, 13(7), 1824; https://doi.org/10.3390/en13071824 - 9 Apr 2020
Cited by 29 | Viewed by 3836
Abstract
In this study, the effects of the use of improved fusel oil on engine performance and on exhaust emissions in a spark-ignition engine were investigated experimentally in consideration of the water, gum, and moisture content at high compression ratios according to TS EN [...] Read more.
In this study, the effects of the use of improved fusel oil on engine performance and on exhaust emissions in a spark-ignition engine were investigated experimentally in consideration of the water, gum, and moisture content at high compression ratios according to TS EN 228 standards. In the study, a four-stroke, single-cylinder, air-cooled, spark plug ignition engine with an 8/1 compression ratio was used at three different compression ratios (8/1, 8.5/1, 9.12/1). Experiments were performed for six different ratios of fuel blends (F0, F10, F20, F30, F40, and F50) at a constant speed and different loads. The data obtained from the experiments were compared with the original operating parameters of the engine while using gasoline. According to the test results, the optimal engine performance was at a 9.12/1 compression ratio and with a F30 fuel blend. With the increase from an 8/1 to 9.12/1 compression ratio for the F30 fuel blend, the overall efficiency increased by 6.91%, and the specific fuel consumption decreased by 2.35%. The effect of the optimum fusel blend on the emissions was also examined and CO emissions were reduced by 36.82%, HC emissions were reduced by 23.07%, and NOx emissions were reduced by 15.42%, while CO2 emissions were increased by 13.88%. Full article
(This article belongs to the Special Issue Environmental and Energy Assessment of Alternative Fuels)
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19 pages, 10882 KiB  
Article
An Online Super-Twisting Sliding Mode Anti-Slip Control Strategy
by Zhiwu Huang 1,2, Wei Du 1,2, Bin Chen 1,2, Kai Gao 2,3, Yongjie Liu 1,2, Xuanheng Tang 1,2 and Yingze Yang 2,4,*
1 School of Automation, Central South University, Changsha 410114, China
2 Hunan Engineering Laboratory of Rail Vehicles Braking Technology, Changsha 410114, China
3 College of Automotive and Mechanical Engineering, Changsha University of Science & Technology, Changsha 410114, China
4 School of Computer Science and Engineering, Central South University, Changsha 410114, China
Energies 2020, 13(7), 1823; https://doi.org/10.3390/en13071823 - 9 Apr 2020
Cited by 5 | Viewed by 2802
Abstract
The variability of rail surfaces can result in wheel–rail slippage, which reduces the accuracy of subway braking systems, or even endangers the operation safety. It is necessary to conduct optimal anti-slip control with the estimation of the wheel–rail adhesion state. In this paper, [...] Read more.
The variability of rail surfaces can result in wheel–rail slippage, which reduces the accuracy of subway braking systems, or even endangers the operation safety. It is necessary to conduct optimal anti-slip control with the estimation of the wheel–rail adhesion state. In this paper, an online super-twisting sliding mode anti-slip control strategy is proposed for subway vehicles. Firstly, real-time wheel–rail adhesion state estimation is performed by utilizing the recursive least squares algorithm under complex and variable rail surface conditions. Then, the differential evolution algorithm is adopted to search the current optimal slip velocity based on the wheel–rail adhesion state. The super-twisting sliding mode controller is designed to implement the optimal sliding velocity tracking. The controller exploits the high-order derivatives of the sliding mode to eliminate chatter vibration and avoid the effect of disturbance, improving the anti-slip control performance. Finally, the effectiveness of the proposed anti-slip strategy is verified by experimental results. Full article
(This article belongs to the Special Issue Next Generation of Electric Vehicles and Railway Transit)
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17 pages, 5538 KiB  
Article
Calculation of External Vehicle Aerodynamic Noise Based on LES Subgrid Model
by Xingjun Hu, Peng Guo, Zewei Wang, Jingyu Wang *, Mo Wang, Jia Zhu and Dejiu Wu
State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130025, China
Energies 2020, 13(7), 1822; https://doi.org/10.3390/en13071822 - 9 Apr 2020
Cited by 4 | Viewed by 3703
Abstract
A dynamic Smagorinsky–Lilly model (DSLM) subgrid model on the basis of the Smagorinsky–Lilly subgrid model (SLM) was introduced in the OpenFOAM software. The flow field of the vehicle was simulated, and the pressure coefficient and sound pressure curve of the monitoring points were [...] Read more.
