Records with Subject: Energy Systems
Showing records 1 to 25 of 9263. [First] Page: 1 2 3 4 5 Last
Experimental Study on Methane Diffusion Characteristics of Different Metamorphic Deformed Coals Based on the Counter Diffusion Method
Jiangang Ren, Liang Gao, Zhihui Wen, Hongbo Weng, Jianbao Liu, Runsheng Lv, Yanwei Qu, Zhimin Song, Yongwang Zhang, Bing Li
February 19, 2024 (v1)
Keywords: confining pressure, counter diffusion method, diffusion coefficient, gas pressure, temperature
The diffusion coefficient (D) is a key parameter that characterizes the gas transport occurring in coal seams. Typically, D is calculated using the desorption curve of particle coal. However, this method cannot accurately reflect the diffusion characteristics under the stress constraint conditions of in situ coal seams. In this study, different metamorphic deformed coals of medium and high coal rank were considered based on Fick’s law of counter diffusion. The change laws of D under different confining pressures, gas pressures, and temperature conditions were tested and analyzed, and the influencing mechanisms on D are discussed. The results showed that D of different metamorphic deformed coals exponentially decreased with an increase in confining pressures, and exponentially increased with increases in gas pressures and temperature. There is a limit diffusion coefficient. The influence of the confining pressure on D can essentially be determined by changes in the effective stress, and... [more]
Selection and Optimization Design of PDC Bits Based on FEM Analysis for Drilling Long Horizontal Sections of Shale Formations
Lulin Kong, Zhaowei Wang, Haige Wang, Mingyue Cui, Chong Liang, Xiangwen Kong, Ping Wang
February 19, 2024 (v1)
Keywords: bit selection, Duvernay area, FEM modeling, long horizontal section, optimization design of PDC bits, shale gas
Well structures with ultra-long sections have become one of the most applied technologies in the field of shale gas development. While there have been many technical challenges, enhancing the breaking efficiency and stability of polycrystalline diamond compact (PDC) bits has become an essential issue of focus. Since 2013, the well structure in the Duvernay area has been optimized multiple times, and the rate of penetration (ROP) of the entire wellbore has nearly doubled. However, there are significant differences in terms of the performances of different PDC bits, and there is still room for improvement to optimize these drill bits. For this reason, a confined compressive strength test was conducted to obtain the rock mechanical parameters from shale cores extracted from the long horizontal section. Using these data, a finite element model (FEM) was developed with a corresponding scale. A calibration of the elastic-plastic damage constitutive models was then performed using the FEM. Th... [more]
Improving the Energy Efficiency of the Production of Pipes Welded with High-Frequency Induction
Zbigniew Techmański, Jacek Stępień, Tomasz Garstka, Paweł Wieczorek, Grzegorz Golański, Jan Supernak
February 19, 2024 (v1)
Keywords: electric power, heat-affected zone, high-frequency induction, inductor, squeeze
This article presents the technical aspects that may reduce electric power consumption during the welding of pipes with the high-frequency induction (HFI) method. Experiments were carried out at Huta Łabędy S.A. Steelworks, during the test production of 323.9 × 5.6 mm pipes of P235GH steel grade. Two sets of HFI heating system settings were studied: with a variable squeeze force of the heated edges and a variable position of the inductor in relation to the welding point. It was proven that the temperature at the welding point increased due to the stronger squeeze of the heated edges, which reduced the electric power consumption. Reducing the distance of the inductor relative to the welding point had the same effect. By optimizing the squeeze force and the position of the inductor, energy consumption was reduced by about 5.5%. Microstructural studies of the welds did not show any adverse effects of the optimization.
