Fundamental investigation of charge injection type of electrostatic oil filter (effect of filter element on filtration speed)

This paper deals with the effect of filter element on the filtration speed of a charge injection type of electrostatic oil filter proposed by Yanada and his coworkers. The effect of the filter elements that are inserted between the emitter and collector electrodes on the filtration speed is examined using several types of oil. In order to discuss the effect of the filter elements on the filtration speed, numerical simulations of electrostatic field are conducted and ion drag flow patterns are measured using two-dimensional filter models. An optimal filter configuration is proposed.     

Effects of electrode and filter element shapes on characteristics of charge injection type of electrostatic oil filter

This paper reports on an improvement of the filtration speed of charge injection type of electrostatic oil filter. Numerical simulations of the ion drag flow field and electric field are performed to compare the charge density distribution, ion drag flow pattern, and electric field strength distribution for different electrode and filter element shapes. Filtration experiments are conducted and the experimental results are discussed in relation to the simulation results. It is shown that the numerical simulations used in this study can contribute in predicting a better structure for electrostatic oil filters.     

Design and charge injection characteristics of an electrostatic dielectric liquid pulsed atomizer

An automotive fuel injector has been retrofitted with novel electrostatic components in order to improve the primary atomization and dispersion characteristics of the device. A specific design variant is presented and discussed outlining how a conventional fuel injector may be modified to house electrostatic components. With 2 bar gauge injection pressure and an electrical power of 2 mW, the injector can successfully supply intermittently charged fuel, containing spray specific charge levels up to ～1.4 C/m³. Root mean square (RMS) spray specific charge and RMS total current vs. voltage curves are presented as a function of voltage pulse and solenoid valve frequencies for both low and high flow-rate operation. The fuel injector was able to operate in a stable manner at pulse train frequencies up to 20 Hz and the charge injection mechanism was identical to previous steady voltage and pulsed voltage steady flow systems. An optimal synchronization between the high voltage (HV) pulse frequency and solenoid valve frequency has been determined, allowing for the prevention of electrical breakdown events within the inter-electrode gap over a negative voltage ranging from 0 to 4.5 kV.     

Measurement of charge transfer in electrostatic discharges

Experimental studies are reported that show the errors that arise in using unshielded probes for measuring charge transfer in electrostatic discharges. Comparable errors will apply where unshielded probes are used for current flow measurements. Errors are avoided by using shielded probes with an appropriate charge measurement circuit. These results are relevant to the design of probes to be included in IEC Standards.     

Novel electrodes of an electrostatic precipitator for air filtration

Using electrostatic precipitators (ESPs) in filtration systems results in higher system energy efficiency than fiber-based filters, but particle re-entrainment could lower the collection efficiency of ESPs. This paper demonstrates a novel ESP that utilizes foam-covered collecting electrodes to reduce particle re-entrainment and enhance collection efficiency. Particles that settle down within the pores of the foam are less likely to re-enter the airflow. Results show that foam-covered ESPs have 99 percent collection efficiency. Parametric plots demonstrate the effects of the key design variables, such as corona voltage, repelling voltage, and free airflow velocity on collection efficiency.     

接近速度对空气静电放电特性的影响

通过理论分析和实验测量,研究了导体接近速度对空气放电的影响。理论计算了两导体相互接近时导体的自（互）电容系数、导体电势差、导体电势差随导体间的间隙（放电间隙）的变化率和导体电势差的时间变化率。实验研究了5 kV和10 kV放电电压下放电电流峰值和耦合电压峰-峰值随接近速度的变化关系。接近速度直接决定了空气击穿时导体电势差的时间变化率,同时也就决定了不同速度下的空气放电特性;接近速度影响了火花击穿的时间延迟,从而对空气放电产生了时间效应。     

