This paper develops a model of the multi-wing finite-conductivity fractures considering stress sensitivity for low-permeability bi-zone composite gas reservoirs. A new semi-analytical solution in the Laplace domain is presented. The main solution includes the theory of source function, Laplace integral transformation, perturbation technique, and Stehfest numerical inversion. Wellbore pressure is obtained by coupling solutions of reservoirs and fractures. The results showed that the pressure and derivative curves generated by this model include a bi-linear flow stage. The model was validated by comparing its results with Wang’s results and the commercial well-test simulator; the results showed excellent agreement. This model illustrated the seepage characteristic of acid fracturing stimulated wells during refracturing treatment and how they are influenced by reservoir and hydraulic fractures parameters (asymmetrical factor and fractures distribution, etc.). The model is suitable to solv... [more]

Along with the technology boom regarding electric vehicles such as lithium-ion batteries, electric motors, and plug-in charging systems, inductive power transfer (IPT) systems have gained more attention from academia and industry in recent years. This article presents a review of the state-of-the-art development of IPT systems, with a focus on low-voltage and high-current electric mobility applications. The fundamental theory, compensation topologies, magnetic coupling structures, power electronic architectures, and control methods are discussed and further considered in terms of several aspects, including efficiency, coil misalignments, and output regulation capability. A 3D finite element software (Ansys Maxwell) is used to validate the magnetic coupler performance. In addition, a 2.5 kW 400/48 V IPT system is proposed to address the challenges of low-voltage and high-current wireless charging systems. In this design, an asymmetrical double-sided LCC compensation topology and a passi... [more]

Inflatable wings are of interest for applications where low weight, compact transport volume, and easy set-up are important. Examples are unmanned aerial vehicles with inflatable wings, paragliders and softkites for sport or airborne wind-energy applications. In this paper, a new method of designing and fabricating conformable inflatable wings by Jacquard three-dimensional weaving is presented. Depending on the weaving pattern, plane-parallel, tapered, or even curved structures can be produced. An analytical framework was developed to determine the shapes of pressurized structures produced by Jacquard weaving. Based on this theory, several design patterns suitable for inflatable wings are proposed. It is shown that the structural efficiency of the woven structure is identical to the structural efficiency of a cylinder. To validate the concept, different wing prototypes were built with the methods used for the mass production of airbags. The new method allows for the cost-efficient fabr... [more]

We are currently seeing an increasing number of devices that support wireless power transfer (WPT) technology. In order to avoid early prototyping and carry out a series of experimental analyses, it was possible to use numerical methods at the design stage to estimate the potential power transfer and efficiency of the system. The purpose of this study is to present a method of analysis for a periodic wireless power transfer system, using periodically arranged planar coils with field and circuit models. A three-dimensional numerical model of a multi-segment charging system with periodic boundary conditions was solved with the finite element method (FEM). An equivalent circuit model of the periodic WPT system was proposed, and the required lumped parameters were obtained using analytical formulas. Mathematical formulas were supplemented with the analysis of several geometric variants, taking into account different sizes of transmitting and receiving coils, as well as different numbers of... [more]

The dynamic behavior of reed valves during suction and discharge is very important in predicting compressor performance and valve fatigue fracture. For an accurate dynamic analysis of reed valves, mass flow rate and effective force area should be accurately modeled. In this study, mass flow rate and effective force area models were developed based on CFD analysis results using the well-known commercial software ANSYS Fluent. CFD analyses were carried out for various values of port radius, valve radius, valve lift, and pressure difference. The mass flow rate and pressure force on valve were obtained from the analysis. Then, effective flow and force area models were proposed and the model coefficients were determined using the CFD results. The average prediction error of the effective flow area and the effective force area were 1.90% and 2.9%, respectively. It was shown that the effective flow area is dependent only on the port radii and valve lift; it is not dependent on the valve radii... [more]

Globally, renewable energies are indispensable resources on account of RE100 and the Paris Agreement. The most developed renewable energies are photovoltaics (PV) and wind energy, and they are continuously expanding. This study aims to optimize and analyze the nuclear power plant (NPP) load-following operation in various PV conditions in a metropolitan region. With theoretically estimated power demand and PV power, a mixed-integer problem (MIP) with ramping cycle constraint (RCC) was constructed for a safe load-following operation and simulated through duck curves under various NPP load-following regions (the extreme, normal, and safe regions). The simulation showed two major results for NPP load-following. Technically, RCC successfully controlled the NPP ramp cycle and was assured to be an optimization tool for NPP operation. Numerically, NPP load-following alleviated PV intermittency to almost 50%, 30%, and 15% depending on the load-following region. However, these effects were restr... [more]

