Numerical Simulation Of Catalyzed Continuously Regenerating Trap Of Diesel Engine

In recent years,the environmental problems and energy crisis caused by motor vehicles have been a hot issue of worldwide concern.At present,particulate matter filter technology is considered as a reliable technology to reduce vehicle particulate matter emissions,and biodiesel as an alternative fuel for vehicles can not only alleviate energy problems,but also enhance engine performance and reduce pollutant emissions.In this paper,the simulation model of the CCRT system was established in GT-SUITE and AVL FIRE software to study the main factors affecting the performance of DOC and CDPF as well as the usage and application on the blended biodiesel engine.In this paper,the model of CCRT system was based on the real object,and was calibrated according to the experimental parameters to make the model conform to the reality.The simulation result of DOC indicates that the expansion angle of the front part of DOC was too large,and the velocity,pressure and temperature distribution were not uniform;the non-uniformity of flow field distribution can be improved by using variable-diameter mixing cavity;the increase of the carrier length could increase the pressure drop of DOC,and reduce the pollutant conversion of DOC;the CO and HC conversion could increase and then remain constant with the growth of the temperature,while the NO conversion could increase and then decrease;the increase of oxygen concentration could increase the pollutants conversion of DOC and decrease the ignition temperature.The simulation result of CDPF indicates that the regeneration reaction of CDPF enhances with the increase of the temperature interacting with trap process,so that the CDPF process will experience about four stages;the increase of carrier length could reduce the partial concentration of particulate matter and the pressure drop of CDPF;the increase of exhaust flow could make the soot mass retianed in trap and the pressure drop rise,which could be not conducive to the secondary oxidation of NO;the increase of oxygen concentration could be conducive to the secondary oxidation of NO,but has an unobvious effect on particulate matter oxidation;the increase of NO₂ concentration could accelerate the oxidation rate of particles and reduces t soot mass retianed in trap in CDPF,while it could also weaken the secondary oxidation of NO.Finally,taking the experimental data as the inlet condition of the model for simulation research.The results indicated that the NO conversion of DOC varied among different working conditions,which is mainly affected by exhaust temperature,and the conversion of CO and HC was high and its remove preformance was well;the conversion of NO using BD20 is higher than that using D100,while the conversion of HC is lower.The soot mass retianed in trap in CDPF at equilibrium could increase with the increase of speed and decrease with the increase of load.The low-load and high-speed condition is the condition with the worst regeneration effect of CDPF.With the increase of biodiesel blending proportion,the NO₂ concentration in outlet and NO conversion of DOC could increase,while the HC and CO remove preformance of DOC could always be well.With the increase of biodiesel blending proportion,the soot mass retianed in trap in CDPF could decrease in the high-speed and increase in the middle and low load.