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With the rapid development of the automotive industry , automobile exhaust increasingly serious pollution caused by the atmosphere , especially NO_x harm has been caused by a high degree of attention of Governments . As the car 's main power source , the emission control of the diesel engine of NO_x gradually becoming a hotspot. At present, the catalytic reduction of exhaust gas recirculation (EGR) and post-processing to be recognized can be used in diesel engines purification NO_x emissions technology . The goal of this paper is to EGR and HC-SCR technology , basic research , and were carried out on a direct injection diesel engine bench test . The contents include: the first part , a way of cooling EGR test study of naturally aspirated diesel engine on the new TR combustion system . The test results show that in each load , the maximum EGR rate was 15.4% : the maximum value of the cylinder pressure of the combustion process and the highest value of the average temperature of the cylinder were reduced ; at rated speed , the combustion of the respective load start point remain basically unchanged in most loads , combustion duration slightly extended. This shows that, under conditions less in the amount of circulating gas , the influence of of cooling EGR on the combustion process of the TR system is mainly reflected in the thermal effects , and the dilution effect is less obvious . Emissions , the EGR and TR combustion system match can greatly improve the original machine NO_x emissions , but at the same time small amplitude increased exhaust smoke and fuel consumption rate . The second part of the trial of the Pt / Rh / Pd / cordierite , and a Cu- ZSM - 5 / cordierite two types of lean-burn catalyst , combined with the particulate filter, and HC as a reducing agent in the use of diesel exhaust by bench tests , emphasis on the catalyst activity, stability , and aspects of performance , from the combustion temperature , the reaction temperature window to provide a reference for future practical use in diesel engines . The experimental results show that , compared with the Cu-ZSM-5 catalyst , the precious metal catalyst applications in diesel purification NO_x has good activity and stability , and the reaction temperature window is wide , but to realize that there are still many problems to be solved in the product of .
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