Gasoline electrification: moisture and temperature influence

In the last decades, car manufacturers have introduced plastic materials into the vehicle fuel circuit. Do these modifications have an influence on electrostatic hazards? Several accidents were listed in Japan and the United States while filling the tank. Flow electrification was suspected to be responsible for some of these accidents. In this context, our laboratory studies flow electrification of fuels on the surface of dielectric and conducting materials on different conditions (fuels, moisture, temperature, Reynolds number, etc.).This paper is interested in flow electrification variation depending on atmospheric conditions (moisture and temperature) and on Reynolds number. We propose to evaluate the electrostatic hazards according to these parameters for a commercial gasoline/stainless steel interface.An experimental setup was developed in our laboratory. It consists of a loop representing fuel flowing through a pipe under a specific gas environment (controlled air moisture and gasoline temperature). The current generated by fuel flow is measured. This study allows to determine the main experimental parameters that modify flow electrification phenomenon in fuel.     

Worst case conditions for electrostatic tests of liquid handling systems

This paper gives a literature survey on recommendations for the worst case test conditions for electrostatic tests of liquid handling systems. The following applications are dealt with: 1) Testing equipment for flowing solvents, 2) Testing equipment for flowing fuel, 3) Testing equipment for flowing contaminated liquids, 4) Spraying liquids, and 5) Reconstruction of accidents.     

Expressions for Entropy Production Rate of Fuel Cells

基于燃料电池的一般模型,应用电化学和热力学理论导出燃料电池系统在不同条件下熵产生率的表示式．为了分析存在实际燃料电池中不可逆损失的影响,引进燃料电池的等效电路,直接将燃料电池的不可逆因子表示为内电阻、漏电阻和负载电阻的函数．进而计算燃料电池的最大输出功率和效率,讨论燃料电池的优化运行,确定负载电阻的匹配条件,从而得到一些有意义的结果．     

Electrostatic hazard and protection: expert system for fuel delivery modules

It is well-known that fuel supplying the engine of vehicles passes through a filtration process. Previously, fuel pump, filter and pressure regulator were separated; nowadays, they are built together in a compact module and placed into the fuel tank of the vehicle. Components of such a module are mainly made of good insulating plastic material, resulting in significant charging and risk of electrostatic discharge. Replacing all of the plastic parts with electrostatically dissipative materials and applying appropriate grounding and bounding risk can be reduced to almost zero, but it requires extremely high costs. To obtain economical construction with acceptable risk, an expert system had to be created to evaluate different constructions from the aspect of electrostatic charging.     

Incident case histories on mobile containers

While handling liquids in rigid intermediate bulk containers (RIBC), the assessment of ignition sources due to electrostatic discharges is of especial interest since it is often difficult to rule out all possible conditions which can lead to the generation of an effective discharge. Far from suggesting new criteria for the selection or construction of RIBC or standards for its design, this paper has the aim of describing three incidents where an electrostatic discharge caused a flammable mixture of vapours with air to ignite. Situations presented could usually be rated as highly remote on its probability of occurrence by operators since they are common and never caused an incident, but on the other hand it is rather easy, from a theoretical point of view, to explain the phenomena observed by applying the basic assessment rules for the generation of electrostatic ignition sources.If existing guidelines were to have been followed (mainly CENELEC 50404 and BGR132), those incidents would have not occurred.     

Possibility of separating spent nuclear fuel components by a plasma method in azimuthal magnetic and radial electric fields

We consider the method of plasma separation of spent nuclear fuel in a system with an azimuthal magnetic field and the electric potential produced by electrodes located in a magnetized plasma. The results of calculation of trajectories of ions simulating uranium and the first peak of its fission products in the oneparticle approximation are described. The effect of the initial position and the initial velocity of ions on their trajectories is analyzed. The conditions ensuring the spatial separation of ions in the groups of masses admissible for practical realization are specified; it is shown that currents on the order of 100 kA through the central conductor and electrostatic potentials on the order of 1 kV are required for this purpose.     

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.     

Polyelectrolyte contributions to transitions in electrostatic persistence length

The manner in which a conformational change determining the polyelectrolyte contribution to chain stiffness is incorporated into existing polyelectrolyte theory is discussed. The full Poisson-Boltzmann equation for the electrostatic potential (rather than a linear version) is incorporated into the calculation of the electrostatic persistence length. Changes in the electrostatic persistence length can then be demonstrated qualitatively to be controlled by the solution dielectric constant.     

Evaluation of the neutron production rate using D–D and D–T fuel in an inertial electrostatic confinement fusion device

The correlation between the neutron production rate and fuel species in a spherical inertial electrostatic confinement fusion (IECF) device is investigated by solving the Poisson equation for various ion and electron distribution functions. The fuel ion energy distribution function is determined at each radial point. The fusion reaction rate is evaluated from the energy distribution function. The dependence of the neutron production rate (NPR) on some important parameters, like the ion convergence, the broadening of the distributions in the energy space, working pressure and fuel species, are also investigated. Compared with the IECF device with D–D, numerical calculations show that by increasing the percentage of tritium in the D–T mixture fuel the neutron production rate grows significantly.     

