Influence of input power in Ar/H2 thermal plasma with silicon powder by numerical simulation

Numerical simulation in inductively coupled thermal plasma was made on the temperature distribution in argon (Ar)+hydrogen (H2) induction thermal plasma torch with silicon (Si) powder injection to obtain the temperature distribution and gas flow fields. The ICTP model was used in this research because it has benefit of good repeatability and no contamination process. Interactions between ICTP and injected powder are very complicated to be understood only by related experiments. Influence of input power in ICTP was numerically investigated on thermal plasma temperature fields and powder evaporation. The temperature distributions of thermal plasma and Si vapor distribution were compared at input powers of 20 kW, 30 kW, and 40 kW. Results indicated that higher input power increases the temperature of the thermal plasma with doughnut shape but it slightly enhances evaporation of the powder at the center axis of the plasma torch

Refractory Organic Solute Decomposition in Water using Microwave Plasma

金沢大学理工研究域サステナブルエネルギー研究センタ

Surface Modification of Fluorocarbon Polymer Film by High Density Microwave Plasma

金沢大学理工研究域サステナブルエネルギー研究センタ

Initial Condition Dependene of Dynamis and Evaporation of Polymer Spallation Partiles Flying in Polymer Ablated Arcs

This paper describes the influence of initial conditions for spallation particles flying in polymer ablation arcs on dynamics and evaporation of the polymer spallation particles using the numerical model. Through our previous experiments, we had found micro-sized `spallation particles\u27 ejected from polyamide materials by thermal plasma contact. To obtain the dynamics of spallation particles in polymer ablation arcs, we have developed a numerical model on dynamics of spallation particles flying in the polymer ablated arcs. The influence of pressure inside the polymer ablated arc, the initial particle diameter and the initial velocity of spallation particles were studied as parameters in the present paper. Under the given temperature and gas flow distributions in specified initial conditions, the trajectories of spallation particles flying in the polymer ablated arc were simulated numerically, considering the time variations in the temperature and the diameter of the particles. The results show that the highest flight altitude of the PA6 spallation particle flying in the PA6 ablated arc is affected by the initial particle diameter and velocity remarkably

Chemically non-equilibrium model of decaying N2 arcs in a model circuit breaker

Nitrogen gas has been investigated as one of the candidate substitutes for SF6 in a high-voltage circuit breaker (HVCB) and also in a low-voltage interrupter. In this paper, a chemically non-equilibrium model was established to investigate N2 arc plasmas in the decaying phase during current interruption in a model circuit breaker. Unlike the conventional model assuming local thermodynamic equilibrium, i.e. both chemical equilibrium and thermal equilibrium, in this work a chemically non-equilibrium model was developed for N2 arc plasmas. Thermal non-equilibrium effects were neglected, meaning a one-temperature model was adopted. The developed model took into account 5 species such as N2, N, N2+, N+ and e-, and 22 chemical reactions including electron impact ionizations, heavy particles impact dissociations and their backward reactions. Temperature dependent reaction rates were used for all considered reactions. The species composition in N2 arc plasma was calculated by solving the mass conservation equation of each species considering diffusion, convection and reaction effects. Then the influence of the chemically non-equilibrium composition on the arc behavior was calculated by updating the thermodynamic and transport properties at each iterative step. Finally, for the decaying N2 arc plasma under a free recovery phase, the time evolutions were derived in the profiles of the temperature and the number densities for each species. The results in this work were compared with the calculated results based on the chemical equilibrium assumption. © 2015 IEEE

Spallation occurrence from polyamide materials irradiated by thermal plasma with water absorption

