Experimental Study On The Active Regeneration Process Of Diesel Particulate Filters

With the increasingly stringent emission regulations,the Euro VI heavy-duty diesel engines require to use the diesel oxidation catalysts(DOC)and diesel particulate filters(DPF)and urea selective catalytic reduction(SCR)technologies.The thesis studied on DPF filter characteristics,pressure drop,regeneration characteristics and soot rapid loading based on the DOC and DPF integrated system.Also the DPF active regeneration process under stationary and transient operating conditions was investigated.Through literature research and bench test methods,this thesis compares the soot fast loading methods used by domestic and overseas research institutions and put forward a highly efficient method.By changing the engine relative parameters to influence diesel spray and oxidation in the cylinder,a large number of soot particulate could be produced.Particles went out of the engine cylinder as exhaust and was trapped by DPF filter to realizing soot rapid loading.The experiment proved that the soot loads rate could reach 2g/L/h under steady state conditions.At the same time,a new concept of flow resistance was put forward to building one-to-one relationship for predicting soot loading.The method greatly reduces the calibration work and improve the accuracy of the soot prediction model.An experiment on the active regeneration process of the catalyzed diesel particulate filter(CDPF)was conducted through diesel engine bench test under steady state conditions.This study illustrated different regeneration influence factors,such as air velocity/regeneration temperature/soot loading,effect on peak temperature and temperature gradient inside CDPF and emission during active regeneration,and provided theoretical basis for CDPF safe and reliable regeneration.Research proved: during active regeneration,the air velocity becoming smaller,the target temperature being higher and soot loading becoming larger would result in the higher maximum temperature and temperature gradient.Besides,temperature becames higher from inlet side edge to outlet side center and temperature gradient was higher from substrate center to edge.On the basis of DPF active regeneration control strategy,the article through bench test,studied on DPF active regeneration process under transient state conditions and analyzed temperature field,concentration field and emission during active regeneration.Experiment proved that in the DTI test the maximum temperature appeared a linear growth with the increase of soot loading.In practical application,the last 0.5g/L soot will arrange for later regeneration process.In the front part of WHTC,duo to the low exhaust temperature,there was no fuel injection.The golden period for active regeneration is latter part of cycle,regeneration efficiency about 82%.