Long-term erosion and repeated scouring of water significantly affect the technical properties of coals, which are the essential elements that must be considered in evaluating an underground reservoir coal column dam’s standing sustainability. In the paper, the coal pillar dam body of the 22 layers of coal in the Shangwan Coal Mine is studied (22 represents No. 2 coal seam), and the water content of this coal pillar dam body is simplified into two types of different water content and dry−wet cycle. Through acoustic emission detection technology and energy dissipation analysis method, the internal failure mechanism of coal water action is analyzed. This study revealed three findings. (1) The crest pressure, strain, and resilient modulus in the coal sample were inversely related to the water content along with the dry−wet cycle number, while the drying−wetting cycle process had a certain time effect on the failure to the sample. (2) As the moisture content and the dry−wet cycle times inc... [more]

The increasing demand for food, the lack of natural resources and arable land, and the recent restrictions on energy consumption require an immediate solution in terms of agricultural activities. This paper’s objective was to review hydroponics (a new soilless cultivation technology) and compare it with conventional agriculture (soil cultivation) regarding its environmental impact and water and energy consumption. The soil loss, the crop/soil contamination, and the greenhouse gas emissions were the criteria for the environmental comparison of conventional agriculture and hydroponics. As for resource consumption, the water consumption rates (L/kg), energy consumption rates (kWh), and energy required (kW) were the criteria for comparing conventional agriculture with hydroponics. Tomato and cannabis cultivation were used as case studies in this review. The review results showed that the advantages of hydroponics over conventional cultivation include zero-soil cultivation, land-use efficie... [more]

The energy transition and the resulting expansion of renewable energy resources increasingly pose a challenge to the energy system due to their volatile and intermittent nature. In this context, energy management systems are central as they coordinate energy flows and optimize them toward economic, technical, ecological, and social objectives. While numerous scientific publications study the infrastructure, optimization, and implementation of residential energy management systems, only little research exists on industrial energy management systems. However, results are not easily transferable due to differences in complexity, dependency, and load curves. Therefore, we present a systematic literature review on state-of-the-art research for residential and industrial energy management systems to identify trends, challenges, and future research directions. More specifically, we analyze the energy system infrastructure, discuss data-driven monitoring and analysis, and review the decision-m... [more]

One of the essential factors for the selection of the drying process is energy consumption. This study intended to optimize the drying treatment of capers using convection (CD), refractive window (RWD), and vacuum drying (VD) combined with ultrasonic pretreatment by a comparative approach among artificial neural networks (ANN) and response surface methodology (RSM) focusing on the specific energy consumption (SEC). For this purpose, the effects of drying temperature (50, 60, 70 °C), ultrasonication time (0, 20, 40 min), and drying method (RWD, CD, VD) on the SEC value (MJ/g) were tested using a face-centered central composite design (FCCD). RSM (R2: 0.938) determined the optimum drying-temperature−ultrasonication-time values that minimize SEC as; 50 °C-35.5 min, 70 °C-40 min and 70 °C-24 min for RWD, CD and VD, respectively. The conduct of the ANN model is evidenced by the correlation coefficient for training (0.976), testing (0.971) and validation (0.972), which shows the high suitabi... [more]

A large research effort is currently ongoing within the framework of the EUROfusion consortium for the study and design of a water-cooled lithium−lead (WCLL) breeding blanket (BB). This concept will be tested in ITER through the installation of a test blanket module (TBM) and it is one of the two candidates adopted as driver BBs in DEMO. In this framework, at the ENEA research centre of Brasimone, the realization of the experimental platform, W-HYDRA, is envisaged. The platform is dedicated to the support of the development of WCLL BB and ITER TBM and the investigation of the DEMO balance of plants. One of the most important experimental infrastructures is the water-loop facility, the aim of which is to provide water at a high pressure and temperature (PWR conditions), with a sufficient mass-flow rate and power for the experimental testing of BB and TBM components. The facility will be equipped with a vacuum chamber and an electron beam gun for the reproduction of high surface heat flu... [more]

The pressure drop for air-water two-phase flow in pipeline systems with S-shaped and vertical risers at various inclinations (−1°, −2°, −4°, −5° and −7° from horizontal) was predicted using an artificial neural network (ANN). In the designing of the ANN model, the superficial velocity of gas and liquid as well as the inclination of the downcomer were used as input variables, while pressure drop values of two-phase flows were determined as the output. An ANN network with a hidden layer containing 14 neurons was developed based on a trial-and-error method. A sigmoid function was chosen as the transfer function for the hidden layer, while a linear function was used in the output layer. The Levenberg-Marquardt algorithm was used for the training of the model. A total of 415 experimental data points reported in the literature were collected and used for the creation of the networks. The statistical results showed that the proposed network is capable of calculating the experimental pressure... [more]

