Optimisation of mixing performance of helical ribbon mixers for high throughput applications using computational fluid dynamics

Mihailova, Olga; Mothersdale, Thomas; Rodgers, Thomas L.; Ren, Zhen; Watson, S.J.; Lister, Vincent Y.; Kowalski, Adam

doi:10.1016/j.cherd.2018.01.053

Cited by 13 publications

(11 citation statements)

References 27 publications

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“…Where, ߛሶ is the shear rate (s -1 ), η is the viscosity (Pa.s), K is the consistency coefficient (-), and n is the power law coefficient (-), whereby the specific K and n values for CMC solution are 0.1215 and 0.784, respectively (R 2 = 0.965) [35].…”

Section: Preparation Of Experimental Fluids and Rheological Charactermentioning

confidence: 99%

Characterisation of flow behaviour and velocity induced by ultrasound using particle image velocimetry (PIV): Effect of fluid rheology, acoustic intensity and transducer tip size

O’Sullivan

Espinoza

Mihailova

et al. 2018

Ultrasonics Sonochemistry

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Acoustic streaming phenomena of ultrasound propagation through liquid media was investigated experimentally employing particle image velocimetry (PIV). Parameters associated with the ultrasonic processor of ultrasonic amplitude (i.e., acoustic power) and transducer tip diameter (i.e., surface area), as well as, fluid rheology (i.e., water, glycerol solution and CMC solution), were studied for their effects on overall flow behaviour and fluid velocity. PIV yielded velocity gradient maps, demonstrating the acoustic streaming phenomena of ultrasound and its associated flow behaviour as a function of ultrasonic amplitude and fluid rheology, whereby increasing amplitude allowed for greater penetration of the acoustic-beam through the bulk of the fluid, and increasing fluid rheology yielded the converse effect. Moreover, upon impingement of the acoustic-beam with the base of vessel, vortex formation occurred, yielding a recirculation pattern. The maximum observed fluid velocities for water, glycerol solution and CMC solution were 0.329 m s, 0.423 m s, and 0.304 m s, respectively (large diameter sonotrode tip for an ultrasonic amplitude of 80%). Furthermore, shear rates were attained (maximum values of 24.25 s), and Reynolds numbers were determined in order to assess the degree of turbulence as a function of investigated parameters.

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Section: Preparation Of Experimental Fluids and Rheological Charactermentioning

confidence: 99%

Characterisation of flow behaviour and velocity induced by ultrasound using particle image velocimetry (PIV): Effect of fluid rheology, acoustic intensity and transducer tip size

O’Sullivan

Espinoza

Mihailova

et al. 2018

Ultrasonics Sonochemistry

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“…Based on the numerical analysis with the use of DEM and the experimental results, Pezo et al [ 35 ] determined a mathematical model in the form of second order polynomial and artificial neural network model describing the quality of mixing in a double-screw mixer. In the paper [ 36 ], Mihailova et al demonstrated using computational fluids dynamics (CFD) that mixer height is a key parameter influencing mixing performance. The influence of some design features of mixing elements on mixing efficiency in cylindrical mixer with use of DEM was presented in [ 37 ] showing, that three bladed mixer has better performance that mixer with two or four blades.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies of the Interaction between Screw Surface and Material in the Mixer

et al. 2021

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Mixing is one of the most commonly used processes in food, animal feed, chemical, cosmetic, etc., industries. It is supposed to provide high-quality homogenous, nutritious mixtures. To provide appropriate mixing of materials while maintaining the process high efficiency and low energy consumption it is crucial to explore and describe the material flow caused by the movement of mixing elements and the contact between particles. The process of mixing is also affected by structural features of the machine components and the mixing chamber, speed of mixing, and properties of the mixed materials, such as the size of particles, moisture, friction coefficients. Thus, modeling of the phenomena that accompany the process of mixing using the above-listed parameters is indispensable for appropriate implementation of the process. The paper provides theoretical power calculations that take into account the material speed change, the impact of the material friction coefficient on the screw steel surface and the impact of the friction coefficient on the material, taking into account the loading height of the mixing chamber and the chamber loading value. Dependencies between the mixer power and the product degree of fineness, rotational speed of screw friction coefficients, the number of windings per length unit, and width of the screw tape have been presented on the basis of a developed model. It has been found that power increases along with an increase in the value of these parameters. Verification of the theoretical model indicated consistence of the predicted power demand with the power demand determined in tests performed on a real object for values of the assumed, effective loading, which was 65–75%.

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“…Therefore, many kinds of mixing equipment and methods were developed to promote laminar mixing. A large impeller like helical ribbon impeller is used to improve laminar mixing (Carreau et al, 1976;Furukawa et al, 2013;Kato et al, 2015;Kato et al, 2018;Mihailova et al, 2018). Another method is unsteady mixing method (Murakami et al, 1980;Kato et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Mixing Performance of Inner Baffle in Shear Thinning Fluid

2021

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A mixing performance of an inner baffle was investigated in shear thinning fluid. The inner baffle was placed with a clearance between baffle and vessel wall. A traditional two-bladed paddle impeller was used. Four planar baffles were vertically placed in two ways: 1) standard baffle condition 2) inner baffle condition. The standard baffle condition was that the baffle was placed on the mixing vessel wall. A mixing pattern was visualized by decolorization method based on an oxidation-reduction reaction with sodium thiosulfate and iodine. Flow field for shear thinning fluid in mixing vessel was measured by particle image velocimetry and was shown as stream line. A pair of isolated mixing regions (IMR) like doughnut-ring formed above and below the impeller under standard baffle condition. However, IMR dissipated under inner baffle condition. As a result, a mixing time under the inner baffle condition was drastically decreased. This study suggested that inner baffle promoted mixing in shear thinning fluid.

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Optimisation of mixing performance of helical ribbon mixers for high throughput applications using computational fluid dynamics

Abstract:  98 Helical mixer designs were screened using STAR-CCM+ and HEEDS package  Experimental validation was performed using ERT and torque measurements  Statistical analysis revealed key design features affecting mixer performance

Cited by 13 publications

References 27 publications

Characterisation of flow behaviour and velocity induced by ultrasound using particle image velocimetry (PIV): Effect of fluid rheology, acoustic intensity and transducer tip size

Characterisation of flow behaviour and velocity induced by ultrasound using particle image velocimetry (PIV): Effect of fluid rheology, acoustic intensity and transducer tip size

Theoretical Studies of the Interaction between Screw Surface and Material in the Mixer

Mixing Performance of Inner Baffle in Shear Thinning Fluid

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