This paper deals with the early detection of fault conditions in induction motors using a combined model- and machine-learning-based approach with flexible adaptation to individual motors. The method is based on analytical modeling in the form of a multiple coupled circuit model and a feedforward neural network. In addition, the differential evolution algorithm independently identifies the parameters of the motor for the multiple coupled circuit model based on easily obtained measurement data from a healthy state. With the identified parameters, the multiple coupled circuit model is used to perform dynamic simulations of the various fault cases of the specific induction motor. The simulation data set of the stator currents is used to train the neural network for classification of different stator, rotor, mechanical, and voltage supply faults. Finally, the combined method is successfully validated with measured data of faults in an induction motor, proving the transferability of the sim... [more]

Fault detection and location is one of the critical issues in engineering applications of modular multilevel converters (MMCs). At present, MMC fault diagnosis based on neural networks can only locate the open-circuit fault of a single submodule. To solve this problem, this paper proposes a fault detection and localization strategy based on a depthwise separable convolutional (DSC) neural network. By inputting the bridge arm circulating current and the submodule capacitor voltage into two serially connected neural networks, not only can this method achieve the classification of submodule open-circuit faults, submodule block short-circuit faults, and bridge arm inductance faults in MMCs, but it can also locate the switch where open-circuit faults occur. The simulation experimental results show that the proposed method achieves fault classification and locates multiple submodule open-circuit faults in the same bridge arm. This method achieves accuracies of ≥99% and 87.7% for the single-p... [more]

This article proposes a single-stage, seven-level (7L), switched-capacitor-based grid-connected inverter architecture with a common ground feature. This topology has the ability to boost the output voltage up to three times the input voltage. The proposed topology can diminish the leakage current in grid-connected photovoltaic (GC-PV) applications, and its capacitor voltages are self-balanced without any additional control strategies. The different operating modes are described in detail with their related mathematical expressions. The design of passive components and a detailed power loss analysis are presented. The merits of the proposed structure are demonstrated using a detailed comparative assessment. The grid-connected operation of the proposed inverter structure is simulated in the MATLAB/Simulink environment, and the results are presented. The laboratory prototype of 935 W is built and analyzed to validate the performance of the proposed structure.

Many countries across the globe are facing the challenge of replacing coal and natural gas-derived process heat with low-emission alternatives. In countries such as New Zealand, which have access to renewably generated electricity, industrial heat pumps offer great potential to reduce sitewide industrial carbon emissions. In this paper, a new Pinch-based Total Site Heat Integration (TSHI) method is proposed and used to explore and identify multi-level heat pump integration options at a meat processing site in New Zealand. This novel method improves upon standard methods that are currently used in industry and successfully identifies heat pump opportunities that might otherwise be missed by said standard methods. The results of the novel method application suggest that a Mechanical Vapour Recompression (MVR) system in the Rendering plant and a centralized air-source heat pump around the hot water ring main could reduce site emissions by over 50%. Future research will develop these preli... [more]

A plate-type Al/Fe−Cr alloy/Al-clad substrate was used to prepare a sandwich-structured plate-type anodic alumina catalyst by anodization, post-modification treatment, and metal loading. The as-prepared plate-type catalyst was utilized in the design of a catalytic plate reactor for a methane steam reforming reaction, and a 3D model was developed to simulate the performance of tube-type and box-type reformers. The experimental results of the preparation of the clad materials showed that the hydrothermal treatment and subsequent high-temperature calcination transformed the amorphous skeletal alumina in the conventional anodic alumina layer into γ-alumina, and significantly increased its specific surface area. Simulation results showed that the temperature difference between the channel wall and the center of the gas phase of the thin-walled catalyst was only 30% of that of the particulate catalyst, indicating the potential advantages of the catalytic plate reactor in terms of heat transf... [more]

