Effect of Pellet-Diameter on Discharge Characteristics and Performance of a Packed Bed Reactor
M. Chen1, 2, K. Takashima1, and A. Mizuno1
1Department of Environmental and Life Sciences, Toyohashi University of Technology, Japan
2On leave from Anhui University of Science and Technology, China
Abstract- Dielectric barrier discharge (DBD) combined with catalyst is an effective way to remove NOx from diesel exhaust gas. To achieve this combination, a packed bed reactor has been tested, and has been proved to improve NOx removal rate and energy efficiency. Effect of the catalyst size on the discharge power and NOx removal rate was investigated. The results show that the catalyst size does not affect the total input power. With increasing of the catalyst size, the discharge power and the NOx removal rate shows maximum and then decrease. There is the optimal size for the packed bed reactor. The size affects the diffusion inside and outside of the catalyst, contact surface area of the catalyst with gas, and electrical characteristics such as the capacitance and discharge power of the reactor. When the catalyst size is bigger than the optimum value, the diffusion resistance inside and outside of the packed catalyst becomes large and the total capacitance becomes small, resulting in the decrease in the NOx removal rate and the discharge power. When the catalyst is smaller than the optimum value, equivalent capacitance of the pellet layer decreases due to increasing in the contacting points between the pellets, resulting in decrease in the discharge power. The theoretical calculation and the experimental result have the same trend. The investigation can provide the theoretical basis for selecting suitable size of catalyst in the packed bed reactor.
Keywords-Non-thermal plasma, dielectric barrier discharge, catalyst size, discharge power, NO removal rate