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In order to reduce the cost of exhaust aftertreatment development, OEMs are increasingly relying on simulation of catalysts, traps and associated control systems. In this regards, for example, considerable progresses have been made on modeling diesel particulate filters. The work described in this paper was sought to provide a valid diesel particulate filter (DPF) model for coupling with engine/vehicle models under the same toolbox. A comprehensive two-level modeling approach, including a lumped parameter model and a detailed 1-D 3-layer-kinetics model, has been proposed for modeling wall-flow diesel particulate filters. Both are capable of modeling virtually all aspects of filter performance in terms of deep-bed filtration, particulate matter loading and filter regeneration.

This article describes a system level 1D simulation tool that has been constructed on the Quasi-steady (QS) method. By assuming that spatial changes are much greater than the temporal ones, rigorous 1D governing equations can be considerably simplified thus becoming less computationally demanding to solve and therefore suitable for control oriented modeling purposes. With the proposed tool exhaust pipe wall temperature profiles, including multiple-wall-layer configurations, are solved through a finite difference scheme. Momentum equation is included for predicting pressure losses due to frictions and geometric irregularity. Exhaust fluid properties (transport and thermodynamic) are evaluated according to NASA or JANAF polynomial thermal data basis. The proposed tool allows the consideration of an arbitrary number of chemical species and reactions in the entire system. A novel semi-automatic approach was developed to handle catalytic reaction kinetics intuitively.

Recently there has been a substantial interest in adopting asymmetric geometry design inside wall-flow diesel particular filters (DPFs) with larger inlet channel width to accommodate soot/ash accumulation and to reduce back pressure and thus to increase filter operation life time. The current work is sought to develop a model based approach to investigate various aspects of this strategy and to compare results with conventional channel design. This paper describes assumptions and modeling methodologies used to evaluate the impact of asymmetries arising out of geometric design as well as due to ash deposition/accumulation on the overall pressure drop across the filter. Special attention is given to the challenges and strategies associated with flow and thermal solutions (during soot loading or regeneration) since transient ash accumulation causes a time varying reduction of effective wall-flow filtration length.

An experimental study was conducted of the heat radiation in a single-cylinder direct injection 142 diesel engine. The engine was operated at speeds ranging from 1000 to 2100 RPM and a variety of loads. The radiation was measured using a specially designed fiber-optics probe operating on the two-color principle. The probe was located in the head at two different locations: in one location it faced the piston bowl and in the other it faced the piston crown. The data obtained from the probe was processed to deduce the apparent radiation temperature and soot volume concentration as a function of crank angle. The resultant profiles of radiation temperature and of the soot volume concentrations were compared with the predictions of a zonal heat radiation model imbedded in a detailed two-zone thermodynamic cycle code. The agreement between the model and the measurements was found to be good, both in trends and in magnitudes.

Numerical simulation of in-cylinder processes can significantly reduce the development and refinement costs of engines. While it can be argued that higher fidelity models improve accuracy of prediction, it comes at the expense of high computational cost. In this respect, a 3D analysis of in-cylinder processes may not be feasible for evaluating large number of design and operating conditions. The situation can be more foreboding for transient simulations. In the current work a phenomenological combustion modeling approach is explored that can be implemented in a lower fidelity modeling framework and can approach the accuracy of higher dimensional models with significant reduction in computational cost. The proposed model uses transported probability density function (tPDF) method within a 0D framework to provide a computationally efficient solution while capturing the essential physics of in-cylinder combustion.