Platinum group metal (PGM)-free oxygen reduction reaction (ORR) catalysts are of utmost importance for the rapid development of anion-exchange membrane fuel cell (AEMFC) technology. In this work, we demonstrate the improved ORR performance and stability of Co and Fe oxide-decorated/N-doped reduced graphene oxide (CoOx-Fe3O4/N-rGO) prepared via a hydrothermal method at the low temperature of 150 °C. The catalysts were characterized thoroughly using transmission electron microscopy, high-angle annular dark field-scanning electron microscopy, X-ray diffraction, N2 physisorption, Raman spectroscopy, and X-ray photoelectron spectroscopy to obtain information about morphology, elemental distribution, phases, porosity, defects, and surface elemental compositions. Significant ORR activity improvement (130 mV@-1.5 mA cm−2) was achieved with this catalyst compared to the pristine graphene oxide, and the ORR limiting current was even 12%@0.5 V higher than the commercial Pt/C. The enhanced ORR act... [more]

Multigroup constants are the foundation of neutron and photon transport problems, and the accuracy of multigroup cross-sections has a significant impact on shielding calculation. Challenges have arisen in generating accurate multigroup macroscopic cross-sections for some problems using the widely used cross-section processing code TRANSX 2.15. We developed the multigroup neutron-photon macroscopic cross-section processing module in the shielding transport code ARES. The module is capable of handling the neutron-photon coupled master libraries in MATXS format and providing the problem-dependent multigroup macroscopic cross-sections tailored to each specific shielding physics problem. The self-designed problems with a single nuclide, as well as the iron and OKTAVIAN experiments, are used to verify and analyze the accuracy of neutron and photon macroscopic cross-sections. Results indicate that the macroscopic cross-sections, neutron flux and neutron-photon leakage spectrum obtained by the... [more]

The unsteady RANS equations for a two-dimensional hydrofoil were solved using ANSYS Fluent to model and simulate the hydrofoil at a constant Reynolds number, Re, of 2 × 105 and a fixed reduced frequency, f*, of 0.14. The simulations were performed by varying parameters, such as the number of deflectors N, tilt angle of the deflectors β, and vertical spacing of the deflectors J* = J/c, to determine the effect of the upstream deflector’s position on the hydrofoil’s performance. The results demonstrated that the deflector was effective at redirecting the separated flow away from the edges, which was then amplified downstream before colliding with the leading edge of the oscillating hydrofoil to increase power extraction. The performance of the oscillating hydrofoil was highly reliant on all three studied parameters. The hydrofoil with two deflectors (N = 2) displayed marginally superior power extraction capability compared to the hydrofoil with a single deflector (N = 1). Furthermore, the... [more]

Organic Rankine cycle (ORC) is an effective technology to harness low-grade energy. Turbine, as a key component of ORC, takes advantages of its high efficiency and compact size compared with other expanders. Currently, developing suitable turbines with a high performance and a low cost is one of the bottlenecks for wide applications of various ORCs. In this context, technical progress on radial inflow turbines (RITs), axial turbines (ATs), and radial outflow turbines (ROTs) is introduced, and loss models used in the preliminary design are compared, especially for small-scale ORCs. RIT is recommended for medium and small ORCs with an expansion pressure ratio of <10. The power outs and rotational speeds of the designed RITs spanned the ranges of 9.3−684 kW and 3000−114,000 r/min with an efficiency of 56.1−91.75%. In comparison, the power outputs and speeds of ATs were 3−2446 kW and 3000−91,800 r/min with an efficiency of 63−89.1%. AT is suitable for large-scale ORCs with a power outpu... [more]

This study proposes the experimental evaluation of alternative refrigerants with low global warming potentials (GWPs) such as R1234ze(E), R513A, and the mixture R516A as a drop-in replacement for R134a in a domestic refrigerator with a volumetric capacity of 513 L. Initially, the optimal charge for each refrigerant was defined based on the minimum energy consumption of the refrigerator, then the thermal and energy performance of the refrigerator was evaluated. Finally, a total equivalent warming impact analysis (TEWI) was performed. The main results indicated that the optimal charge of the alternative refrigerants was below that corresponding to R134a (105 g), of which R516A (86 g) presented the greatest charge reduction. Regarding the average temperature of the refrigerator compartments, very adequate thermal conditions were observed; thus, the alternative refrigerants showed very similar conditions to R134a. For the coefficient of performance (COP) and considering R134a as a referenc... [more]

