In this paper, we propose a photovoltaic emulator (PVE) composed of a series of connected power diodes with a single constant current source, rather than a power converter-based PVE. Accordingly, this enables readily verifying the operation because a the simple hardware structure and lack of a complex control algorithm. The proposed PVE can be intuitively implemented using the proposed selection criteria for the power diode and equivalent resistances. Since there is no feedback control based on complex analog/digital controls and sensors, the control response can be very fast. In addition, the proposed PVE can be easily integrated with a PV power system such as a power optimizer, to allow testing in a simple and flexible manner. Spice simulation was performed based on the electrical characteristics provided by the solar panel manufacturer, and this was utilized to validate the applied emulator circuit model, the Norton Equivalent Circuit. During the design process, the simulation helpe... [more]

In Greece, a new bi-polar high voltage direct current (HVDC) transmission system with a ground return was designed with nominal characteristics of ±500 kV, 1 GW, between Attica in the continental country and the island of Crete, which is an autonomous power system based on thermal diesel units. The interconnection line has a total length of about 380 km. The undersea section is 330 km long. In this paper, the use of the Aegean Sea as an active part of the ground return, based on shoreline pond electrodes, was proposed to avoid EUR 200 Μ of expenses. According to the general guidelines for HVDC electrode design by the International Council on Large Electric Systems (CIGRE) working group B4.61/2017, the electric field and ground potential rise of shoreline electrodes should be studied to analyze safety, electrical interference and corrosion impacts related to the operation of the electrodes. Two kinds of studies are available; one is a simplified approach based on a spherical/pointed ele... [more]

According to the specific requirements of railway engineering, a techno-economic comparison for onboard hydrogen storage technologies is conducted to discuss their feasibility and potentials for hydrogen-powered hybrid trains. Physical storage methods, including compressed hydrogen (CH2), liquid hydrogen (LH2), and cryo-compressed hydrogen (CcH2), and material-based (chemical) storage methods, such as ammonia, liquid organic hydrogen carriages (LOHCs), and metal hydrides, are carefully discussed in terms of their operational conditions, energy capacity, and economic costs. CH2 technology is the most mature now but its storage density cannot reach the final target, which is the same problem for intermetallic compounds. In contrast, LH2, CcH2, and complex hydrides are attractive for their high storage density. Nevertheless, the harsh working conditions of complex hydrides hinder their vehicular application. Ammonia has advantages in energy capacity, utilisation efficiency and cost, espec... [more]

The electrification of the industrial and transportation systems has been an important path toward mitigating climate change [...]

The absence of electricity is among the gravest problems preventing a nation’s development. Hybrid renewable energy systems (HRES) play a vital role to reducing this issue. The major goal of this study is to use the non-dominated sorting genetic algorithm (NSGA)-II and hybrid optimization of multiple energy resources (HOMER) Pro Software to reduce the net present cost (NPC), cost of energy (COE), and CO2 emissions of proposed power system. Five cases have been considered to understand the optimal HRES system for Kutubdia Island in Bangladesh and analyzed the technical viability and economic potential of this system. To demonstrate the efficacy of the suggested strategy, the best case outcomes from the two approaches are compared. The study’s optimal solution is also subjected to a sensitivity analysis to take into account fluctuations in the annual wind speed, solar radiation, and fuel costs. According to the data, the optimized PV/Wind/Battery/DG system (USD 711,943) has a lower NPC t... [more]

In the rotary steering system of oil drilling, both power and data transmission are needed. This paper presents a parallel power and data transmission method for a rotating steering system with output voltage control. To reduce the size of the system, power and data are transmitted through the same rotational coupling mechanism. A power transfer resonance circuit is used to suppress the influence of the power transfer on data transmission. Therefore, crosstalk interference between the power and the data transmission channel is negligible. The experimental prototype is built, and the feasibility of the data transfer method and the closed-loop control method is verified. The experimental results are in good agreement with the theoretical analysis.

Thermo-mechanical energy storage can be a cost-effective solution to provide flexibility and balance highly renewable energy systems. Here, we present a concise review of emerging thermo-mechanical energy storage solutions focusing on their commercial development. Under a unified framework, we review technologies that have proven to work conceptually through project demonstration at a scale above 1 MW by describing the current state of commercial development, quantifying techno-economic parameters, outlining the challenges, and assessing each technology’s potential for commercial viability. The levelized cost of storage for thermo-mechanical energy storage at storage duration between 8 h and 1 week is cheaper than that of lithium-ion batteries and hydrogen storage; however, energy storage for such duration does not pay for itself at the current renewable penetration levels. For medium-term energy storage to be viable, at the realistic storage cost of 15 USD/kWh to 40 USD/kWh, the inves... [more]

