Comparison of the use of real diesel soot and soot surrogate in the performance analysis of diesel particulate filters

Abstract

In fundamental diesel particulate filter (DPF) research, carbon black surrogates like Printex U (PU) are often chosen for practicality, availability, cost-effectiveness, and safety; however, it is crucial to recognize their differences, and this study aims to fill this gap in the existing literature. Comparative findings reveal that diesel soot forms a denser soot-loaded substrate and soot cake, attributed to its smaller particle size, broader size distribution, and presence of soluble organic fractions. Conversely, PU carbon black-formed layers exhibit higher porosity, leading to reduced packing density and pressure drop, culminating in an earlier particle layer collapse during regeneration. Despite this, PU and PU-coated DPFs effectively replicate key characteristics of soot and soot-coated DPFs, as evidenced by their lower carbon content, increased oxygen content, reduced activation energy following thermal aging, and enhanced regeneration efficiency at lower soot loads and higher regeneration temperatures. Consequently, PU carbon black can be deemed a credible surrogate for real diesel soot in foundational DPF studies, furnishing valuable insights for optimizing DPF performance and diesel engine emission control. It is also noteworthy that PU is more suited as a surrogate for aged or dry soot rather than fresh soot, as the high concentrations of soluble organic fractions in the latter can significantly impact its oxidation characteristics and the regeneration performance of DPFs loaded with fresh soot.