Characteristics of vertical sharp-edged orifice discharge（Ⅲ）Effect of geometry on orifice discharge coefficient

通过实验,分别考察了相同流通截面积下,圆形、椭圆形、正方形、矩形和三角形等不同几何形状的垂直锐边典型“大孔”和“小孔”的自由出流特性。所得孔流系数曲线形态基本相同,孔流系数值略有差异,圆孔最高,三角形最低,说明孔几何形状对孔流能量损失有一定影响,但不是关键结构参数,不会从根本上改变孔流机理。其能量损失差异可根据孔口的水力半径、锐角界面张力以及非圆形孔射流的穿透现象加以解释,藉此对前期的圆孔流动机理进行了补充。此后,为了详细考察孔形状对孔流速度分布和能量损失的影响,采用计算流体力学软件Fluent 6.2对其进行了模拟,模拟流场说明孔形状对孔前流动影响区的主体范围和速度分布基本没有影响,孔前流动的机械能损失仍可采用半球形模型研究,进一步说明不同孔形状的孔流机械能损失差异是入孔以后造成的。     

Preparation and characterization of Mg(OH)2 nanorods by liquid–solid arc discharge technique

The Mg(OH)₂ nanorods with diameters of ca. 8–10 nm and lengths of more than 250 nm have been prepared by a novel liquid–solid arc discharge technique. X-ray diffraction (XRD) showed that the Mg(OH)₂ nanorods were well-crystallized with the hexagonal structure. The structure features were also analyzed by TEM, HRTEM, and FTIR. Based on the investigation of the influence of current density, discharge time and pH of the electrolyte, the possible growth mechanism of the Mg(OH)₂ was discussed.     

Energy,exergy, economic and environmental comprehensive analysis and multi-objective optimization of a sustainable zero liquid discharge integrated process for fixed-bed coal gasification wastewater

For a long time, China’s regional water resource imbalance has restricted the development of coal chemical industry, and it is imperative to achieve zero liquid discharge(ZLD). Therefore, the game relationship between technical indicators, costs and emissions in ZLD process of fixed-bed coal gasification wastewater treatment process should be explored in detail. According to the accurate model, the simulation for ZLD of fixed-bed coal gasification wastewater treatment process is established, and...     

Kinetic effects of nanosecond discharge on ignition delay time☆

The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. A modified non-equilibrium plasma kinetic model was developed to simulate the temporal evolution of particles produced during nanosecond discharge and its afterglow. As important roles in ignition, path fluxes of O and H radicals were analyzed in detail. Different strength of E/N and different discharge duration were applied to the discharge process in this study. And the results presented that a deposited energy of 1–30 m J·cm~(-3) could dramatically reduce the ignition delay time. Furthermore, temperature and radicals analysis was conducted to investigate the effect of non-equilibrium plasma on production of intermediate radicals. Finally, sensitivity analysis was employed to have further understanding on ignition chemistries of the mixture under nanosecond discharge.     

Dielectric,energy storage,and charge–discharge properties of Yb-modified Sr0.7Bi0.2TiO3 relaxor ferroelectric ceramic

Dielectric capacitors have been widely studied in advanced electronics systems due to their rapid discharge rate and high-power density. Among them, relaxor ferroelectrics characterized by nanodomains possess broad application prospects as dielectric materials with high energy density and high efficiency. In this paper, the dielectric characteristics, energy storage performance, and charge–discharge behavior of rare-earth Yb-doped Sr_0.7Bi_0.2TiO₃ ceramics are systematically investigated. The Yb-doped SBT ceramics reduced the grain size, improved the insulation and thermal conductivity, and significantly improved the dielectric breakdown strength. Finally, a high recoverable energy density of 2.32 J/cm³ and an excellent energy storage efficiency of 92.2% were obtained at 300 kV/cm. In addition, pulsed charge–discharge tests show that Sr_0.7Bi_0.15Yb_0.05TiO₃ possesses a rapid discharge rate and high-power density with superior thermal stability. Based on these outstanding characteristics, Sr_0.7Bi_0.15Yb_0.05TiO₃ exhibits promising applications in pulsed power systems.     

Product formation during discharge: a combined modelling and experimental study for Li–O $$_2$$ 2 cathodes in LiTFSI/DMSO and LiTFSI/TEGDME electrolytes

Journal of Applied Electrochemistry - Li–air or Li– $$\text{O}_2$$ batteries are a promising energy storage technology due to the potentially high energy density. However, significant...     

Charge–discharge characteristics of polythiopheneas a cathode active material in a rechargeable battery

Polythiophene films were electrochemically deposited on glassy carbon substrates under potentiostatic control and used as cathode active material together with a Zn anode in a rechargeable battery with propylene carbonate, Zn(ClO4)2, LiClO4 electrolyte. Charge–discharge characteristics were studied. The average discharge voltage of the polythiophene/Zn cell was 1.25V. In the low current density region (i.e. 10–50Acm–2) the cycling coulombic efficiency was above 95%, but in the fast charge–discharge region, where current densities were 0.1–0.5mAcm–2, the coulombic efficiency decreased to 55% with increasing discharge rate. Additionally, it was found that the cyclic coulombic efficiency was a function of the charging depth.     