The structure of large biomass circulating fluidized bed (BCFB) boilers is complex, and control schemes for coal-fired boilers cannot be simply applied to biomass boilers. Multivariable coupling and operational disturbances are also common issues. In this study, a state space model of a 130 t/h BCFB boiler was established under different operating conditions. Using the 100% operating point as an example, a model predictive controller was designed and tested under output disturbance and input disturbance conditions. The results show that the predictive control system designed in this study has a fast response speed and good stability.

The high-frequency vibration and resonance of armature assembly in the hydraulic servo valve are the main reasons for instability and failure. Magnetic fluid (MF) operating in the squeeze mode can be taken as an effective damper for resonance suppression in the servo valve. Due to excitation difficulty and the low signal-to-noise ratio of high-frequency vibration signals, the capability of MF to modify multiple-order modal damping ratios in a multi-degree-of-freedom system is still unclear. To reveal the mechanism of magnetic fluid for improving modal damping ratios, an algorithm for modal damping ratio identification is proposed. The modal damping ratios of the armature assembly with and without magnetic fluid are identified based on the tested resonance free decay responses. Four resonance frequencies of armature assembly are observed, and the corresponding damping ratios are identified. The equivalent modal damping ratios due to squeeze flow of MF are obtained. The results show that... [more]

A wireless charging system that supports a large sensor network not only needs to provide real-time charging services but also needs to consider the cost of construction in order to meet the actual applications and considerations. The energy transfer between mobile devices is extremely difficult, especially at large distances, while at close distances a wireless, fast-charging, automatic, and high-precision landing system would be required. However, previous studies that used wireless charging cars, wireless charging unmanned aerial vehicles (UAVs) alone, or wireless charging pads to build a large-scale wireless charging system could not meet the above two conditions at the same time. If we can make good use of the existing high-speed backbone transport, such as the vehicular ad hoc network (VANET), it can not only consider the cost of construction and the speed of movement but also support the real-time charging service required by large-scale sensor networks. In this work, we propose... [more]

The present paper discusses the modeling and analysis of a diesel−wind generating system capable enough to cater to the electrical power requirements of a small consumer group or society. Due to high variations of the load demand or due to changes in the wind speed, the frequency of the diesel−wind system will be highly disturbed, and hence to regulate the frequency and power deviations of the wind turbine system, an effective controller design is a necessary requirement, and therefore this paper proposes a novel controller design based on PID scheme. The parameters of this controller is effectively optimized through a new snake optimizer (SO) in an offline manner to minimize frequency and power deviations of an isolated diesel−wind system. The performance of SO-PID for the diesel−wind system is evaluated by considering the integral of time multiplied absolute error (ITAE), integral absolute error (IAE), and integral of time multiplied square error (ITSE). The results were calculated f... [more]

Guangxi is a typical developing region on the southern coast of China. The current issues encountered in the region’s development are that fossil energy accounts for about 80% of the energy structure, fossil fuels are heavily dependent on imports, and the self-sufficiency rate of resources is only 32%. These challenges have created a disparity between the current regional development state and the country’s dual carbon target. Under the premise of comprehensively considering the multi-sectors of electricity, industry, transportation, and heating, this paper presents a study on the energy system transition towards low-carbon development for Guangxi in four steps. Firstly, to demonstrate EnergyPLAN’s capability in energy modeling, a reference scenario for Guangxi is created using official yearbook data from 2020. Then, a short-term scenario is formulated to analyze the development of Guangxi’s energy system during the 14th Five-Year Plan. Furthermore, two mid-term scenarios are establish... [more]

