Home / Journals / ENERGY / Vol.118, No.6, 2021
  • Open Access

    ARTICLE

    Electricity Demand Time Series Forecasting Based on Empirical Mode Decomposition and Long Short-Term Memory

    Saman Taheri1, Behnam Talebjedi2,*, Timo Laukkanen2
    Energy Engineering, Vol.118, No.6, pp. 1577-1594, 2021, DOI:10.32604/EE.2021.017795
    Abstract Load forecasting is critical for a variety of applications in modern energy systems. Nonetheless, forecasting is a difficult task because electricity load profiles are tied with uncertain, non-linear, and non-stationary signals. To address these issues, long short-term memory (LSTM), a machine learning algorithm capable of learning temporal dependencies, has been extensively integrated into load forecasting in recent years. To further increase the effectiveness of using LSTM for demand forecasting, this paper proposes a hybrid prediction model that incorporates LSTM with empirical mode decomposition (EMD). EMD algorithm breaks down a load time-series data into several sub-series called intrinsic mode functions (IMFs).… More >

  • Open Access

    ARTICLE

    The Effect of Injected Air Bubble Size on the Thermal Performance of a Vertical Shell and Helical Coiled Tube Heat Exchanger

    Saif S. Hasan1, Ali Sh. Baqir1, Hameed B. Mahood2,*
    Energy Engineering, Vol.118, No.6, pp. 1595-1609, 2021, DOI:10.32604/EE.2021.017433
    Abstract In the present study, the effect of injecting air bubble size on the thermal performance of a vertical counter-current shell and coiled tube heat exchanger is experimentally investigated. The experiments were accomplished in a cylindrical shape heat exchanger with a 50 cm height and 15 cm outer diameter. Copper coil with 3.939 m equivalent length and 0.6 cm outer diameter was used to carry the hot fluid (water). Four different cold fluid (shell side) flow rates under laminar flow conditions (316 ≤ Re ≤ 1223), constant hot (coil side) flow rate fluid rates , four different injected air flow rates , invariant… More >

  • Open Access

    REVIEW

    Review on Wind Power Development and Relevant Policies between China and Japan

    Lei Wang1, Zekun Wang2,3,4,*, Yingjian Yang2, Shuni Zhou5, Yehong Dong5, Fanghong Zhang5
    Energy Engineering, Vol.118, No.6, pp. 1611-1626, 2021, DOI:10.32604/EE.2021.016010
    Abstract China has abundant wind energy resources and huge development potential among developing countries. Japan is a developed country that planned to increase the use of renewable energy, especially wind energy. This research is aimed at reviewing the development of wind power and relevant policies between China and Japan. Firstly, we introduced the current status of global wind power development, such as the global installed capacity of wind power. The annual development of wind power generation in China and Japan is compared, and the distribution characteristics of wind resources are compared. Furthermore, the market share in China and Japan is introduced.… More >

  • Open Access

    ARTICLE

    Analysis of Near-Wake Deflection Characteristics of Horizontal Axis Wind Turbine Tower under Yaw State

    Zhen Liu1,3, Jianwen Wang1,2,*, Fuzhong Bai3, Caifeng Wen1,2, Yunchao Du1
    Energy Engineering, Vol.118, No.6, pp. 1627-1640, 2021, DOI:10.32604/EE.2021.016357
    (This article belongs to this Special Issue: Wind Energy Development and Utilization)
    Abstract The yaw of the horizontal axis wind turbine results in the deflection of the wake flow field of the tower. The reasonable layout of wind farm can reduce the power loss of the downstream wind turbine generators due to the blocking effect of the upstream wake flow and increase the output power of the whole wind farm. However, there is still much space for further research. In this paper, experimental research is conducted on the near-wake deflection characteristics of wind turbine tower under yaw state, expecting the effect of throwing away a brick in order to get a gem. In… More >

  • Open Access

    ARTICLE

    Optimal Configuration of an Off-Grid Hybrid Wind-Hydrogen Energy System: Comparison of Two Systems

