Model studies on mixers in the viscous flow region

Hoogendoorn, C. J.; Hartog, A.P. den

doi:10.1016/0009-2509(67)80204-5

Cited by 132 publications

(46 citation statements)

References 2 publications

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“…Thus, the optimum ratio of w/D = 0.102 was obtained for the anchor impeller. The optimum w/D and c/D ratios determined in this study were in good agreement with those reported in the literature [12,18,20,28,29,45]. These results also support that the modified Herschel-Bulkley model was good enough to describe the rheology of the yield-pseudoplastic fluid used in this study.…”

Section: Resultssupporting

confidence: 92%

CFD Investigation of the Mixing of Yield‐Pseudoplastic Fluids with Anchor Impellers

Prajapati

Ein‐Mozaffari

2009

Chem Eng & Technol

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The study was carried out to simulate the 3D flow domain in the mixing of pseudoplastic fluids possessing yield stress with anchor impellers, using a computational fluid dynamics (CFD) package. The multiple reference frames (MRF) technique was employed to model the rotation of the impellers. The rheology of the fluid was approximated using the Herschel-Bulkley model. To validate the model, the CFD results for the power consumption were compared to the experimental data. After the flow fields were calculated, the simulations for tracer homogenization were performed to simulate the mixing time. The effects of impeller speed, fluid rheology, and impeller geometry on power consumption, mixing time, and flow pattern were explored. The optimum values of c/D (impeller clearance to tank diameter) and w/D (impeller blade width to tank diameter) ratios were determined on the basis of minimum mixing time.

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Section: Resultssupporting

confidence: 92%

CFD Investigation of the Mixing of Yield‐Pseudoplastic Fluids with Anchor Impellers

Prajapati

Ein‐Mozaffari

2009

Chem Eng & Technol

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“…This relationship is expected given that the bulk impeller is larger and is located in a position that has been proven to increase mixing efficiencies (Shiue and Wong, 1984). Mixing times appear to correlate well with data from a previous studies (Hoogendoorn and den Hartog, 1967;Shiue and Wong, 1984).…”

Section: Effect Of Mini-impeller Upon Mixing Timesupporting

confidence: 79%

A critical assessment of the impact of mixing on dilution refolding

Mannall

Titchener‐Hooker

Chase

et al. 2005

Biotech & Bioengineering

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Refolding often presents a bottleneck in the generation of recombinant protein expressed as inclusion bodies. Few studies have looked at the effect of physical factors on the yield from refolding steps. Refold reactors typically operate in fed-batch mode with a slow injection rate. This paper characterizes mixing in a novel reactor, and seeks to relate the conditions of mixing to native lysozyme yields after refolding. A novel twin-impeller system incorporating a mini-paddle impeller located in the vicinity of the injection point was used to increase the local levels of energy dissipation experienced by the injected material, and to improve refolding yields. Mixing only affected yields during and immediately after denatured protein addition. Analysis of lysozyme refolding yield, under a variety of conditions, revealed that dispersive mixing affected the yield. The beneficial effect of the mini-paddle impeller in providing a source of localized energy dissipation was limited to conditions where the bulk impeller intensity was low. The effects appeared to become more significant when injection times were longer, because of increased exposure of the injected material to the energy dissipation of the mini-impeller. The results suggest that for fed-batch protein refolding systems, where mixing has been shown to be a critical factor, the local energy dissipation experienced in the vicinity of the injection point is critical to the refolding yields.

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“…• Reynolds Number (concerning the ratio of inertial and viscous forces) • Power Number (power dissipated in the liquid mixing related to impeller properties) 8 • Fourier Number (for comparison of mixing time) 5 .…”

Section: Methodsmentioning

confidence: 99%

Improving the Effectiveness of Isinglass Finings for Beer Clarification by Optimisation of the Mixing Process. Part 1: Laboratory Scale Experiments

Freeman¹,

Gourrierec

Patel

et al. 2003

Journal of the Institute of Brewing

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In order to optimise the process of fining beer there is a need to model the process in terms of addition, mixing and flocculation. Mixing of beer and finings has been achieved in a small laboratory stirred vessel that enables exact characterisation of the shear conditions and residence time. The performance of the finings was evaluated after settling in Imhoff cones. Results identified an optimum mixing regime comprising two stages; a relatively vigorous and short duration first mix followed by a longer more gentle mix.

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Model studies on mixers in the viscous flow region

Cited by 132 publications

References 2 publications

CFD Investigation of the Mixing of Yield‐Pseudoplastic Fluids with Anchor Impellers

CFD Investigation of the Mixing of Yield‐Pseudoplastic Fluids with Anchor Impellers

A critical assessment of the impact of mixing on dilution refolding

Improving the Effectiveness of Isinglass Finings for Beer Clarification by Optimisation of the Mixing Process. Part 1: Laboratory Scale Experiments

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