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A diesel emission control system, which can simultaneously reduce particulate and NOx emissions through filtration and particle-free Exhaust Gas Recirculation (EGR) has been developed and tested. The key element of the system is a novel ceramic fitter which has shown virtually complete soot removal from diesel exhaust streams. Regeneration of the filter was accomplished by periodically backpulsing the filter with short pulses of compressed air. Testing of the system was carried out using a Caterpillar generator set powered by a 65 kW diesel engine, and a separate load bank which allowed the engine to operate at various load settings. The filter unit consisted of four CeraMem filters (150 mm2 x 305 mm long, 4 mm2 cell), a backpulsing system for filter regeneration, and a baghouse for soot collection. NOx reduction of 75% was achieved at full engine load and a 30% EGR rate.

The development of new designs of a diesel particulate control system is discussed herein. The system employs a single high collection efficiency ceramic monolith to filter the particulate emissions of the engine. Regeneration is achieved by intermittent pulses of pressurized reverse-flow air. After every regeneration the soot is collected at the bottom of the device where it is burned in an incinerator chamber. Different configurations of the system were tested satisfactorily for performance and durability for 100 hrs, coupled to a small experimental engine which was sooting at high rates. Subsequently, a system incorporating a long ventless chamber fitted with an electric burner was mounted on a diesel passenger car and tested for on-road performance evaluation and further development.

A new particulate control system has been developed and bench tested coupled with the exhaust of a single cylinder diesel engine. This system uses Ceramic monolith Filters for collecting the soot, however, it does not require thermal regeneration for cleaning the filters. Instead, compressed air is employed to remove the soot from the filter in a reverse flow configuration. This type of regeneration was accomplished in two different ways: By backpulsing the filter with compressed air. By slowly pressurizing the filter casing with air and then suddenly releasing it when the pressure reaches a predetermined value. During filter regeneration period, the engine exhaust was momentarily released to the atmosphere. To avoid this release, a dual configuration of the system consisting of two ceramic filters operating alternatively has also been designed. Particulates blown-off the filter were recaptured in a baghouse or burned in a specially designed electrical burner.