Packed bed of spherical particles approach for pressure drop prediction in wall-flow DPFs (diesel particulate filters) under soot loading conditions

Abstract

ElsevierSerrano Cruz, JR.; Arnau Martínez, FJ.; Piqueras Cabrera, P.; Garcia Afonso, O. (2013) AbstractThe soot loading process in wall-flow DPFs affects the substrate structure depending on the filtration regime and produces the increase of pressure drop. Deep bed filtration regime produces the decrease of the porous wall permeability because of the soot particulates deposition inside it. Additionally, a layer of soot particulates grows on the porous wall surface when it becomes saturated. As soot loading increases, the pressure drop across the DPF depends on the porous wall and particulate layer permeabilities, which are in turn function of the substrate and soot properties. The need to consider the DPF pressure drop influence on engine performance analysis or DPF regeneration processes requires the use of low-computational effort models describing the structure of the soot deposition and its effect on permeability.This paper presents a model to describe the micro-scale of the porous wall and the particulate layer structure assuming them as packed beds of spherical particles. To assess the model's capability, it is applied to predict the DPF pressure drop under different experimental conditions in soot loading, mass flow and gas temperature.

Pre-DPF water injection technique for pressure drop control in loaded wall-flow diesel particulate filters

“…This phenomenon has been shown by different authors covering experimental approaches, such as the works on filtration performance performed by Murtagh et al [31], the development of new techniques for loading characterisation carried out by Fino et al [32], the investigations of Yapaulo et al [33] on the impact of the filtration velocity or the visual analysis of particle matter depositions presented by Liati et al [34]. Theoretical and modelling works have also corroborated this conclusion considering meso-scale porous wall description [28] and micro-scale modelling of the flow and particles path in the porous wall [35] by using Lattice-Boltzmann techniques [36].…”

“…According to the Darcy's law, the pressure drop of this kind of substrate is lower than that of a loaded heterogeneous porous substrate. If there are two regions, their permeabilities act as parallel resistances prevailing the region of very low permeability (soot penetration region with saturated wall) against the high permeability region (clean porous wall without soot penetration) [28]. This kind of response is also confirmed by the response of heterogeneous porous walls, which act in a similar way under clean conditions [37] but find their advantage in pressure drop in the fact that avoid soot penetration into the porous wall.…”

“…It produces the pressure drop reduction. Additionally, water flowing through the porous wall between inlet and outlet channels may increase the thickness of penetration of the soot what causes permeability increase [28]. These hypotheses are discussed and strengthened in following sections with additional experimental data.…”

On the Impact of Particulate Matter Distribution on Pressure Drop of Wall-Flow Particulate Filters

“…Both the porous wall and particulate layer permeabilities are obtained as a function of the porosity of the medium (ε), the collector unit diameter (d c ) and the slip-flow correction given by the Stokes-Cunningham Factor (SCF) as [23]:…”

Experimental assessment of a pre-turbo aftertreatment configuration in a single stage turbocharged diesel engine. Part 2: Transient operation

“…The main components of the engine are indicated in Figure 15: cylinders, in which the combustion process is modelled as a function of the crank angle and the engine operating conditions using an interpolation methodology on a rate of heat release database [14]; charge air and EGR coolers, which are modelled as pipe beams with inlet and outlet volumes [35]; specific models for compressors [36] and turbines [37]; and aftertreatment systems with focus on fluid dynamic aspects for accurate pressure drop and acoustic prediction [38] besides the influence of the heat transfer effects [39] and the consideration of clean [40] and soot loaded substrate [41] in the case of the DPF.…”