Electrode roll-forming refers to rolling a battery electrode into a preset thickness through the electro-hydraulic servo pump-controlled hydraulic roll gap thickness automatic control system (known to as pump-controlled AGC). Compared with the motor servo system, the friction problem of the electro-hydraulic servo system is more serious and the friction problem of the actuator itself is very prominent. Moreover, low-speed performance is one of its core indicators, the friction phenomenon is the most abundant during the low-speed stage and the impact on the servo system is also the most obvious. Therefore, for high-performance electro-hydraulic servo control, friction compensation is not only unavoidable, but also a very difficult problem. Aiming to influence the friction on the position control of the pump-controlled system of a lithium battery pole strip mill, the rolling mechanism and process procedure under micro-displacement position control based on the friction model were studied... [more]

The purpose of this research is to have a clearer understanding of the resource value of electrolytic Zn anode slime, explore its fine structure and treat it in a classified manner. In this paper, the composition, content and distribution of Pb, Mn and Zn in electrolytic Zn anode slime during one production cycle were studied under typical working conditions of enterprises, by using the method of μ-XRF combined with mm-XRF. Based on heatmap and cluster analysis, the resource value of anode slime at different points in the electrolytic Zn silting area and the conventional area was evaluated. The research results were as follows: (1) There were two different areas of electrolytic Zn anode slime: the silting area and conventional area. Between these, the silting area accounted for approximately 15% of the total number of anode plates, and there were significant differences between these areas in terms of surface element content, surface morphology, slime thickness and water content. (2) I... [more]

Intake quality is crucial to gas turbines’ operation. The cartridge filter in the gas turbine intake system filters the gas and outputs a highly clean gas into the gas turbine, while pulse cleaning technology ensures the continuous and efficient operation of cartridge filters. While the current cylindrical pleated filter cartridge used in pulse cleaning usually suffers from insufficient upper cleaning, the conical pleated filter cartridge can effectively solve this issue by providing a greater upper cleaning area with significant application prospects. Despite the existing potential, research on conical filter cartridge cleaning performance is limited; thus, this paper aims to investigate the advantages of pulse cleaning using a conical filter cartridge via numerical simulation. Results demonstrate that while the conical filter cartridge enhances the cleaning strength, cleaning uniformity decreases slightly. To address this shortcoming, this paper innovatively proposes a combination of... [more]

Because of the unclear understanding of the characteristics associated with coupled rock breaking using multiple water jets, a numerical model combining smoothed particle hydrodynamics (SPH) and the finite element method (FEM) was established to investigate the rock-breaking capacity of a high-pressure, double-stranded water jet structure. The effectiveness of this model was verified through field experiments. The study further examined the specific energy required for rock breaking using the high-pressure double water jets and analyzed the effects of jet pressure, nozzle diameter, jet impact angle, and impact point spacing on rock-breaking volume. The results demonstrate that the rock-breaking ability of a high-pressure double water jets is better than that of a single water jet. When the impact angle of the high-pressure double water jets was 15° and the distance between impact points was 2.0 d, the rock damage effect was the best. By comparing the specific energies for rock breaking... [more]

In order to make the average value of each reserve parameter of a set of oil reserves more representative, this paper puts forward the all-factor average method of reserve parameters with crude oil volume and mass constraints. In the first step, the two constraint methods of crude oil volume and mass are adopted to calculate the average value of various parameters of the total items. The weight coefficient when the parameter is averaged is, respectively, the partial derivative of the volume or mass reserve calculation formula with respect to the parameter. Compared with the original calculation results, the average of their parameters all show a shift towards values with a significant share of reserves, especially effective porosity, oil saturation, and crude oil volume factor. The all-factor average method considers a more comprehensive set of factors than the original method. Therefore, each new average parameter should also be much more representative. Since the current reserve spec... [more]