Reaction mechanism in Ti–SiC–C powder mixture during pulse discharge sintering

During pulse discharge sintering (PDS) of Ti/SiC/C powder mixture, combustion synthesis reactions occurred at heating rates above 20 °C/min. With an increase in heating rate, combustion synthesis occurred at higher temperatures. The essential of this combustion reaction is the liquid reaction between Ti and formed Ti₅Si₃. The exothermic TiC formation during PDS process promotes this liquid reaction. We have found that the combustion reactions alone did not finish the formation reactions for Ti₃SiC₂, and further heating following the combustion reactions is necessary for the synthesis process of Ti₃SiC₂.     

Energy storage and discharge performance for (1−x)BaSrTiO3−xBi(Zn1/2Ti1/2)O3 ceramics

Although lead-free dielectric ceramics have been widely studied to obtain excellent dielectric properties and good energy storage properties, the primary challenge of low energy storage density has not yet been resolved. Here, we introduce the concept of crossover relaxor ferroelectrics, which represent a state intermediate between normal ferroelectrics and relaxor ferroelectrics, as a solution to address the issue of low energy density. The (1−x)BaSrTiO₃−xBi(Zn_1/2Ti_1/2)O₃ (x = 0,.05, .1, .15, .2) ceramics were prepared by a solid-state method. Remarkably, 0.85BST–0.15BZT ceramics achieved a high recoverable energy density (W_rec) of 2.18 J/cm³ under an electric field of 240 kV/cm. BST–BZT materials exhibit substantial recoverable energy density, high breakdown strength, and superior energy efficiency, positioning them as a promising alternative to meet the diverse demands of high-power applications.     

Method of power density determination in microwave discharge,sustained in hydrogen–methane gas mixture

We present the results of studying a continuous microwave discharge maintained at a frequency of 2.45 GHz in a CVD reactor based on a cylindrical resonator excited at the TM₀₁₃ mode. The discharge was ignited in hydrogen and a gaseous mixture of hydrogen and methane and was studied by the method of optical emission spectroscopy. Density of atomic hydrogen and gas temperature were measured, as well as the spatial distribution of both optical emission intensity of the plasma and intensity of the Hα line of atomic hydrogen. The main parameters of the discharge were calculated numerically using the two-dimensional self-consistent model of the discharge. Basing on the obtained results, we proposed a method for high-precision experimental determination of the plasma volume and calculation of the specific energy contribution to the plasma, i.e., microwave power density in plasma (MWPD), with minimal errors. According to the calculations, in the experiment performed, the microwave power density in the plasma varied from 50 to 550 W/cm³ as the gas pressure increased from 80 to 350 Torr. The method allows one to perform unified MWPD calculations in different CVD reactors and to compare diamond film deposition regimes.     

Development of spark plasma sintered conductive SiC–TiB2 composites for electrical discharge machining applications

Highly dense electrically conductive silicon carbide (SiC)–(0, 10, 20, and 30 vol%) titanium boride (TiB₂) composites with 10 vol% of Y₂O₃–AlN additives were fabricated at a relatively low temperature of 1800°C by spark plasma sintering in nitrogen atmosphere. Phase analysis of sintered composites reveals suppressed β→α phase transformation due to low sintering temperature, nitride additives, and nitrogen sintering atmosphere. With increase in TiB₂ content, hardness increased from 20.6 to 23.7 GPa and fracture toughness increased from 3.6 to 5.5 MPa m^1/2. The electrical conductivity increased to a remarkable 2.72 × 10³ (Ω cm)^–1 for SiC–30 vol% TiB₂ composites due to large amount of conductive reinforcement, additive composition, and sintering in nitrogen atmosphere. The successful electrical discharge machining illustrates potential of the sintered SiC–TiB₂ composites toward extending the application regime of conventional SiC-based ceramics.     

Hydrogenated amorphous carbon films deposited in an electron cyclotron resonance–chemical vapor deposition discharge reactor using acetylene

Hydrogenated amorphous carbon (a-C:H) films have been deposited from acetylene gas in a microwave electron cyclotron resonance (ECR) plasma reactor. The films were deposited at a pressure of 0.2 mTorr and at radio frequency (r.f.) induced substrate biases from 80–300 V. Selected film properties, including optical bandgap and bonded hydrogen content, were measured. At r.f. induced biases from 150 to 300 V, corresponding to ion energies for C₂H₂⁺ of approximately 150–300 eV, the hydrogen content remains constant and the optical bandgap peaks at a bias of 200 V, or approximately 100 eV per carbon in the C₂H₂⁺ ions. This ECR system result is in agreement with those observed by other researchers using different deposition methods where an optical bandgap maximum and an sp³ maximum occurs at ion energies of 90–100 eV per carbon atom. The discharge properties measured include a partial pressure analysis of the residual exit gas and the substrate current density.     

