Title
Experimental analysis of thermo-physical processes in acoustically levitated heated droplets
Abbreviated Journal Title
Int. J. Heat Mass Transf.
Keywords
Levitated droplet; Droplet vaporization; Acoustic streaming; Nanoceria; VAPORIZATION; CEO2; PARTICLES; FIELD; Thermodynamics; Engineering, Mechanical; Mechanics
Abstract
An experimental setup using radiative heating has been used to understand the thermo-physical phenomena and chemical transformations inside acoustically levitated cerium nitrate precursor droplets. In this transformation process, through infrared thermography and high speed imaging, events such as vaporization, precipitation and chemical reaction have been recorded at high temporal resolution, leading to nanoceria formation with a porous morphology. The cerium nitrate droplet undergoes phase and shape changes throughout the vaporization process. Four distinct stages were delineated during the entire vaporization process namely pure evaporation, evaporation with precipitate formation, chemical reaction with phase change and formation of final porous precipitate. The composition was examined using scanning and transmission electron microscopy that revealed nanostructures and confirmed highly porous morphology with trapped gas pockets. Transmission electron microscopy (TEM) and high speed imaging of the final precipitate revealed the presence of trapped gases in the form of bubbles. TEM also showed the presence of nanoceria crystalline structures at 70 degrees C. The current study also looked into the effect of different heating powers on the process. At higher power, each phase is sustained for smaller duration and higher maximum temperature. In addition, the porosity of the final precipitate increased with power. A non-dimensional time scale is proposed to correlate the effect of laser intensity and vaporization rate of the solvent (water). The effect of acoustic levitation was also studied. Due to acoustic streaming, the solute selectively gets transported to the bottom portion of the droplet due to strong circulation, providing it rigidity and allows it become bowl shaped. (C) 2010 Elsevier Ltd. All rights reserved.
Journal Title
International Journal of Heat and Mass Transfer
Volume
53
Issue/Number
25-26
Publication Date
1-1-2010
Document Type
Article
Language
English
First Page
5663
Last Page
5674
WOS Identifier
ISSN
0017-9310
Recommended Citation
"Experimental analysis of thermo-physical processes in acoustically levitated heated droplets" (2010). Faculty Bibliography 2010s. 722.
https://stars.library.ucf.edu/facultybib2010/722
Comments
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