A numerical study on the effects of catalyst pore diameter and depth on atmospheric air packed-bed dielectric barrier discharge

The regulation mechanism of the catalyst micro-pore structure on the plasma dynamics of Packed-Bed Dielectric Barrier Discharge (PBDBD) is a key scientific issue that has not yet been systematically elucidated in plasma-catalytic systems. In this study, a two-dimensional axisymmetric fluid model of atmospheric air PBDBD is established to systematically investigate the effects of catalyst pellet pore diameter (150–600 µm) and pore depth (0.8–1.2 mm) on streamer discharge characteristics, revealing the physical essence of micro-pore structure-mediated discharge regulation. The results indicate that the edge convergence effect at the pore entrance and the curvature tip effect at the pore bottom induce local electric field distortion. The accumulation of surface charges on the pore wall further reshapes the electric field distribution inside the pore, inducing surface discharge along the wall, forming a non-uniform discharge mode with strong enhancement at the pore bottom and weaker but non-negligible surface discharge along the sidewalls. Small pore diameters significantly enhance the electric field intensification inside the pores, increasing electron density, electron temperature, and the production rates of reactive species such as O atoms and N2(C3Π). Furthermore, increasing pore depth extends the discharge penetration depth, enlarges the plasma-catalyst interaction volume, and enhances thermal effects within the pores. This study clarifies the distinct mechanisms by which the micro-pore structure regulates the electric field strength and electron heating efficiency, and pore depth determines the discharge penetration depth, providing a quantitative theoretical basis for the structural design of catalyst pellets in high-performance PBDBD reactors.