Advances in Triboelectric Nanogenerators for Sustainable and Renewable Energy: Working Mechanism, Tribo-Surface Structure, Energy Storage-Collection System, and Applications
Van-Long Trinh, Chen-Kuei Chung
February 19, 2024 (v1)
Keywords: energy applications, energy collecting system, Energy Storage, renewable and sustainable, triboelectric nanogenerator
Triboelectric nanogenerators (TENGs) are emerging as a form of sustainable and renewable technology for harvesting wasted mechanical energy in nature, such as motion, waves, wind, and vibrations. TENG devices generate electricity through the cyclic working principle of contact and separation of tribo-material couples. This technology is used in outstanding applications in energy generation, human care, medicinal, biomedical, and industrial applications. TENG devices can be applied in many practical applications, such as portable power, self-powered sensors, electronics, and electric consumption devices. With TENG energy technologies, significant energy issues can be reduced or even solved in the near future, such as reducing gas emissions, increasing environmental protection, and improving human health. The performance of TENGs can be enhanced by utilizing materials with a significant contrast in their triboelectrical characteristics or by implementing advanced structural designs. This... [more]
Atomic Orbital Search Algorithm for Efficient Maximum Power Point Tracking in Partially Shaded Solar PV Systems
Md Tahmid Hussain, Mohd Tariq, Adil Sarwar, Shabana Urooj, Amal BaQais, Md. Alamgir Hossain
February 10, 2024 (v1)
Keywords: atomic orbital search (AOS), maximum power point tracking (MPPT), metaheuristic algorithms, partial shading condition (PSC), photovoltaic (PV)
The efficient extraction of solar PV power is crucial to maximize utilization, even in rapidly changing environmental conditions. The increasing energy demands highlight the importance of solar photovoltaic (PV) systems for cost-effective energy production. However, traditional PV systems with bypass diodes at their output terminals often produce multiple power peaks, leading to significant power losses if the optimal combination of voltage and current is not achieved. To address this issue, algorithms capable of finding the highest value of a function are employed. Since the PV power output is a complex function with multiple local maximum power points (LMPPs), conventional algorithms struggle to handle partial shading conditions (PSC). As a result, nature-inspired algorithms, also known as metaheuristic algorithms, are used to maximize the power output of solar PV arrays. In this study, we introduced a novel metaheuristic algorithm called atomic orbital search for maximum power point... [more]
A Review of Macroscopic Modeling for Shale Gas Production: Gas Flow Mechanisms, Multiscale Transport, and Solution Techniques
Yuyang Liu, Xiaowei Zhang, Wei Zhang, Wei Guo, Lixia Kang, Dan Liu, Jinliang Gao, Rongze Yu, Yuping Sun
February 10, 2024 (v1)
Keywords: hydraulic fractures, macroscopic modeling, shale gas reservoir
The boost of shale gas production in the last decade has reformed worldwide energy structure. The macroscale modeling of shale gas production becomes particularly important as the economic development of such resources relies on the deployment of expensive hydraulic fracturing and the reasonable planning of well schedules. A flood of literature was therefore published focused on accurately and efficiently simulating the production performance of shale gas and better accounting for the various geological features or flow mechanisms that control shale gas transport. In this regard, this paper presents a holistic review of the macroscopic modeling of gas transport in shale. The review is carried out from three important points of view, which are the modeling of the gas flow mechanisms, the representation of multiscale transport, and solution techniques for the mathematical models. Firstly, the importance of gas storage and flow mechanisms in shale is discussed, and the various theoretical... [more]
Mechanisms of Stress Sensitivity on Artificial Fracture Conductivity in the Flowback Stage of Shale Gas Wells
Xuefeng Yang, Tianpeng Wu, Liming Ren, Shan Huang, Songxia Wang, Jiajun Li, Jiawei Liu, Jian Zhang, Feng Chen, Hao Chen
February 10, 2024 (v1)
Keywords: artificial fracture, flowback system, fracture conductivity, shale gas, stress sensitivity
