Technical Papers and Presentations

Ultrasonic flow-cell reactors are used for many industrial applications, where fluid substrate is sonicated in a small region, where very high ultrasonic acoustic power is present. The electromechanical transducer (converter) that drive the sonotrode inside the flow-cell is designed in the COMSOL Multiphysics® software with the Structural Mechanics Module, the Acoustics Module and LiveLink™ for SOLIDWORKS®, to get a reliable, efficient and flexible design, thanks to special tuned metal parts and high efficiency hard PZT piezoelectric ceramic rings. Efficiency of such device can reach up to 98%, so thermal loss are quite low. Such results were possible making use of a novel converter structure, that employs two stacks of piezo-rings, with proper positioning in nodal points and phasing. Nevertheless, since the reactor may be in service 24 / 7 and piezo material cannot operate above 150°C, thermal management solutions are very important. Among these , best would be to employ a liquid cooling system inside the converter, where heat is generated, but the device is not generally compatible with standard liquids and the solution could be quite complicated. On the other hand, a high pressure / low flow cooling air (used as standard with such type of converters) cannot guarantee a proper cooling at 3kW power level or more. So a novel low pressure / high flow system was conceived for the application, making use of COMSOL Multiphysics® with the CFD Module and the Heat Transfer Module in order to get efficient thermal drain and temperature control.