Drying of Pastes in Vibro-Fluidized Beds: Effects of the Amplitude and Frequency of Vibration

Abstract

The dimensionless vibration number (Γ) is the parameter most widely applied to quantify the vibration energy of a vibro-fluidized bed. It is defined as a function of the amplitude (A) and of the frequency of vibration (f). Most works in literature present their results as a function of Γ, which is adopted as a single parameter to explain the results on fluid dynamic behavior of vibro-fluidized beds, independent on the magnitudes of A and f. From its definition, however, it is possible to obtain identical values of Γ just by combining different values of A and f, and further studies are necessary for a better analysis of fluid dynamic behavior of vibro-fluidized beds concerning their vibration energy. Therefore, in this work the effects of dimensionless vibration number on the fluid dynamic behavior of a vibro-fluidized bed will be investigated by choosing different combinations of A and f values arranged to provide identical values of Γ. The tests were carried out for dry and wet beds, for values of Γ = 0.0 (fluidized bed), 1.0, 2.0, and 4.0. The results indicate that Γ must be used carefully when applied as the only parameter to characterize the vibration effects in a vibro-fluidized bed since very different fluid dynamic behavior was detected at a fixed Γ at different amplitudes and frequencies.

Keywords:

• Vibro-fluidized bed dryer
• Fluidization
• Dimensionless vibration number
• Glycerol

ACKNOWLEDGMENT

The authors thank the Brazilian funding agencies FAPESP and PRONEX/CNPq for their financial support.