Determination of single-particle drying kinetics in an acoustic levitator

A novel technique for the determination of single-particle drying kinetics in a closed 45 kHz acoustic levitator is presented. Practical handling is trouble-free, the moisture content of the outlet air stream is measured online by a high accuracy dew point hygrometer. Experimental data show low noise and can easily be transformed to drying curves. Investigations with gamma-Al2O3 have been carried out at different air velocities and moderate temperatures. The resulting drying curves are comparable to previous findings from a drying channel or a microbalance. Slightly higher drying rates and a lower critical moisture content in the levitator could indicate moderate interaction between the ultrasonic waves and the drying process. (C) 2002 Elsevier Science B.V. All rights reserved.