Ozone generation by negative direct current corona discharges in dry air fed coaxial wire-cylinder reactors

Abstract

An analytical study was made in this paper for calculating the ozone generation by negative dc corona discharges. The corona discharges were formed in a coaxial wire-cylinder reactor. The reactor was fed by dry air flowing with constant rates at atmospheric pressure and room temperature, and stressed by a negative dc voltage. The current-voltage characteristics of the negative dc corona discharges formed inside the reactor were measured in parallel with concentration of the generated ozone under different operating conditions. An empirical equation was derived from the experimental results for calculating the ozone concentration generated inside the reactor. The results, that have been recalculated by using the derived equation, have agreed with the experimental results over the whole range of the investigated parameters, except in the saturation range for the ozone concentration. Therefore, the derived equation represents a suitable criterion for expecting the ozone concentration generated by negative dc corona discharges in dry air fed coaxial wire-cylinder reactors under any operating conditions in range of the investigated parameters.

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

“…Because the physicochemical reaction processes take place inside the ionization region, the ozone molecules are generated inside this region only. [23][24][25] With the positive dc corona discharges in the atmospheric air at normal temperature and pressure, the volume of the non-thermal plasma V plasma that forms around the thin wires is determined by using the equation 25,32,33 V plasma = π (0.562255r…”

“…With the open systems of single wire-duct reactors, the residence time t r of the flowing air inside the reactor is determined by using the relation 24,25 …”

“…The air flowing from outlet of the reactor has been passed through a quartz cell installed in UV-VIS spectrophotometer (SHIMADZU-1200), where the absorbance of the ozone was recorded at a wavelength of 253.7 nm. [22][23][24][25] The ozone concentration [O3] in the flowing air was calculated from the absorbance measurements by using Beer-Lambert law. 6 The average room temperature during the experimental measurements was about 288 K. Every point of the experimental results represents the mean of three independent readings under the same operating conditions.…”

“…This behavior has been explained in previous studies. 6,25 The different symbols in Figure 3 represent experimental results for the current-voltage characteristics curves of the corona discharges inside the reactor, when the radius of the discharge wire is changed in the range of 2. In order to check the validity of Equation (10) versus the experimental results, Equation (10) is written on the form…”

“…Subsequently, two of the authors of this paper have studied previously the ozone generation with the corona discharges under different operating conditions. [22][23][24][25] From another point of view, single wire-duct arrangement is being used over a wide range as discharge electrodes in the electrostatic precipitators. [26][27][28][29] Therefore, the corona discharges were studied in this paper inside dry air fed single wire-duct reactor under positive dc voltage.…”