Existing electric-field integral inversion methods have limited field application conditions, and they are difficult to arrange electric-field measurement points on high-span overhead lines. This paper proposes a non-intrusive voltage measurement method for overhead transmission lines based on the near-end electric-field integration method. First, the electric-field distribution under 10 kV lines is calculated by finite element simulation software. The electric-field distribution of the plumb line and the discrete integral node below the wire are analyzed. Then, based on traditional electric-field integration, a line-voltage-inversion measurement method based on near-end electric-field integration is proposed. In addition, a voltage-monitoring system based on near-end electric-field integration is constructed. Next, the numerical integration types, the number of integration nodes, and the scale coefficient of the near-end region of the inversion algorithm are optimized with the electri... [more]

To strike a better balance between gas quality and production cost of biomass-based syngas, a process for high-safety and cost-effective syngas production is designed and studied, which takes advantage of biomass O2-enriched air gasification with 40−70% O2 purity and methanation synthesis. Based on the simulation data, the process is evaluated from techno-economic aspects, including syngas composition, higher heat value (HHV), upper and lower explosive limits (UEL and LEL), toxicity, unit production cost (UPC) and levelized cost of energy (LCOE). Five kinds of biomass are studied as feedstock. The effects of O2 purity, methanation pressure, feedstock cost, and plant scale are determined, respectively. The results show that O2 purity is an important parameter for technical performance, while methanation pressure is a minor parameter except for exergy efficiency. With respect to cost indicators, feedstock cost, and plant scale are crucial variables; by contrast, O2 purity plays a relativ... [more]

Space heating is a necessity in Alaska; however, the use of heating fuels carries both economic and environmental costs. In the Fairbanks North Star Borough (FNSB), Alaska, most households utilize heating fuel oil as a primary source for home heating and firewood as a secondary source. In the FNSB, wood-burning devices are the principal source of fine particulate matter with a size of 2.5 microns or less, (PM2.5), but firewood is less expensive when compared to heating fuel oil. The FNSB has been designated as a nonattainment area for PM2.5, which has been linked to negative cardiopulmonary impacts and other adverse health consequences. Electric thermal storage heaters (ETSH) could help solve the PM2.5 problem by displacing firewood used for residential space heating. We use dichotomous choice contingent valuation (DC-CV) to estimate willingness to pay (WTP) for an ETSH program which would allow FNSB residents to offset 100 gallons of heating fuel oil annually. Certainty correction is... [more]

In the last few years, many innovative solutions have been presented to address the climate change crisis. One of the innovative solutions is the participation of community members in the collective production of solar electricity instead of individual production. The current study aims to provide a critical literature review of the collective production of solar electricity, which is called “community-shared solar” (CSS). Sixty-seven peer-reviewed publications were selected based on the setting up of a combination of related keywords. To analyze the concept of CSS in the existing literature, a multi-level perspective (MLP) framework was used to observe the CSS innovation at the niche, regime, and landscape levels. Four aspects, including the technical, economic, socio-political, and regulatory and institutional, were considered to evaluate those three levels. The results revealed that in the technical and economic aspects, CSS has reached maturity and internal momentum that can take i... [more]

Compared to conventional façades, adaptive façades (AFs) can adjust their properties in response to environmental changes and user requirements. Often performed through the integration of actuators, sensors, and control units, this provides benefits such as reduced energy consumption in buildings but also increases the complexity of the façade design. To efficiently deal with the higher complexity, this article aims to provide suitable decision support for the early design phase, identify suitable design goals, and compare these to previously implemented Afs (make-or-buy decision). There is particular focus on the AF-specific characteristics, as these are new compared to well-known conventional façades. To systematically develop decision support, requirements are identified in expert interviews and the literature, and the current state of the art is evaluated against these. Research gaps found in current methods are addressed in this article, and continuous decision support is develope... [more]

