Averaging theory for diesel particulate filter regeneration

Abstract

in Wiley InterScience (www.interscience.wiley.com).Axial thermal gradients play a key role in monolithic diesel particulate filters. For complete particulate regeneration, the ignition location must be near the leading edge of the diesel particulate filter. A new reduced model in terms of the capacitanceweighted and mixing cup average temperature is formulated here using the Liapunov-Schmidt reduction technique to describe the ignition behavior and account for the axial variation. The major advantage of the reduced model is that one can neglect the details of the fine scale dynamics and focus on the large scale dynamics. This new, reduced model has the ability to accurately predict two important ignition characteristics: ignition time and ignition length. Based on the reduced model results, it is shown that the thermal dispersion [a coupling of transverse diffusion (short-scale) and axial convection (long-scale)] plays a dominant role on ignition.

Parametric and Sensitivity Analysis of Diesel Particulate Filter Regeneration

“…In this research we use two models: first, a reproduction of the onedimensional plus time model -the "modified Bissett" model (Bissett, 1984;Kostoglou, Housiada, and Konstandopoulos, 2003;Depcik and Assanis 2008); and second, an averaged model developed by Zheng and Keith (2007). For the sake of brevity we will outline important characteristics of these models but refer the interested reader to the literature for the details of these models.…”

“…In the Averaged Model of Zheng and Keith (2007), it is assumed that there is little change in the gas flows prior to ignition. Focusing solely on the thermal conservation equation, the Liapunov-Schmidt reduction procedure (Chakraborthy and Balakotaiah, 2002ab;Balakotaiah and Chakraborthy, 2003;Balakotaiah and Chang, 2003), of classical bifurcation theory was used to derive a lowdimensional model for a transverse-averaged hyperbolic differential equation.…”

“…This research builds upon the chemical reaction engineering literature (Chakraborthy and Balakotaiah, 2002ab;Balakotaiah and Chakraborthy, 2003), and in particular for automotive catalytic converters (Leighton and Chang, 1995;Keith, Chang, and Leighton, 2001;Ramanathan, Balakotaiah, and West, 2003). In this work, we use this numerical and analytical modeling literature (Bissett, 1984;Kostoglou, Housiada, and Konstandopoulos, 2003;Zheng and Keith, 2007;Depcik and Assanis , 2008) as a basis for performing our analysis. In this work, we use this numerical and analytical modeling literature (Bissett, 1984;Kostoglou, Housiada, and Konstandopoulos, 2003;Zheng and Keith, 2007;Depcik and Assanis , 2008) as a basis for performing our analysis.…”

0D Modelling: a Promising Means for After-treatment Issues in Modern Automotive Applications

“…A Diesel oxidation catalyst is used to convert HC and CO in lean environments, whereas NOx and soot are treated by SCR or LNT catalysts (see Sect. 6 …”

“…First, a residence time (τ t ) must be mentioned. This time is defined from the open volume of the catalyst (V g ), the mass flow rate of exhaust gases (ṁ g ) and the corresponding density (ρ g ): (6) A chemical time (τ ci ) is associated with the main catalytic reaction rate of species #i (ω ci ) and its corresponding concentration (C i ): (7) A thermal characteristic time (τ th ) defines the thermal behaviour of the monolith. It is defined from the monolith's apparent density (ρ app ), its specific heat (Cp m ), the catalyst volume (V c ), the exterior surface of the monolith (S ext ), and its corresponding convective exchange coefficient (h ext ):…”