SCR装置对共轨柴油机稳态颗粒排放特性影响的研究

Study on Influence of SCR without Urea Injection on Steady Particle Emissions of Diesel Engine

以一台重型柴油机为原机,连接到选择性催化还原(selective catalytic reduction,SCR)装置进行ESC 13工况稳态试验,研究稳态下SCR装置在无尿素喷射量时对柴油机颗粒排放的影响。研究结果表明:无尿素喷射的SCR对颗粒排放有影响,柴油机连接SCR装置后颗粒排放低于原机,排气颗粒质量下降60%;原机的颗粒排放以核态颗粒为主,连接SCR系统后的颗粒排放以聚集态颗粒为主;原机连接SCR装置后核态颗粒数量明显下降,各转速下,50%和75%负荷处降幅显著,而25%和100%负荷处核态颗粒的降幅随转速的升高而降低。

On test bench, particle matter （PM） emission characteristics from a heavy-duty diesel engines equipped with selective catalytic reduction （SCR） catalytic converter had not urea injection and with- out after-treatment equipment were compared according to Europe static cycle （ESC） test cycle to study the influence of SCR. Results show that the engine with SCR equipment possesses lower PM emissions, mainly nucleation mode particles dropped by about 60%. The influence of SCR equipment on PM emissions is more obvious under middle load and lower speed conditions and decreases with speed increasing. The main influen- cing factors are operation conditions, exhaust pressure and SCR catalyst carrier etc.