后处理系统在生物柴油发动机上的耐久性研究

Durability of DOC+SCR System on a Diesel Engine with B20 Fuel

使用B20生物柴油(20%体积比生物柴油+80%体积比普通柴油)在发动机上进行500h整机耐久性试验,整机ESC(欧洲稳态循环)试验和催化剂小样试验,研究了DOC(氧化催化转化器)和SCR(选择性催化还原)系统的耐久性能和劣化机理.实验结果表明,耐久性试验后,在ESC试验下测得DOC后CO平均体积分数上升7.3%,且高转速时上升幅度明显高于低转速时;DOC后HC(碳氢化合物)平均体积分数上升8.0%,各转速下升幅没有明显差异;SCR后NOx(氮氧化物)平均体积分数上升50.8%,且上升幅度随着转速的增大而增大.DOC和SCR催化剂比表面积减小,且减小程度与取样处的排气流量相关.

The durability of a DOC+SCR system was studied after a 500 hour engine durability test with B20 fuel.ESC(European stationary cycle)test was conducted and the catalysts were characterized.The results show that after the engine durability test,the CO emission after the DOC(diesel oxidation catalyst)increases by 7.3%,and the increase rate is larger at a higher engine speed.The HC emission after the DOC increases by 8.0%,but the increase rate shows no obvious association with the engine speed.The NOx emissions after the SCR(selective catalytic reduction)increase by 7.3%,and the increase rate increases with the increase of the engine speed.The specific surface areas of the DOC catalyst and SCR catalyst decrease and show association with the flow rate of the exhaust gas.