The presence of a reasonable flowback system after fracturing is a necessary condition for the high production of shale gas wells. At present, the optimization of the flowback system lacks a relevant theoretical basis. Due to this lack, this study established a new method for evaluating the conductivity of artificial fractures in shale, which can quantitatively characterize the backflow, embedment, and fragmentation of proppant during the flowback process. Then, the mechanism of the stress sensitivity of artificial fractures on fracture conductivity during the flowback stage of the shale gas well was revealed by performing the artificial fracture conductivity evaluation experiment. The results show that a large amount of proppant migrates, and the fracture conductivity decreases rapidly in the early stage of flowback, and then the decline gradually slows down. When the effective stress is low, the proppant is mainly plastically deformed, and the degree of fragmentation and embedment is... [more]
Comparison of Engine Emission Characteristics of Biodiesel from High-Acid Oil and Used Cooking Oil through Supercritical Methanol and Alkaline-Catalyst Transesterifications
Cherng-Yuan Lin, Yi-Wei Lin, Hsuan Yang
February 10, 2024 (v1)
Keywords: direct-injection diesel engine, engine emission, fatty acid methyl ester, soybean soapstock, supercritical methanol transesterification
The global trend towards net-zero carbon emissions from burning fuels in combustion engines alerts us to the alternative role of biodiesel. The manufacturing cost of biodiesel hinders the fast development of various types of biofuels. Feedstock cost is one of the major determining factors of biodiesel cost and thus the extent of its competitiveness in the fuel market with other available alternative fuels or fossil fuels. Some low-cost feedstocks such as high-acid oil, which is produced from the acidifying processes of soybean soapstock, frequently contain high contents of free fatty acids (FFAs) and water. Hence, those feedstocks cannot be used to produce biodiesel through strong alkaline catalyst transesterification on an industrial scale. In contrast, the water can be converted to hydroxyl radicals to enhance the formation of esters from the dissociation of the FFA in a supercritical reacting tank. Hence, cheap high-acid oils containing high amounts of water and FFAs were used to pr... [more]
Comparison of Glass−Glass versus Glass−Backsheet Encapsulation Applied to Carbon-Based Perovskite Solar Cells
Nikoleta Kyranaki, Lara Perrin, Lionel Flandin, Emilie Planès, Cynthia Farha, Lukas Wagner, Karima Saddedine, David Martineau, Stéphane Cros
February 10, 2024 (v1)
Keywords: durability, encapsulation process, perovskite, photovoltaics
The record photovoltaic performance of perovskite solar cells is constantly increasing, reaching 26% currently. However, there is a crucial need for the development of simple architectures that are compatible with large-scale industrialization and possess adequate stability. The aim of the work presented here is to compare the efficiency of glass−glass and glass−backsheet encapsulations for carbon-based perovskite solar cell application, which possesses a great potential for industrialization. This was conducted by first separating the relative effects of humidity and heat. A time evolution of the macroscopic power conversion efficiency (PCE) was performed, together with specific characterizations in order to scout the origin of flaws and degradations. A significant contribution of the paper is the identification of both TiO2 and carbon layers as barriers against moisture permeation, which inhibit moisture paths through the interfaces. This is the origin of the equivalent durability of... [more]
Monitoring the Ignition of Hay and Straw by Radiant Heat
Iveta Markova, Zuzana Giertlova, Jana Jadudova, Ivana Turekova
February 10, 2024 (v1)
Keywords: hay, ignition temperature, radiant heat, straw
Hay and straw are commonly used materials in agriculture. They are organic materials and, therefore, flammable. This article examines the behaviour of hay and straw when exposed to radiant heat. The objective of this study is to experimentally determine the ignition temperature of hay and straw under the influence of radiant heat. This research investigates the effects of sample type (hay and straw) and sample quantity on the thermal degradation process, temperature increase within the samples, and ignition temperature of the samples as a function of time. The ignition temperature of hay was determined to be higher (407 °C) compared to straw (380 °C).
