Drop break-up in turbulent pipe flow downstream of a restriction

Galinat, S.; Masbernat, Olivier; Guiraud, Pascal; Dalmazzone, Christine

doi:10.1016/j.ces.2005.05.012

Cited by 110 publications

(115 citation statements)

References 43 publications

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“…The break-up into two to three smaller droplets, as was shown by Kolb et al [25], was observed by both studies (see Figure 2A1,B1). The "explosive droplet disruption" described by Kolb et al [25] seems to be similar to the droplet break-up visualized by Galinat et al [27], as shown in Figure 2B2.…”

Section: Optical Methods For Investigating High-pressure Homogenisationsupporting

confidence: 61%

“…Partially similar droplet deformation and break-up mechanisms were described by Budde et al [24] and Galinat et al [27], as shown in Figure 2. At the outlet of the orifice, the droplet deformation varied from strongly elongated droplets, like it is shown in Figure 2A, to no visible deformation of the droplet ( Figure 2B).…”

Section: Optical Methods For Investigating High-pressure Homogenisationsupporting

confidence: 53%

“…Kolb et al [26] based their scaling on geometrical factors and the Reynolds number in the gap, whereas Budde et al [24] took additionally the Weber number and the viscosity and density ratios between the phases into account. The motivation of Galinat et al [27] was to investigate the droplet break-up induced by a restriction in a pipeline, for the petroleum recovery industry. Therefore, no scale-up was needed.…”

Section: Optical Methods For Investigating High-pressure Homogenisationmentioning

confidence: 99%

“…To improve the signal-to-noise-ratio, droplets were dyed black to increase the contrast between the fluid and the droplet [24,25]. A reproducible droplet size was achieved by using microfluidic capillary devices [25,27].…”

Section: Optical Methods For Investigating High-pressure Homogenisationmentioning

confidence: 99%

“…The first optical investigations of high-pressure homogenisation focused on droplet deformation and droplet break-up of individual droplets. The measurements took place in simple orifices and were recorded by high-speed devices [24,25,27].…”

Section: Optical Methods For Investigating High-pressure Homogenisationmentioning

confidence: 99%

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Optical Measuring Methods for the Investigation of High-Pressure Homogenisation

Bisten

Schuchmann

2016

Processes

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High-pressure homogenisation is a commonly used technique to produce emulsions with droplets in the micro to nano scale. Due to the flow field in the homogenizer, stresses are transferred to the interface between droplets and continuous phase. Cohesive forces within droplets interact with external stresses. To exceed the cohesive forces, high process pressures are necessary, which might cause a complex flow pattern and large flow velocities. Additionally, the pressure drop can induce cavitation. Inline measurements are a challenge, but necessary to understand droplet break-up in a high-pressure homogenizer. Recently, different optical methods have been used to investigate the flow conditions as well as the droplet deformation and break-up in high-pressure homogenisation, such as high speed imaging, particle and micro particle image velocimetry. In this review, those optical measuring methods are considered critically in their applications and limitations, achievable results and further developments.Keywords: high-pressure homogenisation; optical measurement methods; flow field characterisation; droplet break-up; emulsification MotivationHigh-pressure homogenisation (HPH) is widely used in chemical, pharmaceutical and food industry to produce emulsions with desired properties. Properties of emulsions, like mouth feel, colour, flow behaviour, or stability, depend strongly on their microstructure and thus on the droplet size distribution of the emulsion [1]. However, tailor-made adjustments of the droplet size distribution in emulsions is still challenging due to complexity of interactions of the process conditions and the properties of the formulation. In order to decrease the droplet size distributions, the volume-related energy density E v is increased, most often by increasing the pressure drop ∆p in the disruption unit [2]. Unfortunately, this might also lead to cavitation and cavitation-induced wear at the devices. A change in the homogeniser disruption unit design may also improve droplet breakup. As an example, Microfluidics ® offers so-called T-or Z-shaped disruption units which allow droplet size reduction well below <1 µm for specific formulations. Other manufacturers merchandise specific "energy-efficient" disruption units. Even when these disruption units work fine with some formulations, they do not with others. A deep understanding in the influence of disruption unit design and process parameters on flow patterns and resulting droplet sizes is still missing.One possibility to describe the influence of process conditions, and/or product recipe on resulting droplet sizes is to measure the average droplet size or the droplet size distribution (DSD) of the emulsion after homogenisation. Thus, the influence of different parameters like pressure drop [2][3][4][5], geometry of the device [2,6-9], or formulation [10][11][12][13] can be related to homogenisation efficiency, which allows some mechanistic insight into the high-pressure homogenisation process. However, offline measurements always repre...

