故障蓄电池激活充电的仪器研制

本文介绍了对过放电或长期放置自放电严重的铅酸型故障蓄电池进行激活充电的一种方法 .文中分析了蓄电池的故障产生原因和故障蓄电池的激活机理 ,叙述了仪器设计原理框图及主要电路     

空间材料表面充放电性能试验评估方法研究

空间材料的表面充放电可导致材料表面污染加速、热控性能和其他物理性能改变并产生电磁干拢 ,通过材料选择可以减少表面带电及其产生的危害 ,其中对材料进行充放电特性测试与评价是材料选择的重要依据。介绍了用于空间材料表面充放电特性试验评价的主要设备及其工作原理 ,重点介绍了试验的方法。试验结果及数据应用表明 ,利用该设备和试验方法可以较好地评价空间材料表面充放电特性     

Crisis phenomena in metal hydride hydrogen storage facilities

We present the results of experimental studies of heat and mass transfer processes in a metal hydride reactor under absorption and release of pure hydrogen. The hydrogen absorption/release reaction is shown to proceed in three stages: (I) heating/cooling of the absorbing material bed up to the reaction temperature; (II) equilibrium absorption/release; and (III) reaction completion. The transition from the first stage to the second is accompanied by a sharp decrease in the hydrogen flow rate at the reactor input/output. The crisis is caused by the ineffective pick-up/application of hydrogen absorption/release heat from/to the absorbing material bed. The reactor charging/discharging operation modes balanced against heat transfer make it possible to avoid crisis and to proceed under a constant flow rate of hydrogen.     

太阳能空调相变蓄冷理论及实验研究

针对一种自制的能够与太阳能空调系统匹配的相变蓄冷材料,建立了蓄冷球蓄\释冷过程数学模型,得到稳态及非稳态工况下蓄冷球内温度分布、蓄\释冷量、蓄\释冷速率的变化规律及影响因素。同时,在相应工况下对单个蓄冷球进行蓄\释冷循环实验,验证理论结果。研究表明,自制蓄冷球能够在170min完成相变。缩小球径、降低冷冻水温度、增大球壁热导率及减小球壁厚度均可缩短蓄冷时间。稳态运行工况下,蓄冷球的蓄\释冷量分别为17.30kJ和16.46kJ;太阳能空调非稳态运行工况下,蓄冷球在165min完成相变,蓄冷量为16.34kJ。     

A comparison of silver electrodes by the sintering method and the chemically prepared method

Abstract

Silver electrodes were made by the sintering method and by the chemically prepared method. Their charging and discharging performances were compared.

It was found that the capacity of the chemically prepared electrode is larger than that of the sintered electrode at low rate charging current and smaller at high rate charging current at 100 mA discharging rate.

The sintered electrode was more porous than the chemically prepared electrode from observations with scanning electron microscope (SEM).

The difference of performances was tentatively explained by the mass transfer of hydroxyl ions.     

Study on influence of oil discharging hole on clutch oil charging and discharging characteristics

Forschung im Ingenieurwesen - In order to study the influence of oil discharging hole on the oil charging and discharging characteristics of wet clutch, a mathematical model of oil...     

Stress states in RENi5 powders during hydrogen charging and discharging cycles

In this study, the evolution of the stress states in RENi ₅ particles during hydrogen charging and discharging cycles were investigated using coupled diffusion–deformation finite-element method analyses. The results indicate that large tensile stresses, of the order of 20–30% of the modulus of elasticity, develop in the particles even in the absence of both internal and external crack-like defects. The internal and external cracks behave differently from each other during hydrogen charging and discharging cycles. Therefore, the fracture resistance of the particles containing external cracks will be different from the particles having internal cracks. The disc-shaped particles, in addition to having faster charging–discharging cycles, may offer better resistance to fracture than the spherical particles.     