    Zekun Wang1,2,4, Yan Jia1,2,3,*, Yingjian Yang1, Chang Cai4,5, Yinpeng Chen1
    Energy Engineering, Vol.118, No.6, pp. 1641-1658, 2021, DOI:10.32604/EE.2021.017464
    (This article belongs to this Special Issue: Wind Energy Development and Utilization)
    Abstract Due to the uncertainty of renewable energy power generation and the non-linearity of load demand, it becomes complicated to determine the capacity of each device in hybrid renewable energy power generation systems. This work aims to optimize the capacity of two types of the off-grid hybrid wind-hydrogen energy system. We considered the maximum profit of the system and the minimum loss of power supply probability as optimization goals. Firstly, we established steady-state models of the wind turbine, alkaline electrolyzer, lead-acid battery, and proton exchange membrane fuel cell in matrix laboratory software to optimize the capacity. Secondly, we analyzed the operating… More >

  • Open Access

    ARTICLE

    A Study on Heat Transfer Enhancement through Various Nanofluids in a Square Cavity with Localized Heating

    Sheikh Hassan1, Didarul Ahasan Redwan1, Md. Mamun Molla1,2,*, Sharaban Thohura3, M. Abu Taher4, Sadia Siddiqa5
    Energy Engineering, Vol.118, No.6, pp. 1659-1679, 2021, DOI:10.32604/EE.2021.017657
    Abstract A two-dimensional (2D) laminar flow of nanofluids confined within a square cavity having localized heat source at the bottom wall has been investigated. The governing Navier–Stokes and energy equations have been non dimensionalized using the appropriate non dimensional variables and then numerically solved using finite volume method. The flow was controlled by a range of parameters such as Rayleigh number, length of heat source and nanoparticle volume fraction. The numerical results are represented in terms of isotherms, streamlines, velocity and temperature distribution as well as the local and average rate of heat transfer. A comparative study has been conducted for… More >

  • Open Access

    ARTICLE

    Techno-Economic Analysis of a Grid-Connected Waste to Energy Gasification Plant: A Case Study

    Ahmed Abubakar Elwan*, Mohammed Hafiz Habibuddin
    Energy Engineering, Vol.118, No.6, pp. 1681-1701, 2021, DOI:10.32604/EE.2021.016291
    Abstract With population growth around the world, municipal waste disposal and continued energy demand becomes some of the major challenges to deal with. In order to address these, an approach is required for an optimal waste management system that offers the population benefit with a lower environmental impact. This study evaluates the technical-economic and environmental impact analysis of a grid-connected waste to energy (WtE) plant to power a Univerisiti Teknologi Malaysia (UTM) community. The energy recovery potential of the waste stream was assessed using the life cycle assessment (LCA) method with GaBiTM software (version 4). A technical, economic and environmental analysis… More >

  • Open Access

    ARTICLE

    Load Forecasting of the Power System: An Investigation Based on the Method of Random Forest Regression

    Fuyun Zhu, Guoqing Wu*
    Energy Engineering, Vol.118, No.6, pp. 1703-1712, 2021, DOI:10.32604/EE.2021.015602
    (This article belongs to this Special Issue: Advances in Modern Electric Power and Energy Systems)
    Abstract Accurate power load forecasting plays an important role in the power dispatching and security of grid. In this paper, a mathematical model for power load forecasting based on the random forest regression (RFR) was established. The input parameters of RFR model were determined by means of the grid search algorithm. The prediction results for this model were compared with those for several other common machine learning methods. It was found that the coefficient of determination (R2) of test set based on the RFR model was the highest, reaching 0.514 while the corresponding mean absolute error (MAE) and the mean squared… More >

  • Open Access

    ARTICLE

    Quantifying Contribution of DER-Integrated EV Parking Lots to Reliability of Power Distribution Systems

