Power ultrasonic transducers with extensive radiators for industrial processing

Abstract

High-power ultrasonics (HPU) is a green emerging technology that offers a great potential for a wide range of industrial processes. Nevertheless such potential have remained restricted during many years to a limited number of applications which reached commercial development. The possible major problem for extending the range of HPU industrial applications has been the lack of power ultrasonic transducers for large-scale application, adapted to the requirements of each specific problem with high efficiency and power capacity. A new family of HPU transducers with extensive radiators have been recently introduced. It comprises a variety of transducer types designed with the radiators adapted to different specific uses in fluids and multi-phase media. Such transducers implement high power capacity, high efficiency and radiation pattern control. In addition, their design incorporate strategies to eliminate or reduce modal interactions produced at high power as a consequence of their nonlinear behaviour. The introduction of such new transducers has significantly contributed to the development at semi-industrial and industrial level of a number of processes in the food and beverage industry, in environment and in manufacturing. This paper deals with the basic structure and main characteristics of such transducers as well as their performance in the developed application processes.

Description of an ultrasonic technology for food dehydration process intensification

“…The excitation of close undesired modes may provoke a dramatic decrease in the efficiency of the system and other problems related to ultrasonic fatigue, noise, heating, instabilities, etc. Some physical changes may need to be applied in the radiator in order to avoid this undesired modal interaction by adjusting the mass balances between different parts of the radiator and, thus, strengthening the operational mode and weakening or separating the other close modes (Gallego-Juarez et al, 2010). Grooving one side of the plate may provide this adjustment and minimize the modal interactions when applying high power levels.…”

“…However, the development of this kind of device has to deal with the need of a high level ultrasonic field in a gas media, with a good impedance matching between the radiator and the gas and a high amplitude of vibration in the radiating plate (Gallego-Juarez et al, 2010).…”

Ultrasound-assisted acid and enzymatic hydrolysis of yam (Dioscorea sp.) for the production of fermentable sugars

“…Only few companies were able to develop commercial devices and in general the industrial potential of high-power ultrasound remained restricted during many years to a limited number of applications (Gallego-Juárez et al, 2010).…”

Design and scale-up of sonochemical reactors for food processing and other applications

“…The lack of availability of transducers is more from a material science background and therefore not within the main scope of this chapter. The work of Gallego-Juárez et al (2010) presents the difficulties in the effective use of piezoelectric transducers in large-scale operations, namely lower power rating, limited dimensions, and altered performance due to variations in the operating voltage. The basic structure of a new family of high-power ultrasonic transducers with higher power capacity and efficiency, a larger radiating surface area, and a more sophisticated control system such as stepped-plate transducers, grooved-plate transducers, stepped-grooved-plate transducers, and flat-plate transducers with reflectors have been described.…”