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Simulation of Aggregation with Applications to Soot Laden Lubricating Fluids
Author(s) -
Zeidan Michael,
Jia Xiaodong,
Williams Richard A.,
Wedlock David J.
Publication year - 2005
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.200400895
Subject(s) - soot , fractal dimension , aggregate (composite) , materials science , lubricant , dispersant , dispersion (optics) , viscosity , fractal , particle (ecology) , composite material , chemical engineering , mechanics , chemistry , combustion , engineering , geology , physics , organic chemistry , mathematics , mathematical analysis , oceanography , optics
The requirement for heavy duty diesel engines to reduce the level of NOx emissions has resulted in higher soot loading of engine lubricants due to fuel injection retardation and exhaust gas re‐circulation. An improved understanding of the process of soot aggregation and aggregate morphology is therefore required to provide an insight into the consequences of soot‐laden lubricants. These include the effects of dispersant architecture and soot loading rate on aggregate morphology. A 2D and 3D study using a semi‐quantitative random walk based simulation model into the evolution of simulated fractal‐like colloidal aggregates has been carried out and applied to address these issues. The effects of variable soot loading rates, which are engine dependent, are reported. The role of different interaction forces which are, among other things, engine temperature and lubricant formulation dependent is explored. Differences between the simulations run under the same conditions but in different dimensions are highlighted and their implications discussed. The data indicate that a correlation can be established between inter‐particle forces (represented via a sticking probability) and both aggregate morphology (represented by fractal dimension) and aggregate dispersancy and the degree of dispersion of those aggregates (measured by the mean empty space parameter). Significantly, a strong relationship was found between soot‐loading rate and aggregate morphology, with higher loading rates leading to both a much lower fractal dimension and a higher degree of aggregate dispersion, which in turn would lead to a higher lubricant viscosity.