Computational Investigation Of Soot Load And Regeneration Characteristics In Diesel Particulate Filter

AVL-Fire software was used to establish a three-dimensional calculation model of the diesel particulate filter（DPF）to simulate the pressure drop loss,deep particulate deposition,filter cake particulate deposition and total particulate deposition characteristics in the DPF.The effects of different exhaust gas flow rate,exhaust gas temperature,initial ash content,ash distribution,particle distribution,asymmetric pore structure,filter wall thickness,filter hole number and filter hole shape on DPF flowability and particle loading characteristics were studied.The characteristics of DPF pressure drop,particulate deposition,O₂conversion,NO₂conversion,and maximum carrier temperature has been simulated during particle regeneration.The effects of different exhaust gas flow rate,exhaust gas temperature,NO₂content,O₂content,soot particles and structural parameters on DPF regeneration characteristics were studied.The main conclusions are as follows:1)During particle loading,the DPF pressure drop is mainly composed of wall pressure drop loss,particle deep layer drop loss and particle filter cake layer drop loss.Wall pressure drop loss plays a major role.When the exhaust temperature exceeds 610 K,the sum of the wall pressure drop rise rate and the deep lamination drop rise rate are increased compared with the filter cake lamination drop rise rate.Increasing the exhaust temperature and the initial ash,the DPF pressure drop loss increases;Increasing the exhaust flow rate,Deep particle deposition speed and filter cake layer particle deposition speed increase,resulting in increased DPF pressure drop loss.Layered ash has a greater effect on the increase of DPF pressure drop loss than ash in the blocked section;When particles are parabolicly distributed on the surface of the inlet channel（the smallest is in the middle of the DPF carrier）,the DPF pressure drop is minimum.When the exhaust temperature rises to 710 K,the deposition of deep particles increases first and then decreases.The amount of particles deposited in the filter cake layer first remained constant and then slowly increased.2)During particle regeneration,The particles at the front end of the DPF carrier are first oxidized,and then the amount of particles deposited gradually decreases backward along the direction of the carrier axis;The temperature of the front end of the DPF carrier first increases and reaches the highest temperature in advance,and then the carrier temperature gradually increases backwards along the direction of the carrier axis.Increasing the exhaust temperature is conducive to the regeneration reaction between particles and O₂,and the regeneration duration is shortened,but the reaction rate of C and NO₂does not change significantly;With the increase of exhaust flow rate,the oxidation reaction rate of particles with O₂and NO₂is accelerated,the active and passive regeneration of DPF is enhanced,and the duration of DPF regeneration is shortened;The content of NO₂only increased in the exhaust,and the maximum temperature of carrier did not change much.When the inlet/outlet diameter ratio is1.8,the particle regeneration rate is the fastest;When the inlet/outlet diameter ratio is 1.0,the particle regeneration rate is the slowest;The particle regeneration rate of the hexagonal channel structure is greater than that of the quadrangular channel structure.Increasing the initial particle deposition can effectively promote regeneration.However,when the amount of particle deposition is large,the DPF service life is shortened.It is because the rapid combustion exothermic heat of particles has a great thermal impact on DPF.