Ultra-small-angle X-ray scattering characterization of diesel/gasoline soot: sizes and particle-packing conditions
Regulations on particulate emissions from internal combustion engines tend to become more stringent, accordingly the importance of particulate filters in the after-treatment system has been increasing. In this work, the applicability of ultra-small-angle X-ray scattering (USAXS) to diesel soot cake and gasoline soot was investigated. Gasoline-direct-injection engine soot was collected at different fuel injection timings. The unified fits method was applied to analyze the resultant scattering curves. The validity of analysis was supported by comparing with carbon black and taking the sample images using a transmission electron microscope, which revealed that the primary particle size ranged from 20 to 55 nm. In addition, the effects of particle-packing conditions on the USAXS measurement were demonstrated by using samples suspended in acetone. Then, the investigation was extended to characterization of diesel soot cake deposited on a diesel particulate filter (DPF). Diesel soot was trapped on a small piece of DPF at different deposition conditions which were specified using the Peclet number. The dependence of scattering curve on soot-deposition conditions was demonstrated. To support the interpretation of the USAXS results, soot cake samples were observed using a scanning electron microscope and the influence of particle-packing conditions on scattering curve was discussed.
KeywordsUltra-small-angle X-ray scattering Diesel particulate filter Gasoline-direct-injection engine soot Soot cake Particle deposition Unified fits method
- Braun A, Ilavsky J, Seifert S, Jemian PR (2005) Deformatioin of diesel soot aggregates as a function of pellet pressure: a study with ultra-small-angle x-ray scattering. J Appl Phys 98:073513-1–073513-5Google Scholar
- Glatter O, Kratky O (1982) Small-angle X-ray scattering. Academic Press, New YorkGoogle Scholar
- Konstandopoulos AG, Skaperdas E, Masoudi M (2002) Microstructural properties of soot deposits in diesel particulate traps. SAE Technical Paper 2002-01-1015. doi:10.4271/2002-01-1015
- Lee H, Lee K (2013) Development of a 3-D model for analyzing the effects of channel geometry on filtration characteristics in particulate filter system. SAE Technical Paper 2013-01-1583. doi:10.4271/2013-01-1583
- Maricq MM, Podsiadlik D, Brehob D, Haghgooie M (1999) Particulate emissions from a direct-injection spartk-ignition (DISI) engine. SAE Technical Paper 1999-01-1530. doi:10.4271/1999-01-1530