Experimental Study On The Particle Emission Performance During The DPF Regeneration Process

The wall-flow diesel particulate filter(DPF)is one of the most effective devices to reduce particulate matter(PM)of diesel engine,However,after using for a period of time,it will cause the exhaust gas to be pressurized,and the fuel consumption will increase and the power will decrease.Therefore,it is necessary to periodically oxidize and regenerate,and the PN value of the DPF outlet during regeneration is increased by 2-3 orders of magnitude compared with the non-regeneration time.Controlling the emission of particulate matter from the DPF outlet during regeneration has important research significance and application value for controlling diesel engine exhaust pollution.In this paper,the external heating source regeneration performance test bench explores the influence of flow parameters,carbon black deposition characteristics,particle characteristics and partial deposition on DPF regeneration particle emissions and analyzes the data in detail.Firstly,the influence of inflow parameters on the emission characteristics of DPF regenerated particles was studied.By changing the parameters of carbon black loading,regeneration temperature,inflow flow rate and so on,and analyzing the DPF export particle emissions,the results show that: when the carbon black loading and inflow flow rate are constant,the total mass concentration of DPF outlet particles increases with the increase of regeneration temperature;at the heating stage,the export particles are mainly in nuclear mode,and at the regeneration stage,there are obvious temperature peaks in the DPF carrier and the outlet particles.In addition,the regeneration performance of DPF is affected by both inflow flow rate and loading capacity.When the loading capacity of carbon black is 2.5g/L,the total mass concentration of particulate matter increases gradually with the increase of inflow flow rate,and the regeneration efficiency keeps unchanged at first and then increases rapidly.When the loading amount of carbon black is 5g/L,the regeneration efficiency increases first,then decreases gradually,and then remains stable.The total mass concentration of particulate matter at the outlet increases first and then decreases.Secondly,the influence of carbon black distribution and particle characteristics on the emission characteristics of DPF regenerated particles was explored.By adding a transition section at the inlet end of the DPF to achieve different deposition profiles of carbon black and adding parameters such as simulated SOF,the DPF export particle emissions are analyzed.The results show that after the deposition of 50 cm transition zone,the regeneration efficiency and total mass concentration also increase with the increase of regeneration temperature,and regenerate below 575℃.The export particles in the heating and regeneration stages are mainly nuclear mode;when regenerated at 575 ℃,In the warming phase,the particulate matter is dominated by the nuclear mode,and the regeneration phase is dominatedby the aggregated state.SOF can promote DPF regeneration.The higher the mass fraction,the higher the DPF regeneration efficiency and total mass concentration,and the export particulate matter tends to the nuclear mode during regeneration.Finally,the influence of the zone regeneration on the particulate matter of the DPF outlet was explored.The results show:When regenerated in single zone,the second zone deposits have higher regeneration temperature and temperature gradient.The closer the deposition area is to the axis,the higher the regeneration efficiency is,the higher PM emissions are in the second and fourth zones,and the main particulate matter is nuclear membrane.The regeneration efficiency is higher when two zones are involved,and lower when four zones are involved.The greater the distance between sedimentary zones and the farther from the axis,the lower the regeneration efficiency.Particulate matter in the two-zone regeneration process is mainly nuclear membrane.When regenerating in multi-zone,the regeneration efficiency of multi-zone near the axis is also higher,and the total mass concentration of particulate matter at the outlet is higher,mainly aggregated particulate matter.Through the above research,it is found that the particle emission during DPF regeneration is affected by the flow rate,regeneration temperature and the characteristics of carbon black deposition.When DPF is regenerated vigorously,temperature peaks are prone to occur,and the number and concentration of particulate matter at the outlet increase sharply.Nuclear mode particulate matter is the main type of particulate matter,which continues to regenerate.The temperature decreases and the particle size increases.