investigation of evaporation process of drop on plate under microgravity conditions
- Paper number
IAC-08.A2.3.8
- Author
Prof. Jingchang Xie, Chinese Academy of Sciences, China
- Coauthor
Prof. Qiusheng Liu, Institute of Mechanics, Chinese Academy of Sciences, China
- Coauthor
Mr. Zhiqiang Zhu, Institute of Mechanics, Chinese Academy of Sciences, China
- Coauthor
Mr. Hai Lin, Institute of Mechanics, Chinese Academy of Sciences, China
- Coauthor
Prof. Qiang Yu, Center for Space Science and Applied Research, CAS, China
- Coauthor
Prof. Lounès Tadrist, Polytech’ Marseille - IUSTI, UMR 6595 CNRS, France
- Year
2008
- Abstract
Our ground-based experiments of evaporation (Ethanol/Silicone Oil-0.65Cst) indicate that even a strong evaporating liquid/gas interface has interfacial tension and thermocapillary effects.. As temperature gradient is applied to the interface, thermocapillary convection exists, which could be visualized by PIV technique. The thermocapillary convections in liquid and vapor phases are coupled with natural convection to some extent due to buoyancy effect on the ground. The buoyancy effect generally affects the evaporating process and heat and mass transfer. A space experiment of evaporation drop on plate is designed to investigate the evaporation process with the effect of thermocapillary convection. The experiment is to be conducted on board the Chinese recoverable satellite and expected to fly in the year 2010. The effect of thermocapillary convection on the evaporation will be emphasized in the experimental study, e.g. the effect on the mean evaporating rate and the possible deformation of drop shape caused by different local evaporation rate on the liquid-gas interface. Two main conditions will be set. One is that liquid drop on plate has uniform temperature, with given initial ambient temperatures, expecting that thermal conductivity would play a dominative role to evaporate the liquid in this case. For the other condition, the liquid drop will be heated or cooled through the plate, imposing temperature gradient on the drop surface to introduce and enhance the thermocapillay convection. The intensity of thermocapillary convection and related Marangoni number of the system hereby could be controlled by supplying electrical energy to the liquid. The ambient temperature and that both inside and near the drop interface at selected positions will be measured by thermocouples. The temperature distribution on the drop surface will be also measured using a infrared camera. Drop shape and its changing during evaporation can be captured and recorded by a high resolution CCD camera in real time. A feedback close loop control system has been developed and will be used in the experiment, which consists of the CCD camera, image processing unit and liquid injection servo system. A quasi-steady evaporation experiment can be performed, in which the volume of drop liquid will keep constant during the experimental run. The initial pressure will be set for each run and the pressure and temperature variation in the test cell will be recorded. Through this evaporation experiment in microgravity, it is expected to have a better understanding of the evaporation mechanism and to make a comparison to other experimental results.
- Abstract document
- Manuscript document
(absent)