Spectral Characteristics Of Methane Strong Ionization Discharge In Atmospheric Pressure

The non-equilibrium plasma technology can generate high-energy electrons to break the methane chemical bonds to replace thermal energy in traditional industries.Therefore,the use of plasma technology for methane reforming is the current research tendency.The methane conversion rate,hydrogen production rate,and ammonia production rate of methane strong ionization discharge in atmospheric pressure has been studied before.However,there is no diagnosis for spectral characteristics and discharge parameters such as electron density and equivalent field strength.Based on the establishment of an atmospheric methane strong ionization discharge device,this paper focuses on:the diagnosis of methane discharge parameters such as electron density and equivalent field strength during discharge,as well as the methane discharge spectral characteristics.Following the research contents will be carried out:(1)The atmospheric methane strong ionization discharge system has been established to verify the synergetic discharge mode of micro-glow and micro-streamer in methane by the current and voltage waveforms.The discharge power has been calculated by Lissajious graphics,and then the energy utilization efficiency reaches a maximum of 39.65%at the frequency of 8 kHz when the voltage and flow conditions are same,and the frequency range is 6-8 kHz.The one-dimensional numerical model of the strong ionization discharge of methane has been established,by using the collision cross-section data in the LXcat database to calculate the reaction coefficient.The drift-diffusion equation has been used by the Comsol software.The maximum electron density is 9.44×1015 cm-3,and the maximum field strength is 321.2 Td.The Hydrogen selectivity has been measured by gas chromatography.The maximum hydrogen selectivity was 40.39%when the methane flow rate was 400 mL/min,the unit injection energy was 52.5 kJ/L,the input power was 350 W,and the discharge frequency was 8 kHz.(2)The spectrum of atmospheric methane strong ionization discharge has been collected by ICCD combined spectrometer and synchronous trigger.It is determined that the best collection point is the center of the discharge area by analyzing the spatial distribution of methane discharge spectrum.It is known that the microfluidic column discharge of the positive half-cycle was mainly ionization reaction,and the micro-glow discharge of the negative half-cycle reduced the carbon deposition by comparing the types of particles in the methane discharge time-resolved spectrum.The electron energy of atmospheric methane strong ionization discharge system was 2.17 eV calculated by using the emission spectrum with argon added.Aiming at the spectral characteristics of atmospheric methane strong ionization discharge,this study established an atmospheric methane strong ionization discharge system.It diagnoses atmospheric methane strong ionization discharge from two angles of methane discharge parameters and spectral characteristics,and clarifies the key reaction processes and the spectral characteristics which provides a foundation for further research on reforming methane with atmospheric methane strong ionization discharge.