The importance of temperature control in the operation of high power ultrasound reactors

This paper describes the effects of temperature changes on the operation of a 25 kHz sonochemical reactor, which is being developed as a reference facility for studying acoustic cavitation at NPL. Field measurements, acquired using a hydrophone in different locations inside the cavitation reactor, are compared with Finite Element Models at different temperatures, showing that significant changes in the acoustic pressure distribution (and consequent cavitation activity) can result from relatively small temperature variations. Modal analysis was used in this work as a tool to explain the physical reasons behind this behaviour and the effects of a preliminary temperature control system will be described, both in terms of temperature and for the improved stability of the acoustic pressure field. This work also highlights some of the limitations of modal analysis for the design of more complex reactors and associated temperature control methods.