Acoustic vs Hydrodynamic Cavitation for Mixing Applications

Cavitation for Mixing and Blending: Is there a difference between acoustic and hydrodynamic cavitation? And why might one cavitation technology be better for your process?
Acoustic cavitation – also known as ultrasonic cavitation – and hydrodynamic cavitation are both forms of cavitation, which is the process of growth and collapse of vacuum cavities in a liquid. Acoustic cavitation occurs when a liquid is subjected to high-intensity ultrasound waves, while hydrodynamic cavitation occurs when a liquid streams through a constriction or around an obstacle (e.g. Venturi nozzle), causing the pressure to drop and vapour cavities to form.
Cavitational shear forces are used for homogenizing, mixing, dispersing, emulsification, cell disruption as well as for initiating and intensifying chemical reactions.

Although both, acoustic and hydrodynamic cavitation techniques use the same phenomenon and effect of cavitation bubble collapse, there is a significant difference between those two techniques created either by ultrasound or using Venturi nozzles.

Learn here what differences exist between acoustic and hydrodynamic cavitation and why you might want choose a probe-type ultrasonicator for your cavitation-driven process:

Advantages of Acoustic Cavitation over Hydrodynamic Cavitation

1. More efficient: Acoustic cavitation is generally more efficient at producing vacuum cavities, as the energy required to produce cavitation is typically lower than in hydrodynamic cavitation. Therefore, ultrasound-based cavitators and cavitation reactors are more energy-efficient and economical. Ultrasound is the most energy-efficient method to produce cavitation. Acoustic / ultrasonic cavitation generated by probe-ultrasonicators prevents the creation of unnecessary friction. The ultrasonic probe oscillates perpendicularly preventing the generation unnecessary, energy-wasting friction. In contrast to acoustic cavitation, hydrodynamic cavitation uses rotor-stator or nozzle systems to generate cavitation. Both techniques – rotor-stators and nozzles – cause friction as the motor has to drive large mechanical parts. If studies claim energy efficiency of hydrodynamic cavitations, they only take the nominal power of the respective technology into consideration and neglect the actual power consumption. Those studies normally do not consider the loss of friction energy which is a well known and undesired effect of hydrodynamic cavitation technologies.
2. Greater control: Acoustic cavitation can be more easily controlled and regulated, as the intensity of the ultrasound waves can be precisely adjusted to produce the desired level of cavitation. In contrast, hydrodynamic cavitation is more difficult to control, as it depends on the flow characteristics of the liquid and the geometry of the constriction or obstacle. Additionally, nozzles are prone to clog, which results in process interruptions and labour-intense cleaning.
3. Can handle almost all materials: Whilst a Venturi nozzle and other hydrodynamic flow reactors have difficulties to handle solids and especially abrasive materials, ultrasonic cavitators can reliably process almost any type of material. Ultrasonic cavitation reactors can homogenize even high solid loads, abrasive particles and fibrous materials without clogging.
4. Greater stability: Acoustic cavitation is generally more stable than hydrodynamic cavitation, as the vapour cavities produced by acoustic cavitation tend to be more uniformly distributed throughout the liquid. In contrast, hydrodynamic cavitation can produce vapour cavities that are highly localized and can lead to uneven or unstable flow patterns.
5. Greater versatility: Acoustic / ultrasonic cavitation can be used in a wide range of applications, including homogenization, mixing, dispersing, emulsification, extraction, lysis and cell disintegration as well as for sonochemistry. In contrast, hydrodynamic cavitation is primarily designed for flow control and fluid mechanics applications.
   Overall, acoustic cavitation offers greater control, efficiency, stability, and versatility compared to hydrodynamic cavitation, making it a very useful technique for numerous industrial applications.

Ultrasonic Cavitation Reactors

Hielscher Ultrasonics offers you a variety of industrial grade ultrasonic probes and cavitation reactors. All Hielscher ultrasonicators and cavitation reactors are designed for high-intensity applications and 24/7 operation under full load.
Design, Manufacturing and Consulting – Quality Made in Germany
Hielscher ultrasonic cavitators are well-known for their highest quality and design standards. Robustness and easy operation allow the smooth integration of our ultrasonic cavitators into industrial facilities. Rough conditions and demanding environments are easily handled by Hielscher ultrasonic cavitators.

Hielscher Ultrasonics is an ISO certified company and put special emphasis on high-performance ultrasonicators featuring state-of-the-art technology and user-friendliness. Of course, Hielscher ultrasonicators are CE compliant and meet the requirements of UL, CSA and RoHs.

Why Hielscher Ultrasonics?

• high efficiency
• state-of-the-art technology
• reliability & robustness
• batch & inline
• for any volume – from small vials to truckloads per hour
• scientifically proven
• intelligent software
• smart features (e.g., data protocolling)
• CIP (clean-in-place)
• simple and safe operation
• easy installation, low maintenance
• economically beneficial (less manpower, processing time, energy)

If you are interested in ultrasonic cavitation technique, processes and ready-to-operate ultrasonic cavitator systems, please contact us know. Our long-time experienced staff will be glad to discuss your application with you!

The table below gives you an indication of the approximate processing capacity of our ultrasonicators: