Recent Advances in Utilizing the Plasma Fuel Reformer for NOx Trap Regeneration 2005-01-3547

This paper describes recent progress in our program to develop an emissions technology allowing diesel engines to meet the upcoming stringent worldwide regulations for NO_x. The Plasma Fuel Reformer (PFR) has the ability to rapidly convert diesel fuel (with air), to a hydrogen rich gas on-board a vehicle, which is then utilized to efficiently regenerate a NO_x trap. We have made several advances on the PFR as well as on the NO_x reducing system. The Plasma Fuel Reformer operating range has been extended by 120% up to 1.5 g/s fuel flow rate while retaining the high hydrogen and low soot characteristics. The plasma power consumption has been further reduced and the high voltage design has been made more robust. The T₉₀ start-up time during regenerations has been reduced to less than 4 seconds. The NO_x reducing system utilizes a novel algorithm for NO_x trap regeneration that reduces the fuel penalty by 25% while increasing NO_x conversion by 10%. The new method can also be utilized to reduce the NO_x trap volume significantly in a dual leg arrangement. Based on a detailed understanding of the NO_x trap regeneration process, a new method to reduce the magnitude of NO_x spikes has also been developed. Finally, optimization was performed at some steady state points utilizing maps on trap capacity and reductant breakthrough.