Numerical Modeling of Ammonia-Fueled Protonic-Ion Conducting Electrolyte-Supported Solid Oxide Fuel Cell (H-SOFC): A Brief Review
Md. Mosfiqur Rahman, Abdalla M. Abdalla, Lukman Ahmed Omeiza, Veena Raj, Shammya Afroze, Md. Sumon Reza, Mahendra Rao Somalu, Abul K. Azad
February 10, 2024 (v1)
Keywords: ammonia-fueled solid oxide fuel cell, design analysis, Fuel Cells, numerical modeling, physical phenomena, protonic conducting fuel cells, solid oxide fuel cell
Solid oxide fuel cells with protonic ion conducting electrolytes (H-SOFCs) are recognized and anticipated as eco-friendly electrochemical devices fueled with several kinds of fuels. One distinct feature of SOFCs that makes them different from others is fuel flexibility. Ammonia is a colorless gas with a compound of nitrogen and hydrogen with a distinct strong smell at room temperature. It is easily dissolved in water and is a great absorbent. Ammonia plays a vital role as a caustic for its alkaline characteristics. Nowadays, ammonia is being used as a hydrogen carrier because it has carbon-free molecules and prosperous physical properties with transportation characteristics, distribution options, and storage capacity. Using ammonia as a fuel in H-SOFCs has the advantage of its ammonia cracking attributes and quality of being easily separated from generated steam. Moreover, toxic NOx gases are not formed in the anode while using ammonia as fuel in H-SOFCs. Recently, various numerical st... [more]
Combustion Process of the Compound Supply CNG Engine
Zhiqiang Zhu, Defu Zhang, Yunjing Jiao
February 10, 2024 (v1)
Keywords: compound gas supply, natural gas engine, stratified combustion
In order to study the lean combustion process of a natural gas engine by separating the combustor, a spark ignition natural gas engine with separated combustors was retrofitted from a S195 single-cylinder diesel engine. Methods: The electronic control system controlled the gas supply and the spark plug ignition. A low pressure injection valve was set in the inlet pipe to form a lean mixture while a high pressure injection valve was placed in the subsidiary chamber to create a rich mixture, which was then ignited and injected into the main combustor, where the lean mixture was subsequently ignited again to achieve stratified combustion. Results: The test results showed that steady ignition is feasible in the system and verified the impact of the shape of the main combustor on HC, the impact of channel diameter on NOX production, and the impact of the ratios of high-pressure gas and low-pressure gas on HC and NOX. The combustion conditions of high-pressure gas and low-pressure gas in the... [more]
A Tabu-Matching Heuristic Algorithm Based on Temperature Feasibility for Efficient Synthesis of Heat Exchanger Networks
Xiaohuang Huang, Hao Shen, Wenhao Yue, Huanhuan Duan, Guomin Cui
February 10, 2024 (v1)
Keywords: Heat Exchanger Network, heuristic method, tabu matching, temperature interval
The non-structural model of heat exchanger networks (HENs) offers a wide solution space for optimization due to the random matching of hot and cold streams. However, this stochastic matching can sometimes result in infeasible structures, leading to inefficient optimization. To address this issue, a tabu matching based on a heuristic algorithm for HENs is proposed. The proposed tabu-matching method involves three main steps: First, the critical temperature levels—high, medium, and low-temperature intervals—are determined based on the inlet and outlet temperatures of streams. Second, the number of nodes is set according to the temperature intervals. Third, the nodes of streams are flexibly matched within the tabu rules: the low-temperature interval of hot streams with the high-temperature interval of cold streams; the streams crossing cannot be matched. The results revealed that by incorporating the tabu rules and adjusting the number of nodes, the ratio of the feasible zone in the whole... [more]
Exergy Loss Assessment Method for CNC Milling System Considering the Energy Consumption of the Operator
Zhaohui Feng, Hua Zhang, Wei Li, Yajian Yu, Youjia Guan, Xinru Ding
February 10, 2024 (v1)
Keywords: CNC milling system, exergy analysis, the energy consumption of the operator, the specific exergy loss
Modeling and assessing the sustainability of machining systems has been considered to be a crucial approach to improving the environmental performance of machining processes. As the most common machining system, the computer numerical control (CNC) milling system is a typical man−machine cooperative system where the activities of the machine tool and operator generate material and energy consumption. However, the energy consumption of the operator in the CNC milling system has often been ignored in most existing research. Therefore, existing methods fail to provide a comprehensive understanding of the sustainability of the CNC milling system. To fill this gap, an exergy loss assessment method is proposed to investigate the sustainability of the CNC milling system, where the energy consumption of the operator, the energy consumption of the machine tool, and material consumption are taken into consideration. The key performance indexes of the energy consumption of the operator, the energ... [more]
