On the characteristics of the corona discharge in a wire-duct reactor

Abstract

The aim of this paper is to study the effects of the magnitude and direction of air flow rate on the characteristics of the corona discharge generated in a wire-duct reactor. Two air flow directions were attempted: one parallel to, and the other normal to the discharge wire in the reactor. The corona current-voltage characteristics correlative with ozone generation were studied under different modes of applied voltage. The results have shown that dc and ac corona current-voltage characteristics depend significantly on the magnitude of the air flow rate in the reactor, whatever the direction of the air flow. The ozone concentration generated by either dc, ac or pulsed coronas with parallel flow is higher than that generated with normal flow with the same discharge conditions. The ozone concentration generated by pulsed coronas is higher than that generated by either dc or ac coronas with the same discharge conditions irrespective of the polarity of the pulsed corona.

Characteristics of an electrostatic precipitator for submicron particles using non-metallic electrodes and collection plates

“…The average ozone concentration was proportional to the power consumption of the ionizers. This finding was in quite good agreement with the results of previous studies (Yehia, Abdel-Salam, & Mizuno, 2000;Yehia, Mizuno, & Takashima, 2000). In particular, when the maximum 10 kV was applied to the ionizers in 16 channels, the ozone concentration was less than 2 ppb, which was significantly lower than the 60-80 ppb limit set out in the EPA and WHO regulations.…”

“…The maximum result was 40 000 ppb L/min for a power consumption of approximately 5 W (i.e. 2 ppb  20 000 L/min), which is much lower than the value of 500 000 ppb L/min previously reported for the same power consumption (Yehia, Abdel-Salam, & Mizuno, 2000;Yehia, Mizuno, & Takashima, 2000). This indicates that the use of a carbon brush precharger that does not produce ozone as a byproduct could be a more promising environmentally friendly method of charging than that used in existing corona dischargers, particularly those used in industrial ESPs, as well those used indoors.…”

“…4;Wang, Pereira, & Hung, 2004). Furthermore, the ozone that is normally generated as a byproduct of corona discharge in an ESP can cause serious damage to respiratory organs, and causes deterioration in many materials, and thus the daily 8-hour maximum ozone concentration is regulated to less than 60-80 ppb by the WHO, EPA, and EC, among others Bell, Peng, & Dominici, 2006;Liu, Guo, Li, & Sheng, 2000;Yehia, Abdel-Salam, & Mizuno, 2000;Yehia, Mizuno, & Takashima, 2000).…”

From electrostatic precipitation to nanoparticle generation

“…As reported in a previous study (Zhuang et al, 2000), such reudction was due to some of the ions not having enough time to reach the grounded plate as velocity increased. In addition, the number of localized discharge spots on the discharge wire could be affected by the air flow, leading to changes in the corona current (Yehia et al, 2000).…”

Positive direct current corona discharges in single wire-duct electrostatic precipitators

“…With the dc and ac corona discharges, the volume of the non-thermal plasma is always very much smaller than the total internal volume that is confined between the electrodes, while it is relatively large with the pulsed corona discharges. [6][7][8] Therefore, the non-thermal plasmas formed by using the dc and ac corona discharges are suitable only for the industrial applications that need to small concentrations of positive and negative ions for charging particles. Typical examples are indoor air cleaning by using electrostatic precipitators, spray coating, electro-photography machines, drying separation systems, radiation detectors and surface treatment of polymers.…”