Plum stone stands out as an alternative biomass source in terms of obtaining fuel and chemicals with or without catalysts under different conditions. Under variable heating rates (10, 50, and 100 °C min−1) and pyrolysis temperatures (400, 450, 500, 550, and 600 °C), plum stone was pyrolyzed at a constant rate in a constant sweep gas flow (100 cm3 min−1) in a tubular fixed-bed reactor. According to the results, an oil yield reaching a maximum of 45% was obtained at a heating rate of 100 °C min−1 and pyrolysis temperature of 550 °C in the non-catalytic procedure. The catalytic pyrolysis was carried out with two selected commercial catalysts, namely ZSM-5 and PURMOL-CTX and clinoptilolite (natural zeolite, NZ) under optimum conditions with a catalyst ratio of 10% of the raw material. With the addition of catalyst, the quantity and quality of bio-oil increased, including calorific capacity, the removal of oxygenated groups, and hydrocarbon distribution. In the presence of catalysts, an inc... [more]

The development of new electrode materials for electrochemical systems for various purposes is a significant and in-demand task of scientific research. Layered transition metal carbides and nitrides, known as MXenes, show great potential for use as electrodes in electrochemical energy storage devices operating in aqueous electrolytes. In this work, a multilayer Ti3C2Tx MXene was obtained from a Ti3AlC2 precursor and studied as the electrode material of a symmetrical supercapacitor with an aqueous LiCl electrolyte. The formation of the MXene structure was confirmed by the data from X-ray phase analysis and scanning electron microscopy. The X-ray diffraction pattern showed the disappearance of the main reflections related to the Ti3AlC2 phase and the shift of the reflection peak (002) from 9.4° to 6.7°, which indicated successful etching of the Al layers from the Ti3AlC2 precursor. At electrolyte concentrations of 1, 5, 10, and 20 M, the supercapacitors demonstrated high specific capacit... [more]

Injecting CO2 into tight oil reservoirs is a potential approach for enhanced oil recovery (EOR) and CO2 sequestration. However, the effects of different pore-scales on EOR are poorly understood, and this has a significant impact on recovery. In this paper, a pore size correction model based on X-ray computerized tomography (CT) and nuclear magnetic resonance (NMR) was developed in order to establish the relationship between the pore radius and the transverse relaxation time. Different pore-scales are divided according to the cumulative distribution characteristics of the transverse relaxation time (T2). CO2 flooding and huff-n-puff experiments were conducted to investigate the dynamic displacement behaviors in different pore-scales. The results indicate that there are three pore-scales: micropores (T2 < 0.3 ms), intermediate pores (0.3 ms < T2 < 100 ms), and macropores (100 ms < T2). However, there are also pseudo-sweep pores (PPs), equilibrium pores (EPs), and sweep pores... [more]

This paper aims to describe methane adsorption in coal under the conditions of high temperature and high pressure, as well as quantitatively decipher the change rule of energy in the isothermal adsorption process. The isothermal adsorption test was carried out with four groups of middle-rank coals from the Linxing area with different degrees of metamorphism. The impacts of the degree of deterioration of coal, temperature, and pressure on adsorption were analyzed with regard to the adsorption amount, adsorption potential, and adsorption space. Additionally, the energy change during the adsorption of methane by the coal was considered. The results show that the coal adsorption capacity hinges on the degree of deterioration of the coal, as well as the pressure and temperature. Additionally, the impact of temperature upon coal methane adsorption under depth conditions is highlighted. Like the adsorption space, the adsorption potential is an important parameter used to quantitatively charac... [more]

Hydropower stations are an important source of clean energy, usually operating in sandy water flow, and the turbine wheels may suffer severe wear and tear. In addition, during the operation of the unit, it is necessary to operate at different water heads according to the actual situation, which will result in varying degrees of wear and tear. In this paper, the Lagrange method is used to study the wear characteristics of a Francis turbine under different water heads. The research object is the water turbine in Wanjiazhai Hydropower Station. Research has shown that wear on the walls of the turbine volute, guide vanes, and runner is inevitable, and the clearance walls are also vulnerable to wear. The difference in the water head mainly affects the movement trajectory and impact speed of particles. The higher the water head, the more severe the wear on the wall surface of the flow passage components. Both the crown and lower ring of the runner are worn. The impact of particles causes wear... [more]

