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The diesel particulate filter (DPF) technology with the use of fuel additives as regeneration aids is a promising technology for modern and future low-emissions diesel engines. The development of efficient and reliable DPF systems requires understanding of the regeneration process. Although the role of mathematical models in this respect has been widely recognized, few attempts to model the fuel-additive-assisted regeneration have been presented. In this work, a previously developed simplified authors' model is extended, to allow deeper investigation of the process. The 1D mathematical model of the catalytic regeneration in the channel of the particulate filter is based on a dynamic oxygen storage/release mechanism of additive action, coupled to the transport phenomena occurring in the filter. A previously published set of fullscale measurements is employed to validate the model in a wide range of possible regeneration modes. The advantages of the present 1D model over the previous 0D model are illustrated. It is concluded that, at the present stage, the model can sufficiently describe and explain the main features of the regeneration process. The minor deviations of the model results from reality are attributed to the uncertainties of the reaction kinetics and to nonuniformities regarding flow distribution and soot deposition. The possible explanations are discussed, and directions for future work are suggested.

Stricter emission control legislation for diesel use has been increasing interest in highly

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.

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Transient heat transfer computations in automotive exhaust systems are increasingly employed in the design and optimization phases. The complex geometry of the exhaust line and the special flow conditions complicate the problem of accurately estimating several important heat transfer parameters. This paper initially summarizes the current status of knowledge regarding heat transfer phenomena in automotive exhaust systems. A comprehensive transient computer model covering all exhaust piping configurations (single wall, double wall with air gap or insulation) is presented. A novel solution procedure is proposed, resulting in significant savings in processing time. Two-dimensional heat transfer in connecting flanges is also accounted for. The model is validated with the help of full-scale measurements on vehicles. Examples are presented, illustrating the application of the model in the comparative assessment of different exhaust configurations. In conjunction with existing models, which simulate the operation of three-way catalytic converters and of other exhaust gas after-treatment devices, the model can be integrated in a CAE (computer aided engineering) package for the support of exhaust system design optimization.

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