This paper proposes an energy management system (EMS) that aims at managing the modular direct current (DC) microgrids (MGs) of a hybrid DC/AC power system onboard cruise ships. Each shipboard microgrid is an electrically self-sufficient system supplied only by a fuel cell (FC) and a Lithium battery, and it powers the ship’s hotel services. However, continuously varying power demand profiles negatively affect the FC. Thus, the proposed EMS aims to minimize the FC operating point excursion on the source’s characteristic. This goal is pursued by exploiting the battery capability to manage load fluctuations and compensate for power demand forecasting errors. Furthermore, it is accomplished while satisfying all the operational constraints of the shipboard microgrids and ensuring daily battery charging/discharging cycles. The proposed EMS is based on two subsystems: (1) a rule-based microgrid supervisor, which makes the EMS capable of managing black start, normal operating conditions, and t... [more]

Geological CO2 sequestration (GCS) has been proposed as an effective approach to mitigate carbon emissions in the atmosphere. Uncertainty and sensitivity analysis of the fate of CO2 dynamics and storage are essential aspects of large-scale reservoir simulations. This work presents a rigorous machine learning-assisted (ML) workflow for the uncertainty and global sensitivity analysis of CO2 storage prediction in deep saline aquifers. The proposed workflow comprises three main steps: The first step concerns dataset generation, in which we identify the uncertainty parameters impacting CO2 flow and transport and then determine their corresponding ranges and distributions. The training data samples are generated by combining the Latin Hypercube Sampling (LHS) technique with high-resolution simulations. The second step involves ML model development based on a data-driven ML model, which is generated to map the nonlinear relationship between the input parameters and corresponding output intere... [more]

This paper describes the scheme and algorithm for controlling a laboratory setup that result in low uncertainty and high convergence with respect to the characteristics of electric discharges under the conditions of variable parameters of a reaction medium. The article presents current and voltage oscillograms when processing hydrocarbon raw materials. Methods for calculating the energy impact of electrical discharge are described. A comparison is made between the parameters of electric discharge with current pulse limitations and those without current pulse duration limitations. The proposed approach to controlling the characteristics of electric discharges provides the same parameters of nonthermal nonequilibrium plasma and, as a result, a regular composition of the products of plasma pyrolysis of hydrocarbon raw materials.

This paper aims to present new trends in energy-harvesting solutions pertaining to wearable sensors and powering Body Area Network nodes. To begin, we will present the capability of human beings to generate energy. We then examine solutions for converting kinetic and thermal energy from the human body. As part of our review of kinetic converters, we survey the structures and performance of electromagnetic, piezoelectric, and triboelectric systems. Afterward, we discuss thermal energy converters that utilize the heat generated by humans. In the final section, we present systems for converting energy from the electromagnetic waves surrounding a person. A number of these systems are suitable for use as wearables, such as RF harvesters and micro photovoltaic cells.

Electrical heating rods are a commonly used application for switch point heating in order to keep switch points free from ice and snow. Clamps made of spring steel usually attach the heating rod to the rail. They are localized at certain positions at a distance from each other. Thermal images showed significant temperature differences on the surface of the heating rod depending on the longitudinal position. That might be an indicator of a varying heat transfer due to a changing joint force applied by the clamps. In order to investigate the correlation between the joint force and the heat transfer between the heating rod and rail, the clamping force of newly manufactured heating rod clamps was measured initially. Therefore, a modified tensile test was used. Applied thermal and mechanical loads over a period of 4000 h could reduce the clamping force by 13%. Finally, the correlation between the heat transfer resistance, the joint force and the surface condition was experimentally determin... [more]

Fossil fuels, which are widely used in Poland, have negative environmental and health consequences. Photovoltaics, used especially by households, contribute to a reduction in CO2 emissions and indirectly reduce the problem of smog. However, the high cost of photovoltaic installations forces the use of economic incentives, such as direct subsidies to the installation, under the “My Electricity” program (hereinafter referred to as the program). The development of photovoltaics is hindered by the ineffective functioning of transmission grids. In the current edition of the “My Electricity” program, the main emphasis was placed on the use of electricity at the place of generation through the use of energy storage facilities and the transition to a new billing system, so-called net billing. The program indirectly contributes to the growing popularity of heat pumps as an installation that uses electricity generated on-site. Significant changes in the program inspired the authors of the study... [more]