A dynamic Smagorinsky–Lilly model (DSLM) subgrid model on the basis of the Smagorinsky–Lilly subgrid model (SLM) was introduced in the OpenFOAM software. The flow field of the vehicle was simulated, and the pressure coefficient and sound pressure curve of the monitoring points were compared with the wind tunnel test results. The results show that the DSLM subgrid model with a wall function can achieve high simulation accuracy. The investigation of the flow field structure revealed an intermittent detachment of the turbulent vortex after the airflow passed through the rearview mirror, thereby resulting in a violent pressure pulsation on the side window around the rearview mirror. Airflow passed through the A-pillar, separated, and reattached on the upper side window, thereby producing aerodynamic noise. The research results can serve as a good reference for the simulation and test of aerodynamic noises outside the vehicle, and for the reduction of the aerodynamic noises of vehicles. Full article
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14 pages, 8106 KiB  
Article
Analysis of Overvoltages Appearing in One-Sidedly Ungrounded MV Power Cable Screen
by Aleksandra Schött-Szymczak * and Krzysztof Walczak
Faculty of Electrical Engineering, Poznan University of Technology, 60-965 Poznan, Poland
Energies 2020, 13(7), 1821; https://doi.org/10.3390/en13071821 - 9 Apr 2020
Cited by 6 | Viewed by 2431
Abstract
Changing the connection type of a medium voltage (MV) cable screen is linked to a decrease in power loss, although it may also lead to the generation of overvoltage in a metallic cable screen, which is hazardous for proper cable line work. In [...] Read more.
Changing the connection type of a medium voltage (MV) cable screen is linked to a decrease in power loss, although it may also lead to the generation of overvoltage in a metallic cable screen, which is hazardous for proper cable line work. In this paper, results of simulation and field researches are presented, showing the range of voltages that occurs in cable screens during single-phase ground fault. There are considered to be three scenarios according to the applied type of cable screen connection. Conducted researches allow the comparison of chosen methods of simulation with an actual outcome. Results obtained during simulation and field studies lead to the conclusion that the range of overvoltage occurred in a cable screen could in fact be dangerous for the cable line’s sheath insulation without proper overvoltage protection. Full article
(This article belongs to the Section F: Electrical Engineering)
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21 pages, 1125 KiB  
Article
Resilient Event-Triggered Control for LFC-VSG Scheme of Uncertain Discrete-Time Power System under DoS Attacks
by Zihao Cheng 1, Songlin Hu 2,* and Jieting Ma 3
1 School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
2 College of Automation & College of Artificial Intelligence, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
3 State Grid Xinxiang Power Supply Company, Xinxiang 453000, China
Energies 2020, 13(7), 1820; https://doi.org/10.3390/en13071820 - 9 Apr 2020
Cited by 9 | Viewed by 2745
Abstract
This paper is concerned with resilient triggered control problem for load frequency control and virtual synchronous generation (LFC-VSG) scheme of discrete-time multi-area power system with parameter uncertainty, governor dead band (GDB), and low inertia under time delay and aperiodic Denial-of-Service (DoS) attacks. To [...] Read more.
This paper is concerned with resilient triggered control problem for load frequency control and virtual synchronous generation (LFC-VSG) scheme of discrete-time multi-area power system with parameter uncertainty, governor dead band (GDB), and low inertia under time delay and aperiodic Denial-of-Service (DoS) attacks. To reduce communication load of sleep intervals, event triggered mechanism (ETM) is introduced. A discrete-time switched delay system model is established to describe the dynamic of multi-area power system under resilient static output feedback control law. Combining piecewise Lyapunov–Krasovskii functional (LKF) method with switched system theory, a criterion is derived that the tolerant bound of attack duration and attack frequency can be estimated explicitly. Meanwhile, some sufficient conditions are obtained which can preserve weighted H performance. By using linear matrix inequalities (LMIs) techniques, a co-design method is proposed to solve the control gains and trigger parameters. A simulation example of a two-area power system was carried out to verify the efficiency of our proposed resilient event based LFC-VSG scheme. Full article
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13 pages, 5564 KiB  
Article
Electromagnetic–Mechanical Coupling Optimization of an IPM Synchronous Machine with Multi Flux Barriers
by Wenye Wu 1,*, Qingzhang Chen 1,*, Xiaoyong Zhu 2, Fuzhou Zhao 1 and Zixuan Xiang 2
1 School of Automotive Engineering, Changshu Institute of Technology, Suzhou 215500, China
2 School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, China
Energies 2020, 13(7), 1819; https://doi.org/10.3390/en13071819 - 9 Apr 2020
Cited by 7 | Viewed by 3405
Abstract
In this paper, an interior permanent magnet (IPM) synchronous machine with multiflux barriers is proposed to meet the wide speed regulation application requirements of electric vehicles. Based on the flux barrier characteristic, an electromagnetic–mechanical coupling optimization strategy is employed for the machine design. [...] Read more.
