The impact of single-slope solar still with and without flat-plate collector was evaluated experimentally and numerically. Experimental analysis was conducted for four different water depths (3, 6, 9, 12 cm) in on-sunshine hours between 11 AM to 5 PM in Bhopal (23.2599° N, 77.4126° E), India. The thermo efficiency was 51.31% for 3 cm water depth while 24.29% for 12 cm water depth in an active mode of operation. In the case of passive mode, the thermo efficiency was 17.02% for 3 cm water depth and 6.77% for 12 cm water depth. The average exergy efficiency of single-slope solar still is 66.60% for 3 cm depth which is higher than 12 cm depth, i.e., 23.14%. The hourly variation parameters of solar still were also calculated and analyzed. The overall results obtained in the analysis state that solar still performs effectively when coupled with a flat-plate solar collector. According to econometric evaluation, the fabrication expense of a single-slope solar-basin-still is 126.43$ whereas the... [more]

There is a huge requirement for power systems to reduce power losses. Adding distributed generators (DGs) is the most common approach to achieving lower power losses. However, several challenges arise, such as determining the ideal size as well as location of the utilized distributed generators. Most of the existing methods do not consider the variety of load types, the variety and size of the utilized DGs besides reducing the convergence time and enhancing the optimization results. The paper performed an optimization algorithm that integrated a golden search-based flower pollination algorithm and fitness-distance balance (FDB) to find out the optimal size as well as the location of the distributed generators. It was then compared with different optimization methods to determine the best optimization technique, and it was determined to be the best technique. In addition, different types of DGs are considered, including solar energy, wind energy, and biogas, along with optimizing the si... [more]

In the present paper, we introduce a decision-support framework to (a) classify and prioritize the municipalities of a country based on their suitability to host PV energy projects and (b) pinpoint and evaluate suitable technically and economically viable, as well as environmentally and socially sustainable, sites for PV installation in the most suitable municipalities of a country. The proposed framework is applied in Portugal. It consists of two distinctive stages: ‘Energy Roadmap for PV Deployment’ and ‘PV Site-Selection Analysis and Assessment’. In the first stage, the most and least suitable municipalities for PV deployment in Portugal are identified by analyzing important environmental and technoeconomic PV siting criteria in GIS and applying the TOPSIS method. In the second stage, an integrated PV site-selection assessment is conducted in the Portuguese municipality with the highest suitability index for PV installations. This is achieved by combining a proper GIS siting model w... [more]

A recloser requires a fast operating time in the first shot to optimally clear a temporary fault. The operating time is dependent on the time-dial, the pick-up settings, and the fault current. The recloser detects the fault current from the grid supply; however, the connection of the generators in the distribution system can contribute to the fault current. Depending on the location of the generators and the direction of the current, the fault current can decrease and cause an increase in the operating time. Therefore, the optimal settings that can minimize the operating time may need to be determined. This paper simulates the behavior of a recloser in its first shot for clearing a temporary fault and tests its performance in an active distribution system that has two types of distributed generators. It then uses the differential evolution algorithm to find the optimal settings in the active distribution voltage conditions. It also applies modifications to the differential evolution al... [more]

Aluminum AA5052 is an inexpensive and lightweight metal that has been used in a variety of applications, including the Bipolar Plate in Proton Exchange Membrane Fuel Cells (BPs PEMFC). The alloy has good electrical conductivity and low corrosion. Corrosion rate (CR) increases during PEMFC operation with increasing temperature. Inorganic dyes, such as chromate, are commonly used to reduce metal corrosion. Unfortunately, they are toxic and have a negative impact on the environment. Chitosan, which is a green, cheap, non-toxic, and environmentally friendly organic solvent, can be used to solve this problem. Electrophoretic Deposition (EPD) technique was used to coated the surface of AA5052 with chitosan. CR was measured using electrochemical and weight loss methods (in 0.5 M H2SO4). The best research results are as follows. The lowest CR values were obtained at the EPD time of 20 min at a chitosan concentration of 0.5% wt. The results of the study using the weight loss method indicated th... [more]

