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In order to enable the regeneration of NOx traps at low temperatures and reduce the fuel penalty, an innovative fuel reformer has been developed to create a hydrogen-rich gas from diesel fuel to be used as the NOx reductant. This paper outlines the experimental use of this hydrogen generation device on a dual-leg NOx trap system with an 8.3L diesel engine. The system was tested at six ESC modes, and gave satisfactory results at those engine conditions where the NOx trap had good adsorption capacity (exhaust temperature < 450 °C). With the NOx conversion efficiency of 80% as the target, the fuel economy penalty was about 3% for most engine conditions. Since this type of diesel engines are widely used for urban transit buses, the system was also tested at six typical road conditions and showed satisfactory results in terms of both NOx conversion efficiency and fuel economy penalty. A comparison with diesel fuel as the NOx reductant was conducted with the same test setup.

This paper describes the development of an exhaust Thermal Enhancer™ using an airless nozzle fuel system. The purpose of the Thermal Enhancer™ is to increase diesel engine exhaust gas temperatures to a level where catalytic heating can be used for Diesel Particulate Filter regeneration. The system can also be used to achieve adequate temperatures for NOx reduction, employing techniques such as Selective Catalytic Reduction. The Thermal Enhancer™ is used to increase exhaust gas temperatures at conditions that would otherwise be too cold for effective catalyst operation. These conditions include idle and low-load operation. The airless-nozzle fuel system is necessary for engines that do not have a compressed-air system. Performance data, including hydrocarbon slip as a function of Thermal Enhancer™ outlet temperature are presented at steady state conditions. Pressure loss as a function of engine speed indicates it is less than 1 kPa at the maximum exhaust flow rate.