In this paper, an interior permanent magnet (IPM) synchronous machine with multiflux barriers is proposed to meet the wide speed regulation application requirements of electric vehicles. Based on the flux barrier characteristic, an electromagnetic–mechanical coupling optimization strategy is employed for the machine design. In order to facilitate the optimization design, the rotor barriers are divided into two optimization zones, the maximum stress zone and the maximum deformation zone. The electromagnetic–mechanical coupling optimization strategy is divided into two stages accordingly. In the first stage, the machine is regarded as a synchronous reluctance machine by ignoring permanent magnets, where the dimensions of the arc-shaped barriers are optimized to achieve a large reluctance torque and small stress. In the second stage, the dimensions of the arc-shaped PMs and the elliptical barrier are optimized with three objectives of minimum torque ripple, minimum flux linkage, and minimum deformation. After machine optimization, the comparison investigations are carried out on the basis of finite-element analysis by considering both the electromagnetic performances and mechanical performances. Full article
(This article belongs to the Special Issue Permanent Magnet Electrical Machines)
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16 pages, 4727 KiB  
Article
Effects of Fiber and Copper Particles on Conductivity and Breakdown Characteristics of Natural Ester and Mineral Oil under DC Voltage
by Lin Cheng 1,2, Yi Jiang 1,2, Min Dan 3,4, Hao Wen 1,2, Yanqing Li 3, Wei Qin 3 and Jian Hao 3,*
1 Nanjing NARI Group Corp., State Grid Electric Power Research Institute, Nanjing 211000, China
2 Wuhan NARI Co Ltd., State Grid Electric Power Research Institute, Wuhan 430074, China
3 The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China
4 State Grid Chongqing Electric Power Co., Nan’an Power Supply Bureau, Chongqing 400000, China
Energies 2020, 13(7), 1818; https://doi.org/10.3390/en13071818 - 9 Apr 2020
Cited by 13 | Viewed by 3175
Abstract
The converter transformer is a key equipment in high voltage direct current (HVDC) transmission system. Its oil-paper insulation system in the valve winding and outlet bushing experiences AC, DC, AC/DC, and transient impulse voltages simultaneously. The oil contamination problem is more serious under [...] Read more.
The converter transformer is a key equipment in high voltage direct current (HVDC) transmission system. Its oil-paper insulation system in the valve winding and outlet bushing experiences AC, DC, AC/DC, and transient impulse voltages simultaneously. The oil contamination problem is more serious under DC electric field. Therefore, it is significant to investigate the characteristic of particles motion and accumulation under DC electric field. In this paper, first, the movement and accumulation behavior of fiber particles and copper particles in mineral oil and natural ester were recorded and simulated. Then, the influence of fiber and copper particles on the oil conductivity was analyzed. Finally, the DC breakdown strength of mineral oil and natural ester with different particles concentration was compared. Results show that the movement speed of copper particles was larger than that of fiber particles. Fiber impurities were easy to form bridges in mineral oil, while there was no impurity bridge in natural ester. The current density of mineral oil containing particles is larger than that of the natural ester at the same testing time. The DC 50% probability breakdown voltages of oil samples containing fiber and copper particles decreased linearly with the increase of particle concentration, and the decrease rate of DC 50% probability breakdown voltages of oil containing copper particles were faster than that of oil containing fiber particles. Compared to pure mineral oil, the DC breakdown voltages corresponding to 50% probability of contaminated mineral oil showed a decrease from 11.9% to 22.5% when the fiber particle concentration increased from 0.001% to 0.012%. The DC 50% probability breakdown voltages of contaminated mineral oil with copper particles decreased from 23.8% to 45.0% when the particle concentration increased from 0.1 g/L to 1.5g/L. However, the decline range of the figures for natural ester contaminated by fiber or copper particles showed a smaller drop. Full article
(This article belongs to the Section F: Electrical Engineering)
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13 pages, 1689 KiB  
Article
Energy Recovery from Waste Tires Using Pyrolysis: Palestine as Case of Study
by Ramez Abdallah 1, Adel Juaidi 1, Mahmoud Assad 1, Tareq Salameh 2 and Francisco Manzano-Agugliaro 3,*
1 Mechanical Engineering Department, Faculty of Engineering & Information Technology, An-Najah National University, P.O. Box 7, Nablus 00970, Palestine
2 Department of Sustainable and Renewable Energy Engineering, College of Engineering, University of Sharjah, Sharjah 27272, UAE
3 Department of Engineering, ceiA3, University of Almeria, 04120 Almeria, Spain
Energies 2020, 13(7), 1817; https://doi.org/10.3390/en13071817 - 9 Apr 2020
Cited by 60 | Viewed by 8424
Abstract
The first industrial-scale pyrolysis plant for solid tire wastes has been installed in Jenin, northern of the West Bank in Palestine, to dispose of the enormous solid tire wastes in the north of West Bank. The disposable process is an environmentally friendly process [...] Read more.