Advance in renewable penetration has promoted the interaction between the AC and DC power system and multi-energy sources. However, the disparate nature of different energy utilization technologies presents strong challenges for the economic dispatch of such a complex system. This paper proposes a comprehensive characterization of the AC/DC power system considering multi-energy and renewable integration. Detailed models are elaborated for the AC/DC power grid, the district heating system (DHS), coupling units, and renewables to describe their inner interactions accurately. On this basis, an economic dispatch method is developed to minimize the operation cost and renewable’s abandonment. Simulations indicate that the interaction between the AC/DC power systems and multi-energy sources can enhance voltage levels and improve operational economy.

Underground coal gasification (UCG) is a promising technology for extracting synthesis gas from coal seams through in situ gasification. This study aims to investigate the thermo-mechanical behavior and integrity of the surrounding rock in the gasification vicinity to facilitate safe and efficient UCG operations. Rock property testing experiments are conducted under varying temperature conditions, revealing significant temperature dependencies for the thermal and mechanical parameters. A thermo-mechanical coupling model is developed to analyze the stress and damage distribution near the gasification chamber. The influence of the temperature dependency of stress states and failure risks during the gasification process is evaluated. In addition, the effects of panel orientation, chamber width, maintaining duration, operating temperature and operating pressure on the failure behavior of the gasification surrounding rocks are illustrated through parametric analysis. The findings have pract... [more]

The Mahu conglomerate reservoir is characterized by strong heterogeneity and the uneven stimulation of the horizontal lateral during hydraulic fracturing. The optimization of the perforation number per cluster is of great value for horizontal well multi-stage fracturing (HWMF) because the suitable perforation number not only promotes the uniform propagation of multiple fractures but also prevents excessive perforation erosion. In this work, a typical well in the Mahu conglomerate reservoir was selected, and a field test of optimizing the perforation number was carried out. The perforation schemes of three, five, and eight perforations per cluster were designed in nine fracturing stages, respectively. The wellhead pressure under different perforation schemes was compared and analyzed with the step-down flow rate test, and the optimal perforation number per cluster in the Mahu conglomerate reservoir was selected as eight. The theoretical calculation results show that eight perforations p... [more]

This paper documents the 2D numerical study of magnetohydrodynamic unsteady natural convective heat transfer in a circular enclosure with four heating cylinders in both the horizontal and the vertical mid-plane. The fluid is an incompressible Newtonian fluid. The main transport equations based on the conservation of mass, momentum, and energy are calculated and solved using a finite element numerical solver with the following parameter ranges: dimensionless distance between cylinders S = 0.05−0.29, Rayleigh number Ra=103−106, and Hartmann number for Ha = 0−120. COMSOL Multiphysics, a numerical simulation program, was used to solve the governing equations. It was demonstrated that for lower Ra values, heat transfer through an applied magnetic field is unaffected for a specific S value because the mechanism of transport is diffusion, whereas for larger Ra, there is a complex interaction among magnetic field and physical thermal properties. The features of the heat transfer rate are deter... [more]

The problem of casing deformation caused by large-scale hydraulic fracturing in shale oil wells severely restricts the efficient development of Gulong shale oil. In order to clarify the mechanism of casing deformation in shale oil wells, comprehensive analysis was conducted on engineering factors, multi-arm caliper logging, seismic attributes, and the distribution characteristics of casing deformations. This study shows that casing strength, cementing quality, and wellbore curvature are not the main controlling factors for casing deformation. Casing deformation is caused by the communication between hydraulic fractures and natural fractures during the fracturing process, which increases the fluid pressure in the natural fracture and induces shear slip, resulting in casing deformation due to shear stress. Based on the understanding of the mechanism of casing deformation in shale oil wells, two targeted casing deformation prevention and control methods are proposed. First, temporary plug... [more]

