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Precipitation of a solid product from aqueous ionic solutions, including mixing, fast chemical reaction, nucleation, growth and agglomeration of crystals is considered. This work concentrates on the phenomenon of particle agglomeration which dominates the precipitation process at high supersaturation. Modeling of particle collision includes effects of bulk fluid motion, Brownian diffusion and colloidal forces for particles of equal and unequal size. The concept of probability of agglomeration based on multifractal formalism is introduced and applied. A simplified version of the model is linked to CFD and results of computations are compared with experimental data for barium sulfate precipitation.

To enhance oil’s tribological and rheological properties, various nano-additives are used. An example of such a nano-additive is nanosized molybdenum disulfide (MoS2). Due to its unique properties, MoS2-based materials used as lubricants have attracted significant attention. In our previous work, we developed a novel, scalable, and low-cost method for MoS2-based materials production using an impinging jet reactor. Hybrid nanostructures based on MoS2 and carbon nanomaterials (MoS2/CNMs) decreased the friction factor of the base oil. In the present study, a mathematical model that accounts for the viscous heating effects in rheograms was formulated. The model was used to interpret the results of rheological measurements conducted for the base oil 10W40 and its mixtures with different nanosized lubricant additives. The model of the non-isothermal Couette flow allowed us to correct the rheograms of the engine oils in the region of high shear rates where viscous heating effects become significant. The temperature correlations for the consistency and flow behavior indexes were proposed. The nanohybrid suspensions of MoS2 in the base oil were found to have the lowest apparent viscosity at low temperatures, typical for the cold engine startup.

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