The microgrids operate in tie-up (TU) mode with the main grid normally, and operate in isolation (IN) mode without the main grid during faults. In a dynamic operational regime, protecting the microgrids is highly challenging. This article proposes a new microgrid protection scheme based on a state observer (SO) aided by a recurrent neural network (RNN). Initially, the particle filter (PF) serves as a SO to estimate the measured current/voltage signals from the corresponding bus. Then, a natural log of the difference between the estimated and measured current signal is taken to estimate the per-phase particle filter deviation (PFD). If the PFD of any single phase exceeds the preset threshold limit, the proposed scheme successfully detects and classifies the faults. Finally, the RNN is implemented on the SO-estimated voltage and current signals to retrieve the non-fundamental harmonic features, which are then utilized to compute RNN-based state observation energy (SOE). The directional a... [more]

The validation of the potential energy yield of bifacial PV systems of various configurations at low latitudes under West African climatic conditions is critical for evaluating performance and for promoting market expansion of the technology since validation has mostly occurred in high-latitude regions. In this paper, the potential energy yield from an inclined south-facing bifacial PV module and a vertically mounted east−west bifacial PV module are compared to an inclined south-facing monofacial PV module using an analytical model, field-measured data, and simulations. For measured/modelled and PVsyst/modelled monofacial systems, the model predicts RMSE values of 1.49 and 9.02, respectively. An inclined bifacial PV system has RMSEs of 1.88 and 7.97 for measured/modelled and PVsyst/modelled, respectively, and a vertically installed system has RMSEs of 10.03 for measured/modelled and 3.76 for PVsyst/modelled. Monthly energy yield is predicted by the model, with deviations from measured... [more]

The transformer is one of the most important electrical machines in electrical systems. Its proper operation is fundamental for the distribution and transmission of electrical energy. During its service life, it is under continuous electrical and mechanical stresses that can produce diverse types of damage. Among them, short-circuited turns (SCTs) in the windings are one of the main causes of the transformer fault; therefore, their detection in an early stage can help to increase the transformer life and reduce the maintenance costs. In this regard, this paper proposes a signal processing-based methodology to detect early SCTs (i.e., damage of low severity) through the analysis of vibroacoustic signals in steady state under different load conditions, i.e., no load, linear load, nonlinear load, and both linear and nonlinear loads, where the transformer is adapted to emulate different conditions, i.e., healthy (0 SCTs) and with damage of low severity (1 and 2 SCTs). In the signal process... [more]

Compared to mechanical compressors, ejector-based refrigeration systems can make direct use of many forms of thermal energy, including waste heat, solar thermal, or biogases. It is known that SE systems have a lower thermal efficiency compared to mechanical compressors because of their lower performance at high compression ratios. In the present work, binary fluid ejector heat pumps with high efficiency are presented based on a proper selection of the binary fluids and the ejector geometry for specific operating conditions of a ground-source heat pump cooling system (GSHP). The existing literature on ejector-based refrigeration systems considers the thermal COP and does not account for many energy losses across the system. In the present paper, the system COP of an ejector-based GSHP that accounts for all energy exchange processes is determined. A method for the calculation of the work done by the boiler feed pump, the refrigeration expansion valve, and the ground loop circulation pump... [more]

Modern electric power systems consist of large-scale, highly complex interconnected systems projected to match the intense demand growth for electrical energy. This involves the decision of generation, transmission, and distribution of resources at different time horizons. They also face challenges in incorporating new forms of generation, distributed generations, which are located close to consumer centers, and new loads such as electric vehicles. Traditionally, the nonlinear Newton−Raphson optimization method is used to support operational decisions in such systems, known as Optimal Power Flow (OPF). Although OPF is one of the most practically important and well-researched sub-fields of constrained nonlinear optimization and has a rich history of research, it faces the convergence difficulties associated with all problems represented using non-linear power flow constraints. The proposal is to present an approach in a software component in cloud Application Programming Interface (API)... [more]

