Demonstration of Extremely Low NOx Emissions with Partly Close-Coupled Emission Control on a Heavy-Duty Truck Application

Authors

Dr. P. Mendoza Villafuerte, Dr. J. Demuynck, D. Bosteels MSc MBA, AECC, Brussels; Dipl.-Ing T. Wilkes, Dr. L. Robb, Dr. M. Schönen, FEV GmbH, Aachen:

Year

2021

Print Info

Production/Publication ÖVK

Summary

Based on the technologies required to comply with the Euro VI-D emission standards, this paper examines ways to improve these technologies to meet future regulatory requirements. Experimental results including PEMS measurements obtained while operating from a demonstrator vehicle on public roads will be shown, including a variety of local and regional delivery operations as well as current Euro VI in-service conformity trips. Special attention will be given to the robustness of the emission performance at cold and urban low load stop and go driving. The paper discusses how NO_x emissions can be reduced to ultra-low levels in a broad range of operating conditions. This is achieved through an enhanced integration of proven emission control technologies with an advanced engine strategy on an existing Euro VI longhaul truck. The innovative exhaust aftertreatment layout combines a close-coupled Diesel Oxidation Catalyst (ccDOC) with an adapted catalyst setup within the available space of the standard control emission box (EATS box). The technology package includes two sections of Selective Catalytic Reduction (SCR/ASC), a twin urea dosing system, a catalysed diesel particulate filter (cDPF) and Ammonia Slip Catalysts (ASCs). The location of the first SCR at the entry of the EATS box enables a very early start of the NO_x conversion due to fast warm-up. In addition, the close coupling of the first DOC to the turbocharger exit prevents poisoning of the SCR by HC/CO and increases the NO₂/NO_x ratio. Behind the first DOC a urea injector and mixer are included in the downpipe leading to a homogeneous urea feed to the ccSCR. This configuration will allow lowest NOx emissions at low engine load and vehicle speed as well as during cold-start operation. A hydrocarbon injector is located downstream the SCR for thermal management of the DOC and cDPF in terms of passive and active regeneration. Finally, the second urea injector will feed the second SCR to govern the NOx emissions when the SCR has reached sufficient temperature for dosing release at high engine load and vehicle speed operation. Both SCR catalysts include downstream ASC for ammonia slip reduction. A smart and advanced control strategy is implemented to ensure optimal interaction between all components. Additionally, the pollutants NH₃, N₂O and PN₁₀ will be investigated. Finally, some limitations of the demonstrator system will be discussed as part of the outlook.

Number of pages

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