Mixing of fluids with dissimilar viscosities in Confined Impinging Jets

Brito, M.S.C.A.; Esteves, Luís; Fonte, Cláudio P.; Dias, Madalena M.; Lopes, José Carlos B.; Santos, Ricardo J.

doi:10.1016/j.cherd.2018.04.020

Cited by 12 publications

(7 citation statements)

References 18 publications

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“…According to Li et al [30], the onset of the impingement point position is determined by injectors' velocity profile and the jets' Reynolds number. A similar chaotic flow regime was first identified for confined impinging jets (CIJs), setting two necessary operational conditions: the jets Reynolds number should be above 120, and the opposed jets had to be balanced [26][27][28]. For T-jets mixers, the issue of the opposed jets balancing and mixing fluids with dissimilar properties or at different flow rates remains unexplored for chaotic flow regimes.…”

Section: Effect Of Reynolds Number On Mixing Of Similar Fluidsmentioning

confidence: 90%

“…A viscosity ratio of 3 is finally tested, and the mixing dynamics are reported from PLIF images (Case 2). The glycerol solutions were designed according to the method proposed in Brito et al [28] for refractive index matching, which is essential for PLIF images of flows with two fluids to minimize reflection, refraction, and diffraction. The first step is measuring the refractive index of the more viscous aqueous solution of glycerol, i.e., the MV fluid.…”

Section: Working Fluidsmentioning

confidence: 99%

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Flow Regimes and Mixing of Dissimilar Fluids in T‐Jets Mixers

et al. 2022

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Efficient mixing conditions for similar fluids in T-Jets mixers are well-established. This paper extends the characterization of the mixing of dissimilar fluids. Planar laser-induced fluorescence images were captured using fluids with a viscosity ratio between 1.2 and 3. Flow visualizations showed that the best mixing conditions are achieved when the jets are well-balanced, and the onset of a chaotic flow regime is determined by the Reynolds number of the more viscous fluid (Re Hjet > 100). Computational fluid dynamics simulations were also performed to get deeper insight into the flow field and mixing dynamics, enabling the prediction of the impingement point position. An analytical model based on jets' kinetic energy rate balance is proposed as a design tool to predict the impingement point position.

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Section: Effect Of Reynolds Number On Mixing Of Similar Fluidsmentioning

confidence: 90%

Section: Working Fluidsmentioning

confidence: 99%

Flow Regimes and Mixing of Dissimilar Fluids in T‐Jets Mixers

et al. 2022

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“…The CIJ mixing chamber in RIM machines operates at production rates from 0.17 to 1.67 kg·s −1 . These production rates are generally in the range of operation Reynolds numbers 120 < Re < 600, where Re is based on the more viscous fluid that plays the key role in the flow regime features 25 …”

Section: Cfd Modelmentioning

confidence: 99%

“…The mixing scales evolution is kept approximately constant after the onset of the chaotic flow regime, at

Re \approx 120

, up to at least

Re = 600 .

33 Thus, the analysis of scales made in this study is valid in this range of Reynolds numbers where the flow is chaotic. For some industrial formulations, the Reynolds number from the lower viscosity stream is often above this range, but the flow features are mainly determined from the smaller Re stream 25 . Detailed analysis of flow regimes in CIJs from PLIF and other visualization techniques is well established in the literature 34–36 …”

Section: Cfd Modelmentioning

confidence: 99%

“…These production rates are generally in the range of operation Reynolds numbers 120 < Re < 600, where Re is based on the more viscous fluid that plays the key role in the flow regime features. 25 The actual mixing conditions in CIJs have an impact on the final RIM products, as it has been shown in previous studies mainly for PUmolded parts, 10,[26][27][28][29] and studied using test reactions for assessment of micromixing. [30][31][32] In general, product development for RIM is made with actual production conditions in pilot machines, and thus the formulations screening becomes a lengthy process.…”

Section: Product Development For Rimmentioning

confidence: 99%

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Rheokinematics for product development—Formulation screening in rotational rheometers

et al. 2022

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Product formulations for industrial processes are typically developed at laboratory scale. However, the mixing conditions are not easily mimicked in the laboratory. A rotational device is proposed in this study as a fast laboratory‐scale formulation development, which enables mimicking the mixing conditions in the industrial process. The geometrical configurations of the rotational device are from rheometry devices (plate‐plate and cone‐plate). The main advantages of this method are the small amounts of raw materials and shorter testing times. This methodology is applied to an industrial case study, the reaction injection molding (RIM) process. The mixing length scales evolution in the rotational rheometer were matched to those in RIM machines. The main novelty of this study is the introduction of a protocol that bridges the processing conditions at laboratory using small amounts of raw materials to high throughput continuous flow reactors.

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Impinging jet mixers: A review of their mixing characteristics, performance considerations, and applications

Devos,

Mukherjee,

Inguva

et al. 2024

AIChE Journal

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Optimal control over fast chemical processes hinges on the achievement of rapid and effective mixing. Impinging jet mixers are a unique class of passive mixing devices renowned for their exceptional ability to achieve rapid mixing at micro‐length scales, whilst offering the possibility of a high throughput. Comprising of two co‐linear jets flowing in opposite directions and colliding with each other within a small (usually confined) volume, these devices effectively intensify various mixing‐controlled processes in a reproducible manner. Impinging jet mixers find extensive use in both the chemical and pharmaceutical industry for a plethora of applications, such as reaction injection molding and precipitation processes. This review provides an overview of research related to impinging jet mixers, with an emphasis on the mixing characteristics and the influence of design and process parameters on the mixing performance. Lastly, specific applications for which these devices are exceptionally suited are discussed.

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Mixing of fluids with dissimilar viscosities in Confined Impinging Jets

Cited by 12 publications

References 18 publications

Flow Regimes and Mixing of Dissimilar Fluids in T‐Jets Mixers

Flow Regimes and Mixing of Dissimilar Fluids in T‐Jets Mixers

Rheokinematics for product development—Formulation screening in rotational rheometers

Impinging jet mixers: A review of their mixing characteristics, performance considerations, and applications

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