Yixi Cai

Experimental Study of Non-thermal Plasma Injection System Converting NOx in Simulated Diesel Emissions

In order to study the removal effect of non-thermal plasma (NTP) after-treatment system on diesel engine harmful emissions, a dielectric barrier discharge (DBD) plasma reactor is designed, and the NOx removal effect is studied under the conditions of different NTP injected gas flow rates and simulated diesel engine exhaust gas temperatures using a NTP injection system which is located outside the diesel engine exhaust pipe. The results show that the injection system can play an effective role in dealing with the harmful emissions of diesel engines; in NTP environment, conversion of NO to NO2 is the main reaction; with increasing the peak-to-peak applied voltage, NO conversion rate first rises and then falls; correspondingly, when the flow rates of simulated diesel engine exhaust gas are different, the flow rates of NTP injected gas are various, there is an optimum value which lead to the maximum conversion rate of NO; high temperature goes against the NO conversion.

Study on Optimal Matching of DBD Load and Inverter Power of Series Resonant Type

Inverter power of series resonant type are commonly used in dielectric barrier discharge, By means of theoretical analysis and experiments based on Q-V Lissajous figures, study on optimal matching of DBD load and inverter power are carried out to improve the working performance and efficiency of DBD device. The result indicate that: as the DBD equipments discharge power enhanced, the dielectric equivalent capacitance would increase, and the air gap equivalent capacitance would diminish. There are two different resonance frequency of DBD devices powered by medium frequency inverter power of series resonant type, when the DBD device works at the resonance frequency of the pre-discharging circuit, the discharge starts easily, and works near the resonance frequency of the after-discharging circuit would be benefit to the systems discharge power, and because of the dynamic load characteristics of DBD device, the resonance frequency of the after-discharging circuit will decrease with the increase of input voltage.

Conversion of NO in NO/O2/N2 System by Dielectric Barrier Discharge Plasma

An experimental study on the conversion of NO in the NO/O 2 /N 2 system has been carried out using Dielectric Barrier Discharge (DBD) Plasma at atmospheric pressure. The emphases are on energy consumption and the efficiency for NO conversion in the system. By measuring the concentration of NO and NO 2 as a function of specific energy density (SED), it is possible to determine the energy consumption for NO conversion and the effect of O 2 concentration and NO initial concentration on the efficiency for NO. It is conformed in this study that NO to NO 2 is the main reaction in the NO/O 2 /N 2 system; the efficiency for NO conversion is reduced with the increase of O 2 concentration, the yield of NO 2 increases with the increase of O 2 concentration; initial concentration of NO is smaller, the efficiency for NO conversion is higher. When initial concentration of NO is 260times10 -6 in the system, 75-95% NO can be conversed in the SED range of 440-700 J/L.

Experimental Study on NO Conversion in N2/NO Mixtures by Non-Thermal Plasma Based on Spectroscopy Diagnosis

The experimental system of NO conversion in N2/NO mixtures by non-thermal plasma (NTP) based on spectroscopy diagnosis was established. The NO chemical mechanism was analyzed by combining with emission spectroscopy diagnosis of dielectric barrier discharge (DBD). The impact of NTP system operating parameters and N2 volume flow rate on NO conversion rate was also studied. The ratio between N2 emission spectral intensity and NO emission spectral intensity and the spectral intensity of N2 second positive bands increase as applied voltage rises, which indicates increasing concentration of high-energy electrons in the discharge gap. As a result, more N2 molecules are dissociated into N atoms which promote the reduction of NO. With the increasing of N2 volume flow rate, the conversion rate of NO reduces and the concentration of NO2 increases.

Study on Harmful Emissions of Diesel Engine with Non-Thermal Plasma Assisted Catalyst Technology

An active catalyst of Ag/γ-Al2O3 was prepared by impregnation method. The main components of the catalyst were characterized by X-ray diffraction (XRD). A non-thermal plasma (NTP) reactor was designed based upon dielectric barrier discharge and the non-thermal plasma assisted catalyst (NPAC) system was established. The bench test was carried out and the reduction of diesel engine harmful emissions with NPAC had been investigated. Results showed that the particulate matter was reduced effectively and the maximum of soot removal efficiency was around 62%. The NOx emission was decreased remarkably by NPAC system.