Authors: Casper Lindberg, Manoel Y. Manuputty, Edward K. Y. Yapp, Jethro Akroyd, Rong Xu, and Markus Kraft*

• New multivariate PBM with detailed morphological description of titania aggregates.
• Overlapping spheres model of aggregates, resolving position of individual primaries.
• Particles evolve under inception, condensation, coagulation and sintering.
• Convergence behaviour investigated for a batch reactor test case.
• Experimental hot-wall reactor simulated.

The mathematical description of a new detailed particle model for polydisperse aggregate particles is presented. An aggregate particle is represented as a collection of overlapping spherical primary particles and the model resolves the composition, radius and position coordinates of each individual primary to form a detailed geometrical description of aggregate morphology. Particles transform under inception, coagulation, surface growth, sintering and coalescence processes. The new particle description is used to model the aerosol synthesis of titanium dioxide (TiO₂) aggregates from titanium tetraisopropoxide (TTIP) precursor. TiO₂ particles are formed through collision-limited inception and growth reactions of Ti(OH)₄ from the gas-phase, produced from the thermal decomposition of TTIP. Coupling between the particle population balance and detailed gas-phase chemistry is achieved by operator splitting. A numerical study is performed by simulating a simple batch reactor test case to investigate the convergence behaviour of key functionals with respect to the maximum number of computational particles and splitting time step. Finally, a lab-scale hot wall reactor is simulated to demonstrate the advantages of a detailed geometrical description. Simulated particle size distributions were in reasonable agreement with experimental data. Further evaluation of the model and a parametric sensitivity study are recommended.

• This paper draws from preprint 215: A detailed particle model for polydisperse titanium dioxide aggregates
• Access the article at the publisher: DOI: 10.1016/j.jcp.2019.06.074

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