PIC/MCC Simulations Of Dielectric Barrier Discharge Towards Plasma Catalysis

Plasma catalysis,which combines the high activity of plasma and the selectivity of catalytic materials,has been successfully applied in material processing and chemical substance synthesis.As a widely used plasma catalysis reactor,dielectric barrier discharge(DBD)receives more and more attention.In this thesis,by using particle-in-cell/Monte Carlo Collision(PIC/MCC)models,we studied the stability of DBD,as well as the effects of catalyst pores,adjustable parameters,and lateral electrodes on DBD plasma catalysis discharge mechanism.The main results are summarized as follows.(1)Using a one-dimensional electrostatic and implicit PIC/MCC model,the effects of the dielectric barrier layer and the applied voltage on the DBD discharge stability were studied.The results showed that:(a)DBD at low voltages was stable,while DBDs at high voltages were unstable.(b)the dielectric barrier layer enhanced the stability of discharge and maintained discharges at high voltage.(2)Using a two-dimensional electrostatic explicit PIC/MCC model,the effects of catalyst pores and related parameters on DBD plasma catalysis discharge characteristics were studied.The results showed that:(a)catalyst pores helped to enhance surface discharge;(b)in catalyst pores,the surface discharge was stronger than volume discharge;(c)the denser the arrangement of catalyst pores,the better the overall effect of the surface discharges in catalyst pores;(d)the larger the size of catalyst pores,the more obvious the characteristic of volume discharge weaker than surface discharge.(3)Based on the fixed shape,number,and size of catalyst pores,the effects of adjustable parameters on the catalysis discharge characteristics of DBD plasma were studied by adopting a two-dimensional electrostatic explicit PIC/MCC model.The results showed that:(a)with increasing the applied voltage,the volume discharges in catalyst pores were getting more and more strong;(b)the narrower the discharge interval,the more intense the discharge in catalyst pore;(c)different gas mixing ratio caused the different proportion of charged particles and active particles generated on the surface of catalyst pores;(d)the higher the O₂content,the weaker the advantage of the surface discharges in catalyst pores.(4)Based on fixed parameters,using a two-dimensional electrostatic explicit PIC/MCC model,the effects of the lateral electrode on the propagation direction of DBD streamers and the DBD plasma catalysis discharge characteristics were studied.The results showed that:(a)the stronger the lateral electrode voltage on one side,the greater the deviation of streamers to the other side;(b)the stronger the lateral electrode voltage on both sides,the narrower the propagation channel of streamers;(c)when both lateral electrode voltages were-15kV,the deposited charge density on the surface of N₂⁺and O₂⁺was the largest.The surface discharge in catalyst pores,the propagation direction of the streamers,and the composition of products are three essential factors that could affect the energy efficiency and catalytic efficiency of plasma catalysis.By using the PIC/MCC model,this thesis studied the influence of relevant parameters on catalysis discharge characteristics of DBD plasma.The results showed that parameters,including the size of catalyst pores,applied voltage,dielectric constant,discharge interval,gas mixing ratio,and side electrode voltage,had essential impacts on these three factors.