Analysis of the concentration dependence of
ultrasonic cavitation in suspensions by considering particle analysis and
particle manipulation factors.
M. Neményi, A. Lőrincz
University of West Hungary, Faculty of Agricultural and Food sciences,
Mosonmagyaróvár;
Institute of Agricultural, Food and Environmental Engineering**
Summary
In our experiments we studied how the qualitative and quantitative
properties of water based suspensions effect the occurrence and threshold
levels of the ultrasonic phenomena, standing wave, acoustic streaming and
especially cavitation. In our experiments commercial pressed (hydrated) and
lyophilized (dehydrated) baker’s yeast (Saccharomyces cerevisiae), and a dolomite suspension that has the same
average particle size as of the yeast were used. The experiments were conducted in the ultrasonic treating vessel under the
conditions of 1.117 [MHz] frequency and 0-12 [W/cm2]
ultrasound output. We examined the levels of particle concentration [g/l] in
the ultrasound field that were needed to terminate cavitation (that is the cavitation
threshold concentration), and we measured the length of time that passed from
the start of the experiment until the restart of cavitation, which is the time
period required for the formation of cavitation. These experiments were carried
out under concentration levels that were 1.5 times higher than the cavitation
threshold concentrations. The acoustic
phenomena taking place in the ultrasound field, and through these, the effects
of ultrasound can be characterized by these two measures. This study is
suitable for further expanding the application area of ultrasound towards
particle analysis, selective particle manipulation, biological extraction, cell
inactivation and fermentation techniques.
PACS: 43.35.+d, 43.38.+n, 43.58.+z.
Keywords: Ultrasound field, Acoustic phenomenon, Cavitation threshold, Suspended
particles, Concentration
* Correspondence Address: Mosonmagyaróvár, Vár 2. 9200 Hungary
Phone: + 36-96-566-635, Fax: +36-96-566-641
e-mail: lorincza@mtk.nymc.hu