Surface effects in a capacitive argon discharge in the intermediate pressure regime

One-dimensional particle-in-cell/Monte Carlo collisional (PIC/MCC) simulations are performed on a capacitive 2.54 cm gap, 1.6 Torr argon discharge driven by a sinusoidal rf current density amplitude of 50 A/m2 at 13.56 MHz. The excited argon states (metastable levels, resonance levels, and the 4p manifold) are modeled self-consistently with the particle dynamics as space- and time-varying fluids. Four cases are examined, including and neglecting excited states, and using either a fixed or energy-dependent secondary electron emission yield due to ion and/or neutral impact on the electrodes. The results for all cases show that most of the ionization occurs near the plasma-sheath interfaces, with little ionization within the plasma bulk region. Without excited states, secondary electrons emitted from the electrodes are found to play a strong role in the ionization process. When the excited states, secondary electron emission due to neutral and ion impact on the electrodes are included in the discharge model, the discharge operation transitions from α-mode to γ-mode, in which nearly all the ionization is due to secondary electrons. Excited states are very effective in producing secondary electrons, with approximately 14.7 times the contribution of ion bombardment. Electron impact of ground state argon atoms by secondary electrons contributes about 76 % of the total ionization; primary electrons, about 11 %; metastable Penning ionization, about 13 %; and multi-step ionization, about 0.3 %.

Influence of the Condition of the Exposed Electrode Edge in the SDBD on the Discharge Operation Mode in Argon

The paper is devoted to the phenomenological study of the operating modes of a surface barrier discharge in argon in the case of treated by the discharge and new aluminum and copper electrodes. It is shown that without preliminary treating of the edges of the electrodes in the case of copper and aluminum electrodes, the discharge has a different spatial structure determined by the self-organization of the DBD. After erosion cleaning of the electrode edges, the identical operating modes are established. Such effects confirm the former assumption that the key factor determining the mode of the discharge operation for various electrode materials is the surface charge built on the oxides deposited on the edge. The different dynamics of oxides in the case of copper and aluminum electrodes is determined by the resistance of the oxides of these metals to sputtering, which is indirectly confirmed by the estimation of the binding energy for these materials.

Intensification of mixing of fuel with supersonic air flow when injection and electric discharge are combined

This paper presents the results of experimental investigations of DC discharge influence on mixing intensification of transvers injected gas jet into supersonic aiflow. The air was used as injected gas to prevent the influence of chemical reactions on measurements. The data obtained during discharge includes current and voltage acquisition, registration of pressure pulsations in the jet downstream of discharge operation accompanied by correlation and Fourier analysis allowed to conclude that discharge significantly increase the pressure pulsations in a wide frequency range of 1000 Hz to 50kHz. Increase of the oscillations near the jet boundary is assumed to be related to kinematic mixing intensification of the injected gas with the oncoming flow.

Flow control in cavity by means of sDBD actuator

This paper presents results of controlling the hydrodynamic cavity pulsations by plasma sDBD actuators. The study was held at flow velocity 36 m/s. The discharge was organized near the upstream edge of cavity. The discharge pulse energy was 0.03 J, Excitation of resonant modes, whose frequency coincides with the modulation frequency of the discharge, is obtained. Also, in the case of the detuned discharge operation, locking of the cavity to the discharge modulation frequency occurs.

Thermal Energy Production in an Electrochemical Cell and Heat Transfer to Its Dark Surroundings

The theoretical formulation presented in this abridged paper was developed to predict the transient cell average temperature of a lithium-based cell during its discharge in dark, extremely low material density surroundings where the predominant mechanism of heat exchange between its shroud surface and surroundings is the thermal radiation process for a given cell discharge current and its initial temperature. The average computed temperature of an ideal lithium-based button cell, such as Li(s)/electrolyte/CF(s), is presented as a function of time in the form of plots at two discharge currents as an example of the application of the derived formulation. The presented data are briefly discussed in light of the lithium-based cell component stability and its safe discharge operation.

