Yimin Zhu

Experimental study of removing benzene from indoor air by needle-matrix to plate streamer discharge

The degradation of benzene by needle-matrix to plate streamer discharge was investigated at normal temperature and pressure in indoor air. The effects of benzene initial concentration, air speed, discharge power and relative humidity (RH) on benzene removal rate were systematically studied. Meanwhile, the benzene removal efficiencies by adding MnO2/SiO2-active carbon catalyst to the system were also studied. The results showed that the benzene removal rate increased with the rise of the air speed and discharge power, decreased with the rise of the benzene initial concentration, and firstly increased and then decreased with the rise of the of RH. Under the same experimental conditions, adding MnO2 catalyst to the system did not significantly improve the removal efficiency of benzene.

Indoor Formaldehyde Oxidation by Needle Matrix to Plate Corona Discharge

Abstract This work studies the removal efficiency of indoor formaldehyde (HCHO) by a needle matrix to plate discharge reactor in a 90 m3 closed room. The work concludes that HCHO can be reduced rapidly and efficiently, and the removal rate is closely related with HCHO concentration and disposal time. Also, it outlines the principles of HCHO chain reaction, and identifies carbon dioxide as the final product. Radicals and UV generated by non-thermal plasma are suggested to enhance the HCHO self-oxidation.

Removal of NO2 and O3 generated from corona discharge in indoor air cleaning with MnO2 catalyst

The production rules and removal efficiency of harmful byproducts such as NO2 and O3 generated from DC corona discharge in indoor air cleaning were investigated. The production behaviours of NO2 and O3 and the relationship between the amount of catalyst (MnO2) and the removal rate of harmful byproducts were experimentally studied. Further, indoor application tests were carried out in a closed room with 90 m3. The results showed that the concentrations of NO2 and O3 produced by corona discharge linearly increased with discharge time. The NO2 yield is larger than O3 by almost one order of magnitude under the same discharge power. To satisfy the demand of Standard of Indoor Air Quality (GB/T18883-2002), the power consumption of unit volume should be less than 1 W m−3 and the catalyst MnO2 consumptions in positive-negative corona discharge were 200 cm3 W−1 and 100 cm3 W−1, respectively.

Study on Bipolar Corona Discharge in Emitting Needle Electrode Configuration

Abstract This paper systematically studied the current-voltage characteristics and the spectrum characteristics of bipolar corona discharge in multi-needle electrode configuration, and determined the optimized space between electrodes. The experimental results show that the discharge current I decreases with an increase in the needle radius a or the space between electrodes d, and increases with an increase in the space between needles s. Due to the symmetry of the discharge electrode configuration, the polarity of the HV electrode has no obvious influence on the discharge. Using the method of OES for measuring N2 emission spectrum, the spacial distribution of energetic electrons in multi-needle bipolar corona discharge has been investigated. According to the distribution of N2 second positive band’s intensity ISPB, the outline of ionization region was drawn accurately. The relationship between ISPB and discharge current I has been obtained through the sum of ISPB. The sum of ISPB is nearly linear to I, so the distribution of ISPB is corresponding to the density distribution of energetic electrons. The effects of space between electrodes on discharge energy density have been studied. Generally, discharge energy density reduces with increase in space between needles at the same electrode s, but it has small change when s is in the range from 12 mm to 22 mm. At the same time, discharge energy density reduces with increase in space between electrodes d. The allowable discharge energy density is up to its maximum when d is about 32 mm.

Study on Trapping Inhalable Particles by Non-Thermal Plasma

Publisher Summary This chapter presents the experiments that study the dust collection of a novel nonthermal plasma (NTP) mode on inhalable particulates (IPs) and compares the collection results with other commercial air cleaners. The results reveal that DC streamer discharge has the same discharge energy with pulsed corona discharge and thus, makes particulates overload charging; applied DC high voltage (HV) produces even and stable electric field and increases the collection rate of charged particulates. In fact, the collection rate of IPs from 0.3μm to 10μm has reached above 80% within 20min, and the Clean Air Delivery Rate (CADR) is up to the magnitude of 100m 3 /h. The air cleaner adopting this technology has been proved to reduce suspending particulates concentration to below 0.15 mg/L in 30min running in an artificial smoking room; under light particulate pollution, the particulates concentration can be reduced to the magnitude of 10 -2 mg/m 3 . The chapter verifies that the NTP air cleaner performs a high efficiency on IPs collection and explains the theoretical reasons of the high collection rate on IPs.