Viscoelastic flow instabilities in static mixers: Onset and effect on the mixing efficiency

Liquid-liquid emulsions will undergo a phase inversion, in which the dispersed phase becomes the continuous phase and vice versa, under certain conditions. A phase inversion is not a smooth transition and an emulsion close to the inversion point may oscillate back and forth between the oil-in-water (O/W) and water-in-oil (W/O) forms, creating flow instabilities that may be detrimental in certain industrial situations. The results of laboratory laminar flow experiments in which an aqueous and an organic liquid phase are emulsified as they flow through a circular tube containing a commercial high-shear static mixer are discussed. As the concentration of the dispersed phase and/or its flow rate is increased, flow instabilities are initiated in the test-section and are measured as fluctuations in pressure drop. The intensity of these fluctuations reaches a maximum as the liquid-liquid system approaches the phase inversion point. Once a stable phase inversion is achieved, the fluctuations subside. This phenomenon was observed over a wide range of viscosity ratios for the two liquid phases, but was absent for low viscosity ratios and low-shear static mixers.

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Mixing Efficiency and Residence Time Distributions of a Side-Injection Tubular Reactor Equipped with Static Mixers

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.1c00575 ◽

2021 ◽

Author(s):

Jody Albertazzi ◽

Federico Florit ◽

Valentina Busini ◽

Renato Rota

Keyword(s):

Residence Time ◽

Tubular Reactor ◽

Mixing Efficiency ◽

Static Mixers ◽

Residence Time Distributions

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Granular flow in static mixers by coupled DEM/CFD approach

Hemijska industrija ◽

10.2298/hemind151013060p ◽

2016 ◽

Vol 70 (5) ◽

pp. 539-546 ◽

Cited By ~ 1

Author(s):

Lato Pezo ◽

Milada Pezo ◽

Aca Jovanovic ◽

Nenad Kosanic ◽

Aleksandar Petrovic ◽

...

Keyword(s):

Granular Flow ◽

Fluid Dynamic ◽

Mixing Time ◽

Numerical Approach ◽

Mixing Efficiency ◽

Multiphase Model ◽

Static Mixer ◽

Mixing Process ◽

Static Mixers ◽

Relative Standard

The mixing process greatly influence the mixing efficiency, as well as the quality and the price of the intermediate and/or the final product. Static mixer is used for premixing action before the main mixing process, for significant reduction of mixing time and energy consumption. This type of premixing action is not investigated in detail in the open literature. In this article, the novel numerical approach called Discrete Element Method is used for modelling of granular flow in multiple static mixer applications (1 - 3 Komax or Ross mixing elements were utilized), while the Computational Fluid Dynamic method was chosen for fluid flow modelling, using the Eulerian multiphase model. The main aim of this article is to predict the behaviour of granules being gravitationally transported in different mixer configuration and to choose the best configuration of the mixer taking into account the total particle path, the number of mixing elements and the quality of the obtained mixture. The results of the numerical simulations in the static mixers were compared to experimental results, the mixing quality is examined by RSD (relative standard deviation) criterion, and the effects on the mixer type and the number of mixing elements on mixing process were studied. The effects of the mixer type and the number of mixing elements on mixing process were studied using analysis of variance (ANOVA). Mathematical modelling is used for optimization of number of Ross and Komax segments in mixer in order to gain desirable mixing results.

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Ion Beam Mixing of Ni-Ti Bilayered Thin Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118345 ◽

1985 ◽

Vol 43 ◽

pp. 290-291

Author(s):

A. K. Rai ◽

R. S. Bhattacharya ◽

M. H. Rashid

Keyword(s):

Crystal Structure ◽

Thin Films ◽

Amorphous Alloys ◽

Ion Beam ◽

Ion Bombardment ◽

High Energy ◽

Mixing Efficiency ◽

Ion Beam Mixing ◽

Enhanced Diffusion ◽

Binary Metal

Ion beam mixing has recently been found to be an effective method of producing amorphous alloys in the binary metal systems where the two original constituent metals are of different crystal structure. The mechanism of ion beam mixing are not well understood yet. Several mechanisms have been proposed to account for the observed mixing phenomena. The first mechanism is enhanced diffusion due to defects created by the incoming ions. Second is the cascade mixing mechanism for which the kinematicel collisional models exist in the literature. Third mechanism is thermal spikes. In the present work we have studied the mixing efficiency and ion beam induced amorphisation of Ni-Ti system under high energy ion bombardment and the results are compared with collisional models. We have employed plan and x-sectional veiw TEM and RBS techniques in the present work.

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