Simulation-driven formulation of transportation fuel surrogates

An alternative way to formulate transportation fuel surrogates using model predictions of gas-phase combustion targets is explored and compared to conventional approaches. Given a selection of individual fuel components, a multi-component chemical mechanism describing their oxidation kinetics, and a database of experimental measurements for key combustion quantities such as ignition delay times and laminar burning velocities, the optimal fractional amount of each fuel is determined as the one yielding the smallest error between experiments and model predictions. Using a previously studied three-component jet fuel surrogate containing n-dodecane, methyl-cyclohexane, and m-xylene as a case study, this article investigates in a systematic manner how the surrogate composition affects model predictions for ignition delay time and laminar burning velocities over a wide range of temperature, pressure and stoichiometry conditions, and compares the results to existing surrogate formulation techniques, providing new insights on how to define surrogates for simulation purposes. Finally, an optimisation algorithm is described to accelerate the identification of optimal surrogate compositions in this context.     

带电粒子与静电波相互作用单粒子方程的严格解

研究了带电粒子与静电波之间的相互作用, 给出了带电粒子运动方程的严格解, 得出了粒子的速度的解析表达式, 同时推导出了带电粒子被静电波俘获的数学条件, 讨论了粒子与波能量交换的物理过程, 对现有等离子体物理的教材中相关的问题是一个补充. 本文结果对带电粒子加速器、微波管以及基础等离子体问题的研究有一定参考意义.     

线-铝箔电极电晕放电激励器的推力理论与实验研究

空气电晕放电离子风激励器无需旋转部件, 仅通过消耗电能就能直接产生驱动力, 它是一种新型的动力技术, 备受国内外航空航天界的广泛关注. 目前对空气电晕放电离子风激励器的推力产生机理虽有各种解释, 但是现有理论均不能统一各种条件下的实验结果, 仍需要开展进一步的分析与研究. 本文以线-铝箔电极电晕放电激励器为研究对象, 通过实验研究发现作用在线电极与铝箔电极上的静电力不对称, 而且改变铝箔电极纵向高度和气压均能影响激励器的推力大小; 通过理论分析, 考虑电晕层与空间电荷的影响, 建立了线-铝箔电极电晕放电激励器的推力计算模型, 其计算值与实测值比较一致. 基于上述实验现象与理论建模分析, 本文认为线-铝箔电极电晕放电激励器的推力主要来源于线电极电晕产生的空间电荷对电极系统产生了不对称静电力作用, 使激励器出现净静电力作用.     

基于悬滴法的纳米燃油表面张力测量与分析

以柴油为基液、溴化十六烷三甲基铵(Cetyltrimethyl Ammonium Bromide,CTAB)为助溶剂,通过两步法配制CNT(Carbon Nanotube),CeO2及Co3O4纳米燃油.采用悬滴法测量柴油与纳米燃油的表面张力,探究纳米物质种类、粒径、质量分数及温度对纳米燃油表面张力的影响.研究发现,在...     

On the nonlinear primary resonances of a piezoelectric laminated micro system under electrostatic control voltage

In this article, a comprehensive nonlinear analysis for a piezoelectric laminated micro system around its static deflection is presented. This static deflection is created by an electrostatic DC control voltage through an electrode plate. The micro system beam is assumed as an elastic Euler-Bernoulli beam with clamped-free end conditions. The dynamic equations of this model have been derived by using the Hamilton method and considering the nonlinear inertia, curvature, piezoelectric and electrostatic terms. The static and dynamic solutions have been achieved by using the Galerkin method and the multiple-scales perturbation approach, respectively. The results are compared with numerical and other existing experimental results. By studying the primary resonance excitation, the effects of different parameters such as geometry, material and excitations voltage on the system?s softening and hardening behaviors are evaluated. In a piezoelectrically actuated micro system it was showed that because of existence of curvature and inertia nonlinear terms a small change in excitation amplitude can lead to the formation and expansion of nonlinear response. In this paper, it is demonstrated that by applying an electrostatic DC control voltage, these nonlinearities can be controlled and altered to a linear domain. This model can be used to design a nano or micro-scale smart device.     

Chargeability of ethanol–petrol biofuels

Chargeability of ethanol–petrol biofuels during refuelling has been studied in real dispenser environment in order to assess safety risks due to fuel charging at fuel filling stations. Two biofuel blends were studied: E10 containing 10 vol-% of ethanol and 90 vol-% of petrol, and E85 containing about 85 vol-% of ethanol and 15 vol-% of petrol. Charging of standard 95 Octane petrol was studied as a reference. The results show that the charging of E85 is negligible and no charge will be accumulated as long as the fuel dispenser system is properly grounded. In the case of refuelling with E10, charge is accumulated but the level of total charge is still so low that no real electrostatic ignition hazards exist due to fuel charging at filling stations as long as the system is properly grounded. Electrostatic ignition hazards due to fuel charging are real only for standard petrol fuel.     