This paper first describes the effect of water absorption in polyamide material irradiated by thermal plasmas on the occurrence of spallation phenomena. The interaction between polyamide materials and arc plasmas occurs particularly in the low voltage circuit breaker and aerospace fields. Spallation phenomena are those in which polymer particles are ejected from polymer bulk materials irradiated by high heat flux. To confirm the effect of water absorption into the polyamide material on spallation phenomena, polyamide specimens with and without water absorption were irradiated by Ar inductively coupled thermal plasma. The results show that the polyamide specimen with water absorption ejected spallation particles, whereas the polyamide specimen without water absorption were only slightly ejected, indicating that water absorption promotes the occurrence of spallation. The cooling effects of the spallation polyamide 66 (PA66) particles ablation were also estimated in hot air to assess the arc quenching ability from the spallation particle inclusion. This estimation showed that 10 and more PA66 particles inclusion might decrease the air temperature by 3000 K effectively, which can be useful to enhance arc quenching in circuit breakers working in air. © 2016 IOP Publishing Ltd.Embargo Period 12 month

Effective Dissolution of Biomass in Ionic Liquids by Irradiation of Non-Thermal Atmospheric Pressure Plasma

Biomass was dissolved in ionic liquids under non-thermal atmospheric pressure plasma irradiation. On plasma irradiation, the amount of dissolved biomass in the ionic liquids increased from 15 to 29mg for bagasse and from 26 to 36mg for Japanese cedar. The high solubility was attributed to the deconstruction of the lignin network by active chemical species generated by the plasma. Selective extraction of cellulose from biomass was observed under plasma irradiation. © CSIRO 2017.This study was also partly supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science. | Japan Society for the Promotion of Science 日本学術振興

Experimental investigation of magnetic arc blow in plasma arc cutting

Oxygen plasma arc cutting is widely employed in various industrial fields. In the case of cutting magnetized plates, the magnetic field is concentrated around the cutting front as cutting progresses, and the electromagnetic force induced by the leakage of magnetic field deflects the plasma jet. The deflected plasma jet leads to poor cutting quality and sometime causes damage to the electrode and nozzle because of double arc abnormal discharge. This phenomenon is called magnetic arc blow, and it is a critical issue when applying plasma cutting on magnetized plates. In this study, magnetic arc blow behavior is investigated, and a method to prevent it is devised. We examined the relationship between operating conditions and the double arc using external magnetic fields on a plasma jet. We found criteria regarding operation conditions that induce arc blow. In addition, we succeeded in suppressing the double arc caused by the leakage external magnetic field by using a magnetic shield cap composed of ferromagnetic material around the nozzle

Characterization of surface dielectric barrier discharge influenced by intermediate frequency for ozone production

The aim of this study is to investigate the effect of the intermediate frequency (1–10 kHz) of the sinusoidal driving voltage on the characteristics of a developed surface dielectric barrier discharge (SDBD)-based reactor having spikes on its discharge electrode. Moreover, its influence on the production of ozone and nitrogen oxide byproducts is evaluated. The results show that SDBD is operated in the filamentary mode at all the frequencies. Nevertheless, the pulses of the discharge current at high frequencies are much denser and have higher amplitudes than those at low frequencies. The analysis of the power consumed in the reactor shows that a small portion of the input power is dissipated in the dielectric material of SDBD source, whereas the major part of the power is consumed in the plasma discharge. The results of the ozone production show that higher frequencies have a slightly adverse effect on the ozone production at relatively high energy density values, where the ozone concentration is slightly decreased when the frequency is increased at the same energy density. The temperature of the discharge channels and gas is not a crucial factor for the decomposition of ozone in this reactor, while the results of the measurements of nitrogen oxides characteristics indicate that the formation of NO and NO2 has a significant adverse effect on the production efficiency of ozone due to their oxidation to another nitrogen oxides and their catalytic effect

Two-dimensional spectroscopic observation of a pulse-modulated induction thermal plasma torch for nanopowder synthesis

The two-dimensional distributions of spectral radiation intensities in the plasma torch were observed for the pulse modulated induction thermal plasmas (PMITP) with continuous or intermittent feedstock feeding for TiO2 nanopowder synthesis. For this observation, an imaging spectrophotometer with a high speed video camera were adopted. The evaporation of feedstock Ti powder, the formation of TiO and TiO transportation were investigated from the observation results of a Ti atomic spectral line and TiO molecule spectra as well as those of Ar and O atomic lines. An interpretation was suggested from the observation results for Ti feedstock evaporation and TiO formation in nanoparticle synthesis using a PMITP with intermittent feedstock feeding