Ultrasonic disinfection using large area compact radial mode resonators

Osman, Hafiiz (2018) Ultrasonic disinfection using large area compact radial mode resonators. PhD thesis, University of Glasgow.

Abstract

Ultrasonic water treatment is based on the ability of an ultrasonic device to induce cavitation in the liquid, generating physical and chemical effects that can be used for biological inactivation. Effective treatment requires the ultrasonic device to generate intense cavitation field in a large treatment volume. Most conventional ultrasonic radiators fulfil only the first of these two requirements, rendering such devices highly unsuitable for use in high-volume, high-flow liquid processes. The present research investigates the design and performance of a new type of radial resonator in terms of their electromechanical characteristics, nonlinear behaviour, and their ability to treat synthetic ballast water with lower power consumption and short treatment times.

The radial resonators were designed using finite element (FE) modelling, and the best designs related to their predicted modal behaviour and vibration uniformity were selected for fabrication and experimental evaluation. Experimental modal analysis (EMA) of the radial resonators showed excellent correlation with the FE models, deviating by only 0.3% at the tuned mode. Impedance analysis showed that the mechanical quality factor of the radial resonators are 28–165% higher than the commercial high-gain probe, but their coupling coefficients are 40–45% lower.

Harmonic response characterisation (HRC) revealed shifts in the resonance frequencies at elevated excitation voltages. Duffing-like behaviour were observed in all resonators. RP-1 exhibited the Duffing-like behaviour to a far greater extent compared to the RPS-16 and RPST-16 multiple orifice resonators, indicating the influence of geometric parameters on the overall stiffness of the structure.

Finally, experiments with Artemia nauplii and Daphnia sp. showed excellent biological inactivation capability of the radial resonators. Comparison with previous studies showed that 90% reduction in Artemia nauplii can be achieved with up to 33% less energy and using just one radial resonator compared to the dozens of conventional resonators used in precedent investigations.

The present research have successfully demonstrated the use of FE modeling, EMA, and HRC to develop, validate, and characterise a new type of radial resonator. Experimental analysis showed that the radial resonators exhibited promising electrical, mechanical, and acoustical characteristics that has the potential to be cost-efficient, scalable, and a viable alternative water treatment method.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Power ultrasonics, ballast water treatment.
• Subjects: T Technology > TJ Mechanical engineering and machinery; V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering
• Colleges/Schools: College of Science and Engineering > School of Engineering > Systems Power and Energy
• Supervisor's Name: Lim, Dr. Fannon and Lucas, Prof. Margaret
• Date of Award: 2018
• Depositing User: Dr Hafiiz Osman
• Unique ID: glathesis:2018-30592
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 20 Jun 2018 08:36
• Last Modified: 31 Jul 2018 12:52
• URI: https://theses.gla.ac.uk/id/eprint/30592