Design of a Diesel Particulate Trap-Incinerator with Simultaneous Filtration and Compressed Air Regeneration (CAR)

A new design of a self-cleaning diesel particulate trap is discussed herein. Past research at Northeastern University has demonstrated the feasibility of using compressed air, counterflow to the exhaust, for regeneration of ceramic wall-flow particulate traps, thus, eliminating the need for thermal regeneration. The performance of these systems, however satisfactory it might have been, was hindered by potential reliability problems of mechanical components such as rotating monoliths and collection of soot in bag houses. Thus, the present work concentrated in designing a reliable and inexpensive system incorporating passive regeneration devices and a soot incinerator. Upon satisfactory completion of laboratory bench-scale tests, the system was mounted on a 1.4 liter diesel-powered vehicle and was field-tested for 2000 km.

The core of the system is a high soot collection efficiency ceramic monolith. To dislodge the collected soot from the channels of the monolith, regeneration is performed periodically (ca. every 1/2 hour) utilizing a few short bursts (1/2 s duration each) of compressed air (≈7 atmospheres). A system of jets and baffles permits concurrent regeneration and flow of engine exhaust through the system (in opposite directions), thus eliminating the need of either using a parallel alternative trap or channeling the engine exhaust momentarily to the atmosphere. Upon regeneration, the soot settles in an incinerator chamber, equipped with multiple high-temperature electrically-powered ceramic elements. Field tests indicated that the system performed very well in filtering the particulates and regenerating the monolith. The effectiveness of the soot burner was partially successful.