    Bo Zeng*, Yixian Liu, Yangfan Luo
    Energy Engineering, Vol.118, No.6, pp. 1713-1728, 2021, DOI:10.32604/EE.2021.016678
    (This article belongs to this Special Issue: Advances in Modern Electric Power and Energy Systems)
    Abstract In the future smart cities, parking lots (PLs) can accommodate hundreds of electric vehicles (EVs) at the same time. This trend creates an opportunity for PLs to serve as a potential flexibility resource, considering growing penetration of EVs and integration of distributed energy resources DER (such as photovoltaic and energy storages). Given this background, this paper proposes a comprehensive evaluation framework to investigate the potential role of DER-integrated PLs (DPL) with the capability of vehicle-to-grid (V2G) in improving the reliability of the distribution network. For this aim, first, an overview for the distribution system with DPLs is provided. Then, a… More >

  • Open Access

    ARTICLE

    FCS-MPC Strategy for PV Grid-Connected Inverter Based on MLD Model

    Xiaojuan Lu, Qingbo Zhang*
    Energy Engineering, Vol.118, No.6, pp. 1729-1740, 2021, DOI:10.32604/EE.2021.014938
    Abstract In the process of grid-connected photovoltaic power generation, there are high requirements for the quality of the power that the inverter breaks into the grid. In this work, to improve the power quality of the grid-connected inverter into the grid, and the output of the system can meet the grid-connected requirements more quickly and accurately, we exhibit an approach toward establishing a mixed logical dynamical (MLD) model where logic variables were introduced to switch dynamics of the single-phase photovoltaic inverters. Besides, based on the model, our recent efforts in studying the finite control set model predictive control (FCS-MPC) and devising… More >

  • Open Access

    ARTICLE

    Loss Analysis of Electromagnetic Linear Actuator Coupling Control Electromagnetic Mechanical System

    Jiayu Lu1, Qijing Qin1, Cao Tan1,*, Bo Li1, Xinyu Fan2
    Energy Engineering, Vol.118, No.6, pp. 1741-1754, 2021, DOI:10.32604/EE.2021.014977
    Abstract As an energy converter, electromagnetic linear actuators (EMLAs) have been widely used in industries. Multidisciplinary methodology is a preferred tool for the design and optimization of EMLA. In this paper, a multidisciplinary method was proposed for revealing the influence mechanism of load on EMLA’s loss. The motion trajectory of EMLA is planned through tracking differentiator, an adaptive robust control was adopted to compensate the influence of load on motion trajectory. A control-electromagnetic-mechanical coupling model was established and verified experimentally. The influence laws of load change on EMLA’s loss, loss composition and loss distribution were analyzed quantitatively. The results show that… More >

  • Open Access

    ARTICLE

    Aging Characteristics and Influencing Factors of the Sheds of Composite Insulators in Karst Regions of China

    Wei Zhao1, Miao Jiang2, Jun Dong1, Lee Li2,*
    Energy Engineering, Vol.118, No.6, pp. 1755-1766, 2021, DOI:10.32604/EE.2021.015467
    Abstract In recent years, more and more high-voltage overhead transmission lines were built passing through the karst regions in southwestern China. This type of special landform seems to have an adverse effect on the aging of the sheds of the line suspension composite insulators, which may lead to unexpected flashover and line tripping. In order to find out the particularity of the aging characteristics of insulators operating in the karst regions, samples in operation were selected from both the karst regions and the flatlands. Hydrophobicity, amount of surface contamination, and contaminant composition of the sheds were studied, then a comparison of… More >

  • Open Access

    ARTICLE

    Modelling and Optimal Design of Hybrid Power System Photovoltaic/Solid Oxide Fuel Cell for a Mediterranean City

    Bachir Melzi1, Nesrine Kefif2, Mamdouh El Haj Assad3,*, Haleh Delnava4, Abdulkadir Hamid5
    Energy Engineering, Vol.118, No.6, pp. 1767-1781, 2021, DOI:10.32604/EE.2021.017270
    (This article belongs to this Special Issue: Advanced Materials and Technologies for Sustainable Energy)
    Abstract This work presents a hybrid power system consisting of photovoltaic and solid oxide fuel cell (PV-SOFC) for electricity production and hydrogen production. The simulation of this hybrid system is adjusted for Bou-Zedjar city in north Algeria. Homer software was used for this simulation to calculate the power output and the total net present cost. The method used depends on the annual average monthly values of clearness index and radiation for which the energy contributions are determined for each component of PV/SOFC hybrid system. The economic study is more important criterion in the proposed hybrid system, and the results show that… More >

