Case Studies of Urea SCR Integration on Passenger Cars Monitoring of Urea Inside the Tank During Hot and Cold Environment Test Missions

SCR technology allows engines with high raw NOx generation to comply with new exhaust emission regulations, especially Light Duty Vehicles (pick-up trucks, SUV's and larger passenger cars). The complete SCR system consists of a tank for storing urea fluid, a pump, injection system and a dedicated catalyst. The Automotive Industry has defined and standardized a urea fluid called AdBlue™ which is now being implemented worldwide. To comply with the more stringent regulations (Euro 4 to 6), Europe selected SCR as the preferred technology with market introduction in January 2005 (infrastructure, commercial introduction...). This choice is likely to be standardized on a global scale, especially in the US and Asia, on HDV's and LDV's by 2010. For US Tier 2 Bin 5 requirements, the Automotive Industry will adopt the European approach by implementing SCR with on board urea fluid storage. The worldwide NOx emissions standards evolution from 2005 to 2012 requires the automotive industry to evaluate SCR technology as leading solution for meeting emission regulations. This paper will describe one completely integrated SCR system (plastic tank with venting, heating and filling, a pump, lines, additional sensors for monitoring temperatures, fluid level). Also, this presentation gives the main results obtained during vehicle test missions in hot and cold environments with a focus on urea stability, NH3 vapour release and heating management.