Application Research Of Diesel DOC+CDPF System

Diesel Particulate Filter as currently recognized as the most effective after-treatment system to control the Diesel Particulate emission, which has been get more and more attention. DOC + CDPF system can be regenerated under low temperature condition, and then this system can greatly reduce active regeneration frequency and reduce the negative effect on engine performance and its fuel economy, which has great application value. The filtration performance and passive regeneration performance of the DOC + CDPF system, and the temperature characteristics of DOC, and the active regeneration performance of CDPF was studied in this paper, using the theoretical analysis, experiment research and numerical calculation method.In order to study the filtration performance of the DOC+CDPF system, the engine test bench was built under laboratory. In order to obtain the particle number concentration and filtration efficiency before and after the system, the particle size distribution were measured before and after the system, using the combustion DMS500 fast particulate spectrometer. The results show that, the particles filtration efficiency of this system can reach above 95%.In order to study the passive regeneration performance of the DOC+CDPF system, the soot loading condition of engine was selected as speed of 1500 r/min and torque of 70 N?m for lower emission temperature and higher soot concentration, and the soot loading mass in CDPF were selected as 3 g/L and 6 g/L. The steady state regeneration performance of the system was investigated under the engine speed of 2200 r/min with different emission temperature condition. The regeneration efficiency and regeneration rate were obtained under different operating conditions.In order to study the temperature rising characteristic of DOC, the inlet boundary conditions were obtained by engine experimental emission data, using the AVL Fire software to simulate its performance. Four extreme operating conditions were selected to investigate the temperature rising characteristic of DOC under steady state condition with different far post fuel injection quantity. Besides, the performance of varying conditions was also investigated to obtain the temperature rising curves under both steady and varying state condition.In order to study the active regeneration performance of CDPF, the inlet boundary conditions were obtained by engine experimental data, and using the AVL Fire software to simulate its performance. The steady state regeneration performance of CDPF was investigated under two flow rates and oxygen concentration. Besides, the regeneration performance of drop to idle(DTI) and drop to flow rate(DTLF) were also investigated to obtain the variation performance of the maximum regeneration temperature and the residual particle mass during the CDPF regeneration process.Through the above investigation, the filtration and regeneration performance of DOC+CDPF system were studied using the experimental and simulation method to get some valuable results, and provide a good reference on practical application.