Ignition analysis of wall-flow monolith diesel particulate filters

Document Type

Conference Proceeding

Publication Date

12-1-2004

Department

Department of Chemical Engineering

Abstract

During regeneration the diesel particulate filter (DPF) is a dynamic system whose trajectory depends on various parameters, especially the inlet gas temperature. Parametric sensitivity signifies large changes in the DPF trajectory induced by small changes in parameters across threshold values. This is a form of critical behavior and can lead to ignition conditions, which is necessary for complete regeneration. In this paper a transient one-phase model is used to derive analytical ignition criteria for a wall-flow monolith diesel particulate filter, which defines the ignition boundaries. The ignition criterion is a function of three parameters: α (a ratio of reaction time to convection time), B (a ratio of adiabatic temperature rise to the characteristic temperature for reaction), and γ (a ratio of total heat capacities of the soot bed to the substrate wall) and is given by α/ β < e when reactant consumption is unimportant (B ≫ 10) and α/β +f(γ)B-g(γ) < e when reactant consumption is important. For most practical cases of the DPF f(γ) = 6.0074 and g(γ) = 0.6411. The validity of the ignition criteria is verified by numerical simulations using the transient one-phase model. The effect of several parameters, i.e., the wall thickness, the total filtration area, the initial loading, the gas flow rate, the oxygen feed concentration, and on the critical inlet gas temperature are also discussed. It is shown that a thin channel wall, a high total filtration area, a high initial loading, a low gas flow rate and a high oxygen feed concentration are desirable for an efficient regeneration.

Publication Title

Catalysis Today

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