Quantitative experimental determination of evaporation influencing factors in single droplet levitation
| Autor: | Malte Junk, Jörn Hinrichs, Werner Pauer, Jonas Fechner, Fritz Polt |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Fluid Flow and Transfer Processes
Materials science Mechanical Engineering Fluid mechanics 02 engineering and technology Mechanics 021001 nanoscience & nanotechnology Condensed Matter Physics Acoustic levitation Thermal conduction 01 natural sciences Temperature measurement 010305 fluids & plasmas Physics::Fluid Dynamics Particle image velocimetry Thermocouple Mass transfer 0103 physical sciences Levitation 0210 nano-technology |
| Zdroj: | International Journal of Heat and Mass Transfer. 149:119057 |
| ISSN: | 0017-9310 |
| DOI: | 10.1016/j.ijheatmasstransfer.2019.119057 |
| Popis: | Acoustic levitation has been used successfully as a model system for spray polymerization processes and the determination of particle morphology. The experimental extension for the investigation of heat and mass transfer in levitated liquid droplets requires much more effort. In order to enable the levitation method as a universal tool for the tracking of heat and mass transfer, influencing experimental parameters and their effect on relevant characteristics like droplet deformation, temperature and surrounding flow field were analyzed. These parameters were elucidated experimentally to reveal their mutual dependencies. It was shown that the evaporation rate is affected by the aspect ratio of a droplet, which is directly correlated with its wet-bulb temperature. This was primarily explained by varying acoustic flow field patterns based on classical fluid mechanics, gas velocities and acoustic boundary layer thicknesses, which were visualized and quantified by particle image velocimetry. In order to study the wet-bulb temperature, thermocouple measurements on the levitated droplet were performed. It turned out, that the wet-bulb temperature is dependent on the power input and the resulting sound pressure level as it changes the acoustic field around the droplet. Moreover, the temperature measurement revealed the necessity to establish a temperature correction to account for heat conduction effects along the thermocouple shaft into the droplet. The illustrated experimental setup and measurement procedure is supposed to provide guidelines for the experimental determination of heat and mass transfer in evaporating droplets. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect