High-pressure microfluidic systems (HPMS): flow and cavitation measurements in supported silicon microsystems

Gothsch, T.; Schilcher, Christiane; Richter, Claudia; Beinert, S.; Dietzel, Andreas; Büttgenbach, S.; Kwade, Arno

doi:10.1007/s10404-014-1419-6

Cited by 56 publications

(37 citation statements)

References 18 publications

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“…Different measurement methods, like shadow graphic imaging [39,40], sono-chemiluminescence [41] or µPIV [34], are applied for the visualization of cavitation pattern. A brief overview of the three measurement techniques is given below:…”

Section: Visualisation Of Cavitationmentioning

confidence: 99%

“…With a µPIV set-up the emitted light of the dye can be recorded. Concentration differences lead to a visualisation of the vapour and liquid phase [34].…”

Section: Visualisation Of Cavitationmentioning

confidence: 99%

“…Schematic geometries of the orifices, which were investigated by Kelemen [35][36][37]88] and Gothsch [34], are shown in Figure 5. Fully turbulent flow was not analysed since the maximal velocity, which could still be analysed in good quality, was limited to 150 m/s [35] and 200 m/s [34], respectively. The velocity fields were used to calculate the shear and elongation stresses in the inlet and in the orifice itself [35].…”

Section: Micro-piv Mesurementsmentioning

confidence: 99%

“…Velocity profiles were also investigated in Gothsch et al [34] with a µPIV set-up in a highpressure microfluidic system (HPMS). The geometry of the orifice is depicted in Figure 5B.…”

Section: Micro-piv Mesurementsmentioning

confidence: 99%

“…However, the differences from Håkansson et al [33] were measured after the gap, so further experiments after the orifice are necessary to confirm the results from [33]. Velocity profiles were also investigated in Gothsch et al [34] with a µPIV set-up in a high-pressure microfluidic system (HPMS). The geometry of the orifice is depicted in Figure 5B.…”

Section: Micro-piv Mesurementsmentioning

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: Visualisation Of Cavitationmentioning

confidence: 99%

“…With a µPIV set-up the emitted light of the dye can be recorded. Concentration differences lead to a visualisation of the vapour and liquid phase [34].…”

Section: Visualisation Of Cavitationmentioning

confidence: 99%

Section: Micro-piv Mesurementsmentioning

confidence: 99%

“…Velocity profiles were also investigated in Gothsch et al [34] with a µPIV set-up in a highpressure microfluidic system (HPMS). The geometry of the orifice is depicted in Figure 5B.…”

Section: Micro-piv Mesurementsmentioning

confidence: 99%