Analysis of Power-Supply Interference Effects on Direct Sensor-to-Microcontroller Interfaces

This paper analyzes the effects of power-supply interference on direct sensor-to-microcontroller interfaces based on measuring the charging/discharging time of an RC circuit that includes the sensor. Power-supply interference becomes a source of trigger noise that affects the measurement of the charging/discharging time and, hence, the measurement of the sensor resistance or capacitance. The measurement uncertainty increases proportionally to the amplitude of the interference and depends on its frequency. Such interference effects are smaller when measuring the discharging time and can be further reduced by placing an additional resistor in the interface circuit. Experimental data obtained from a PIC microcontroller agree with the theoretical predictions     

壳聚糖金属螯合物对LaNi5储氢合金电化学性能的影响

通过向LaNi5储氢舍金电极中添加一定量的壳聚糖金属螯合物，用电化学阻抗谱线分析了其对LaNi5储氢合金电化学性能影响；同时也对LaNi5储氢合金电化学容量以及高倍率充放电性能的影响进行了研究；与LaNi5储氢合金进行了对比，结果表明：添加了壳聚糖螯合物的LaNi5储氢合金其放电平台与高倍率克放电性能都得到了提高，其中添加量为2％时催化效果最好。     

Transport calculations in hydrogen storage as metal hydrides

A method is described for analyzing reactive transport in a metal hydride layer, which has been checked on a model for a hydrogen accumulator.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 57, No. 1, pp. 100–107, July, 1989.     

Hydrogen effects in gamma titanium aluminides

The results of X-ray diffraction studies on Ti-48Al-1V at %(Ti-48-1) are reported. The objective of this study is to investigate the effects of hydrogen on phase changes and hydride formation in these alloys. Hydrogen-induced cracking was found to occur as a result of hydrogen charging. The cracking appears after the hydride phase formation and is observed to be dispersed throughout the material. The hexagonal hydride formed is unlike any previously reported titanium hydride. The hydride exhibits an 8% volume contraction compared to Ti₃Al which is made up of a 10% contraction in the a-direction, and a 12.5% expansion in the c-direction. This revised version was published online in November 2006 with corrections to the Cover Date.     

An electrochemical model of low-frequency dispersion

The widely observed phenomenon of low-frequency dispersion is interpreted in terms of an electrochemical process in which ionic charge carriers migrating under the action of an external field combine to form neutral molecules, thereby eliminating charges which would be necessary to sustain the very high capacitances at low frequencies. Both charging and discharging currents are almost independent of time with the discharge currents consistently lower than the charging currents. The neutral molecules provide a reservoir of charge and of energy which become released on discharging the system after step-function charging, most of the charge and energy being dissipated in what is a highly lossy system. The frequency-domain response is then interpreted using the new concept of “energy criterion” which is particularly suited to the analysis of fractional power-law dependence on frequency. This provides a self-consistent and realistic theory of low-frequency dispersion and enables the connection to be made between time and frequency-domain responses, despite the fact that the strong non-linearity of the response makes the Fourier transformation of limited usefulness.     

Charge equalization circuit for discharging series‐connected batteries with regulated output

Abstract

Charge equalization during the charging process has been extensively discussed for series‐connected batteries. However, charge inequality may also happen to batteries during discharging. The imbalance among batteries may result in over‐discharging and consequently damage to the batteries. To solve the problem, a balanced discharging method for a series‐connected battery bank is proposed. A flyback conversion circuit is designed with a pulse‐width‐modulation controller to achieve output voltage regulation as well as balanced discharging. The applicability of the proposed method is confirmed by experiments.     

Ion beam effects on dust grains: 2—Influence of charging history

Dust grains in space are charged by various processes. Impacts of energetic ions lead to deposition of positive charge on the grain, increasing the grain potential and, as a consequence, the electric field at its surface. The accumulated charge is spontaneously released as an emission current when the electric field reaches a threshold. This discharging current is usually attributed to field ionization of any gas surrounding the grain or to ion field emission and would thus be predominantly a function of the surface potential. However, preliminary studies [Velyhan A, Z?ilavý P, Pavl? J, S?afránková J, Něme?ek Z. Ion beam effects on dust grains. Vacuum 2004;76:447-55] using melamine formaldehyde spheres have shown that the discharging current depends strongly on the energy of primary ions. The present paper continues these investigations with the motivation to understand the whole charging/discharging process. The experiment is based on the capture of a single dust grain in an electrodynamic quadrupole. The trapped grain is exposed to an ion beam with different energies up to 5 keV and its charge and surface potential are estimated from the frequency of its oscillations in the quadrupole. The charging/discharging currents are determined from temporal changes of the grain charge. Our results suggest that the grain charge is accumulated in a thick surface layer of non-conducting samples. The thickness of this layer depends on the mass and energy of primary ions. On the other hand, the beam ions probably recombine on the metallic surfaces and create an adsorbed layer there. We believe that the main discharging process is field desorption complemented in this particular case with post-ionization.     