Thermal Energy Production and Heat Exchange between an Electrochemical Cell and Its Surroundings

The theoretical formulation presented in this paper was developed to predict the cell average temperature as a function of time for a given cell discharge current and its initial temperature under adiabatic and nonadiabatic conditions. The cell average temperature versus time data calculated from the derived formulation is presented in the form of plots for an ideal lithium-based button cell (for example, lithium(s)/electrolyte/carbon monofluoride(s)) during its discharge period. The presented data are briefly discussed in light of cell component stability and safe discharge operation.

Migration Characteristics of Boring Mud in Roadway Floor Anchor Wire Hole and Test in Coal Mine

Given the difficulty in drilling the anchor holes in the roadway floor of the coal mine, the characteristics of slag movement in the process of positive and negative circulation drilling are analyzed. It is concluded that the interaction between the three zones of drilling and slag is the fundamental reason restricting the rapid drilling of the anchor cable hole in the floor, and it is proposed that the pump reverse circulation drilling can effectively prevent the formation of the three zones of drilling and slag. According to the actual situation, the relationship between drilling depth, vacuum degree of the pump, and the velocity of drilling fluid and the volume of drilling slag is obtained. The results show that the pump suction reverse circulation is feasible for the rapid drilling of the anchor hole of the floor. A set of pump suction reverse circulation drilling systems has been developed, and floor anchor wire hole drilling and slag discharge operation at the same time were realized. The field test shows that the effective drilling time of the anchor cable hole in the depth of 5.6 m can be controlled within 30 min, which solves the problem of deep hole drilling in the anchor hole of the bottom plate and purifies the working environment.

Th e Possibility of the Inert Gas Generator Environmental Operation Mode Utilization on Long Range 2 Oil Tankers During Discharge Operation

Long Range 2 tankers are the largest ships used for the transportation of petroleum products. Although more than 400 Long Range 2 tankers are navigating the world’s sea, many of the terminals, at which these ships discharge their cargo, do not utilize their discharging capacity to the full extent. This is due to the technological obsolescence of the terminal and the fact that these terminals are primarily designed to accommodate smaller tankers, such as Medium Range and Long Range 1 tankers. The reduced discharge capacity leads to longer ship stay in the port and increased air pollution due to the release of inert gas into the atmosphere since terminals unnecessarily insist on the continuous operation of the inert gas generator. This paper explains a possible solution to this problem by using environmentally friendly START/STOP operation mode of an inert gas generator using methods of analysis and synthesis, comparative methods and elements of the mathematical method. Environmentally friendly operation mode requires minimal modification of the software program and it is very easy to perform. This mode has a positive effect on reducing overall gas emissions and significant fuel savings.

INFLUENCE OF METAL HYDRIDE HOLLOW CATHODE ON PENNING ION SOURCE OPERATION

The influence of metal hydride hollow cathode on a Penning ion source operation has been carried out. The feature of investigation is hydrogen injection only due to its desorption from metal hydride under ion-stimulated processes. The regimes of optimal discharge operation in the hollow cathode mode are determined. It has been revealed that the transition to the hollow cathode mode occurs at lower voltages, the discharge works without external gas supply, and the working pressure in the cell is set at the level determined by the discharge current. The supply of a negative bias to the metal hydride hollow cathode weakly affects the features of the emission of axial particles, although it allows the increase of plasma density near the metal hydride hollow cathode.

Proposed energy management for a decentralized DC-microgrid based PV-WT-HESS for an isolated community

Microgrids are small-scale power systems destined to supply isolated villages and optimum utilization of renewable energies. For this reason, this paper presents a DC-MG of 150 Kwp to feed an island village. The configuration of the proposed system consists of four interconnected sub-sections supplied by the centralized unit through PV and Wind Distributed Energy Resources DERs, in addition to the supercapacitor storage device. In the other hand, internal batteries of each sub-section cover its load demand separately, where electrical and chemical storage devices can be advantageous hybrid energy storage system HESS for the system. Thus, the control structure of the DC-MG is based on current hysteresis method to assure the charge/discharge operation and the stability of the DC-bus voltage, then a proposed management strategy to manage the shared energy of the DCMG system. The system behavior is tested under variable parameters and conditions using Matlab/Simulink.