接近速度对空气静电放电特性的影响

 通过理论分析和实验测量,研究了导体接近速度对空气放电的影响。理论计算了两导体相互接近时导体的自（互）电容系数、导体电势差、导体电势差随导体间的间隙（放电间隙）的变化率和导体电势差的时间变化率。实验研究了5 kV和10 kV放电电压下放电电流峰值和耦合电压峰-峰值随接近速度的变化关系。接近速度直接决定了空气击穿时导体电势差的时间变化率,同时也就决定了不同速度下的空气放电特性;接近速度影响了火花击穿的时间延迟,从而对空气放电产生了时间效应。     

静电屏蔽演示实验的改进

笔者按照教科书上的要求去做静电屏蔽的演示实验时,效果不明显.有时当带电金属球靠近验电器时,验电器的指针不张开,再将实验器材做清洁、干燥处理后,验电器指针还是不张开.笔者经过分析认为验电器的指针不张开的原因可能是:电荷在金属球上的分布比较分散,使验电器处场强比较弱.于是用尖形布电器代替金属球,使之带电后,将其尖端靠近验电器,验电器指针明显张开,效果很好.当用金属网罩将验电器罩住后,验电器的指针就不张开了,从而达到了实验预期效果.静电屏蔽演示实验的改进@陈烈福$汉源一中!四川雅安625302     

Filtration characteristics of fibrous filter following an electrostatic precipitator

This study presents the results of investigations of a hybrid electrostatic filtration system (HEFS), which combines an electrostatic precipitator (ESP) and a fibrous filter installed downstream of the ESP. The particles escaping from the ESP carry large amount of charge and this can increase the filtration efficiency of the fibrous filter. The filtration characteristics, including the efficiency, pressure drop and ozone generation, were investigated experimentally. The influence of system parameters, including the filter type, applied voltage, and distance between the ESP and fibrous filter on the overall efficiency were also studied. The measured results show that utilizing the non-high-efficient fibrous filter to remove the charged particle could provide a much higher efficiency without adding the pressure drop due to the electrostatic force. If the efficiency was similar, the ozone generated by HEFS was much lower than that of the single ESP. The results proved that filter efficiency increased with a higher applied voltage and higher initial mechanical filtration efficiency. The distance between the filter and ESP had no influence on the system filtration efficiency. The efficiency of filter in HEFS supplied with the positive voltage was slightly lower than for the negative voltage. In addition, the mathematical model was utilized to model the air filter efficiency in HEFS. The modeled and measured results agreed reasonably. Overall conclusion is that the HEFS could operate at a high efficiency with the lower applied voltage, ozone generation and pressure drop.     

Variable electrostatic transformer: controllable coupling of two charge qubits

We propose and investigate a novel method for the controlled coupling of two Josephson charge qubits by means of a variable electrostatic transformer. The value of the coupling capacitance is given by the discretized curvature of the lowest energy band of a Josephson junction, which can be positive, negative, or zero. We calculate the charging diagram of the two-qubit system that reflects the transition from positive to negative through vanishing coupling. We also discuss how to implement a phase gate making use of the controllable coupling.     

HITFL注入引出高压静电偏转板的物理设计

根据兰州重离子治疗专用装置（HITFL）物理设计的要求,采用三维电磁场程序ANSYS建立HITFL环上注入引出高压静电偏转板的物理模型。模型中高压电极的倒角半径为20 mm,电极半宽度为55 mm,计算出静电偏转板物理要求区域内电场的非均匀度为-0.24%～0.24%,区间的电场集中系数为1.37（小于2）,满足物理设计的要求。同时,利用了HIRFL-CSR（兰州重离子冷却储存环）工程CSRm环上注入引出高压静电偏转板物理设计的经验,HITFL环上的静电偏转板采用表面经过氧化处理的锻铝板材以满足耐压性和机械强度的要求。     