Chelating agents’ application for EOR and well stimulation is fast growing nowadays. However, reagents of this class have some drawbacks, with high values of interfacial tension (IFT) being among them. IFT may be lowered with the addition of surfactants; however, the simultaneous application of chelating agents and surfactants has not yet been widely studied. This paper focuses on the experimental and theoretical investigation of the interaction between chelating agent (ethylenediaminetetraacetic acid, EDTA) and surfactants of anionic and cationic types (sodium dodecyl sulfate, SDS, and dodecyl trimethynlammonium bromide, DTAB). IFT measurement was performed at ambient conditions, with normal octane being as the reference hydrocarbon to eliminate the temperature and salinity effects and compare surfactant-containing systems. The experimental results show that chelating agents’ addition to the solutions of surfactants leads to a decrease in IFT value. Moreover, surfactants’ critical mic... [more]

This article presents a neural algorithm based on Reinforcement Learning for optimising Linear Quadratic Regulator (LQR) creation. The proposed method allows designing such a target function that automatically leads to changes in the quality and resource matrix so that the target LQR regulator achieves the desired performance. The solution’s stability and optimality are the target controller’s responsibility. However, the neural mechanism allows obtaining, without expert knowledge, the appropriate Q and R matrices, which will lead to such a gain matrix that will realise the control that will lead to the desired quality. The presented algorithm was tested for the derived quadrant model of the suspension system. Its application improved user comfort by 67% compared to the passive solution and 14% compared to non-optimised LQR.

The primary purpose of recent research on solar cells is to achieve a higher power conversion efficiency with stable characteristics. To push the developments of photovoltaic (PV) technology, tandem solar cells are being intensively researched, as they have higher power conversion efficiency (PCE) than single-junction cells. Perovskite solar cells (PSCs) are recently used as a top cell of tandem solar cells thanks to their tunable energy gap, high short circuit current, and low cost of fabrication. One of the main challenges in PSCs cells is the stability issue. Carbon perovskite solar cells (CPSCs) without a hole transport material (HTM) presented a promising solution for PSCs’ stability. The two-terminal monolithic tandem solar cells demonstrate the commercial tandem cells market. Consequently, all the proposed tandem solar cells in this paper are equivalent to two-terminal monolithic tandem devices. In this work, two two-terminal tandem solar cells are proposed and investigated usin... [more]

This paper used the energy, exergy, and economic analysis of a carbon dioxide (CO2) transcritical two-stage compression system based on organic Rankine cycle (ORC) waste heat recovery technology. When the intermediate pressure and high-pressure compressor outlet pressure were changed, respectively, this study simulated the change in system energy efficiency by adding the ORC for waste heat recovery, calculated the ratio of exergy loss of each component, and performed an economic analysis of the coupled system. The results show that adding waste heat recovery can effectively increase the energy efficiency of the system, and among all components, the heat exchanger had the largest exergy loss, while the evaporator had the highest capital investment and maintenance costs.

Availability of reliable and extended datasets of recorded power output from renewables is nowadays seen as one of the key drivers to improve the design and control of smart energy systems. In particular, these datasets are needed to train artificial intelligence methods. Very often, however, datasets can be corrupted due to lack of records connected to failures of the acquisition system, maintenance downtime periods, etc. Several recovery (imputation) methods have been used to guess and replace missing data. In this paper, we exploit the matrix completion approach. The available measures of several variables referring to a real onshore wind farm are organized into a matrix in a daily range and the Singular Value Thresholding method is used to carry out the matrix completion process. Numerical results show that matrix completion is a reliable and parameter-free tuning tool to impute missing data in these applications.

The solar trough concentrator is used to increase the solar radiation intensity on absorbers for water heating, desalination, or power generation purposes. In this study, optical performances of four solar trough concentrators, viz. the parabolic trough concentrator (PTC), the compound parabolic concentrator (CPC), the surface uniform concentrator (SUC), and the trapezoid trough concentrator (TTC), are simulated using the Monte Carlo Ray Tracing method. Mathematical models for the solar trough concentrators are first established. The solar radiation distributions on their receivers are then simulated. The solar water heating performances using the solar trough concentrators are finally compared. The results show that, as a high-concentration ratio concentrator, the PTC can achieve the highest heat flux, but suffers from the worst uniformity on the absorber, which is only 0.32%. The CPC can generate the highest heat flux among the rest three low-concentration ratio solar trough concentr... [more]

The accurate prediction of heat fluxes and, thus, metal wall temperatures of gas turbine (GT) combustor liners is a complicated and numerically expensive task. Computational Fluid Dynamics (CFD) support for the design of cooling systems is essential to ensure safe and proper operation of the entire gas turbine engine. Indeed, it is well known how complicated, and, at the same time, expensive it is to carry out experimental campaigns inside combustors operating under working conditions, and, therefore, pressurized and having high temperatures. The correct prediction of thermal fluxes in a CFD simulation depends on the proper modeling of all the involved phenomena and their interactions with each other. For this reason, Conjugate Heat Transfer (CHT) simulations are mandatory in gas turbine cooling system applications. Multiphysics and multiscale simulations, based on loosely-coupled approaches, have emerged as extremely effective numerical tools, providing enormous computational time sav... [more]

