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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.

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.