Is closed-loop SCR control required to meet future emission targets?
To meet 2010 emission targets, optimal SCR system performance is required. In addition, attention has to be paid to in-use compliance requirements. Closed- loop control seems an attractive option to meet the formulated goals. This study deals with the potential and limitations of closed-loop SCR control. High NO<,x> conversion in combination with acceptable NH<,3> slip can be realized with an open-loop control strategy. However, closed-loop control is needed to make the SCR system robust for urea dosage inaccuracy, catalyst ageing and NO<,x> engine-out variations. Then, the system meets conformity of production and in-use compliance norms. To demonstrate the potential of closed-loop SCR control, a NO<,x> sensor based control strategy with cross-sensitivity compensation is compared with an adaptive surface coverage/NH<,3> slip control strategy and an open-loop strategy. The adaptive surface coverage/NH<,3> slip control strategy shows best performance over simulated ESC and ETC cycles. SCR catalyst dynamics, time delay in the urea injection and maximum NH3 slip targets limit the performance of closed-loop SCR control. If new reagent dosage systems and future catalyst technology are able to-relieve these limitations, closed-loop, control has the potential to reduce the calibration effort and to improve the transient control performance.
Frank Willems Robert Cloudt Edwin van den Eijnden Marcel van Genderen Ruud Verbeek Bram de Jager Wiebe Boomsma Ignace van den Heuvel
TNO Automotive Eindhoven University of Technology DAF Trucks
国际会议
2007年(中国内燃机学会第六届学术年会暨国际内燃机学术研讨会和第六届中国国际内燃机及制造装备展览会)两会一展国际学术会议
上海
英文
202-217
2007-10-09（万方平台首次上网日期，不代表论文的发表时间）