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Selective catalytic reduction (SCR) technology is capable to deliver significant reduction of NOx emissions from diesel engines. This system relies on the use of urea as a reductant that is sprayed into the exhaust flow before reaching the ceramic substrate containing the SCR catalyst. This study describes the effect of urea exposure on substrate support mats when installed in full scale SCR units. Individual systems were aged to 500, 1000, 2000 and 3500 hours. After the aging was completed the devices were torn down and testing was completed on the mat and substrate. Tests were performed to search for the presence of crystalline urea inside the support mat fiber matrix and several analytical tests were performed to determine whether urea exposure and built up caused deterioration of mat pressure and its long term durability.

This paper employs a systematic approach to packaging design and testing of a system and its components in order to determine the long term durability of light duty diesel filters. This effort has utilized a relatively new aluminum titanate filter technology as well as an advanced support mat technology engineered to provide superior holding force at lower temperatures while maintaining its high temperature performance. Together, these two new technologies form a system that addresses the unique operating conditions of diesel engines. Key physical properties of both the filter and the mat are demonstrated through laboratory testing. The system behavior is characterized by various laboratory techniques and validation procedures.

Diesel oxidation catalysts and particulate filters are recognized as proven solutions for reducing diesel emission levels. However, such systems now operate under extreme and unique conditions in order to meet even more demanding emission regulations. Long term cold holding performance, erosion resistance and high temperature stability are issues that must be addressed to assure a robust design in diesel oxidation catalysts and diesel particulate filters. This paper will describe the application of new concepts for support mat systems and results from internal lab testing. It will describe three different case histories, present the design parameters, and compare results with traditional support mat systems.

There is presently a great opportunity for reduction of diesel emissions for heavy duty, automotive, and off-road applications. A wide variety of devices have been designed and further development is proceeding at a fast pace. Technologies include normal oxidation catalysts, particulate filters, and NOx (oxides of nitrogen) traps among others. A broad range of temperature requirements, coupled with large components and the use of steel structures with high thermal expansion coefficient, present unique challenges for designers. This paper explores these design variables in detail, giving examples of where the design problems occur. The analysis points to potential strategies for achieving robust designs within some of the technology areas. Several remaining design problems are discussed. A thermo-mechanical model of the system is presented which helps in understanding the reasons for the design issues.