The powertrain performance in an electric vehicle is fully dependent on the electrical and thermal constraints of the static converters ensuring the power transfer taking place between the energy storage systems and the electromechanical machines. These constraints depend on the architectures of the power converters, and their control strategies. Particularly, the maximal limits are reached in maneuvers such as hard regenerative braking circumstances. Indeed, braking recovery is a critical phase in the vehicle’s operation, and its duration and intensity may strongly impact the vehicle’s battery behavior or integrated hybrid storage system. The innovative objective of the paper is to propose an electrothermal multicriteria comparative study based on electrical and thermal criteria for two competitive powertrains. These semi-active power configurations (a 3-level DC/DC converter-based, and a Z-source converter-based) are implemented in a two-front wheel driven electric vehicle during ext... [more]

The low permeability and submicron throats in most shale or tight sandstone reservoirs have a significant impact on microscale flow. The flow characteristics can be described with difficultly by the conventional Darcy flow in low-permeability reservoirs. In particular, the thickness of the boundary layer is an important factor affecting the formation permeability, and the relative permeability curve obtained under conventional conditions cannot accurately express the seepage characteristics of porous media. In this work, the apparent permeability and relative permeability were calculated by using non-Darcy-flow mathematical modeling. The results revealed that the newly calculated oil−water relative permeability was slightly higher than that calculated by the Darcy seepage model. The results of the non-Darcy flow based on the conceptual model showed that the area swept by water in non-Darcy was smaller than that in Darcy seepage. The fingering phenomenon and the high bottom hole pressur... [more]

One of the best precursors for winter wheat is fallow. Its application aims to solve two important tasks: preserving and accumulating soil moisture and weed control. The authors of this paper have designed a new modular harrow for fallow tillage, which can work stably at a depth of 5−6 cm tillage while maintaining and even accumulating soil moisture. This article describes a method designed by the authors for a reasonable selection of the design parameters concerning the working devices mounted inside the new harrow, such as their length and working width, as well as the angles of vertical inclination (ε) and horizontal deviation (γ) of blades, depending on the accepted depth of the upper soil layer loosening. To reduce the soil tillage resistance of the harrowing unit resulting in a reduction in the tractor fuel consumption, the value of the inclination angle (ε) of its vertical blade should be chosen so that the corresponding change in the value of the deflection angle of the horizon... [more]

Frequency, voltage, and power flow between different control zones in an interconnected power system are used to determine the standard quality of power. Therefore, the voltage and frequency control in an IPS is of vital importance to maintaining real and reactive power balance under varying load conditions. In this paper, a dandelion optimizer (DO)-based proportional-integral-proportional-derivative (PI-PD) controller is investigated for a realistic multi-area, multi-source, realistic IPS with nonlinearities. The output responses of the DO-based PI-PD were compared with the hybrid approach using artificial electric field-based fuzzy PID algorithm (HAEFA), Archimedes optimization algorithm (AOA)-based PI-PD, learning performance-based behavior optimization (LPBO)-based PI-PD and modified particle swarm optimization (MPSO)-based PI-PD control schemes in a two-area network with 10% step load perturbation (SLP). The proposed strategy was also investigated in a two- and three-area IPS in t... [more]

This review is devoted to an overview of the prospects for the development of the global hydrogen market and the strategies of individual countries aimed at transforming energy systems in favor of decarbonization and greening through the use of hydrogen. Special attention is paid to the prospects for the development of the Russian hydrogen market. The authors of the review used the method of comparative analysis and analytical generalization of publications, programs and regulatory documents from different countries. The results of the comparative analysis led to the conclusion that most of the publications currently focus on the technical and technological aspects of hydrogen energy, solving the problem of increasing the efficiency of methods for the production, transportation, distribution and storage of hydrogen fuel. The results of the analytical generalization led to the conclusion that in all countries of the world, the technology for the production of highly environmentally frie... [more]

