Pressure drop modelling is a subject of special Due to the fuel penalty resulting from the increased backpressure of the loaded filter, it is necessary interest for the design and control of diesel particulate for the filter to be regenerated. This regeneration filters. Based on previous experience, an improved pressure involves oxidation of the accumulated particulate, drop model is presented. Special emphasis is given on the which may be periodical or continuous, during soot permeability properties and its dependence on temregular engine operation. The initiation and control perature and pressure. With the assumption of uniform of the regeneration process is the main issue in diesel wall flow distribution throughout the channel length, it filter technology, as regeneration should be as safe is possible to derive an analytic expression for pressure as possible to avoid excessive thermal stresses and drop calculation. The main difference with previously profailure of the filter material. Regeneration systems posed analytic expressions lies in the inclusion of gas are based on the use of catalysts (catalytic coatings density dependence on local pressure, which necessitates or fuel-borne catalysts) to lower the reaction teman iterative calculation procedure. The importance of this perature and/or engine measures (e.g. post-injection) improvement is illustrated parametrically. The new model or electrical heating to increase the exhaust gas is validated against experimental data on an engine bench, temperature. using a double filter configuration to ensure constant filter Understanding the flow phenomena contributing soot loading throughout the test.to the pressure drop in particulate filters is of great importance for the emissions engineer. On the one Key words: diesel engine, after-treatment technology, hand, filter design should target the minimization of exhaust emissions, mathematical modelling, pressure drop pressure drop in real-world conditions by careful selection of filter geometry (volume, cell density, wall thickness, porosity). On the other hand, the

The diesel particulate filters (DPFs) technology has impressively advanced especially during the last years, driven by the interest in the reduction of automobile particulate emissions. This paper is concerned with the effect of NO 2 as an active oxidation agent in the regeneration process of the soot accumulated in the particulate filter. Experiments at realistic conditions using a diesel engine equipped with a standard oxidation catalyst and a particulate filter are carried out at a wide range of operating conditions. These results are used to validate an already available mathematical model of the NO 2 -assisted regeneration phenomena in the particulate filter. The combined use of experimental and modeling results provides interesting conclusions regarding the significance and the chemistry of the reaction of soot with NO 2 . The advantages and drawbacks of such an approach compared to standard laboratory synthetic gas studies are discussed. The agreement between experimental and simulation results in terms of engineering interest (rate of soot accumulation or depletion) is quite satisfactory and indicates that such a type of model could be a promising design tool.

An increasing environmental concern for diesel particulate emissions has led to the development of efficient and robust diesel particulate filters (DPF). Although the main function of a DPF is to filter solid particles, the beneficial effects of applying catalytic coatings in the filter walls have been recognized. The catalyzed DPF technology is a unique type of chemical reactor in which a multitude of physicochemical processes simultaneously take place, thus complicating the tasks of design and optimization. To this end, modeling has contributed considerably in reducing the development effort by offering a better understanding of the underlying phenomena and reducing the excessive experimental efforts associated with experimental testing. A comprehensive review of the evolution and the most recent developments in DPF modeling, covering phenomena such as transport, fluid mechanics, filtration, catalysis, and thermal stresses, is presented in this article. A thorough presentation on the mathematical model formulation is given based on literature references and the differences between modeling approaches are discussed. Selected examples of model application and validation versus the experimental data are presented.

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