For tight reservoirs, horizontal wells and multi-stage fracturing can generate a complex fracture network that realizes economic and effective development. The volume and complexity of the fracture network are of great significance to accurately predicting the productivity of tight oil wells. In this work, a mathematical model of a multiphase flow is proposed to evaluate the stimulation effect based on the early flowback data. The model showing the early slope of the material balance time (MBT) and production balance pressure (RNP) can help estimate the effective stimulated volume of the horizontal well. The linear flow region can be determined from the slope of the log−log plot of the MBT versus RNP curve, which equals 1. The method is verified by commercial simulation software, and the calculated stimulated volume is consistent with the statistical results of simulation results. Results also show that the flow pattern of the fracture−matrix system can be judged by the slope of the fl... [more]

The cooling performance of motorized spindles plays an important role in accuracy in high-speed machining. Aiming at improving the cooling performance of traditional motorized spindles, convex columns were built in the cooling channel. Based on field synergy, the effects of quadrilateral, circular and triangular convex columns on the heat transfer performance of the cooling channel were analyzed numerically. We also compared the pressure drop between the inlet and outlet under the same conditions. The results show that the cooling channels with triangular convex columns provide the best cooling effect with the smallest increase in area compared to quadrilateral convex columns and circular convex columns. The pressure drop in the cooling channels with a circular convex column is minimized. By optimizing the spacing of the convex column, the best effect was found at a spacing of 7 mm. By optimizing the angle of the top angle of the triangular column, it is found that the enhanced heat tr... [more]

Aquathermolysis is a promising process for improving the quality of heavy oil under reservoir conditions. However, the application of catalysts during the process can significantly promote the transformation of the heavy fragments and heteroatom-containing compounds of crude oil mixtures into low-molecular-weight hydrocarbons. This research paper conducted a comparative analysis of the catalytic effectiveness of water-soluble metal salts like NiSO4 and FeSO4 in the process of aquathermolysis to upgrade heavy oil samples extracted from the Ashal’cha reservoir. The temperature of the experiment was 300 °C for a duration of 24 h. Compared to the viscosity of the native crude oil, the Fe nanoparticles contributed to a 60% reduction in viscosity. The viscosity alteration is explained by the chemical changes observed in the composition of heavy oil after catalytic (FeSO4) aquathermolysis, where the asphaltene and resin contents were altered by 7% and 17%, accordingly. Moreover, the observed... [more]

Conventionally, methanol is derived from a petroleum base and natural gas, but biomethanol is obtained from biobased sources, which can provide a good alternative for commercial methanol synthesis. The fermentation of molasses to produce biomethanol via the production of biohydrogen (H2 and CO2) was studied. Molasses concentrations of 20, 30, or 40 g/L with the addition of 0, 0.01, or 0.1 g/L of trace elements (TEs) (NiCl2 and FeSO4·7H2O) were investigated, and the proper conditions were a 30 g/L molasses solution combined with 0.01 g/L of TEs. H2/CO2 ratios of 50/50% (v/v), 60/40% (v/v), and 70/30% (v/v) with a constant feed rate of 60 g/h for CO2 conversion via methanol synthesis (MS) and the reverse water−gas shift (RWGS) reaction were studied. MS at temperatures of 170, 200, and 230 °C with a Cu/ZnO/Al2O3 catalyst and pressure of 40 barg was studied. Increasing the H2/CO2 ratio increased the maximum methanol product rate, and the maximum H2/CO2 ratio of 70/30% (v/v) resulted in met... [more]

The significant vertical heterogeneity, variations in ground stress directions, and irregular bedding interfaces make it extremely challenging to predict fracture propagation in continental shale reservoirs. In this article, we conducted a series of triaxial laboratory experiments on continental shale outcrop rocks to investigate the effects of formation dip angle and wellbore orientation on crack propagation under horizontal well conditions. Our study revealed that fracture propagation features can be categorized into four distinct types: (1) hydraulic fractures pass through the bedding interface without activating it; (2) fractures pass through and activate the bedding interface; (3) hydraulic fractures open and penetrate the bedding interface while also generating secondary fractures; and (4) hydraulic fractures open but do not penetrate the bedding interface. We found that as the dip angle decreases, the likelihood of fractures penetrating through the bedding interface increases. C... [more]

