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Communication Dans Un Congrès Année : 2022

Approximating the van der Waals interaction potentials between agglomerates and their coagulation enhancement

Résumé

The van der Waals (vdW) forces between fine and ultrafine powders are due to the interaction between permanent or induced dipoles or multipoles. These forces play an important role in powder handling, filtration of colloidal particles, resuspension, restructuring, and agglomeration. While vdW forces between spherical particles and their collision enhancement effect is well understood (Ouyang et al., 2012), interactions between agglomerates is still an ongoing topic of research (Neumann & Bunz, 1993; Babick et al., 2011; De Martin & van Ommen, 2013). The vdW interactions between agglomerates having 2 different morphologies are studied: this includes hollow raspberry-like aggregates (primary particles in a 2d spherical configuration) and diffusion-limited aggregates (DLCA) with a fractal dimension of 1.78. They are generated by a discrete element code (Morán et al., 2020). The role played by their fractal-like structure, their anisotropy, and their finite size on the resulting vdW interaction potentials is investigated. Comparison between simple functions (e.g., volume-equivalent sphere) to predict their interactions and new improved equations are proposed (see Fig. 1). These equations are used to predict the coagulation enhancement of agglomerated powders and the results are validated by comparison with first-time passage Langevin Dynamics simulations (Gopalakrishnan and Hogan, 2011). In these simulations, the role played by agglomerates rotation (typically neglected in the literature) is also investigated. Equations to predict the coagulation enhancement as a function of the agglomerates Hamaker’s constants and morphological parameters are proposed. These equations can be directly used in Population Balance simulations of powders agglomeration relevant for particles transport, pollutant formation, pharmaceutical/food granulation, and metal powders synthesis.
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Dates et versions

hal-04518792 , version 1 (24-03-2024)

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  • HAL Id : hal-04518792 , version 1

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Jerôme Yon, José Morán, M. Reza Kholghy. Approximating the van der Waals interaction potentials between agglomerates and their coagulation enhancement. World Congress on particle technology - WCPT9, Sep 2022, Madrid, Spain. ⟨hal-04518792⟩
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