Modeling of filtration efficiency of nanoparticles in standard filter media

The goal of this study is to model the data from the experiments of nanoparticle filtration performed at the Particle Technology Lab, University of Minnesota and at the 3M Company. Comparison shows that the experimental data for filter efficiency are bounded by the values computed from theoretical expressions which do not consider thermal rebound. Therefore thermal rebound in the tested filter media is not detected down to 3 nm particles in the present analysis. The efficiency measured experimentally is in good agreement with the theoretical expression by Stechkina (1966, Dokl. Acad. Nauk SSSR 167, 1327) when the Pectlet number Pe is larger than 100; it agrees well with the theoretical expression by Kirsch and Stechkina (1978, Fundamentals of Aerosol Science. Wiley, New York) when Pe is of the order of unit. We develop an empirical power law model for the efficiency depending on the Peclet number, which leads to satisfactory agreement with experimental results.     

Superconductivity of polymers with charge injection doping

We show that conductivity measurements on sandwiches of a polymer between normal‐metal and superconducting‐metal electrodes can be interpreted in terms of intrinsic superconductivity due to injection of charge into the polymer.     

A model of charge injection at metal-insulator contacts

A phenomenological model of charge carrier injection at metal-insulator contacts is proposed to quantify the injection property of such contacts, especially of non-Ohmic ones. The model contains two parameters: one is the injection current G at a given field, and the other is the field-dependence power p of the injection. It is shown that the values of G and p for a given contact can be determined from the results of step-voltage experiments. When applied to the data on Au-As₂Se₃ contact, it is found that the injection current is G≈10^?6 A cm^?2 at a field of 10⁵ V cm^?1, and the field dependence is approximately quadratic, p≈2. In addition, the field-dependence and the thickness-independence of the peak current can be explained.     

Neutralization of electrostatic charge on spacecraft surfaces by fluxes of cold plasma ions

The results of laboratory experiments on the neutralization of electrostatic charge on elements of the outer surfaces of high-orbit spacecraft are described. The charge is neutralized by the action of a flux of cold plasma ions on the material of the surface. It is established that the charge is completely neutralized for all types of studied materials when the ratio of the ion current of cold plasma to the electron current of hot space plasma is within 0.25–1.0.     

Anti-static charge character of the plasma treated polyester filter fabric

Polyester fabrics were subjected to low temperature plasma (LTP) exposure. The anti-static behaviours of the plasma treated fabric were greatly improved. The discharge power of 50 V and the electrode gap of 4 mm were recommended for an optimum result. Acrylic acid treatment further enhanced the anti-static properties of the specimens. Influences of the acid concentration, the treating duration and the temperate during the acrylic acid treatment on the anti-static properties of the fabric were revealed.     

Direct observation of charge inversion by multivalent ions as a universal electrostatic phenomenon

We have directly observed reversal of the polarity of charged surfaces in water upon the addition of trivalent and quadrivalent ions using atomic force microscopy. The bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size, and lipophilicity of the ions, but is very sensitive to their valence. These results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion.     

Analysis of the electrostatic force on a dielectric particle with partial charge distribution

This paper presents the analysis of the electrostatic force acting on a charged dielectric particle on a grounded plane. The force has been determined by a numerical field calculation method to make clear the effect of particle dielectric constant and charge distribution on the particle surface. The charge is treated to be distributed in three ways: (a) uniformly over entire surface, (b) partially on the upper, or (c) on the lower part of a particle. The calculation results show that, if a particle with dielectric constant ?_p = 3 is partially charged on the lower part by a zenith angle π/2, π/4 and π/8, the force shall be higher by 0.7, 4.3 and 20 times, respectively, than that for a uniform charging with the same charge amount. On the other hand, the force becomes weaker when charge is on the upper part. The effect of the particle dielectric constant is found to be dependent on the charge distribution. With charge uniform on the entire surface or on the upper part, the force always increases with the dielectric constant. However, when surface charge is restricted to a small area at the lower part of the particle (θ_q < π/4), the force may decrease with increasing the dielectric constant.