A second-order accurate finite volume method for the computation of electrical conditions inside a wire-plate electrostatic precipitator on unstructured meshes

In this paper, an unstructured cell-centered second-order accurate finite volume method is presented for the computation of electrical conditions inside wire-plate electrostatic precipitators. The potential equation was discretized using a second-order accurate scheme by invoking a new type of special line-structure. The space–charge density equation was discretized using a second-order upwind scheme, and solved using a new direct method. The local gradients are reconstructed by a weighted least-square reconstruction method. The method can deal with complex geometries by using unstructured meshes. Numerical experiments show that the predicted results agree well with the existing experimental data.     

Nanoparticle electrostatic loss within corona needle charger during particle-charging process

A numerical investigation has been carried out to examine the electrostatic loss of nanoparticles in a corona needle charger. Two-dimensional flow field, electric field, particle charge, and particle trajectory were simulated to obtain the electrostatic deposition loss at different conditions. Simulation of particle trajectories shows that the number of charges per particle during the charging process depends on the particle diameter, radial position from the symmetry axis, applied voltage, Reynolds number, and axial distance along the charger. The numerical results of nanoparticle electrostatic loss agreed fairly well with available experimental data. The results reveal that the electrostatic loss of nanoparticles increases with increasing applied voltage and electrical mobility of particles; and with decreasing particle diameter and Reynolds number. A regression equation closely fitted the obtained numerical results for different conditions. The equation is useful for directly calculating the electrostatic loss of nanoparticles in the corona needle charger during particle-charging process.     

Experimental study of V–I characteristics of wire–plate electrostatic precipitators under clean air conditions

In this paper a laboratory-scale model for prediction of the voltage–current characteristics of wire–plate electrostatic precipitators under clean air conditions is presented and experimentally validated. The model investigates the effect of electrode configurations, wire diameter, spacing between wire electrodes, number of discharge wires and distance between collecting plates that on voltage–current characteristic of wire–plate electrostatic precipitators. Also, this paper presents a simulation model, based on the Finite Difference Method (FDM), to simulate electric conditions of wire–plate electrostatic precipitators under clean air conditions. The experimental results of some models are compared with those obtained from the simulation models.     

Catalytic ignition and autothermal combustion of JP-8 and its surrogates over a Pt/γ-Al2O3 catalyst

With the aim of utilizing JP-8 fuel for small scale portable power generation systems, catalytic combustion of JP-8 is studied. The surface ignition, extinction and autothermal combustion of JP-8, of a six-component surrogate fuel mixture, and the individual components of the surrogate fuel over a Pt/γ-Al₂O₃ catalyst are experimentally investigated in a packed bed flow reactor. The surrogate mixture exhibits similar ignition–extinction behavior and autothermal temperatures compared to JP-8 suggesting the possibility of using this surrogate mixture for detailed kinetics of catalytic combustion of JP-8. It is shown that JP-8 ignites at low temperatures in the presence of catalyst. Upon ignition, catalytic combustion of JP-8 and the surrogate mixture is self-sustained and robust combustion is observed under fuel lean as well as fuel rich conditions. It is shown that the ignition temperature of the hydrocarbon fuels increases with increasing equivalence ratio. Extinction is observed under fuel lean conditions, whereas sustained combustion was also observed for fuel rich conditions. The effect of dilution in the air flow on the catalytic ignition and autothermal temperatures of the fuel mixture is also investigated by adding helium to the air stream while keeping the flow rate and the equivalence ratio constant. The autothermal temperature decreases linearly as the amount of dilution in the flow is increased, whereas the ignition temperature shows no dependence on the dilution level under the range of our conditions, showing that ignition is dependent only on the type and relative concentration of the active species.     

Electrostatic microtrap on the surface of the chip

As is well known in atomic optics, the nonadiabatic transitions induce the loss of atoms trapped in a magnetic well which seriously affects the formation of the Bose-Einstein condensates. Electrostatic traps have widespread applications in molecular optics. While, for most existing electrostatic traps, the electric field strength in the trap center is nearly zero which may cause the nonadiabatic transitions. Especially for a chip-based microtrap, ingenious design is need to overcome this problem. In the paper, we propose a novel electrostatic microtrap composed of four arc-shaped electrodes. The influences of the voltages and the geometrical parameters of the electrodes on the electric field strength as well as the height of the potential well are studied. The distributions of electrostatic field are numerically calculated. We firstly simulate the trajectory of one molecule in the processes of loading and trapping. After that, we simulate the movements of a large number of molecules using the method of Monte Carlo. Then we calculate the temperature of trapped cold molecules. After that, we analyze the impacts of voltages and the geometrical parameters on the efficiency of our microtrap. At last, we show that our scheme can evolve into electrostatic microtrap arrays which should be a powerful tool for a variety of basic research and applications.