Rock mass has typical pore structure, and the induced coupling effects of fluid and solid matrix appear in the disaster evolution process of deep energy exploitation and overground rock hydration. As a representative case, influenced by the water absorption environment, the surrounding rock and murals of Mogao Grottoes produce hydration diseases, which may be related to unclear interaction mechanisms between the surrounding rock and water. In this study, the self-developed physical experimental system for real-time experimental monitoring was applied to test the water absorption evolution behaviors of sandstone. The experimental results showed that the water evaporation of the rock sample during the process of water absorption could be measured through this well-designed physical experimental system, and the actual water absorption of the rock sample is the difference between the decrease of water in the water storage bucket, measured by the balance and the water evaporation in the pro... [more]

The transportation industry is a high carbon emission industry, and China has also put forward strict requirements for the transportation industry to achieve carbon emission reduction. By measuring the total factor carbon emission efficiency of the transportation industry, we can understand the change trend and the influencing factors of the total factor carbon emissions. To fully consider the problem of multiple inputs and outputs in the transportation industry and obtain a more accurate efficiency evaluation value, this paper adopted the slack-based model-data envelopment analysis method and global Malmquist—Luenberger index to study the change in the total factor carbon emission performance of the transportation industry. The combination of static analysis and dynamic analysis was used to calculate the TFP of the transportation industry and increase the content of output indicators. The results indicate that the average TFP and GML index values exhibited significant heterogeneity na... [more]

To mitigate the consequences of climate change, there is an increasing need to minimize the usage of fossil fuels, especially in the industrial sector because the majority of the industrial sector primarily rely on fossil fuels to meet their needs for heat energy, and a practical strategy to reduce reliance on fossil fuels is to use energy from the sun. Due to their environmental advantages, energy security, and viability as a potential substitute for fossil fuels, solar thermal collectors are acknowledged as promising technology to harness solar thermal energy fir process heating applications. This review is a thorough compendium and evaluation of contemporary literature on solar thermal collectors and their applications in industry. Apart from applications, this review paper also assesses the challenges and limitations currently hindering the global acceptance of this technology in the industrial sector.

Under the condition of fully mechanized top coal caving in close-distance coal seams, the surrounding rock of the stopping space easily loses stability during the withdrawal of mining equipment in the working face because the lower coal seam working face is located under the goaf and the overburden rock has a large range of complex interaction. Field investigation, theoretical analysis, laboratory experiment, similar simulation experiment, numerical simulation, and field industrial tests are used to carry out the research on the stability and control of the surrounding rock in the large section stopping space under the goaf in this paper. The research conclusions are as follows. (1) It is determined that the lower coal seam working face can only stop mining under the goaf, and the reasonable stopping position under the goaf should ensure that the key block fracture line of the main roof is behind the support. (2) The interaction law between the main roof’s key blocks of the upper and l... [more]

Research over several years has shown that municipal engineering is an important source of humic substance formation (HS). Effluents from municipal landfills and digested sludge, due to high concentrations of organic pollutants, including HS and inorganic pollutants, are discharged to a biological treatment plant, where their largely non-biodegradable pollutants constitute a burden on the activated sludge and generate problems related to wastewater treatment. To demonstrate that humic substances, primarily soluble acids, are the carriers of micro-pollutants, their isolation was carried out from samples taken at different municipal management sites. The following analyses were performed: elemental composition, and the content of inorganic micropollutants, including heavy metals. In addition, the sorption affinity of pure HS to selected pharmaceuticals was investigated. The sorbed pharmaceuticals were Diclofenac and Estrone. HS commonly found in municipal engineering have been shown to b... [more]

