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Mixing
Published in Ko Higashitani, Hisao Makino, Shuji Matsusaka, Powder Technology Handbook, 2019
As mentioned previously, mixing progresses by the convective mixing, the shearing mixing and the diffusive mixing. The progress of the mixing can be described schematically by Figure 5.8.2. In the normal mixing devices, the convective mixing takes place at the initial stage of the mixing, where the mass of powder largely moves inside the vessel (macro mixing), followed by the shearing mixing. In these stages, the mixing rate can be expressed as follows; σσ0=exp(−kt)
Mixing and Packing of Powders
Published in Mohamed N. Rahaman, Ceramic Processing, 2017
The mechanisms of mixing are usually classified into three types: diffusive, shear, and convective mixing [9]. Diffusive mixing occurs when neighboring particles exchange places, such as when particles roll down a sloping surface. In shear mixing, shear stresses give rise to slip zones and mixing occurs by interchange of particles between layers within the zones. Convective mixing occurs by transport of groups of particles from one region of the powder mass to another. These mechanisms cannot be completely separated and all three occur to some extent in a given process. Different mixers, however, show different predominating mechanisms.
Granulation, Mixing, and Packing of Particles
Published in Mohamed N. Rahaman, Ceramic Processing, 2017
The mechanisms of mixing are usually classified into three types: diffusive, shear, and convective mixing [11]. Diffusive mixing occurs when neighboring particles exchange places, such as when particles roll down a sloping surface. In shear mixing, shear stresses give rise to slip zones and mixing occurs by interchange of particles between layers within the zones. Convective mixing occurs by transport of groups of particles from one region of the powder mass to another. These mechanisms cannot be completely separated, and all three occur to some extent in a given process. Different mixers, however, show different predominating mechanisms.
Simulation based investigation of 2D soft-elastic reactors for better mixing performance
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Changyong Li, Stefan Gasow, Yan Jin, Jie Xiao, Xiao Dong Chen
To analyse differences better in the mixing performance of SERs with different values of , the effects of convective and diffusive mixing are considered in the mixing process. Convective mixing involves the bulk movement of the fluid. Diffusive mixing is caused by random motion of molecules. Generally, the mixing rate by diffusion is low compared with convection (Levy & Kalman, 2001). In the present model, owing to the small diffusion coefficient, convection is considered to be a main factor in the mixing; the rate of convective mass transfer is dependent on the extent of the fluid flow.