Numerical Simulation Of Loading And Regeneration Characteristics Of Asymmetric DPF

The diesel engine with its superior power and economy in transportation,have a very broad application space in engineering operations.However,the emission problem has been one of the problems that researchers have been trying to solve,especially with the national mandatory emission standards been more and more tight,the country’s six emission standards have more stringent requirements for diesel particulate matter emissions,not only for PM（Particulate Matter）but also for PN（Particulate Number）limited.Diesel Particulate Filter（DPF）is the most efficient after-treatment equipment to meet stringent regulatory requirements.In this paper,from the DPF installation for the in-use vehicles start the data of the real vehicle had been analyzing.Found the pressure drop problem of the loading process and the maximum regeneration temperature of the regeneration process is the very urgent problem.These issues have a great impact on the economics and dynamics of diesel engines.After the analysis and summarization of the practical application problems,the related models in the process of DPF loading and regeneration were established.The loading and regeneration performance of symmetric and asymmetric porous carrier DPF were studied by numerical simulation method to guide the engineering reconstruction.The influence of soot and ash distribution on the pressure drop of the symmetric and asymmetric porous DPF carrier is analyzed numerically,and the reasons for the pressure drop of the symmetric and asymmetric pore carrier are analyzed.Also the influence of structural factors and exhaust gas flow factors on the pressure drop is analyzed.It is found that the ratio of the pressure drop of the outlet channel and the soot layer forms the main components of the low soot loading and the high soot loading situation respectively,which leads to the formation of the pressure drop intersection.The soot loading corresponding to the pressure drop intersection between symmetric and asymmetric porous DPF carrier increases with the increase of pore density（CPSI）,wall thickness and aspect ratio,and increases with the increase of flow rate.With the increase of DPF pre-exhaust temperature,the pressure drop of the DPF increases,while the intersection of pressure drop shows a trend of first decreased and then increased.In addition,through the numerical simulation of the asymmetric DPF carrier regeneration process,the regeneration characteristics of the asymmetric DPF channel carrier were investigated.With the increasing of the pore diameter ratio of the inlet and outlet channels,the DPF carrier regeneration maximum temperature increases from the symmetric pore to the asymmetric pore with the ratio of 1.6,and the regeneration duration decreases.Ash accumulation increases the maximum regeneration temperature.The maximum regeneration temperature of DPF decreases with the increase of CPSI and wall thickness,but the regeneration duration increases with the increase of length to diameter ratio,and the regeneration duration was shortened.The maximum regeneration temperature of the asymmetric pore DPF carrier decreases with the increase of the exhaust gas flow rate and the regeneration duration increases.The oxygen concentration in the exhaust gas increases and the maximum regeneration temperature increases and the regeneration duration shortens.The effect of NO₂concentration on regeneration temperature and duration was not obvious.