Experimental and numerical investigation of surface streamers in a nanosecond pulsed packed bed reactor
Experimental and numerical investigation of surface streamers in a nanosecond pulsed packed bed reactor
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DOI：
10.1088/1361-6595/acdbe7
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发表时间：
2023-06
影响因子：
3.8
通讯作者：
Mengbo Li;She Chen;Yifei Zhu;Yunjie Li;Feng Wang;Yingzhe Cui;C. Zhuang
中科院分区：
文献类型：
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作者：
Mengbo Li;She Chen;Yifei Zhu;Yunjie Li;Feng Wang;Yingzhe Cui;C. Zhuang
填充床反应器（PBR）是等离子体催化中最常用的结构，其等离子体特性已得到广泛研究。PBR中的填充催化剂使得进行电场的原位测量具有挑战性，并且已经获得的实验数据有限。通过模拟和实验研究了简化PBR中表面流注的传播和电场分布。实验中的简化PBR由在放电间隙中填充有Al 2 O3柱（λ r = 9）的叶片-平板电极结构组成。采用ICCD摄像机和电场诱导二次谐波产生（EFISH）诊断方法，建立二维流体模型进行模拟。根据ICCD图像和模拟结果，识别出PBR中的4种放电类型，包括接触区域的极性放电、沿着介质柱的表面流光放电、沿着介质柱的表面放电扩展和沿着介质板的表面电离波。在模型中发现了具有相反传播方向的表面流光，即在脉冲上升时间期间的正向流光和在脉冲下降时间期间的反向流光。值得注意的是，反向拖缆与正向拖缆相比表现出明显更低的速度。实验测量和模拟进行了调查的时空电场附近的表面的填充材料。Eexp和Esim的结果均显示极性相反的峰，且具有相似的趋势。在模拟中，与反向流光头相比，前向流光头显示出更高的电场。此外，在休息脉冲时间期间，表面电场在接触区域比在其他区域更强。这项工作的结果提供了有价值的见解放电机制和电场的催化材料表面内的PBR。
Packed bed reactor (PBR) is the commonly used configuration in plasma catalysis, and its plasma characteristics have been extensively investigated. The filled catalysts in PBR make it challenging to carry out in-situ measurements of electric fields, and limited experimental data have been obtained. We investigated the surface streamer propagation and electric field distribution in a simplified PBR through simulations and experiments. The simplified PBR in the experiments is comprised of a blade-plate electrode structure filled with an Al2O3 column (ϵr = 9) in the discharge gap. An ICCD camera and an electric field diagnosis method called EFISH (electric field induced second harmonic generation) were employed, and a two-dimensional fluid model was established for the simulation. Four discharge types in the PBR were identified based on ICCD images and simulation results, including polar discharge at the contact areas, surface streamer along the dielectric column, expansion of surface discharge along the dielectric column, and surface ionization waves along the dielectric plate. Surface streamers with opposite propagation directions were found in the model, namely the forward streamer during the pulse rising time and the reverse streamer during the pulse falling time. Notably, the reverse streamer exhibits a significantly lower velocity compared to the forward streamer. Both experimental measurements and simulation were conducted to investigate the spatiotemporal electric field near the surface of the packing material. The results of both E exp and E sim showed peaks with opposite polarities, and exhibited similar trends. In the simulation, the forward streamer head showed a higher electric field compared to the reverse streamer head. Moreover, during the rest pulse time, the surface electric field was more intense at the contact areas than in other regions. The findings of this work provide valuable insights into the discharge mechanism and electric field on the catalytic material surface within the PBR.