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Technical Paper

Advanced Simulation Technologies for Diesel Particulate Filters, A Fundamental Study on Asymmetric Channel Geometries

2007-04-16
2007-01-1137
The pressure drop as well as the overall lifetime of wall flow diesel particulate filters is strongly influenced by the capability of storing non-combustible ash. One approach to reach low pressure drops and long filter lifetimes is the application of optimized channel geometries. This study presents a comprehensive simulation approach for filters with asymmetrical channel structures in the presence of soot and ash. The wall flow model, soot loading and regeneration approaches are discussed with all model equations. The soot filtration model distinguishes between the regimes of depth and cake filtration. The regeneration model takes into account soot regeneration reactions, catalytically supported soot reactions and catalytic wall reactions. The simulated pressure drop of filters with different channel diameters at different operating conditions is compared to measured values. The predicted pressure drop due to depth and cake filtration is compared to experimental data.
Journal Article

Modeling of Catalyzed Particulate Filters - Concept Phase Simulation and Real-Time Plant Modeling on HiL

2016-04-05
2016-01-0969
The present work introduces an extended particulate filter model focusing on capabilities to cover catalytic and surface storage reactions and to serve as a virtual multi-functional reactor/separator. The model can be classified as a transient, non-isothermal 1D+1D two-channel model. The applied modeling framework offers the required modeling depth to investigate arbitrary catalytic reaction schemes and it follows the computational requirement of running in real-time. The trade-off between model complexity and computational speed is scalable. The model is validated with the help of an analytically solved reference and the model parametrization is demonstrated by simulating experimentally given temperatures of a heat-up measurement. The detailed 1D+1D model is demonstrated in a concept study comparing the impact of different spatial washcoat distributions.
Technical Paper

Ash Transport and Deposition, Cake Formation and Segregation-A Modeling Study on the Impact of Ash on Particulate Filter Performance

2019-04-02
2019-01-0988
Non-combustible particles, commonly summarized as ash, influence the lifetime performance of wall flow filters. This study aims to investigate this influence by means of simulation. An existing transient 1D+1D wall flow filter model is extended by dedicated transport balances for soot and ash (1), by a discrete cake model describing changing soot and ash compositions over the cake height (2), by a phenomenological cake filtration model (3), by dedicated cake property models (4) and by a phenomenological model capturing the radial mobility of solids within the cake (5). Results of three different types of simulations are shown. First, the various sub-models are assessed in isolated simulation configurations. The combination of these shall serve as theoretical model validation. Second, isolated loading and passive regeneration simulations are performed.
Technical Paper

Diffusion Supporting Passive Filter Regeneration- A Modeling Contribution on Coated Filters

2018-04-03
2018-01-0957
Wall flow particulate filters have been used as a standard exhaust aftertreatment device for many years. The interaction of particulate matter (PM) regeneration and catalytically supported reactions strongly depends on the given operating conditions. Temperature, species concentration and mass flow cause a change from advective to diffusive-controlled flow conditions and influence the rate controlling dominance of individual reactions. A transient 1D+1D model is presented considering advective and diffusive transport phenomena. The reaction scheme focuses on passive PM conversion and catalytic oxidation of NO. The model is validated with analytical references. The impact of back-diffusion is explored simulating pure advective and combined advective diffusive species transport. Rate approaches from literature are applied to investigate PM conversion at various operating conditions.
Journal Article

Particulate Matter Classification in Filtration and Regeneration-Plant Modeling for SiL and HiL Environment

2017-03-28
2017-01-0970
The present work describes an existing transient, non-isothermal 1D+1D particulate filter model to capture the impact of different types of particulate matter (PM) on filtration and regeneration. PM classes of arbitrary characteristics (size, composition etc.) are transported and filtered following standard mechanisms. PM deposit populations of arbitrary composition and contact states are used to describe regeneration on a micro-kinetical level. The transport class and deposit population are linked by introducing a splitting deposit matrix. Filtration and regeneration modes are compared to experimental data from literature and a brief numerical assessment on the filtration model is performed. The filter model as part of an exhaust line is used in a concept study on different coating variants. The same exhaust line model is connected to an engine thermodynamic and vehicle model. This system model is run through a random drive cycle in office simulation.
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