The evaluation of pore structure is critical in understanding reservoir characteristics. This study aims to analyze the microscopic pore structure characteristics of tight reservoirs from various provenances through physical property analysis, casting thin sections, scanning electron microscopy (SEM), and constant−rate mercury injection. The pore throat parameters of the Chang 7 reservoir were analyzed and compared to those of the Xin’anbian and the Heshui areas. The results show that intergranular pores dominate the pore type of the Chang 7 reservoir in the Xin’anbian area, followed by feldspathic dissolution pores, with high-necked and tubular throat content caused by weak compaction and dissolution, respectively. On the other hand, feldspar dissolution pores dominate the pore type of the Chang 7 reservoir in the Heshui area, followed by intergranular pores, with a high content of tube−bundle throats caused by dissolution and flake−bent flake throats caused by compaction. The differe... [more]

Seas and oceans offer great potential as a widely available source of clean and renewable energy near high energy consumption centers. This source of energy is a valuable option in the energy transition and in energy matrix decarbonization. Wave energy and an oscillating water column (OWC) device stand out as the types of ocean energy with the most potential. An onshore OWC requires locations with rocky outcrops and steeper slopes as the device needs to be physically installed and has lower energy dissipation due to friction with the seabed. However, Brazil has approximately 7490 km of coastlines, with various shoreline geometries and geomorphologies, some of which are very suitable for OWC implementation. Some authors have estimated that the Brazilian coast has a total potential of 114 GW, distributed between wave and tidal energy, with a great possibility of contributing to global decarbonization efforts. This study aimed to identify and quantify the potential of locations suitable f... [more]

Recently, the reverse osmosis (RO) process is widely used in the field of desalinating brackish water and seawater to produce freshwater, but the disadvantage of using this technology is the increase in the rates of electrical energy consumption necessary to manage these units. To reduce the rates of electrical energy consumption in RO desalination plants, geothermal energy and photovoltaic/thermal panels were used as preheating units to heat the feed water before entering RO desalination plants. The proposed system in this study consists of an RO desalination plant with an energy recovery device, photovoltaic/thermal panels, and a geothermal energy extraction unit. To evaluate the system performance, three incorporated models were studied and validated by previous experimental data. The results indicated that incorporating the geothermal energy and photovoltaic/thermal panels with the RO desalination plants has positive effects in terms of increasing productivity and reducing the rate... [more]

Energy in microgrids (MGs) can now be generated from a variety of renewable sources, but their effective and sustainable use is dependent on electrical energy storage (EES) systems. Consequently, the expansion of MGs is greatly reliant on EES systems. The high infiltration of electric vehicles (EVs) causes some problems for the smooth functioning of the electric power system. However, EVs are also able to offer ancillary services, such as energy storage, to power systems. The research presented in this paper aims to develop a novel frequency regulation (FR) approach for biogas diesel engines (wind), the organic Rankine cycle (ORC), and solar-based two-area islanded microgrids with EVs in both areas. This article discusses the introduction of a fuzzy logic controller (FLC) for FR with scaled factors configured as proportional integral (PI) and proportional derivative with filter (PDF), i.e., a FLC-SF-PI-PDF controller. A recently created modified dragonfly algorithm is used to determine... [more]

The aim of this review was to analyze to what extent the relationship between corporate social responsibility (CSR), environment and energy has been addressed in the specialized literature and which are the deficient segments in this regard. VOSviewer was used for data extraction, mapping and grouping the articles from journals that have been indexed in Web of Science (WOS). A total of 102 papers were found approaching the topic of corporate social responsibility, environment and energy policy, 5192 research papers for CSR and the environment and 320 on CSR and energy policy. Following the bibliometric analysis, we can conclude that we are facing a shortage of works that analyze the relationship between the three fields together. The number of published articles was reduced to establish the direction of influence between the three variables, as well as the impact between them. However, the advantage that emerges from this lack of works is that there are many opportunities to find news... [more]