| Diesel particulate filter(DPF)is considered to be one of the most effective ways to reduce particulate matter(PM).However,there are still some obstacles in DPF regeneration.Recently,the application of non-thermal plasma(NTP)technology on exhaust purification has been widely studied because NTP is easy to react with PM and NOx in exhaust gas for its strong oxidation ability.In this paper,experiments about DPF regeneration by NTP under different gas atmospheres were carried out.Optimal performance test for NTP reactor was firstly conducted and then DPF regeneration experiments by NTP technology under different conditions were implemented based on the optimization results,including NTP under O2 atmosphere,O2+N2atmosphere and NTP assisted by simulated exhaust gas condition.The detailed studies and results are as follows:(1)Comparative investigation on oxygen and air dielectric barrier discharge in a self-designed NTP reactor was implemented.The influence of working parameters on discharge performance and O3 generation was analyzed by evaluating different indexes including the discharge power,charge flux,O3 concentration,O3 output and O3 output efficiency.The results showed that for a designed NTP reactor,larger discharge electrode area was recommended in consideration of O3 concentration and there was an optimum peak-peak voltage and an optimum volume flow rate respectively.(2)In order to further analyze the generation mechanism of active substance,O2+N2discharge was conducted by O3 and NOx measurement analysis and optimal emission spectra technology,in which the influence of electric parameters and gas properties on the generation of active substance and spectral intensity was studied.The results indicated that O3 and NO2 were the main products and they showed a similar regularity under different working conditions.At the same time,the second positive bands of N2(C3Πu→B3Πg)could be detected.(3)Based on the optimal NTP injection system,experiments of fouled DPF regeneration by NTP under different gas atmospheres were carried out.Under O2 atmosphere,analysis on removal mass,DPF pressure drop and regeneration efficiency were carried out.Under O2+N2atmosphere,temperature distribution in DPF was analyzed and the removal mass was calculated and was compared with that under O2 atmosphere.The results showed that under O2 atmosphere,large O2 flow rate(10 L/min)was more beneficial to DPF regeneration and medium flow rate(5L/min)was more economical.Under O2+N2 atmosphere,temperature at each point increased at first and then decreased.On the radial direction,temperature showed a decline from axis to the wall of DPF and on the axial direction,the maximum temperature at each point varied andexisted in different orders.Compared with the condition under O2 atmosphere,the total deposit removal mass was larger than that under O2 atmosphere with O2 flow rate of 7 L/min,which indicated it had a good regeneration effect under O2+N2 atmosphere.(4)In order to utilize the energy from exhaust gas and simplify the system,DPF regeneration by NTP assisted by simulated exhaust gas heat was conducted.Temperature distribution in DPF and COx concentration were analyzed.The results showed that after DPF regeneration,the total deposit removal mass reached 11.3 g and pressure drop decreased from235 Pa to 57 Pa.This illustrated that this method was effective and offered a reference to the application of DPF regeneration by NTP assisted by real exhuast gas heat. |
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