Papers by Keyword: Discharge Characteristics

Abstract: The underwater shock-wave phenomenon has been applied in various fields such as manufacturing and food processing and was investigated using many experimental and numerical analyses in the past. An underwater shock-wave is produced by various methods, e.g., underwater wire explosion and pulse-gap electrical discharge. Therefore, clarifying the shock characteristics depending on the stored electrical energy, wire dimension and material is extremely important. However, predicting the pressure and its distribution induced by underwater electrical wire explosion is hard because the phenomena associated with an elementary process are significantly complicated. In this study, to predict the discharge characteristics induced by underwater electrical wire explosion, numerical simulation based on the “simplified model of underwater electrical discharge” was performed. The numerical results show good agreement with the experimental ones.

Abstract: In order to optimize the design of UHV substation and reduce its construction investment, it is necessary to take further research of UHV substation air-gap discharge characteristics. In this paper, by using sub-conductor and tower to simulate UHV substation air-gap, lightning and switching impulse discharge characteristics tests of UHV substation are taken in the UHV AC test base of SGCC. The results show that, when the distance of conductor between tower is in range of 4m to 7m, the 50% lightning impulse and switching impulse discharge voltage rise along with the rise of air gap distance. As the air-gap increases, the switching impulse discharge voltage presents the trend of saturation. According to the analysis of test results, we can draw a conclusion that the gap factor of switching impulse discharge can be 1.22 when the minimum distance between conductors and tower is 5~8m.

Abstract: Discharge is critical physical process in pulsed electromagnetic accelerators for arc plasma jet device, and its characteristics directly determines the accelerator performance. The mechanisms of discharge plasma and flow in the accelerator are analyzed by magnetohydrodynamics (MHD). The model is coupled with electric circuit model based on weakly nonideal plasma conductivity and ablation model. Calculation results show that there is some nonideal plasma region which has important effects on electrical conductivity; most ablated gases are ionized at the half cycle of the discharge time and are accelerated by Lorentz force to high exhaust velocity; electrical conductivity, plasma temperature and density are increasing with discharge energy unleashed, and gradually reduce in the post-discharge.

Abstract: Treatment technology for ballast water is in need. High-voltage pulsed discharge has great potentiality to inactivating micro-algae living in ballast water. In this study, effects of discharge reactor parameters and ballast water parameters to discharge characteristics were studied, the efficiency of the micro-algae inactivation was confirmed preliminarily, and the principle of designing discharge reactor parameters was discussed. The main conclusions are: UP increased with the increasing of d, while decreased with the increasing of r; IP increased with the increasing of r, while decreased with the increasing of d; UP and IP both increased with the increasing of U. E decreased with the increasing of d; when d=2mm, the value of E was far larger than that of d≥6mm; when d was 2mm，larger r, larger E; when d was between 6-20mm, larger r, smaller E. The optimized structure of discharge reactor should be r=3mm and d=6mm. Up increased with the increasing of Q while decreased with the increasing of T. η increased with the increasing of U and d, decreased with the increasing of r.

Abstract: The configuration of discharge electrode is closely related to the uniformity and the strength of corona plasma, which has big effect on the efficiency of plasma in destructing pollutants, treating materials and so on. A novel sheet electrode was devised to enhance the input energy and the uniformity of plasma’s distribution, and its production performance of plasma was compared with other discharge electrodes including wire, needle and multi-needles. Corona images and I-V characteristic curves of discharge electrodes indicate that ultra-thin sheet electrode could produce more uniform and stronger corona plasma zone than other electrodes in this paper, which is advantageous for decomposing pollutants, treating material surface and so on. Primary VOCs decomposition experiments were conducted, and the results indicated that the highest energy yield of VOCs decomposition reached 1.8 g (benzene) • (kWh)-1 /3.5 g (toluene) • (kWh)-1.

Abstract: This paper studies the effect of spool valve diametral clearance of electro-hydraulic servo valve on orifice discharge characteristic. To ensure that the freely sliding between spool and sleeve, there must be given diametral clearance between spool and sleeve, which will have an impact on valve orifice discharge characteristic, this paper first individually sets up a 3D models of clearance from 0 to 5 μm, opening value from 0 to 40 μm, then calculates each model’s discharge on the condition that valve orifice’s inlet and outlet differential pressure is constant, finally according to the result of the discharge plots the diametral clearance curve of spool valve. The quantitative numerical relationship of diametral clearance and spool valve characteristic index is given after doing the analysis, Finally, an experimental verification of the simulation results is to be done to prove the simulation results are correct and reliable. The research of this paper provides the basic guidelines for spool valve designing and testing.

Abstract: As the number of delicate semiconductor devices in the electric equipment increases, it is also getting more important to prohibit the surge wave from intruding the equipment. The better surge-wave protection can be achieved when we reduce the earth resistance further in the earthing system. It is practically best, however, to set an appropriate value of earth resistance if we consider the cost and effort required to install the earthing system. In this work, we demonstrated an example of extracting an optimized earth resistance by using a simulator that theoretically predicts the evolution of discharge current of the earthing system. The measure discharge currents of the real earthing system with the optimum earth resistance has confirmed that our method was efficient and useful.

Abstract: This paper deals with the effect on orifice discharge characteristic by the round angle of electro-hydraulic servo valve spool metering edge. The machining method of spool metering edge can cause micro round angle on the edge. This paper firstly provides 3D geometry model and computational grids of spool valve where the round angle’s range is 0-10μm and orifice opening is 0-40μm. Secondly calculates the flow rate of the orifice on the constant differential pressure circumstances. The numerical analysis is performed by using the commercial code ‘‘Fluent’’, and the numerical results show the complete flow field inside the valve. The analysis result is to obtain the influence of round angle on discharge characteristic, quantitatively. An experimental result is used in this paper to evaluate and validate the numerical analysis of the valve. The aim of this analysis is to provide a designation reference of the spool valves which are important parts of servo valve.

Abstract: A series of experiment has been carried out to study the electrochemical performances of lithium primary cells using different cathode materials. The cathode material was made of metal oxide, electrolyte, activated carbon, and PVdF with a wt. ratio of 60: 20:10:10. PVdF was added as a binder. The metal oxides used are MnO2 and V2O5. The anode was made up of lithium metal and LiI-Li2WO4-Li3PO4 compound is used as an electrolyte. In this work the open circuit voltage (OCV) of Li/MnO2 and Li/V2O5 obtained is about 3.0 V and 3.2 V respectively. This shows that LiI-Li2WO4-Li3PO4 compound is lithium ion conductor. Lithium cell showed better performance at 100º C than at room temperature. Among these two types of cells investigated, cell Li/V2O5 worked better than the Li/MnO2 cell at room temperature and at 100°C as this cell exhibits the longest continuous discharge time and the highest OCV.

Abstract: Ti and Ni sulfides were formed on the surface of Ti-Ni alloys by isothermal annealing at various sulfur pressures, and then microstructures of the surface sulfide layers were investigated by means of scanning electron microscopy and X-ray diffractions. Morphology of sulfurized surface changed from granular shape to porous shape at the sulfur pressure of 80 kPa, which is related to the change in sulfide from NiS1.97 to NiS. Two-layered sulfide was observed in which the inner layer was mainly Ti8.2S11 , and the outer layer was a mixture of NiS1.97 and NiS. The discharge curve of the Ti and Ni sulfides cathode formed on the Ti-Ni current collector at the first cycle showed a plateau voltage of 1.6 V, and the discharge capacity was found to be about 530 mAh/g-NiS1.97.