The concept and methodology of traditional Defense in Depth (DID) was challenged in the Fukushima nuclear accident. In order to fix the weakness of the traditional emergency strategies of nuclear power plants (NPPs) and to enhance the DID for nuclear safety, the U.S. Nuclear Energy Institute (NEI) put forward the concept of Diverse and Flexible Coping Strategies (FLEX) for the special purpose of beyond-design-basis external event (BDBEE) hazard mitigation and the corresponding FLEX support guidelines (FSG). The theory has been wildly spread and accepted by many countries that generate nuclear power. The research on the FLEX strategy is a new trend in nuclear engineering in the recent decade. It provides not only fixed on-site equipment/devices but also on- and off-site portable resources to strengthen the reliability of the nuclear safety system, especially for the disaster/hazards (similar to the Fukushima nuclear accident) triggered by BDBEEs. After a brief introduction of the FLEX s... [more]

In this paper, we present an investigation into the influence of the load power factor of secondary winding on the metrological performance of inductive CTs with frequencies from 50 Hz to 5 kHz of the harmonic of a transformed distorted current. The results clearly indicated that the inductive load caused a deterioration in the transformation accuracy of the inductive CT. To ensure the most advantageous conditions of their operation, a resistive load should be used. The inductive CTs for the frequencies of the transformed harmonic of a distorted primary current from 50 Hz to 5 kHz may ensure the accuracy class designated for the transformation of the sinusoidal current of a frequency of 50 Hz with the same limiting values of errors. Moreover, an analysis of the generated low-order harmonics by a 300 A/5 A CT determined for the power factor of 0.8 inductive and 1.0 of the secondary winding was investigated. These results for the transformed distorted currents of 3rd, 5th and 7th higher... [more]

The development of the aircraft industry seeks an increase in compressor loading, bringing unique flow phenomena and design problems; thus, insights into the ultrahigh loaded compressor are in great need. To reveal the loss characteristics of the ultrahigh loaded subsonic axial compressors, four well comparable compressor stages are carefully designed with the loading coefficient varying from 0.41 to 0.65. A novel flow-based loss decomposition method is performed to investigate the variation of different kinds of losses (including blade profile loss, tip leakage loss, casing endwall loss, and hub endwall loss) with the change in compressor loading level and operating condition. Results show that the blade profile loss always occupies the largest part of the total loss. In rotor passages, the percentage of the blade profile loss at the design point is increased from 69% to 76% with the increase in the compressor loading. Meanwhile, the proportion of the tip leakage loss decreases as the... [more]

High-frequency transformers are becoming an essential component in the integration of power resources that rely on power electronic converters; their efficiency and performance are influenced by parasitic characteristics in the interface. In this article, the design of a high-frequency toroidal transformer has been explained in detail using the ANSYS Maxwell platform. Various parameters, such as leakage inductance, magnetic flux density, magnetic field strength and uniform magnetic flux line are analyzed using Finite element analysis. High-frequency transformers using a toroidal core with different winding configurations are examined and all parameters obtained through simulation are validated by an analytical approach. Analysis of each design is based on its leakage inductances, which will aid in the appropriate selection of transformers as a function of their operating frequency. This analysis is expected to guide designers to optimize the high-frequency transformer parameters based... [more]

Bioethanol-derived biomass is a green sustainable source of energy that is highly recommended as an efficient alternative to the replacement of fossil fuels. However, this type of bioethanol production is always expensive with very low bioethanol concentration. Therefore, this work aims to represent a facile and green approach for bioethanol production with high concentration and purity as well as reasonable cost from corn stover (CS). The goal of this study is to characterize CS and its treated samples with maleic acid (CSM) using various characterization analyses, such as proximate and ultimate analysis, HHV, TGA, FTIR, SEM, and CHNS. The bioethanol production stages: Pretreatment, enzymatic degradation, fermentation, and finally bioethanol separation and purification via the pervaporation process, which have been investigated and optimized are associated with the economic analysis. The optimum operating condition of the pretreatment process was 2% maleic acid, 1:20 solid-to-liquid r... [more]

Eddy current losses in magnets are a major consideration in the rotor design of permanent magnet synchronous motors (PMSMs). Stator design choices and the use of modern inverters with high switching frequency introduce harmonics that can contribute to significant losses in the magnets, causing the rotor to heat up. In typical PMSMs, the lack of rotor cooling can cause the magnet’s performance to degrade at high temperatures and eventually demagnetize. This review examines a large number of studies analyzing magnet eddy current losses using analytical methods and finite-element analysis. In some of these studies, magnet segmentation is carried out to reduce the losses; however, their loss-reduction effects depend highly on the type of PMSM and the mix of stator harmonics. Magnet segmentation without considering these effects can, in fact, increase the magnet losses, in addition to the extra manufacturing efforts. Multiple design analysis show the influence of rotor−stator geometric feat... [more]

