电极长度对纳秒脉冲同轴介质阻挡放电特性的影响

同轴介质阻挡放电(DBD)在环境保护和能源领域具有重要的应用价值,而其电极结构是影响其放电特性的关键因素之一。为此采用纳秒脉冲电源驱动同轴双阻挡介质反应器,研究外电极长度对其放电特性的影响。利用电学、光学和温度测量诊断了放电特性,依据等效电气模型分离得到放电各电气参量,并进一步得到放电功率和能量效率,研究了不同电极结构下的放电均匀性、放电功率、能量效率的变化规律,并通过建立热传导模型分析了纳秒脉冲同轴双阻挡介质反应器运行温度及能量损失。结果表明:纳秒脉冲同轴双介质阻挡放电在不同外电极长度下均表现为均匀放电形式,且受外电极长度影响较小;随外电极长度的增大,反应器气隙平均放电功率及能量效率均增大;反应器温度随运行时间增加而增加,运行900 s后反应器温度达到饱和值;电压24 kV、外电极长230 mm时反应器气隙平均放电功率最高可达34.3 W,能量效率为71.3%,此时,反应器运行900 s后,运行温度为80.1℃,内介质层温度为135.3℃;通过热传导模型分析得到同轴DBD反应器能量损失途径为热量损失(热量损耗),随长度的增大,运行温度与内介质层温度升高,反应器热量损耗率降低。

Influence of Electrode Length on Characteristics of Coaxial Dielectric Barrier Discharge Driven by Nanosecond Pulsed Power Supply

Coaxial dielectric barrier discharge(DBD)is very important in environmental protection and energy fields.The electrode structure is one of the key factors to influence the discharge characteristics of the coaxial DBD reactor.We developed a coaxial double dielectric barrier reactor driven by a nanosecond(ns)pulsed power supply,and investigated the influence of outer electrode length on characteristics of coaxial DBD.The electrical,optical,and temperature diagnoses methods were adopted to analyze the discharge characteristics.The electrical parameters of the coaxial DBD were obtained using an equivalent electrical model.The power deposition and energy efficiency with various electrode structures were further calculated.Moreover,the discharge uniformity,discharge power and energy efficiency with various electrode structures were studied,and the operation temperature and heat loss of the coaxial DBD reactor were analyzed by a heat conduction model.The results show that ns pulsed coaxial DBDs with various outer electrode lengths are uniform and the effect of the outer electrode length on the discharge uniformity is negligible.With the increase of the outer electrode length,the energy efficiency and the average discharge power across the air gap increase accordingly.With the increase of operation time,the operation temperature increases first and reaches a saturated value after 900 s operation.At 230 mm outer electrode length and 24 kV applied voltage,the energy efficiency of the coaxial DBD is 71.3%and the average discharge power across the air gap is 34.3 W.The corresponding operation temperature of the coaxial DBD reaches 80.1℃after 900 s operation and the temperature of the inner dielectric barrier is 135.3℃.Analysis with the heat conduction model shows that the energy loss of the reactor presents the heat loss.The operation temperature and the temperature of the inner dielectric barrier increase with the increase of the outer electrode length.The heat loss rate decreases with the outer electrode length.