Mass transfer enhancement produced by laser induced cavitation

Birkin, Peter R.; Hirsimäki, Hanne-Maria; Frey, Jeremy G.; Leighton, Timothy G.

doi:10.1016/j.elecom.2006.07.026

Cited by 13 publications

(3 citation statements)

References 25 publications

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“…This jetting, together with acoustic streaming, is thought to lead to random punctuation and disruption of the mass-transfer boundary layer at the electrode surface at close electrode-to-horn separations. Birkin et al 21,22 also showed that the nature of the solvent is paramount in assigning limiting currents. For example, the violence of cavitational events is strongly dependent on solvent vapor pressure as well as the ultrasonic power.…”

mentioning

confidence: 99%

Transport Limited Currents Close to an Ultrasonic Horn

Pollet

Hihn

Doche

et al. 2007

J. Electrochem. Soc.

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The effect of changing the distance of an ultrasonic horn tip from a stationary platinum disk electrode on limiting current density at various electroanalyte concentrations, ultrasonic frequencies ͑20 and 40 kHz͒, and ultrasonic intensities was studied in an attempt to find the optimum position required for maximum sonoelectrochemical effect in "face-on" mode. Our findings were compared to mathematical models available in the literature, for the mass transport of electroactive species to the electrode under hydrodynamic flow conditions normal to the ultrasonic horn. A good fit with experimental results was found and confirmed the dependence of limiting current to operating parameters such as ultrasonic power, electrode-to-horn distances and electroactive species diffusion coefficient, and also highlighting the importance of ultrasonic frequency. From mass balance equations, it was then possible to develop an approach by analogy to an electrode subjected to pure hydrodynamic flow. A Levich-like equation relating the limiting current density, the square root of ultrasonic intensity, and the inverse square root of the electrode-horn distance was generated for ultrasonic frequencies of 20 and 40 kHz, allowing the generation of an "equivalent" flow velocity under sonication, an important and useful parameter in chemical engineering.

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confidence: 99%

Transport Limited Currents Close to an Ultrasonic Horn

Pollet

Hihn

Doche

et al. 2007

J. Electrochem. Soc.

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“…89,90 Studies were also undertaken on the bubble activity which leads to cleaning, such as bubble collapse and the formation of high-speed jets as bubbles involute during collapse. 91,92 This combined experience led to the development of cleaning apparatus which is currently under discussion for commercialization in a University of Southampton spin-out company.…”

Section: Ultrasonic Cleaningmentioning

confidence: 99%

Innovation to Impact in a Time of Recession

Leighton

2011

J. Comp. Acous.

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Whilst most people in developed societies would celebrate the route from innovation to impact, particularly in the context of engineering and biomedicine, it is not often acknowledged that the definitions of the start, mid-points and even end-points of that route vary between groups in society. Since that route requires funding, this variety of opinion leaves regions of the route vulnerable to underfunding, particularly in times of recession. This paper explores how this can lead to failure to foresee problems and underpin solutions on the 10-50 year timescale. Furthermore, policies designed to support the route from innovation to impact can have the opposite effect. The route is illustrated with examples from the author's research. a

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“…5,6 Numerous techniques have been developed to create cavitation in a laboratory setting, including boiling, 7 syringe injection, spark generation, 8 focused ultrasound, 9 neutron sources, 10 and focused lasers. 11,12 Compared with other methods, focused laser nucleation is attractive because it offers excellent spatial and temporal control and does not require any intrusive parts to contact the cavitating medium. Focused laser nucleation generally works by optical dielectric breakdown of the medium [13][14][15] at the focal point but can also work by quickly depositing heat to impurities 15,16 or nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Optical nucleation of bubble clouds in a high pressure spherical resonator

Anderson

Sampathkumar

Murray

et al. 2011

The Journal of the Acoustical Society of America

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An experimental setup for nucleating clouds of bubbles in a high-pressure spherical resonator is described. Using nanosecond laser pulses and multiple phase gratings, bubble clouds are optically nucleated in an acoustic field. Dynamics of the clouds are captured using a high-speed CCD camera. The images reveal cloud nucleation, growth, and collapse and the resulting emission of radially expanding shockwaves. These shockwaves are reflected at the interior surface of the resonator and then reconverge to the center of the resonator. As the shocks reconverge upon the center of the resonator, they renucleate and grow the bubble cloud. This process is repeated over many acoustic cycles and with each successive shock reconvergence, the bubble cloud becomes more organized and centralized so that subsequent collapses give rise to stronger, better defined shockwaves. After many acoustic cycles individual bubbles cannot be distinguished and the cloud is then referred to as a cluster. Sustainability of the process is ultimately limited by the detuning of the acoustic field inside the resonator. The nucleation parameter space is studied in terms of laser firing phase, laser energy, and acoustic power used.

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Mass transfer enhancement produced by laser induced cavitation

Cited by 13 publications

References 25 publications

Transport Limited Currents Close to an Ultrasonic Horn

Transport Limited Currents Close to an Ultrasonic Horn

Innovation to Impact in a Time of Recession

Optical nucleation of bubble clouds in a high pressure spherical resonator

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