Coughing and sneezing are the main ways of spreading coronavirus-2019 (SARS-CoV-2). People sometimes need to work together at close distances. This study presents the results of the computational fluid dynamics (CFD) simulation of the dispersion and transport of respiratory droplets emitted by an infected person who coughs in an indoor space with an air ventilation system. The resulting information is expected to help in risk assessment and development of mitigation measures to prevent the infection spread. The turbulent flow of air in the indoor space is simulated using the k-ε model. The particle equation of motion included the drag, the Saffman lift, the Brownian force and gravity/buoyancy forces. The innovation of this study includes A: Using the Eulerian−Lagrangian CFD model for the simulation of the cough droplet dispersion. B: Assessing the infection risk by the Wells−Riley equation. C: A safer design for the ventilation system (changing the ventilation supplies and exhausts in... [more]

This study proposes a framework of environmental and energy performance indicators identified and critically evaluated within the scientific literature and the Agricultural European Database for the monitoring and evaluation of the Common Agricultural Policy of the European Union. The identified set of performance indicators encompasses the whole life cycle of agri-food systems from primary production stage until end-of-life stage in agreement with the circular economy and EU “farm to fork strategy” frameworks. In particular, the practices/goals/targets suggested in the latter (e.g., organic farming goals, more relevance assigned to plant-based diets, support for the creation of short supply chains, and reduction in food losses and waste) have guided the search for the main topics of interest in our analysis and the associated environmental and energy indicators. The results of this study evidence a proposed set of performance indicators selected from the literature among LCA and non-L... [more]

Around the globe, electric power networks are transforming into complex cyber−physical energy systems (CPES) due to the accelerating integration of both information and communication technologies (ICT) and distributed energy resources. While this integration improves power grid operations, the growing number of Internet-of-Things (IoT) controllers and high-wattage appliances being connected to the electric grid is creating new attack vectors, largely inherited from the IoT ecosystem, that could lead to disruptions and potentially energy market manipulation via coordinated load-altering attacks (LAAs). In this article, we explore the feasibility and effects of a realistic LAA targeted at IoT high-wattage loads connected at the distribution system level, designed to manipulate local energy markets and perform energy storage (ES) arbitrage. Realistic integrated transmission and distribution (T&D) systems are used to demonstrate the effects that LAAs have on locational marginal prices at t... [more]

The research on renewable energy is actively looking into electrocatalysts based on transition metal chalcogenides because nanostructured electrocatalysts support the higher intrinsic activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). A major technique for facilitating the conversion of renewable and sustainable energy is electrochemical water splitting. The aim of the review is to discuss the revelations made when trying to alter the internal and external nanoarchitectures of chalcogenides-based electrocatalysts to enhance their performance. To begin, a general explanation of the water-splitting reaction is given to clarify the key factors in determining the catalytic performance of nanostructured chalcogenides-based electrocatalysts. To delve into the many ways being employed to improve the HER’s electrocatalytic performance, the general fabrication processes utilized to generate the chalcogenides-based materials are described. Similarly, to... [more]

Parameter estimation represents an important aspect of modeling electromagnetic systems, and a wide range of parameter estimation strategies has been explored in literature. Most parameter estimation methodologies make use of either time-domain or frequency-domain responses as measured from the terminals of the device under test. Very limited research has, however, been conducted into exploring the use of modal decomposition strategies on the time-domain waveforms for parameter estimation applications. In this paper, the use of Empirical Mode Decomposition for estimating the parameters of a three-section lumped parameter transformer model is explored. A novel approach is proposed to define the optimization cost function in terms of the intrinsic modes of simulated time-domain waveforms. The results are compared with results obtained using classical time-domain and frequency-domain approaches. It is shown through an impulse response test that weighting the modes obtained from the Inferr... [more]

In the material transfer area, the belt is exposed to considerable damage, the energy of falling material is lost, and there is significant dust and noise. One of the most common causes of failure is transfer chute blockage, when the flow of material in the free fall or loading zone is disturbed by oversized rock parts or other objects, e.g., rock bolts. The failure of a single transfer point may cause the entire transport route to be excluded from work and associated with costly breakdowns. For this reason, those places require continuous monitoring and special surveillance measures. The number of methods for monitoring this type of blockage is limited. The article presents the research results on the possibility of visual monitoring of the transfer operating status on an object in an underground copper ore mine. A standard industrial RGB camera was used to obtain the video material from the transfer point area, and the recorded frames were processed by a detection algorithm based on... [more]