Investigation of Natural Weak Interface Properties and Their Impact on Fracture Propagation in Shale Reservoirs
Qi Chen, Zhiqiang Huang, Xingjie Ling, Pengju Xu, Lanke Tu, Wenjing Liao, Jun Xie, Meng Wang, Yijing Chen, Lingli Li
February 10, 2024 (v1)
Keywords: 3D geological model, fracturing propagation path, multi cluster fracturing, natural fracture, shale reservoirs
Horizontal well multi-cluster fracturing technology is crucial for the economic development of fractured shale reservoirs. The abundance of natural fractures in shale reservoirs significantly influences the propagation path of hydraulic fractures and determines the formation of complex fracture networks. To investigate the impact of natural weak planes on the geometric parameters of fractures in shale reservoirs, we first conducted tests on the mechanical characteristics of core samples from outcropping shale in the Weiyuan area using the indoor three-point bending method and digital image correlation (DIC) technology, providing data validation for subsequent numerical models. Secondly, considering the interaction between hydraulic and natural weak planes in three-dimensional space, we established a three-dimensional numerical model for horizontal well fracturing to simulate the synchronous competition and expansion of fractures in multi-cluster fracturing. Based on this foundation, we... [more]
Structural Optimization of Annular Thermoelectric Module Applied to Liquefied Natural Gas Cold Energy Recovery
Yulong Zhao, Hongmei Diao, Wenjie Li, Zhiwei Xuan, Qi Zhang, Yulin Wang, Minghui Ge
January 12, 2024 (v1)
Keywords: annular, cold energy, liquefied natural gas, structural optimization, thermoelectric
The gasification of liquefied natural gas (LNG) is characterized by a substantial release of cold energy, which can be utilized for power generation via thermoelectric generator (TEG). Employing a gasifier integrated with a thermoelectric generator for LNG gasification allows for the recovery of cold energy and its conversion to useful power, a process that holds significant potential for widespread application. In the study, a thermoelectric model has been developed for an annular thermoelectric module, which formed a new category of gasifier tube. The influence of the module’s structure as well as the heat transfer parameters on the thermoelectric performance was examined. The results revealed that an optimum height of the thermoelectric leg, specifically 2 mm, maximized the output power while allowing the thermoelectric conversion efficiency to reach a peak of 3.25%. Another noteworthy finding is that an increase in the central angle of the thermoelectric leg leads to a concomitant... [more]
Integration of Renewable-Energy-Based Green Hydrogen into the Energy Future
Ismail Marouani, Tawfik Guesmi, Badr M. Alshammari, Khalid Alqunun, Ahmed Alzamil, Mansoor Alturki, Hsan Hadj Abdallah
January 12, 2024 (v1)
Keywords: efficiency improvement, electrolysis, green hydrogen production, leading countries in this field, net-zero gas emissions, optimization techniques, Renewable and Sustainable Energy, Renewable and Sustainable Energy, technologies used
There is a growing interest in green hydrogen, with researchers, institutions, and countries focusing on its development, efficiency improvement, and cost reduction. This paper explores the concept of green hydrogen and its production process using renewable energy sources in several leading countries, including Australia, the European Union, India, Canada, China, Russia, the United States, South Korea, South Africa, Japan, and other nations in North Africa. These regions possess significant potential for “green” hydrogen production, supporting the transition from fossil fuels to clean energy and promoting environmental sustainability through the electrolysis process, a common method of production. The paper also examines the benefits of green hydrogen as a future alternative to fossil fuels, highlighting its superior environmental properties with zero net greenhouse gas emissions. Moreover, it explores the potential advantages of green hydrogen utilization across various industrial, c... [more]
Evaluation of Hydrogen Addition on Combustion and Emission Characteristics of Dual-Fuel Diesel Engines with Different Compression Ratios
Su Wang, Youchang Li, Junshuai Lv, Zhonghang Liu, Sheng Gao, Jingyi Hu, Jian Zhang, Weihuang Zhong, Ziheng Zhao
