Modeling catalytic regeneration of wall-flow particulate filters

The problem of initiating and controlling the regeneration of diesel particulate filters is the major obstacle in the wide application of trap systems in diesel-powered vehicles. The most promising solution approaches. to this problem, in terms of minimization of system cost and of additional fuel consumption, are based on the use of catalysts to lower soot ignition temperatures. Various mechanisms have been invoked so far to explain and model catalytic filter regeneration. However, a significant gap is still observed between experimental findings and modeling predictions. This paper presents an attempt to shorten this gap, starting from the special case of fuel additive assisted trap regeneration. The mechanism proposed is based on a dynamic oxygen storage/release model of the metal oxides accumulated in the trap and is applicable to most types of fuel additives. The mechanism was embodied in an existing zero-dimensional regeneration model. The results of simple, full scale experiments are employed in the process of model development and evaluation. Dimensional analysis is used for the evaluation of the parameters affecting the evolution of catalytic regeneration in a concise form. Methods of the comparative assessment of different fuel additives, based on the theory presented, are discussed. Finally, the application of the mathematical model in the design of regeneration control systems is illustrated in a real-world filter failure scenario.