Laminar Mixing in Stirred Tank Agitated by an Impeller Inclined

Takahashi, Koji; Sugo, Yoshiharu; Takahata, Yasuyuki; Sekine, Hitoshi; Nakamura, Masayuki

doi:10.1155/2012/858329

Cited by 19 publications

(12 citation statements)

References 10 publications

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“…In order to enhance mixing under laminar condition, many works have been reported about the advantage of utilizing unsteady impeller motion. − Yao et al adopted two unsteady stirring approaches, coreverse periodic rotation and time-periodic variation of rotational speed, to enhance global mixing in a stirred tank with highly viscous fluid. Nomura et al also revealed that coreverse rotation of the impeller prevented the formation of a segregated mixing region and reduced mixing time.…”

Section: Introductionmentioning

confidence: 99%

“…Spatial disturbance places less demanding requirements on the machinery, so it has been widely applied in industry. Takahashi et al found that the effectiveness of setting the impeller inclined is verified through the comparison of mixing time obtained over a vertical setting impeller. Hidalgomillán et al obtained little effect of eccentricity when they investigated geometrical perturbations by using two coaxial impellers under off-centered conditions in the laminar regime, but obtained the best results with a novel configuration consisting of a dual turbine with connecting plates.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced Micromixing of Non-Newtonian Fluids by a Novel Zigzag Punched Impeller

Yang

Zhang

Mao

et al. 2019

Ind. Eng. Chem. Res.

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In this work, a novel impeller with zigzag punched blades is developed to produce impinging jet streams from face-to-face holes to enhance mixing in a 0.282 m diameter baffled stirred tank. The micromixing experiments on non-Newtonian fluids are conducted to compare among standard six straight blade turbine (DT), down-pumping pitched blade turbine (PBTD-45°) and our novel zigzag punched impeller (ZPI). Results show that at low Reynolds numbers (700 < Re < 3000), the segregation index of ZPI is the lowest. It shows that the ZPI exhibits higher micromixing performance than other two traditional ones. Moreover, the effect of geometric parameters of blade like holes size, single section length of paddle and the zigzag angle of the novel zigzag impeller on micromixing are also investigated. It is found that the ZPI with larger zigzag angle, shorter single section length and smaller holes leads to significant improvement on micromixing efficiency.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced Micromixing of Non-Newtonian Fluids by a Novel Zigzag Punched Impeller

Yang

Zhang

Mao

et al. 2019

Ind. Eng. Chem. Res.

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“…Numerous research reports have been published on the mixing times of stirred tanks with other types of impellers. The mixing time in a stirred tank can be measured experimentally using the electron conductivity method (Bujalski et al, 2002a;Giona et al, 2002), decolorization method (Aizawa et al, 2009;Takahashi et al, 2012), electrical resistance tomography (Rodgers et al, 2009(Rodgers et al, , 2011, planar laser induced fluorescence (PLIF) (Zadghaffari et al, 2009;Hu et al, 2012), and thermographic technique (Lee and Yianneskis, 1997). Ascanio (2015) summarized the methods, theories, and advantages and disadvantages of these experimental measurement techniques in detail.…”

Section: Introductionmentioning

confidence: 99%

Mixing Process in a Tank Stirred with Improved Double Intermig Impellers

Zhou

Wang

et al. 2019

J. Chem. Eng. Japan

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The mixing process in a 0.42-m diameter transparent stirred tank with improved double Intermig impellers was experimentally studied using the decolorization method with four di erent tracer injection points. The time dependence of the tracer concentration distribution was recorded using a high-speed camera. The turbulent ow and tracer dispersion were calculated by a large eddy simulation (LES) combined with the dynamic Smagorinsky-Lilly model. The tracer di usion process, tracer concentration response, and mixing time in the tank stirred with the improved double Intermig impellers were investigated. The results showed that the mixing process predicted by LES was consistent with that by the decolorization method experiment. The predicted mixing time was 14% longer than the experimental time. The mixing time was the shortest when the injection point was in the middle of two impellers. The mixing time increased when the injection point moved to the top or bottom of the tank. The mixing times at the monitoring points near the injection point were shorter than those at distant points. The bottom of the tank with the improved double Intermig impellers was the crucial region that was di cult to mix. The mixing times at the monitoring points at the bottom were the longest for all the injection points. Increasing the mixing speed could promote the mixing process of the medium in the stirred tank and reduce the mixing time without changing the ow eld structure. Therefore, the results could serve as a guide for the design and engineering application of such a stirred tank.

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“…With the rapid development of computer science, Computational Fluid Dynamics (CFD) has been widely employed to help in predicting flow distribution and mixing performance, which greatly promotes advances of the mixing studies [12,13] . Takahashi et al [14] conducted CFD simulation to study impacts of mixing paddles with different slopes on SRs and mixing time, without the investigation the blade's geometry. Qiao et al [15] studied effects of geometrical design and physical property on mixing quality of floating solids in the up-pumping PBT stirred tanks by using CFD technique qualitatively, didn't conduct the blade's optimal design.…”

Section: Introductionmentioning

confidence: 99%

Computational and experimental investigation of laminar flow mixing system in a pitched-blade turbine stirred tank

Cui

Zhang

et al. 2018

International Journal of Agricultural and Biological Engineering

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The flow distribution and mixing performance of the laminar flow in the PBT impeller-stirred tank were investigated in this study. The variation along with mixing time of the flow distribution and concentration at the selected positions was visualized by means of the CFD and experiment methods. The CFD simulations results had a good agreement with the experimental results. In order to minish the Segregated Regions, the PBT impeller was optimally designed by means of orthogonal factorial experiment with selecting the θ 99 mixing time as evaluation criteria. With the aim to increase the mixing efficiency, the optimal design results were obtained with the geometrical parameters of impeller diameter of 0.084 m, discharge angle of 45º, blade width of 0.018 m, and clearance of 0.05 m, and the mixing time of the optimal impeller-stirred flow was about 180 s, so this optimal design PBT impeller is more proper for the agricultural industries.

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Laminar Mixing in Stirred Tank Agitated by an Impeller Inclined

Cited by 19 publications

References 10 publications

Enhanced Micromixing of Non-Newtonian Fluids by a Novel Zigzag Punched Impeller

Enhanced Micromixing of Non-Newtonian Fluids by a Novel Zigzag Punched Impeller

Mixing Process in a Tank Stirred with Improved Double Intermig Impellers

Computational and experimental investigation of laminar flow mixing system in a pitched-blade turbine stirred tank

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