The bottom hole fluctuating pressure has a large influence on the wellbore instability. To address this problem, firstly, according to the principle of seepage mechanics, we established a calculation model of the change in pore pressure around the wellbore radius under fluctuating pressure; then, through laboratory rock mechanics test and rock damage mechanics theory analysis, the change law of formation strength under the action of static hydration and dynamic damage are determined; finally, based on the theory of rock mechanics in porous media, a quantitative evaluation method for the risk of wellbore instability under fluctuating pressure is established and the changing pattern of wellbore instability risk is analyzed. The results show that the pore pressure around the well shows a trend of fluctuation increase under fluctuating pressure, and there is a certain lag in the fluctuation of pore pressure inside the formation; the longer the muddy shale is immersed in drilling fluid, the... [more]

By taking into account the turbine type, terrain, wind climate and layout, the effects of wind turbine wakes and other losses, engineering models enable the rapid estimation of energy yields for prospective and existing wind farms. We extend the capability of engineering models, such as the existing deep-array wake model, to account for additional losses that may arise due to the presence of clusters of wind farms, such as the global blockage effect and large-scale wake effects, which become more significant with increasing thermal stratification. The extended strategies include an enhanced wind-farm-roughness approach which assumes an infinite wind farm, and recent developments account for the upstream flow blockage. To test the plausibility of such models in capturing the additional blockage and wake losses in real wind farm clusters, the extended strategies are compared with large-eddy simulations of the flow through a cluster of three wind farms located in the German sector of the... [more]

Micro-gas turbines are used for power generation and propulsion in unmanned aerial vehicles. Despite the growing demand for electric engines in a world striving for a net zero carbon footprint, combustion gas turbines will continue to play a critical role. Hence, there is a need for improved micro-gas turbines that can meet stringent environmental regulations. This paper is the first part of a comprehensive study focused on understanding the fundamental performance and emission characteristics of a micro-gas turbine model, with the aim of finding ways to enhance its operation. The study used a multidisciplinary CFD model to simulate the reacting flow in the combustion chamber and validated the results against experimental data and throughflow simulations. The present work is one of the few work that attempts to address both the aerothermal performance and emissions of the gas turbine. The findings highlight that parameters such as non-uniform outlet pressure, fuel-to-air ratio, and fue... [more]

The topic of frost formation on the heat exchanger surface has been gaining interest since the late 1940s. Scientists and industrial engineers from many scientific and R&D units around the world have been trying to understand the nature of frosting and implement solutions to prevent such an unwanted phenomenon from having a significant impact on the performance of heat exchangers (such as a decrease in heat transfer efficiency, mechanical damage, and condensation risk). The aim of this article is to summarize the present state of knowledge dedicated to frost formation types and morphology, review, and discuss the most recent studies relevant to the challenge of frost formation, focusing on the evaporator of the domestic refrigerator. The different types of domestic refrigerators are summarized, as are the different types of evaporators inside them. Common methods of testing frost formation phenomena on the evaporator are revisited in this article, and the analysis of the most recent ma... [more]

Due to the economic inefficiency of material recycling of general industrial waste and urban waste, the use of solid recovered fuels (SRFs) not only mitigates the environmental loadings from waste incineration plants and sanitary landfills but also creates green electricity and/or heat and thus reduces the use of fossil fuels. In this regard, the Taiwan government formulated the “Solid Recovered Fuel Manufacturing Guidelines and Quality Standards” in 2020 to ensure the manufacturing quality of SRFs. This paper focused on the status of waste management and energy supply, the current regulations for adopting SRFs, and the challenges in the development of SRFs from the viewpoints (or life cycle) of the environmental, economic, and engineering (or technological) characters in Taiwan. Based on the database of the official handbook/yearbook, the energy supply from indigenous biomass and waste was 1678.7 × 103 kiloliters of oil equivalent (KLOE) in 2021, which only accounted for about 1.2% of... [more]

Intelligent sensing systems based on the edge-computing paradigm are essential for the implementation of Internet of Things (IoT) and Agriculture 4.0 applications. The development of edge-computing wireless sensing systems is required to improve the sensor’s accuracy in soil and data interpretation. Therefore, measuring and processing data at the edge, rather than sending it back to a data center or the cloud, is still an important issue in wireless sensor networks (WSNs). The challenge under this paradigm is to achieve a sustainable operation of the wireless sensing system powered with alternative renewable energy sources, such as plant microbial fuel cells (PMFCs). Consequently, the motivation of this study is to develop a sustainable forage-grass-power fuel cell solution to power an IoT Long-Range (LoRa) network for soil monitoring. The stenotaphrum secundatum grass plant is used as a microbial fuel cell proof of concept, implemented in a 0.015 m3-chamber with carbon plates as elect... [more]