To comprehensively study the influence of the guide vane inlet slope on the axial-flow pump, eight groups of axial-flow pumps with different guide vane inlet slopes are designed and studied in this paper. Four groups of schemes increase the relative slope at the rim of the guide vane blade, and the other four groups increase the relative slope at the hub. Numerical simulations have been verified experimentally and show good simulation accuracy. The numerical simulation results show that reducing the hub height of the guide vane can improve the head and efficiency of the axial-flow pump. Compared with the original scheme, the scheme H2/S2 is more stable in velocity and turbulent kinetic energy and has fewer vortices and low-speed areas at the guide vane. The scheme H3/S3 also exhibits excellent hydraulic performance and internal flow characteristics. It is recommended that when designing an axial-flow pump, the distance between the impeller and the guide vane at the hub can be appropria... [more]

This paper deals with the analysis of a suitable compensation topology of a wireless power transmission system for powering the rotating parts of modern automatic machine tools. It summarizes the important properties of the serio-parallel compensation topology suitable for this application and demonstrates a detailed mathematical derivation using the first harmonic approximation. The paper details the industrial implementation of the system in a specific automatic machine tool application and demonstrates the strong technical advantages of the proposed design. Important theoretical conclusions and technical assumptions made when considering the system layout are verified by experimental laboratory measurements and the final deployment of the technology in the professional tool DMU 40 eVo linear.

International Criticality Safety Benchmark Evaluation Project (ICSBEP) criticality analyses were conducted using the McCARD Monte Carlo code for 85 selected benchmark problems with 7 evaluated nuclear data libraries (ENDLs): ENDF/B-VII.1, ENDF/B-VIII.0, JENDL-4.0, JENDL-5.0, JEFF-3.3, TENDL-2021, and CENDL-3.2. Regarding the analyses, it was confirmed that the keff results are sensitive to the ENDL. It is noted that the new-version ENDLs show better performance in the fast benchmark cases, while on the other hand, there are no significant differences in keff among the different ENDLs in the thermal benchmark cases. The sensitivity of the keff results depending on the ENDL may impact nuclear core design parameters such as the shutdown margin, critical boron concentration, and power defects. This study and keff results will be a good reference in the development of new types of nuclear cores or new design codes.

This manuscript presents performed laboratory studies and the analysis of the impact of current shunt values used in the differential connection on the wideband metrological performance of inductive current transformers. Moreover, a comparison of the accuracy of wideband and 50 Hz-type inductive current transformers in the specified frequency range from 50 Hz to 5 kHz is presented. The main factor which may influence the wideband accuracy of inductive current transformers is the phenomenon of self-generation. This causes rapid changes in the accuracy, and simultaneously causes the most positive and the most negative values of current error and phase displacement. To evaluate the metrological performance in the differential measurement setup for higher harmonics of the distorted current, a digital acquisition board was used. Obtained results show that if proper values of current shunt resistance are chosen, such devices may be used to evaluate the wideband accuracy of inductive current... [more]

Conveying systems play an essential role in the continuous horizontal transportation of raw materials in mining sites. Regular inspections of conveyor system structures and their components, especially idlers, are essential for proper maintenance. Traditional inspection methods are labor-intensive and hazardous; therefore, robot-based thermography can be considered a quality assessment tool for the precise detection and localization of overheated idlers in opencast mining sites. This paper proposes an infrared image processing pipeline for the automatic detection and analysis of overheated idlers. The proposed image processing pipeline can be used for the identification of significant temperature anomalies such as hotspots and hot areas in infrared images. For the identification of such defects in idlers, firstly, the histogram of captured infrared images was analyzed and improved through the pre-processing stages. Afterward, the location of thermal anomalies in infrared images was ext... [more]

Gas drainage in deep coal seam is a critical issue ensuring the safety of mining and an important measure to obtain gas as a kind of clean available energy. In order to get a better understanding of gas flow and diffusion for gas drainage in deep coal seams, a dual-zone gas flow model, including the drainage damage zone (DDZ) and the non-damaged zone (NDZ), are characterized by different permeability models and anomalous diffusion models to analyze the influence of damage induced by drilling boreholes on gas flow. The permeability model and anomalous diffusion model are verified with experiment and field data. A series of finite-element numerical simulations based on developed models are carried out, indicating that, compared with normal diffusion model, the anomalous diffusion is more accurate and appropriate to field test data. The coal fracture permeability increases rapidly with the distance decreasing from the borehole, and the area of DDZ is increasing significantly with the extr... [more]

