微秒和纳秒脉冲激励下甲烷DBD电学特性研究

Electric Characteristics Research of Methane Discharge Based on DBD Reactor Under Microsecond and Nanosecond Pulse Power Sources

利用等离子体技术可以裂解甲烷,产生C2烃和氢气等具有更高价值的物质。对等离子体放电参数优化以提高甲烷等离子体转化效率具有重要意义。文中基于同轴DBD反应装置,在自主研制的微秒和纳秒脉冲电源的激励下,改变电源参数和气体流速,研究了甲烷裂解过程中不同参数下初始击穿电压的变化规律、放电图像、Lissajous图形以及单脉冲内的能量和功率,为甲烷转化提供参考。实验结果表明,两台电源作用下气体初始击穿电压均随脉冲重复频率的增加而下降,但纳秒源作用时该趋势更明显;放电强度均随脉冲重复频率增加而加强,相同参数下,微秒源作用时放电更强;施加电压一定时,不同脉冲重复频率以及不同气体流速下Lissajous图形形状几乎一致,微秒源作用时的图形更接近典型的平行四边形;气体流速和脉冲重复频率相同时,两台电源单脉冲内放电能量与所加电压几乎成直线关系变化,气体流速和施加电压相同时,单脉冲内放电能量几乎不受脉冲重复频率的影响,但是纳秒源可以得到更高的瞬时功率。实验表明,脉冲电源可以作用于DBD反应器用于转化甲烷,纳秒源作用时系统的效率比微秒源更高。

More valuable C2 hydrocarbon and hydrogen can be produced from cracking methane by plasma tech- nology. It is very important to optimize the plasma discharge parameters to increase methane conversion efficiency. In this paper, methane cracking by coaxial DBD reactor driven by homemade pulse power supply（microsecond pulse and nanosecond pulse） was characterized. The influence of power parameters and gas flow rate on breakdown voltage, discharge images, Lissajous figures and pulse energy and power were well studied, which provides solid experimental references for methane conversion. The results showed that, the initial breakdown voltage decreased with the pulse repetition rate increase, but this relationship was more evident under nanosecond pulse power. Dis- charge intensity increased with the pulse repetition rate increase and the microsecond pulse power could bring more intensity of discharge. Under the same applied voltage, the repetition frequency and gas flow rate had no in- fluence on the Lissajous figures and the figures under microsecond pulse power was more close to typical parallel- ogram. The discharge energy was correlated with applied voltage when under the same gas flow rates and pulse rep- etition frequencies. The discharge energy in the single discharge was not dependent on the repetition frequency when kept the same gas flow rate and applied voltage. Besides, higher instantaneous energy was obtained by nanosecond pulse power supply compared to microsecond pulse power supply. The experiments showed that pulse power could be used to crack methane in the DBD reactors and it can get higher system efficiency under the nanosecond pulse power.