The first industrial-scale pyrolysis plant for solid tire wastes has been installed in Jenin, northern of the West Bank in Palestine, to dispose of the enormous solid tire wastes in the north of West Bank. The disposable process is an environmentally friendly process and it converts tires into useful products, which could reduce the fuel crisis in Palestine. The gravimetric analysis of tire waste pyrolysis products from the pyrolysis plant working at the optimum conditions is: tire pyrolysis oil (TPO): 45%, pyrolysis carbon black (PCB): 35%, pyrolysis gas (Pyro-Gas): 10% and steel wire: 10%. These results are depending on the tire type and size. It has been found that the produced pyrolysis oil has a High Heating Value (HHV), with a range of 42 43   ( MJ / kg ) , which could make it useful as a replacement for conventional liquid fuels. The main disadvantage of using the TPO as fuel is its strong acrid smell and its low flash point, as compared with the other conventional liquid fuels. The produced pyrolysis carbon black also has a High Heating Value (HHV) of about 29 (MJ/kg), which could also encourage its usage as a solid fuel. Carbon black could also be used as activated carbon, printers’ ink, etc. The pyrolysis gas (Pyro-Gas) obtained from waste tires mainly consist of light hydrocarbons. The concentration of H2 has a range of 30% to 40% in volume and it has a high calorific value (approximately 31   MJ / m 3 ), which can meet the process requirement of energy. On the other hand, it is necessary to clean gas before the burning process to remove H2S from Pyro-Gas, and hence, reduce the acid rain problem. However, for the current plant, some recommendations should be followed for more comfortable operation and safer environment work conditions. Full article
(This article belongs to the Special Issue Energy Saving at Cities)
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18 pages, 4377 KiB  
Article
Effect of Bypass Control and Room Control Modes on Fan Energy Savings in a Heat Recovery Ventilation System
by Kyungjoo Cho 1,2, Dongwoo Cho 1,* and Taeyeon Kim 2
1 Korea Institute of Civil Engineering & Building Technology, 283 Goyangdae-Ro, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 10223, Korea
2 Department of Architectural Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea
Energies 2020, 13(7), 1815; https://doi.org/10.3390/en13071815 - 9 Apr 2020
Cited by 8 | Viewed by 5168
Abstract
This study makes a novel attempt to analyse the effect of the bypass control and room control modes on ventilation energy saving in an 84 m2 housing unit, which is the most frequently constructed unit-type among newly constructed apartment buildings in Korea. [...] Read more.