Monitoring and controlling thermoelectric power plants (TPPs) operational parameters have become essential to ensure system reliability, especially in emergencies. Due to system complexity, operating parameters control is often performed based on technical know-how and simplified analytical models that can result in limited observations. An alternative to this task is using time series forecasting methods that seek to generalize system characteristics based on past information. However, the analysis of these techniques on large diesel/HFO engines used in Brazilian power plants under the dispatch regime has not yet been well-explored. Therefore, given the complex characteristics of engine fuel consumption during power generation, this work aimed to investigate patterns generalization abilities when linear and nonlinear univariate forecasting models are used on a representative database related to an engine-driven generator used in a TPP located in Pernambuco, Brazil. Fuel consumption pr... [more]

At present, the non-intrusive load decomposition method for low-frequency sampling data is as yet insufficient within the context of generalization performance, failing to meet the decomposition accuracy requirements when applied to novel scenarios. To address this issue, a non-intrusive load decomposition method based on instance-batch normalization network is proposed. This method uses an encoder-decoder structure with attention mechanism, in which skip connections are introduced at the corresponding layers of the encoder and decoder. In this way, the decoder can reconstruct a more accurate power sequence of the target. The proposed model was tested on two public datasets, REDD and UKDALE, and the performance was compared with mainstream algorithms. The results show that the F1 score was higher by an average of 18.4 when compared with mainstream algorithms. Additionally, the mean absolute error reduced by an average of 25%, and the root mean square error was reduced by an average of... [more]

Global population growth and rising living standards have significantly impacted global energy consumption [...]

Spray cooling is a heat transfer technology that has already shown its advantages and limitations. There has been increasing interest from academia and industry in combining this technology with nanofluids as coolants, owing to their potential for heat transfer enhancement. Nevertheless, there is a lack of understanding of the physical mechanism leading to this enhancement with the presence of technical problems that prevent the use of nanofluids in spray cooling applications. In this study, we investigate the effect of water-based TiO2 nanofluids on both spray characteristics and heat transfer using an industrial full-cone pneumatic nozzle. For this purpose, three mass concentrations (0.05 wt.%, 0.1 wt.%, and 0.2 wt.%) were prepared and tested. We monitored the droplet sizes and velocity profiles with a particle dynamics analysis system. Moreover, the temporal temperature decrease of a heated aluminum block from 190 to 65 °C was measured via an infrared camera to calculate the heat tr... [more]

Fast and accurate fault detection is important for the long term, stable operation of the distribution network. For the resonant grounding system, the fault signal features extraction difficulties, and the existing detection method’s accuracy is not high. A ground fault detection method based on fault data stitching and image generation of resonant grounding distribution systems is proposed. Firstly, considering the correlation between the transient zero-sequence current (TZSC) of faulty and healthy feeders under the same operating conditions, a fault data stitching method is proposed, which splices the transient zero-sequence current signals of each feeder into system fault data, and then converts the system fault data into grayscale images by combining the signal-to-image conversion method. Then, an improved convolutional neural network (CNN) is used to train the grayscale images and then implement fault detection. The simulation results show that the proposed method has high accurac... [more]

The influence of stacking patterns, through the different spacer and skid sizes, on the transient temperature distribution uniformity of large-size forgings in a 112-m3 electrical heat treatment furnace was investigated by conducting CFD simulations and real-scale experimental validation. A 3D CFD model of the electrical furnace was generated, including a heat-treating chamber, axial flow fans, large size blocks, skids, and spacers. Real-scale temperature measurements on instrumented test blocks during the heat treatment process were carried out to validate the CFD simulations. Results indicated that the CFD model was capable enough to determine the transient temperature evolution of the blocks with a maximum average deviation of about 6.62% compared to the experimental measurements. It was found that significant temperature non-uniformities of up to 379 K on the surfaces of the blocks due to the non-optimum stacking pattern were experienced by the blocks. Such non-uniformities could b... [more]

This article proposes a novel framework to develop computationally efficient energy consumption models of electric and internal combustion engine vehicles. The number of calculations in a conventional energy consumption model prevents the model’s usage in applications where time is limited. As many fleet operators around the world are in the process of transitioning towards electric vehicles, a computationally efficient energy consumption model will be valuable to analyse the vehicles they trial. A vehicle’s energy consumption depends on the vehicle characteristics, drive cycles and vehicle mass. The proposed modelling framework considers these aspects, is computationally efficient, and can be run using open source software packages. The framework is validated through two use cases: an electric bus and a diesel truck. The model error’s standard deviation is less 5% and its mean is less than 2%. The proposed model’s mean computation time is less than 20 ms, which is two orders of magnit... [more]

