The effects of soot properties on the regeneration behaviour of wall-flow diesel particulate filters

Abstract

Abstract:In recent years, significant effort has been put into studying the regeneration process of diesel particulate filters (DPFs) either through experiments or modelling. However, less attention is paid to understanding the important influence of soot properties on the regeneration process. In this paper, for the first time, five fundamental soot properties, namely activation energy, frequency factor of the reaction, soot bulk density, porosity and mean soot particulate diameter, are investigated. Sensitivity analyses are carried out for each of these parameters based on a one-dimensional generalized DPF regeneration model. It is found that activation energy is the most important factor in the regeneration process, followed by frequency factor, bulk density, porosity and mean particulate size. In addition, the results also indicate that the concentration of exhaust gas oxygen has a significant influence on the role played by each parameter. This clearly shows the importance of gas diffusion in the regeneration process.

A lumped parameter model for diesel soot morphology evaluation and emission control

“…In this work, we consider a small diesel engine, thus the exhaust is characterized by low velocities and low Pe numbers. 7 Table 3 reports the main values related to soot deposition, computed by means of equations ( 16), (19) and (22). The value for porosity is kept constant and equal to 0.97, due to the low Pe numbers in all the engine conditions: 7 the value of u w for Pe computation is obtained by means of the LP predictions performed with Darcy's equation: the values of Pe reported in Table 3 are the average values along the channel.…”

“…Starting from the soot deposit properties, like permeability, thickness and activation energy, the temperature trends during regeneration can be predicted. 18,19 In previous works, 8,20 a lumped parameter model was developed to predict pressure losses during loading and temperature trends during regeneration, accounting for soot layer thickness variation along the axis of the diesel filter. The trend of deposited soot is recovered by means of 3D-CFD (computational fluid dynamics) works 21,22 and experimental measures.…”

Assessment by means of gas dynamic modelling of a pre-turbo diesel particulate filter configuration in a turbocharged HSDI diesel engine under full-load transient operation

“…Most filters are made of ceramic substrates conforming to honeycomb wall-flow monoliths [6] with high filtration efficiency and less penalty on fuel consumption due to the combination of active regeneration techniques and passive solutions [7]. In this regard, future developments are devoted to obtaining long mechanical and chemical durability, looking for an increase in the capacity for ash accumulation [8], multifunctional monolith reactors [9,10], advances in catalysts with regard to porous ceramic materials [11], characterization of soot for filtration efficiency and regeneration improvement [12,13], or novel multi-functional configurations of the exhaust line involving the DPF placement upstream of the turbine [14,15].…”

“…In this regard, future developments are devoted to obtain long mechanical and chemical durability looking for an increase of the capacity for ash accumulation [8], multifunctional monolith reactors [9][10], advances in catalyst for porous ceramic materials [11], characterisation of soot for filtration efficiency and regeneration improvement [12] [13] or novel multi-functional configurations of the exhaust line involving the DPF placement upstream of the turbine [14] [15].…”

Degradation Resistance of Cordierite Diesel Particulate Filters to Diesel Fuel Ash Deposits

“…Particulate matter combustion is, of course, a highly exothermic reaction, and if uncontrolled, can cause local temperature increases well above 1000°C. 8 As a result of multiple regenerations, a residual ash comprising the contaminant oxides from the lubricating oil, iron from engine abrasion, and oxides from catalytic fuel additives, will remain on and in the wall of the filter. At elevated temperatures (>1100°C), which may be generated during in situ incineration, this residual ash may react with the ceramic structure.…”