Charge–discharge performance of Cr-substituted V-based hydrogen storage alloy negative electrodes for use in nickel-metal hydride batteries

To improve the charge–discharge cycle durability of a TiV_2.1Ni_0.3 alloy negative electrode with a discharge capacity of ～470 mAh g^?1, the vanadium constituent was partially substituted with chromium. The TiV_2.1?xCr_xNi_0.3 (x = 0.1–0.4) alloys, which were prepared by arc-melting, were composed of two phases, similar to the TiV_2.1Ni_0.3 alloy. Each constituent was distributed in both phases, and the V and Cr content in the primary phase was higher than that in the secondary phase, although the Ti and Ni content was higher in the secondary phase. The maximum discharge capacity for the TiV_2.1?xCr_xNi_0.3 (x = 0.1–0.4) negative electrodes showed a slight decrease as the x value increased, and their cycle durability was significantly improved due to the effective suppression of the dissolution of V. In particular, the loss of discharge capacity per cycle for the TiV_1.7Cr_0.4Ni_0.3 negative electrode was about one-tenth that for the TiV_2.1Ni_0.3 negative electrode. The high-rate dischargeability (HRD) was also greatly improved by increasing the Cr content. At 200 mA g^?1 the variations of the HRD and the charge transfer resistance (R_ct) with the Cr content were similar, while at 400 mA g^?1 the change in the HRD at a lower Cr content was markedly different from the change in R_ct. Moreover, at a lower Cr content the potential at a 50% degree of discharge stagnated at specific discharge currents over 200 mA g^?1. These results strongly suggest that hydrogen diffusion in the primary phase served as the main hydrogen reservoir.     

Initiation of homogeneous combustion in a high-velocity jet of a fuel–air mixture by an optical discharge

The effect of a focused pulsed-periodic beam of a CO₂ laser on initiation and evolution of combustion in subsonic and supersonic flows of homogeneous fuel–air mixtures (H₂ + air and CH₄ + air) is experimentally studied. The beam generated by the CO₂ laser propagates across the flow and is focused by a lens at the jet axis. The flow structure is determined by a schlieren system with a slot and a plane knife aligned in the streamwise direction. The image is recorded by a high-speed camera with an exposure time of 1.5 μs and a frame frequency of 1000 s^?1. The structure of the combustion region is studied by an example of inherent luminescence of the flame at the wavelengths of OH and CH radicals. The distribution of the emission intensity of the mixture components in the optical discharge region is investigated in the present experiments by methods of emission spectroscopy.     

Synthesis of β-MoO3 nanowhiskers from core/shell molybdenum/molybdenum oxide wire by pulsed wire discharge

β-MoO_3, the molybdenum oxide phase with the highest catalytic activity, is a promising material in optical, chemical, and electronics applications as a replacement for α-MoO₃. α-MoO₃ 1D nanostructures such as whiskers and fibers have been investigated and used in applications. However, difficulties in the synthesis of one-dimensional β-MoO₃ have obstructed researchers in the study of its properties. In this research, β-MoO₃ nanowhiskers were synthesized from core/shell molybdenum/molybdenum oxide wires by pulsed wire discharge in mixed oxygen and argon gases. X-ray diffraction analysis identified the main phase in the obtained samples as β-MoO₃. Electron microscopy observations revealed whiskers with an average length and width of 216 nm and 23 nm, respectively. Transmission electron microscopy lattice imaging confirmed the successful synthesis of β-MoO₃ nanowhiskers. Various models were considered to explain the formation of β-MoO₃ nanowhiskers, including mechanical fragmentation of α-MoO₃ layers as well as vapor-liquid-solid and vapor-solid mechanisms. The phase transformation from α to β-MoO₃ under a nucleation process was explained based on the Mo-O phase diagram. To the best of our knowledge, this is the first report of β-MoO₃ nanowhisker synthesis.     

Characteristics and Application of Andalusite Material and Andalusite-Based Refractory

Andalusite material and Andalusite-based refractory are very popular in Europe and Japan, but its applications are restrained because of its low quality and misunderstanding in China. The paper introduced in detail the characteristics of andalusite material and andalusite-based refractory based on the authors‘ research work in recent years and on some references. Some information is illustrated clearly by figures and microstructure photographs. It is concluded the property of raw material and refractory is not determined by alumina content but by type and quantity of the impurities and microstructure.Mullitisation provide andalusite-based refractories more excellent macro and micro properties that guarantee itspopular application.     

vince and Shij

1前言据不完全统计,上个世纪90年代,全国曾有各种类型的立窑数量近万台,立窑水泥的年产量,约占我国水泥年总产量的80%以上。但是立窑生产带来的粉尘污染却十分严重,预计达千万吨之多,约占我国水泥行业粉尘年总排放量的90%。自国家经贸委发布在2000年以前,淘汰直径<2.2m的立窑和     

Economy and Business

<正> China Releases Tire Industry Policy The Ministry of Industry and Information Technology on October 11th released the tire industry policy to encourage the development of safe, energy-saving and environmental-friendly high-performance radialtires. The tires include giant OTR (off the road) tires, wide cross-section and flat passenger car radial tires and truck radial tire swith no inner tubes. By 2015, radial tires should be used for all passenger cars, and for 85% of light trucks and for 90% of heavy-duty trucks. China will focus on the development of radial tires for OTR, airplanes, and low-speed vehicles.