According to the requirements of weak current measurement in power grid, a weak current sensor with anti-low frequency interference ability is developed. The sensor adopts the principle of fluxgate detection and adds a magnetic ring on the original basis. The structure of the magnetic ring is simulated using comsol to further improve detection sensitivity. In order to solve the problem that the electromagnetic current sensor is vulnerable to the interference of geomagnetic field and power frequency magnetic field in weak current measurement, a magnetic shielding method with low cost is selected, and the shielding shell structure is designed using a finite element analysis method. The experimental results show that the minimum measurable current is 1 mA, the measurement range is 1 mA−1 A, and the bandwidth is DC-16 kHz. The designed magnetic shielding shell can effectively reduce 97.3% of the DC magnetic field interference and 95.7% of the power frequency magnetic field interference. Th... [more]

Photovoltaic-thermal (PVT) technologies have demonstrated several attractive features, such as higher power and comparative efficiencies. Improving the thermal recovery from the PVT system would further improve the power output and the efficiency of the PVT system. This paper identifies the best operating factors of nanofluid-based PV thermal/nano-enhanced phase change material using artificial intelligence. The target is the maximization of thermal energy and exergy outputs. The suggested approach combines ANFIS modelling and particle swarm optimization (PSO). Four operating factors are taken into consideration: PCM (phase change material) layer thickness, HTF (heat transfer fluid) mass flow rate, MFNPCM (“mass fraction of nanoparticles in PCM”) and MFNfluid (“mass fraction of nanoparticles in nanofluid”). Using a dataset, an “adaptive neuro-fuzzy inference system” (ANFIS) model has been established for simulating the thermal energy and exergy outputs in terms of the mentioned operati... [more]

There have been consequences regarding the increment of the greenhouse effect, such as the rise in the planet’s global temperature, and climate change. Refrigerants have an important contribution to the aforementioned environmental impact. In particular, hydrofluorocarbons (HFCs) contribute to the destruction of the ozone layer and the increase of the greenhouse effect. Protocols, international agreements, and legislation were developed to slow down the emission of greenhouse gases. Prohibition and definition of deadlines for the gradual elimination of various refrigerants have been proposed to replace them with others that are environmentally sustainable. Soon, the refrigeration sector will have to replace some refrigerants with others that are alternative and/or sustainable with minimal or zero environmental impact. A computational tool to support decision-making regarding the selection of alternative and/or sustainable refrigerant to replace the old one is developed to be used by re... [more]

Smart grid training system needs to evaluate actions during power grid operations in order to complete training for relevant personnel. The commonly used action evaluation methods are difficult for evaluating fine actions during power grid operations, and the evaluation results are subjective. The use of an effective method to evaluate the actions of the power grid operation is important for improving the smart grid training system, enhancing the skills of the trainers, and ensuring the personal safety of operators. This paper proposes a cloud attention mechanism and an evaluation method of grid-related actions based on a multidimensional adaptive entropy cloud model to complete the evaluation of fine actions in the grid’s operation process. Firstly, the OpenCV technique is used to obtain the data related to hand actions during grid operation and to extract the action features to complete the construction of multiscale date sets; then, the adaptive entropy weight matrix at different sc... [more]

The energy sector plays a crucial role in addressing the global challenges of achieving sustainability by using renewable energy sources as well as by increasing energy efficiency and conservation while gaining energy security and safety. Choosing an appropriate research method to investigate the energy sector’s management has become more complex, involving multiple factors such as technical, environmental, social, political and economic. Additionally, considering the important role of energy in modern society, it is imperative to study the current methods used in examining the energy sector and to create an appropriate theory of the managing energy sector enterprises in the future. The main purpose of this review paper is to explore which research methods and approaches are utilized by researchers studying the issues of the managing energy sector enterprises. This article presents a systematic review based on a qualitative synthesis of the accessible publications from the Scopus datab... [more]