Pulsed Discharge In Water Research Articles

One-dimensional bubble model of pulsed discharge in water

In this paper, a one-dimensional bubble model of pulsed discharge in water is presented. With a total input energy of 0.63J, the simulation results show that when the bubble collapses at the center of the bubble, the plasma pressure oscillates strongly. It oscillates between 800 and 1150atm with an oscillation frequency of about 6.9MHz, while at r=R∕2 (R: bubble radius), the gas velocity oscillates intensely at the same frequency. It oscillates between −235 and 229m∕s when the bubble radius reaches its minimum. But it does not oscillate at r=R because of the inertia of the surrounding water. The bubble collapses and reexpands with almost the same speed as that of the zero-dimensional (0D) model. This further confirms why the shock wave pressure from the 0D mode has a good agreement with the experimental results since the shock wave pressure is only determined by the bubble wall velocity v(R).

Prolonged microbial resistance of water treated by a pulsed electrical discharge

The main characteristics of pulsed discharges in water are studied, such as the discharge current, voltage drop across the discharge gap, temperature of the discharge column, and plasma conductivity, as well as compression waves and ultraviolet radiation, which are induced by the discharge. The physicochemical properties of water treated by pulsed discharges are considered in the context of the effect produced on microorganisms. The mechanism underlying the prolonged microbial resistance of water—its capability of retaining a high activity against virtually all known pathogenic microorganisms and human-opportunistic fungi for many months after the discharge treatment—is explained.

Characteristics of ultraviolet light and radicals formed by pulsed discharge in water

In this investigation, the ultraviolet light characteristics and OH radical properties produced by a pulsed discharge in water were studied. For the plate–rod reactor, it was found that the ultraviolet light energy has a 3.2% total energy injected into the reactor. The ultraviolet light changed with the peak voltage and electrode distance. UV characteristics in tap water and the distilled water are given. The intensity of the OH radicals was the highest for the 40 mm electrode distance reactor. In addition, the properties of hydrogen peroxide and ozone were also studied under arc discharge conditions. It was found that the OH radicals were in the ground state and the excited state when a pulsed arc discharge was used. The ozone was produced by the arc discharge even if the oxygen gas is not bubbled into the reactor. The ozone concentration produces a maximum value with treatment time.

Inactivation of Chlorine-Resistant Microorganisms by a Pulsed Discharge in Water

A pulsed discharge in water was applied to inactivate Cryptosporidium parvum (C. parvum) in filter backwash water from a water purification plant. Effects of water quality and discharge conditions on the degree of inactivation were investigated by batch experiments. A high inactivation ratio (> 99%) was obtained under conditions of low turbidity and high total energy. In 10L backwash water of turbidity 40, 98% of oocysts were inactivated by applying a total energy of 17520 J for 10L (1752 J/L). Experimental results suggest that UV emission is mainly effective for inactivation.

Effects of Ambient Pressure on Bubble Characteristics

The effects of the ambient pressure Pambient onthe bubble characteristics of pulsed discharge in water are investigated.The simulation results show that, when Pambient increasesfrom 1 atm to 100 atm, the bubble radius R decreases from 4 cm to7 mm,and its pulsation period decreases from 8 ms to 0.2 ms. The results also showthat the peak pressure of the first shock wave is independent of Pambient, but the peak pressure of the second shock wave caused by thebubble re-expansion decreases when Pambient increases. On theother hand, the larger the ambient pressure, the larger the peak pressure ofthe plasma in the bubble, while the plasma temperature is independent ofPambient.

Characteristics of Ring-to-Cylinder Type Electrode System on Pulsed Discharge in Water

AbstractThe pulsed streamer corona discharge in water has been investigated for oxidation of organic contaminants in water solution. The reactor with ring-to-cylinder electrode system has been designed and tested in this investigation. It was found that the insulation method of the ring electrode was the most important factor to lower streamer initiation voltage. A large volume of streamer corona discharge was generated around the ring electrode and the streamer corona discharge formations are greatly dependent on the electrode geometry, polarity and the water conductivity. The degradation of phenol was also tested by this electrode system. It was found that the degradation rate of phenol was higher for the positive pulse than that of negative pulse, and the intermediate products were removed when the treatment time increased.

Spark model of pulsed discharge in water

Underwater sparks have long been used in many fields, but up until now there are no widely accepted model for them. In this article we present a more practical model for them, taking into account the nature of the plasma of pulsed discharge in water, where the following corrections are included: (1) correction of the ionization potentials; (2) pressure caused by the effect of charge interaction on the bound state electrons; (3) line spectra; and (4) mass flow caused by evaporation, condensation, and bubble wall ablation. Using this model, the time-varying pressure, temperature, and density can be obtained for given circuit parameters. The simulation results are in good agreement with the experimental measurements. We also give a simulation with capacitance of 1.25 nF, initial voltage of 4×104 V, circuit inherent inductance of 20 nH, and circuit resistance of 15 mΩ; the maxima of the pressure, temperature, and electron density are about 5×104 K, 5×103 atm, and 4×1026 m−3, respectively.

Bubble dynamics, shock waves and sonoluminescence

Sound and light emission by bubbles is studied experimentally. Single bubbles kept in a bubble trap and single lasergenerated bubbles are investigated using ultrafast and highspeed photography in c...

Photolytic properties of a pulsed discharge in water

Results are presented of an experimental investigation of the photolytic properties of a pulsed discharge in water. A model is proposed for this process which satisfactorily describes the dependence of the hydrogen peroxide concentration on the specific discharge energy.

Mechanism of electrode erosion in pulsed discharges in water with a pulse energy of ∼ 1 J

It has been shown that electrode erosion in pulsed discharges in water is governed by a thermal cavitation effect. Blowing gas through the water modifies the cavitation effect, simplifies breakdown, and allows solid electrodes to be used.

Energy of a gas bubble formed in a pulsed discharge in water

Energy of a gas bubble formed in a pulsed discharge in water