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Automotive SCR systems for diesel NOx reduction are dimensioned to reduce NOx efficiently in all driving conditions. In this regard the DEF storage and delivery system is developed to operate in a full range of temperatures, voltages, pressures, etc. To allow a control for optimal performance, sensors are added in the system (temperature, level, pressure sensor). Recently, a DEF quality sensor has been added to assure the correct concentration of urea in water in the onboard DEF tank. Now the question is raised how to assure that the DEF quality sensor is operating correctly and is giving an accurate indication of the liquid in the tank. The objective of this study is to define an independent method (PQD) to verify liquid quality, and challenge the signal generated by the DEF quality sensor. This study describes a possible method and the progress on its validation in various automotive driving conditions.

As electronics make their way into the fuel system, a shift in problem solving can be seen. Previously high risk items were tackled mainly through proving component durability and decreasing the statistical odds of the problem occurring. With an electronically controlled system however it is possible and necessary to define degraded modes, in the event that certain components fail, in order to provide at least a limited functionality for the customer. This paper will discuss some different use cases, and how embedded software can be used to improve functionality over a passive system.

Automotive SCR systems are dimensioned to reduce NOx efficiently in normal driving conditions. In markets such as North America and Europe, extreme winter conditions are common over a period of many weeks where temperatures are usually below DEF (Diesel Exhaust Fluid) freezing temperatures at −11°C (12°F). In previous studies and applications, DEF was heated in the tank in a dedicated pot or alternatively by a standardized central heater. Due to the local character of these heating solutions, it was not possible to thaw the full tank volume. The objective of this study is to demonstrate how to significantly improve performance of the SCR system in cold weather conditions for passenger car, light commercial vehicles and SUV applications. The performance improvement is demonstrated by sustainability testing showing how much of the full tank content can be thawed and made available for injection in the exhaust system.

Passenger Car and SUV Selective Catalytic Reduction (SCR) systems were first introduced to the market in 2008. These systems were developed to meet the stringent LEV-II Tier 2 Bin 5 exhaust emissions regulation in US and EURO 6-1 regulation in Europe. New emission regulations are being proposed. For Europe EURO 6-2 is about to be defined and will start to apply in 2017. In US, LEV-III SULEV requirements phase in from 2015 to 2025 and are mandatory for all vehicles starting in 2020. These amendments generate a new evolution of requirements for automotive SCR systems: A first effect of this evolution is that the most efficient NOx reduction technology, combined with more efficient combustion in the engine for CO₂ reduction, needs to be adopted on a wider range of cars. As a result, compact diesel vehicles will need to apply SCR technology. Also, the increased need for NOx reduction leads to an increase in AdBlue®/DEF consumption on each vehicle.

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.