  • Open Access

    ARTICLE

    Investigation of Plans Shape and Glazing Percentage for the Energy Efficiency of Residential Buildings

    Tayyebeh Yazarlou*, Mohammad Djavad Saghafi
    Energy Engineering, Vol.118, No.6, pp. 1783-1797, 2021, DOI:10.32604/EE.2021.017282
    Abstract The room's plan shape, the area of the window, and the impact of the materials are significant parameters in determining the thermal needs of buildings. In traditional houses of the hot and dry climate of Iran, the plan shape of the room, the ratio of the window area to the floor area, and the comparison between traditional and prevalent materials have been less studied. This study investigated the thermal performance of seven different models of the plan shape, five different ratios of window area to plan area, and three material structures in a selected room of Yazd City using EnergyPlus… More >

  • Open Access

    ARTICLE

    Classification and Visualization of Surrounding Rock Mass Stability Based on Multi-Dimensional Cloud Model

    Liming Xue1,*, Wenlong Shen1, Zhixue Zheng2,*, Jiming Chen1, Hongtao Liu3
    Energy Engineering, Vol.118, No.6, pp. 1799-1810, 2021, DOI:10.32604/EE.2021.015124
    Abstract The classification of the stability of surrounding rock is an uncertain system with multiple indices. The Multi-dimensional Cloud Model provides an advanced solution through the use of an improved model of One-dimensional Cloud Model. Setting each index as a one-dimensional attribute, the Multi-dimensional Cloud Model can set the digital characteristics of each index according to the cloud theory. The Multi-dimensional cloud generator can calculate the certainty of each grade, and then determine the stability levels of the surrounding rock according to the principle of maximum certainty. Using this model to 5 coal mine roadway surrounding rock examples and comparing the… More >

  • Open Access

    ARTICLE

    Coal Seam Permeability Improvement and CBM Production Enhancement by Enlarged Borehole: Mechanism and Application

    Xiyuan Li1, Peng Chu2,3,*, Zhuang Lu2,3, Yuanyuan Liu2,3, Zibin Zhu2,3, Jin Gao2,3, Xiaoxue Liao2,3, Tao Yang2,3
    Energy Engineering, Vol.118, No.6, pp. 1811-1825, 2021, DOI:10.32604/EE.2021.015751
    Abstract The permeability is a key factor to determine the efficiency of coalbed methane (CBM) production. The borehole enlargement technology using hydraulic and mechanical measures to cut coal is an effective method to increase the coal seam permeability and improve the efficiency of gas drainage. Reasonable design of the layout of boreholes is the prerequisite for efficient and economical gas drainage. In this paper, based on the strain-softening model, the stress and permeability model of the coal seam around the enlarged borehole was built, and based on the dual-medium model, the gas migration model in the coal seam was established. Then… More >

  • Open Access

    ARTICLE

    Effect of Dust and Shadow on Performance of Solar Photovoltaic Modules: Experimental Analysis

    Ramkiran Bhallamudi1,2, Sudhakar Kumarasamy3,4,5, Chinnayan Karuppaiyah Sundarabalan1,*
    Energy Engineering, Vol.118, No.6, pp. 1827-1838, 2021, DOI:10.32604/EE.2021.016798
    Abstract This study presents an experimental performance of a solar photovoltaic module under clean, dust, and shadow conditions. It is found that there is a significant decrease in electrical power produced (40% in the case of dust panels and 80% in the case of shadow panels) and a decrease in efficiency of around 6% in the case with dust and 9% in the case with the shadow, as compared to the clean panel. From the results, it is clear that there is a substantial effect of a partial shadow than dust on the performance of the solar panel. This is due… More >

  • Open Access

    ARTICLE

    A Novel Starting Impulse Suppression Method for Active Power Filter Based on Slowly Rising Curve