January 12, 2024 (v1)
Keywords: combustion characteristics, compression ratio, dual-fuel engine, emission characteristics, hydrogen energy share
In this paper, a computational fluid dynamics (CFD) model was established and verified on the basis of experimental results, and then the effect of hydrogenation addition on combustion and emission characteristics of a diesel−hydrogen dual-fuel engine fueled with hydrogenation addition (0%, 5%, and 10%) under different hydrogenation energy shares (HESs) and compression ratios (CRs) were investigated using CONVERGE3.0 software. And, this work assumed that the hydrogen and air were premixed uniformly. The correctness of the simulation model was verified by experimental data. The values of HES are in the range of 0%, 5%, 10%, and 15%. And, the values of CR are in the range of 14, 16, 18, and 20. The results of this study showed that the addition of hydrogen to diesel fuel has a significant effect on the combustion characteristics and the emission characteristics of diesel engines. When the HES was 15%, the in-cylinder pressure increased by 10.54%. The in-cylinder temperature increased by... [more]
Research on Downhole Throttling Characteristics of Gas Wells Based on Multi-Field and Multi-Phase
Jie Zheng, Jiahui Li, Yihua Dou, Zhihao Hu, Xu Yang, Yarong Zhang
January 12, 2024 (v1)
Keywords: downhole throttling characteristics, multi-field and multi-phase coupling, temperature and pressure field model
The formation of natural gas hydrates seriously affects the production efficiency of gas wells. Obtaining the correct temperature and pressure profile along the wellbore of gas wells is a prerequisite for accurately predicting the location of hydrate formation and using downhole throttling technology. According to the numerical iterative transfer law of wellbore microelement state parameters, a multi-field and multi-phase coupling method is proposed. Based on the analysis of typical temperature and pressure models, considering the gas well velocity field and density field, a gas well multi-phase correction coefficient is introduced. Based on the judgment method of multi-phase flow pattern, the friction gradient equation of multi-phase flow is obtained, and the respective theoretical prediction equations are created for the temperature field, pressure field, density field, and velocity field. Thereby, a wellbore temperature and pressure field model with multi-field and multi-phase coupl... [more]
Special Issue “Multiphase Flows and Particle Technology”
Xizhong Chen, Li Ge Wang, Liping Li
January 12, 2024 (v1)
Research into multiphase flow and particle technology is closely related and holds significant importance in various fields of engineering and scientific applications [...]
Study on the Migration and Transformation of Nitrogen in Mine Water under the Action of Water−Coal Interactions
Binbin Jiang, Ze Zhao, Zhiguo Cao, Deqian Liu, Jiawei Tang, Haiqin Zhang, Yuan Liu, Dingcheng Liang
January 12, 2024 (v1)
Keywords: coal mine underground reservoir, migration transformation, nitrogen, water–coal interaction
The coal pillar dam of underground reservoirs and residual coal in goaves have a direct impact on the quality of mine water. In this paper, the coal pillar dam of an underground reservoir and residual coal in the goaf and mine water in the Daliuta coal mine are used as research objects. The adsorption mechanism of residual coal with respect to NO3− in mine water was analyzed by carrying out adsorption experiments. The composition and variation of organic matter in mine water at different times were simulated using three-dimensional fluorescence spectrum analysis. The influence of residual coal and microorganisms in underground reservoirs on the change in NO3− contents in mine water was explored. Moreover, the mechanism of NO3− changes in the water body was clarified. The results showed that the concentration of NO3− in the water first decreased and then increased, showing a downward trend as a whole. The adsorption of NO3− by residual coal led to a decrease in its concentration, which... [more]
Characteristics and Stabilization Mechanism of Three-Phase Foam: Improving Heavy Oil Recovery via Steam Stimulation through Two-Dimensional Visual Model
Mingxuan Wu, Zengmin Lun, Yongqiang Tang, Jinming Dai, Mingkai Liu, Deqiang Wang, Zhaomin Li
January 12, 2024 (v1)
Keywords: heavy oil, steam stimulation, temperature field, three-phase foam
