Effect of soot layer microstructure on diesel particulate filter regeneration

Diesel particulate filter (DPF) behavior depends strongly on the microstructural properties of the deposited soot aggregates. In the past the issue of the growth process of soot deposits in honeycomb ceramic filters has been addressed under nonreactive conditions, and the influence of the filter operating conditions has been defined in terms of the dimensionless Peclet number. Appropriate soot cake microstructural descriptors are studied under reactive conditions for different oxidation modes. To this end the effect of deposit microstructure on the soot oxidation kinetics is investigated. Different microstructural models for the reacting soot deposit are examined in a unified fashion and a generalized constitutive equation is obtained, describing several modes of microstructure evolution (shrinking layer, shrinking density, discrete columnar and continuous columnar). Understanding the structural evolution of soot deposits during oxidation is of major importance for intelligent operation and simulation of DPFs, and for practical estimation of their soot mass load. © 2005 American Institute of Chemical Engineers AIChE J, 2005