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Section: Optical Methods For Investigating High-pressure Homogenisationsupporting

confidence: 61%

Section: Optical Methods For Investigating High-pressure Homogenisationsupporting

confidence: 53%

Section: Optical Methods For Investigating High-pressure Homogenisationmentioning

confidence: 99%

Section: Optical Methods For Investigating High-pressure Homogenisationmentioning

confidence: 99%

Section: Optical Methods For Investigating High-pressure Homogenisationmentioning

confidence: 99%

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Optical Measuring Methods for the Investigation of High-Pressure Homogenisation

Bisten

Schuchmann

2016

Processes

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Breakup of a drop in a liquid–liquid pipe flow through an orifice

et al. 2006

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in Wiley InterScience (www.interscience.wiley.com).The drop breakup in a heterogeneous turbulent pipe flow developing downstream of an orifice is reported. A two-phase flow is considered of n-heptane drops in a water-glycerin solution at three distinct volume concentrations: f d ¼ 0 (single-phase flow), 0.1, and 0.2. The maximum pressure drop across the orifice, DP max , is found to be a linear function of the kinetic energy of the mixture that weakly depends on f d . The continuous-phase velocity field is measured by means of high-speed particle image velocimetry in an optically homogeneous medium. The turbulence energy level and its spatial distribution are strongly influenced by both the continuous-phase viscosity and the presence of the dispersed phase. Drop breakup is driven by an inertial mechanism and is observed where the turbulence is the most intense. The breakup probability, the mean number of fragments, and the daughter-drop Sauter diameter are plotted against the global Weber number based on DP max . For concentrations up to 0.1, breakup statistics are close to those obtained with an isolated drop in a single-phase flow of water. For f d ¼ 0.2, the increase of breakup probability with the Weber number becomes weaker because of the volume reduction of the region of intense turbulence. The evolution of breakup probability with the distance from the orifice indeed shows strong differences between the test cases, arising from modifications in the local structure of the heterogeneous turbulence field.

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Consideration of low viscous droplet breakage in the framework of the wide energy spectrum and the multiple fragments

et al. 2015

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An improved model for low viscous droplet breakage has been developed. Unlike the previous work that considered the inertia subrange and adopted the assumption of binary breakage, this work considered the breakage of droplets in the framework of the multiple fragments and the wide energy spectrum (i.e., including the dissipation range, the inertia subrange, and the energy containing range simultaneously). The previous interactions between the droplet and the surrounding fluids have been considered through introducing the interaction forces. The effect of the surface deformation and oscillation resulting from these interactions on the constraints of multiple breakages has been accounted for. These factors have been neglected in the existing models. The wide energy spectrum distribution was found to have an important effect on the nonmonotone evolution of breakage frequency with increasing parent droplet size. The cumulative volume fractions predicted by this work showed a better agreement with the experimental data. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2147–2168, 2015

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Drop break-up in turbulent pipe flow downstream of a restriction

Cited by 110 publications

References 43 publications

Optical Measuring Methods for the Investigation of High-Pressure Homogenisation

Optical Measuring Methods for the Investigation of High-Pressure Homogenisation

Breakup of a drop in a liquid–liquid pipe flow through an orifice

Consideration of low viscous droplet breakage in the framework of the wide energy spectrum and the multiple fragments

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