Analysis of thermal stability of conduction-cooled LTS magnet

The temperature stability of the conduction-cooled or cryogen-free magnet is governed by the heat balance between the heat generation rate and the cooling rate by the cryocooler through the thermal links. The dynamic thermal profile of a conduction-cooled NbTi magnet during charging and discharging process has been analyzed in terms of theoretically evaluated dynamic heat loss profile. The NbTi coil was energized up to 90 A with 2 A/min, 4 A/min, and 6 A/min sweep rates and the corresponding hysteretic AC loss and resistive heat loss have been estimated with all three sweep rates. The equilibrium temperatures of the magnet are 3.23 K and 3.82 K at zero and 90 A current respectively. At the beginning of the charging process, the AC loss has dominant role in the thermal profile of magnet but resistive heat loss takes over the dominant role towards the end of charging process. The thermal profile of the magnet during continuous charging has been compared with discharging of the magnet and step-wise charging.     

Thermal behavior and energy storage of a suspension of nano-encapsulated phase change materials in an enclosure

The energy storage capability of a suspension of Nano-Encapsulated Phase Change Material (NEPCM) nanoparticles was addressed in an enclosure during the charging and discharging process. The nanoparticles contain a Phase Change Material (PCM) core, which are capable to absorb a notable quantity of thermal energy on melting. There is a heat pipe in the cavity at the bottom corner, which is enhanced by a layer of metallic matrix. The natural convection flow occurs due to a temperature gradient during the charging or discharging process. The particles of NEPCM move with the natural convection flow and contribute to heat transfer & storage of thermal energy. The regulating equations for the heat transfer & flow of the NEPCM suspension were established & converted in the non-dimensional type. The finite element method (FEM) was utilized in resolving the equations. The results show that there was a rise in the rate of heat transfer & storage of total energy with a rise in nanoparticles volume fraction. The decrease of the Stefan number from 0.2 to 0.6 increases the total stored energy by 25%. The fusion temperature is another important parameter in which its behavior depends on the charging or discharging process.     

Studies on iron-chromium redox storage system

The performance of the redox storage battery based on the Fe-Cr redox couple is studied in charging and discharging modes of the system. The stability of each charged species is determined by measuring the variation of half-cell potential with time. The spectra of the electrolytes are recorded before and after charging of the system. The effect of atmosphere on the charged species has also been investigated.     

GEANT4-RIC方法在卫星内放电监测器研制中的应用研究

围绕CRRES卫星内放电监测器在轨试验,国外开展了大量空间内带电的关键性研究,为NASA-HDBK-4002等规范的建立奠定了坚实的基础。针对实验室研制的内放电监测装置,采用GEANT4-RIC数值模拟和地面试验相结合的方法对内放电监测器的放电状况进行了对比研究,验证了模拟方法的正确性,为进一步开展空间辐射效应监测器研制提供了一种新的设计方法 。     

掺硼酚醛树脂热解碳的制备及嵌锂性能研究

将热固性酚醛树脂与H3BO3溶解并混合,得到含硼酚醛树脂,经进一步炭化制成掺硼硬碳材料。充放电结果表明,硼的掺杂使锂的嵌／脱容量明显提高,同时1V以下的脱嵌电位降低,且电位平稳性有所改善。XRD分析表明,掺硼后使硬碳的d002明显减小,即碳结构的有序化程度提高。     

电动汽车充电对电网安全风险影响及管控措施研究

随着政府的重点扶持和政策激励,电动汽车市场蓬勃发展,这极大地刺激了电动汽车充换电设施的建设运营,对电网运行检修的安全带来较大影响。通过介绍电动汽车充电对电网的安全风险影响因素,识别影响因素和仿真模拟,分析了电动汽车充电和放电对配网的影响,并对安全风险影响进行评估,最后在电动汽车的规划、建设、运维、自建自管等方面做出安全风险管控措施建议。