Spectral Study on Combustion Supporting Effect of Plasma Jet for Methane Combustion in Air
ZHANG Xiao-lin1, LI Shou-zhe2*, JI Chun-jun1*, NIU Yu-long2, BAI Yang2, LIAO Hong-da2
1. School of Energy and Power Engineering, Dalian University of Technology，Dalian 116024, China
2. Key Laboratory of Materials Modification by Laser, Ion and Electron Beams Ministry of Education, School of Physics, Dalian University of Technology，Dalian 116024, China
Abstract：Atmospheric pressure argon plasma jet (APAPJ) is a non-equilibrium plasma producing a large number of electrons, positive ions, excited particles and active groups, which can significantly reduce the activation energy in reactions, and the dynamic effect caused by APAPJ also imposes influence on the transportation process, thereby they both play a very important role in the process of plasma-assisted combustion. In this experiment, By OES, the intermediate radicals (OH, CH and C2) generated in the non-premixed and premixed combustions are identified. The variation of emission intensity of those radicals is measured with respect to the fuel equivalent ratio and discharge voltage, respectively. It is found that the application of the APPJ causes the overall length of flame to become short and the flame surface appears wrinkled, with the blue area of the flame root continuously enlarged, which accounts for about 1/2 of the total flame area at discharge voltage of 22 kV, indicating that the combustion becomes complete and intense. When the voltage reaches 16 kV, the spectral intensity of the free radical OH(A-X), CH(A-X) and C2(d) becomes remarkable, but when the voltage is 22 kV, the spectral intensity decreases, which is because the plasma enhances the gas flow rate in the tube, causing the combustion region to move away from the nozzle so that the less intensity is collected by fiber during the spectrum acquisition process. In addition, the combustion process of premixed gas assisted by plasma jet under different fuel equivalence radio is studied. In the case of Φ=2, it is found that the spectral intensity of OH(A-X) increases with discharge voltage, while those of CH(A-X) and C2(d) decline when the discharge voltage is large enough that the APPJ is merged into flame near the nozzle. It is found that APAPJ plays an importance role in CH4 combustion in open air due to the active radicals generated in APAPJ and the mixing effect caused by ion wind by APAPJ.
张小林，李寿哲，冀春俊，牛裕龙，白 阳, 廖宏达. 甲烷在空气燃烧的等离子体射流助燃效应的光谱研究[J]. 光谱学与光谱分析, 2021, 41(10): 3251-3255.
ZHANG Xiao-lin, LI Shou-zhe, JI Chun-jun, NIU Yu-long, BAI Yang, LIAO Hong-da. Spectral Study on Combustion Supporting Effect of Plasma Jet for Methane Combustion in Air. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(10): 3251-3255.
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