There is a problem of a rapid decline in production caused by the repeated heating of the near-wellbore zone during steam stimulation. Finding a suitable foam system to expand the area of the steam chamber and slow down the rapid production of hot water during the recovery process can effectively improve the effect of steam stimulation. In this paper, CGS foam was prepared with high-temperature-resistant surfactant GD, graphite particles, and clay particles. Through the study of foam properties, it was found that with the addition of particles, the strength of the foam’s liquid film, half-life time, and temperature resistance was greatly improved. The appropriate permeability of the CGS foam and the movement characteristics of it in formations with different permeabilities were studied through a plugging experiment with a sand pack. The plugging performances of the GD foam, CGS foam, and pure particles in a simulated reservoir were compared. The development of the steam cavity during t... [more]
Effects of Layering Angle and Prestress on Dynamic Load Energy Conversion and Damage Mechanism of Sandstone
Wenbing Fan, Junwen Zhang, Yang Yang, Kailun Fang, Shaokang Wu, Yulong Xing
January 12, 2024 (v1)
Keywords: damage mechanism, failure mechanism, internal energy conversion, layered sandstone, mining application, phased energy characteristics
Previously conducted studies have established the conversion relationship between incident energy, reflected energy, transmitted energy and absorbed energy of rocks under dynamic load. In this paper, the combined dynamic and static loading tests of sandstone under different prestress and different bedding angles are carried out to explore the law of the influence of prestress and bedding angles on energy evolution and damage evolution. The purpose is to provide some reference for deep mining, rock engineering design and geological hazard assessment. The energy conversion and damage characteristics of sandstone in the whole process of deformation are studied, and the internal energy conversion mechanism of sandstone under dynamic load is proposed. It is found that the increase in prestress will lead to the increase in the initial energy value of sandstone and further affect the shape of the energy evolution curve. In addition, the relationship between strain and energy transformation is... [more]
Study on Brittleness Characteristics and Fracturing Crack Propagation Law of Deep Thin-Layer Tight Sandstone in Longdong, Changqing
Changjing Zhou, Zhonghua Sun, Yuanxiang Xiao, Guopeng Huang, Dan Kuang, Minghui Li
January 12, 2024 (v1)
Keywords: brittleness characteristics, fracture propagation, hydraulic fracturing, tight sandstone, triaxial compression
Tight-sandstone oil and gas resources are the key areas of unconventional oil and gas resources exploration and development. Because tight-sandstone reservoirs usually have the characteristics of a low porosity and ultralow permeability, large-scale hydraulic fracturing is often required to form artificial fractures with a high conductivity to achieve efficient development. The brittleness of rock is the key mechanical factor for whether fracturing can form a complex fracture network. Previous scholars have carried out a lot of research on the brittleness characteristics of conglomerate and shale reservoirs, but there are few studies on the brittleness characteristics of sandstone with different types and different coring angles in tight-sandstone reservoirs and the fracture propagation law of sandstone with different brittleness characteristics. Based on this, this paper carried out a systematic triaxial compression and hydraulic fracturing experiment on the tight sandstone of Shan 1... [more]
Comprehensive Evaluation Index System and Application of Low-Carbon Resilience of Power Grid Containing Phase-Shifting Transformer under Ice Disaster
Jing Zhang, Huilin Cheng, Peng Yang, Bingyan Zhang, Shiqi Zhang, Zhigang Lu
January 12, 2024 (v1)
Keywords: fuzzy comprehensive evaluation, ice disaster, low-carbon resilience indicators, phase-shifting transformer
In view of the high impact of extreme disasters, this paper comprehensively evaluates power grid performance from a new low-carbon toughness perspective. First, considering the increase in carbon emissions and the recovery time of carbon emissions, low-carbon resilience indicators are proposed. At the same time, considering the power-regulation effect of the phase-shifter transformer, the fault and response model of a power grid under an ice disaster is established, and then, a comprehensive evaluation index system of low-carbon toughness of the power grid is constructed. The weight determination is carried out using the fuzzy analytic hierarchy process-entropy-based weight method, while the fuzzy comprehensive evaluation center of gravity method is used to evaluate the power grid comprehensively. Finally, examples are presented to verify the feasibility of the proposed method, emphasizing its potential for evaluating the comprehensive performance of low-carbon and toughness of the pow... [more]
Showing records 1 to 25 of 9263. [First] Page: 1 2 3 4 5 Last
[Show All Subjects]