In recent years, policymakers of urban agglomerations in various regions of the world have been striving to reduce environmental pollution from harmful exhaust and noise emissions. Restrictions on conventional vehicles entering the inner city are being introduced and the introduction of low-emission measures, including electric ones, is being promoted. This paper presents a method for scenario analysis applied to study the reduction of exhaust emissions by introducing electric vehicles in a selected city. The original scenario analyses relating to real problems faced by contemporary metropolitan areas are based on the VISUM tool (PTV Headquarters for Europe: PTV Planung Transport Verkehr AG, 76131 Karlsruhe, Germany). For the case study, the transport model of the city of Bielsko-Biala (Poland) was used to conduct experiments with different forms of participation of electric vehicles on the one hand and traffic restrictions for high emission vehicles on the other hand. Scenario analyse... [more]

Environment management is one of the key aspects of hydropower development in acquiring sustainable energy. However, there has been limited research demonstrating the overall aspects of environment management of hydropower development with support of sound empirical evidence. In present study, the status of environment management in hydropower development was comprehensively investigated by conducting a case study based on the data collected from a field survey. The results show that, as environment management is largely subject to legal requirements, the environment management system needs to be established by integrating the legal requirements and needs of project implementation. This could potentially reduce the influence of legal restrictions on hydropower development. The main hydropower project environment management processes include identifying key environmental factors, implementation, monitoring, and performance measurement, which deal with environmental issues such as terres... [more]

Power systems face failures, attacks and natural disasters on a daily basis, making robustness and resilience an important topic. In an electrical network, robustness is a network’s ability to withstand and fully operate under the effects of failures, while resilience is the ability to rapidly recover from such disruptive events and adapt its structure to mitigate the impact of similar events in the future. This paper presents an integrated framework for jointly assessing these concepts using two complementary algorithms. The robustness model, which is based on a cascading failure algorithm, quantifies the degradation of the power network due to a cascading event, incorporating the circuit breaker protection mechanisms of the power lines. The resilience model is posed as a mixed-integer optimisation problem and uses the previous disintegration state to determine both the optimal dispatch and topology at each restoration stage. To demonstrate the applicability of the proposed framework,... [more]

In this article, a novelty control structure of grid-connected doubly-fed induction generator (DFIG) based on a function link (FL)-based Wilcoxon radial basis function network (FLWRBFN) controller is proposed. The back-propagation (BP) method is used online to train the node connecting weights of the FLWRBFN. To improve the online learning capability of FLWBFN, differential evolution with particle swarm optimization (DEPSO) is used to tune the learning rates of FLWRBFN. For high randomness of wave energy generation, the transmission power between generators and electrical grids is easy to unstable and AC bus voltage and DC voltage will also lose constant under the conditions of variable generator speed and variable load. Therefore, the proposed intelligent controller can maintain the above power balance and voltage constant and reduce fluctuation. Finally, PSCAD/EMTDC software is used to simulate and study various cases to confirm the robustness and usefulness of the proposed intellige... [more]

The purpose of this study is to determine the impact of households’ energy autonomy on a country’s energy independence level, to identify prospects and risks. To assess the economic efficiency of households’ energy autonomy, the study used a modeling method based on maximizing the net present value, determining the average notional cost of energy efficiency and the level of energy independence in 20 countries. Based on the analysis of the volumes of electricity consumption by households in the studied countries for the period 2000−2018, it was revealed that in developed and developing countries there is an increase in this indicator. Diagnostics of the investment attractiveness of the installation and operation of energy systems for households makes it possible to determine the boundaries of a possible increase in the level of their energy autonomy. The scientific novelty of the research is represented by the proposed methodological approach, which makes it possible to assess the level... [more]

The 2030 Agenda with 17 Sustainable Development Goals (SDGs) is a challenge for all countries in the world. Their implementation may turn out to be a compromise or the creation of effective interactions that dynamize sustainable development. To achieve the SDGs, it is essential to understand how they interact with each other. It seems that in the times of the climate and health crisis caused by the COVID-19 pandemic, caring for the environment and ensuring a healthy life and promoting well-being at all ages is the basis for environmental, economic and social sustainable development. The aim of the study is to compare the degree of implementation of the goals of sustainable development in the scope of goal 13 “Climate action” and goal 3 “Good health and well-being” in the EU countries. In addition, we analyze how trade-offs and synergies between these goals have developed. Data from the Eurostat database were used to achieve the goal. The study used the method of multivariate comparativ... [more]