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A Diesel Particulate Filter (DPF) is needed to meet the Particulate Matter (PM) requirements of US EPA 2007 regulations for diesel engines. A catalyzed diesel particulate filter (cDPF or CSF) in combination with a diesel oxidation catalyst (DOC) is effective if the DOC has achieved light-off. However, for some applications, exhaust temperature will be too low to achieve DOC light-off. Therefore a reliable active regeneration means will be required. This paper presents a diesel-fired filter regenerator that works with an uncoated DPF. During regeneration, the thermal regenerator raises the exhaust temperature to 650 °C at the filter face at any engine condition, including idle. The thermal regenerator was tested on a cordierite filter placed on a heavy-duty diesel engine with cooled-EGR (2007 calibrations). THC, CO and NOx emissions, as well as opacity, in the tailpipe were measured at both steady state and transient engine conditions.

An active diesel particulate filter regeneration system has been developed to remove diesel particulate matter (PM) accumulation from diesel particulate filters. Diesel particulate filters (DPF) are an effective means of significantly reducing PM emissions from vehicles powered by diesel engines. This paper outlines the use of the ActiveClean™ Thermal Regenerator (TR) system to reduce PM emissions in several different applications. Test cell data was collected using a 15.8L diesel engine to provide exhaust flow. The objective of this test was to evaluate the steady state HC, CO and NOx emissions of the engine and TR combination during regeneration of the filter. The data reveals only a slight increase in HC and CO emissions depending on configuration (single-or dual-leg) for steady state regenerations. It also showed that the TR had very little impact on NOx emissions during regeneration.

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.