In order to improve the heat transfer characteristics of the air impingement freezer, an impingement freezer experimental table was designed as the research object in this paper. Numerical simulation technology was used to simulate the impingement freezer experimental table on the basis of test verification. When the other structural parameters in the impingement freezer experimental table were constant, the effect of the inclination angle of the orifice plate (θ = 60°, 65°, 70°, 75°, 80°, 85°, and 90°) on the heat transfer characteristics of a steel strip surface was analyzed by two aspects, the average Nusselt number and the heat transfer uniformity. The results showed that with the increase in the inclination angle of the orifice plate (60° ≤ θ ≤ 90°), the average Nusselt number of the steel strip surface was increased by 19.39%, and the heat transfer uniformity index was decreased by 33.69%. When θ = 90°, the average Nusselt number on steel strip was the maximum, which was 263.68,... [more]

Solar energy is one of the main alternatives for the decarbonization of the electricity sector and the reduction of the existing energy deficit in some regions of the world. However, one of its main limitations lies in its storage, since this energy source is intermittent. This paper evaluates the potential of an underground thermal energy storage tank supplied by solar thermal collectors to provide hot water for the activation of a single-effect absorption cooling system. A simulator was developed in TRNSYS 17 software. Experimentally on-site measured data of soil temperature were used in order to increase the accuracy of the simulation. The results show that the underground tank reduces thermal energy losses by 27.6% during the entire hot period compared with the air-exposed tank. The electrical energy savings due to the reduction in pumping time during the entire hot period was 639 kWh, which represents 23.6% of the electrical energy consumption of the solar collector pump. It can b... [more]

In this paper, an experimental study of a system for heating an air-conditioned bed during a 2 h lunch was carried out. The results show that the power consumption of heat conduction heating was only 0.34 kW·h and that the average heat dissipation was 81.3 W, while the power consumption of convection heating was 1.43 kW·h, accompanied by an average heat dissipation of 748.7 W. Regardless of the power consumption or the heat dissipation, the convection heating was significantly higher than the heat conduction heating. As a result, the room air temperature increased from 12.3 °C to 17.3 °C under convection heating, but only increased from 14.4 °C to 15.2 °C under heat conduction heating. The study results indicate that when using heat conduction heating, water temperatures in the range of 38~40 °C could meet the thermal comfort needs of the human body; however, a higher temperature range was required when using convection heating. In contrast, the grade of the hot water required for heat... [more]

The combination of the hydraulic impactor and positive displacement motor (PDM) is becoming more and more popular in drilling engineering. However, the negatives of the PDM on the impactor cannot be ignored. To improve the performance of the technique, the influence of fluid pulsation from the PDM on the hydraulic impactor was studied first; then, the structure of the impactor was optimized to improve its impact force; finally, field tests were carried out in 2 wells in the shallow formation. The results indicate that the fluid fluctuation generated in the PDM can restrain the performance of the impactor, and that the impact force can be increased by 24.4% to 28.6% through the optimization of design. Field tests show that this technique can further improve the drilling efficiency and rotating stability of the polycrystalline diamond compact bit, and that the rate of penetration and bit footage increase by 32.5% and 34.6%, respectively. In the study, the effect of inlet fluid fluctuatio... [more]

A new fault location method based on the three-terminal travelling wave method is proposed for the fault location problem of multi-branch overhead line−cable transmission lines. Firstly, the process of fault travelling wave propagation in overhead transmission lines and the phenomenon of refraction are analysed, and an improved phase-mode transformation is introduced to decouple the electromagnetic coupling and perform fault phase selection. Secondly, the Pearson correlation coefficient is introduced to compare the similarity of the current travelling waveforms at different measurement points in order to implement fault segmentation. To solve the problems of the complexity of the fault travelling wave propagation process and the difficulty of identifying the travelling wavehead, the Hilbert−Huang transform is used to extract the fault signal characteristics, and the travelling wave arrival moment is accurately calculated by the sampling error correction method to determine the fault lo... [more]