Different types of automated vehicles (AVs) have emerged promptly in recent years, each of which might have different potential impacts on traffic flow and emissions. In this paper, the impacts of autonomous automated vehicles (AAVs) and cooperative automated vehicles (CAVs) on capacity, average traffic speed, average travel time per vehicle, and average delay per vehicle, as well as traffic emissions such as carbon dioxide (CO2), nitrogen oxides (NOx), and particulate matter (PM10) have been investigated through a microsimulation study in VISSIM. Moreover, the moderating effects of different AV market penetration, and different freeway segments on AV’s impacts have been studied. The simulation results show that CAVs have a higher impact on capacity improvement regardless of the type of freeway segment. Compared to other scenarios, CAVs at 100% market penetration in basic freeway segments have a greater capacity improvement than AAVs. Furthermore, merging, diverging, and weaving segmen... [more]

Permanent magnet wall-climbing robots are widely used in the maintenance of tanks in the petrochemical industry and the overhaul of large-pressure pipelines in the hydropower industry. One of the difficulties is to achieve the safe and reliable adsorption of wall-climbing robots. Based on the Halbach array, a double-layer superposition magnetic circuit magnetization method is designed in this paper. Under the same constraints, the adsorption force of the permanent magnetic chuck is increased by at least 8% compared with the traditional magnetic circuit design method. Under the working air gap of 1∼9 mm, the average magnetic energy utilization rate is increased by at least 16.46%. This approach not only improves the magnetic energy utilization of the permanent magnetic chuck but also improves the adsorption safety of the wall-climbing robot.

The paper deals with a techno-economic comparison between utility-scale diabatic compressed air energy storage (D-CAES) systems equipped with artificial storage and Battery Energy Storage (BES) systems based on consolidated technologies, such as Sodium-Sulfur (Na-S) and Lithium-ion (Li-Ion). The comparison is carried out on the basis of the levelized cost of storage (LCOS). Analyses have been performed by varying key inputs, such as the rated power, the storage capacity, the price of electricity absorbed from the grid during the charging phase, and the cost of fuel fed to D-CAES during the discharge phase. Na-S technology-based systems always show better techno-economic performance in respect to Li-Ion based ones. The economic performance of both D-CAES and BES improves by increasing the storage capacity. The D-CAES performance improvement rate, however, is higher than that estimated for BES based systems. Moreover, the economic performance of D-CAES systems is less sensitive to the pr... [more]

Oil−water flows are widely encountered in petroleum, chemical, nuclear reactors, and other crucial industrial processes. Due to gravity and interaction between phases, horizontal and inclined oil−water two-phase flows are characterized by remarkable multi-scale structure characteristics, such as large-scale stratified interface and small-scale droplets entrainment. Moreover, a slight change in the pipe inclination will lead to significant changes in the local oil−water flow structures, which results in great challenges in the measurement of the interface structures. In this study, we design a 10 × 10 conductance wire-mesh sensor (WMS) to detect the interfacial characteristics of horizontal and inclined oil−water flows. Firstly, we carry out horizontal and inclined oil−water flow experiments. The influence of pipe inclinations on the flow transition boundary is analyzed. The three-dimensional (3D) structures of oil−water flows are visualized based on the WMS measurement response. Then,... [more]

The United Arab Emirates is moving towards the use of renewable energy for many reasons, including the country’s high energy consumption, unstable oil prices, and increasing carbon dioxide emissions. The usage of electric vehicles can improve public health and reduce emissions that contribute to climate change. Thus, the usage of renewable energy resources to meet the demands of electric vehicles is the major challenge influencing the development of an optimal smart system that can satisfy energy requirements, enhance sustainability and reduce negative environmental impacts. The objective of this study was to examine different configurations of hybrid renewable energy systems for electric vehicle charging in Abu Dhabi city, UAE. A comprehensive study was conducted to investigate previous electric vehicle charging approaches and formulate the problem accordingly. Subsequently, methods for acquiring data with respect to the energy input and load profiles were determined, and a techno-eco... [more]

The performance of droplets captured by the wire mesh demister in a seawater desalination system seriously affects the quality of water desalination. Therefore, it is of great significance to study the droplet impact in the wire mesh demister to improve the demister’s efficiency. In this paper, a two-dimensional model of the droplet impacting the wire is established. The processes of the droplet impacting a flat wire and a circular wire are simulated by using the VOF model in Fluent, and a comparative analysis is conducted. The results demonstrate that both wires experience spreading and splashing stages, but when the wire is circular, the length of the lifted lamella is longer, the peak force on the wall is larger, the splash’s start time is earlier, and the number of secondary droplets is greater; the variation rule of the force on the wall caused by the change of initial velocity is similar, and the increase in initial velocity will promote the occurrence of splash phenomenon, but t... [more]