    Jianfeng Yang*, Yu Ding
    Energy Engineering, Vol.118, No.6, pp. 1839-1853, 2021, DOI:10.32604/EE.2021.015930
    Abstract With the widespread application of power electronic equipment in the power grid, the harmonic problem of the power grid becomes more pronounced, reducing the efficiency of power production, transmission, and utilization, and interfering with the normal operation of the power grid. Based on the requirements of harmonic suppression and power system protection, a shunt active power filter (SAPF) is proposed as an effective harmonic suppression method. However, there are problems with impulse current and impulse voltage in the starting process of SAPF. Impulse current and impulse voltage cause the power grid and switchgear to bear greater current stress and voltage… More >

  • Open Access

    ARTICLE

    Research on the Flow and Heat Transfer Characteristics of a Water-Cooling Plate in a Heat Dissipation System

    Yukun Lv, Zhuang Wei*, Quanzhi Ge, Fan Yang, Shuang Yang
    Energy Engineering, Vol.118, No.6, pp. 1855-1867, 2021, DOI:10.32604/EE.2021.015248
    Abstract The water-cooling heat dissipation technology can solve the heat dissipation and noise problems of the calculation plate. Therefore, the structural design of the water-cooling plate directly affects its flow and heat transfer characteristics, which restricts the promotion and application of the technology. To this end, the water-cooling plate of a heat dissipation system was taken as the research object, and its flow and heat transfer characteristics were numerical simulated and experimental studied. Through comparative analysis, the rationality of the numerical simulation method was verified. Based on this, three improved schemes of water-cooling plate structure were proposed and numerical simulation was… More >

  • Open Access

    ARTICLE

    A Hybrid Model Based on Back-Propagation Neural Network and Optimized Support Vector Machine with Particle Swarm Algorithm for Assessing Blade Icing on Wind Turbines

    Xiyang Li1,2, Bin Cheng1,2, Hui Zhang1,2,*, Xianghan Zhang1, Zhi Yun1
    Energy Engineering, Vol.118, No.6, pp. 1869-1886, 2021, DOI:10.32604/EE.2021.015542
    Abstract With the continuous increase in the proportional use of wind energy across the globe, the reduction of power generation efficiency and safety hazards caused by the icing on wind turbine blades have attracted more consideration for research. Therefore, it is crucial to accurately analyze the thickness of icing on wind turbine blades, which can serve as a basis for formulating corresponding control measures and ensure a safe and stable operation of wind turbines in winter times and/or in high altitude areas. This paper fully utilized the advantages of the support vector machine (SVM) and back-propagation neural network (BPNN), with the… More >

  • Open Access

    ARTICLE

    Comprehensive Study, Design and Economic Feasibility Analysis of Solar PV Powered Water Pumping System

    K. Karthick1,*, K. Jaiganesh2, S. Kavaskar3
    Energy Engineering, Vol.118, No.6, pp. 1887-1904, 2021, DOI:10.32604/EE.2021.017563
    (This article belongs to this Special Issue: The Role of Artificial Intelligence for Modeling and Optimizing the Energy Systems )
    Abstract The energy efficient product can be operated with longer duration. They offer wonderful solutions compared to other conventional water pumping system as it needs less maintenance, simple in installation, zero fuel cost, longer operating life, highly reliable and free from production of greenhouse gases. In this paper we analyzed the different topologies of DC–DC converter in terms of their operating region of MPPT, quality of input and output currents. We discussed the MPPT algorithms to address partial shading effects in SPV array, present state of the technology, factors affecting the performance of the system, efficiency improvements and identified the research… More >

  • Open Access

    ARTICLE

    Performance Analysis of Multi-Energy Hybrid System Based on Molten Salt Energy Storage

    Xin Xu*, Lian Zhang*
    Energy Engineering, Vol.118, No.6, pp. 1905-1920, 2021, DOI:10.32604/EE.2021.016738
    Abstract This paper briefly summarizes the current status of typical solar thermal power plant system, including system composition, thermal energy storage medium and performance. The thermo-physical properties of the storage medium are some of the most important factors that affect overall efficiency of the system, because some renewable energy sources such as solar and wind are unpredictable. A thermal storage system is therefore necessary to store energy for continuous usage. Based on the form of storage or the mode of system connection, heat exchangers of a thermal storage system can produce different temperature ranges of heat transfer fluid to realize energy… More >

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