This study makes a novel attempt to analyse the effect of the bypass control and room control modes on ventilation energy saving in an 84 m2 housing unit, which is the most frequently constructed unit-type among newly constructed apartment buildings in Korea. A heat recovery ventilation system was installed. The fan power consumption was measured via field experiments and analyses were made for potential energy savings. Experiments to confirm the power-saving effect owing to the application of the room control mode were performed under the heat recovery and bypass modes, using three air flow rates (0.5, 1.0 and 1.5 ACH). Additionally, the annual energy saving based on the application of the mixed mode (both bypass and room control modes) was calculated. The results obtained showed that when the mixed mode was employed, ventilation energy saving up to 10.76%–16.56%, which is greater than that obtained using only the heat recovery mode, was realized. Additionally, compared with all-room-ventilation, 26.69%–61.84% of ventilation energy could be saved if the mixed mode was applied only to the living room. Full article
(This article belongs to the Special Issue Low and Zero Energy Highly Performing Buildings)
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14 pages, 5788 KiB  
Article
Zero-Sequence Differential Current Protection Scheme for Converter Transformer Based on Waveform Correlation Analysis
by Tao Zheng 1,*, Xinhui Yang 1, Xingchao Guo 1, Xingguo Wang 2 and Chengqi Zhang 1
1 State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
2 State Key Laboratory of Power Grid Safety and Energy Conservation, China Electric Power Research Institute Co., Ltd, Beijing 100192, China
Energies 2020, 13(7), 1814; https://doi.org/10.3390/en13071814 - 9 Apr 2020
Cited by 6 | Viewed by 4947
Abstract
Through the analysis of the recovery inrush current generated by the external fault removal of the converter transformer, it is pointed out that the zero-sequence current caused by the recovery inrush may result in the saturation of the neutral current transformer (CT), whose [...] Read more.
Through the analysis of the recovery inrush current generated by the external fault removal of the converter transformer, it is pointed out that the zero-sequence current caused by the recovery inrush may result in the saturation of the neutral current transformer (CT), whose measurement distortion contributes to the mis-operation of zero-sequence differential current protection. In this paper, a new scheme of zero-sequence differential current protection based on waveform correlation is proposed. By analyzing the characteristics of zero-sequence current under internal fault, external fault and external fault removal, the waveform correlation of the zero-sequence current measured at the terminal of the transformer and the zero-sequence current measured at the neutral point of the transformer is used for identification. The polarity of the CT is selected to guarantee the zero-sequence currents at the terminal and neutral point of the transformer exhibit a "ride through" characteristic under external fault, then the waveform similarity is high, and the correlation coefficient is positive. On the other hand, when internal fault occurs, zero-sequence current waveforms on both sides differ from each other largely, and the correlation coefficient is negative. Through a large number of simulations verified by PSCAD/EMTDC, this criterion can accurately identify internal and external faults, exempt from effects of the recovery inrush. Moreover, it presents certain ability for CT anti-saturation. Full article
(This article belongs to the Section F: Electrical Engineering)
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20 pages, 1627 KiB  
Article
Optimal Asset Planning for Prosumers Considering Energy Storage and Photovoltaic (PV) Units: A Stochastic Approach
by Eleonora Achiluzzi, Kirushaanth Kobikrishna, Abenayan Sivabalan, Carlos Sabillon * and Bala Venkatesh
Department of Electrical, Computer and Biomedical Engineering, Ryerson University, Toronto, ON M5B 2K3, Canada
Energies 2020, 13(7), 1813; https://doi.org/10.3390/en13071813 - 9 Apr 2020
Cited by 14 | Viewed by 3526
Abstract
In the distribution system, customers have increasingly use renewable energy sources and battery energy storage systems (BESS), transforming traditional loads into active prosumers. Therefore, methodologies are needed to provide prosumers with tools to optimize their investments and increase business opportunities. In this paper, [...] Read more.
In the distribution system, customers have increasingly use renewable energy sources and battery energy storage systems (BESS), transforming traditional loads into active prosumers. Therefore, methodologies are needed to provide prosumers with tools to optimize their investments and increase business opportunities. In this paper, a stochastic mixed integer linear programming (MILP) formulation is proposed to solve for optimal sizes of prosumer assets, considering the use of a BESS and photovoltaic (PV) units. The objective is to minimize the total cost of the system, which is defined as the combination of a solar PV system investment, BESS investment, maintenance costs of assets, and the cost of electricity supplied by the grid. The developed method defines the optimal size of PV units, the power/energy capacities of the BESS, and the optimal value for initial energy stored in the BESS. Both deterministic and stochastic approaches were explored. For each approach, the proposed model was tested for three cases, providing a varying combination of the use of grid power, PV units, and BESS. The optimal values from each case were compared, showing that there is potential to achieve more economic plans for prosumers when PV and BESS technologies are taken into account. Full article
(This article belongs to the Section F: Electrical Engineering)
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