Home > Academic Announcements > (Mar. 30) 75th Academic Lunch Seminar of Sino-French Institute of Nuclear Engineering and Technology

(Mar. 30) 75th Academic Lunch Seminar of Sino-French Institute of Nuclear Engineering and Technology

Last updated :2018-03-26

Topic: Flow and heat transfer of viscoelastic fluids at microscale
Speaker: Xiaobin LI
Time:
12:40 – 14:00, Friday, March 30, 2018 
Venue: F309 in the teaching building, Zhuhai Campus, SYSU
Organizer: Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University
Language: English
 
Abstract: 
Micro-Electro-Mechanical System, has pioneered a new area and new stage for microscopic flow and heat transfer. The flow in the microscaled devices is usually at very low Reynolds number (Re), and the normal Newtonian fluid flow is constrained to be laminar, thus, the mass transfer effect (such as for micro-mixing and micro-reaction) will be deteriorated, hereby the heat transfer performance will be greatly decreased. Introducing the enough nonlinearity is the main way to destabilize the flow and then enhance the heat transfer, and modification of the microchannel and changing fluid properties will be the important and feasible means to enhance heat transfer performance.

Based on the unique characteristics of Non-Newtonian fluids, this work proposes a new idea to enhance the microscaled heat transfer by changing fluid properties, mainly concentrating on heat transfer enhancement effect and the micro mechanism of viscoelastic fluid flow at microscale. The microscaled flow and heat transfer setup is accomplished, and the micro particle image velocimetry is utilized to get the delicate flow field information of elastic turbulence under varied flow conditions with different thermo-physical properties and flow geometries. Also, the heat transfer coefficients in microchannel will be measured in order to understand the heat transfer performance under various flow conditions. Then, the boiling heat transfer performance by changing flow properties will be investigated, and the enhancement mechanism will be analyzed theoretically.

For the microscaled flow measurement, the experiments of Newtonian fluid and viscoelastic fluid flows in curved microchannels are conducted.  The confocal micro-PIV technique, digital holographic microscope (DHM) technique and polarized camera are used to obtain the velocity fields and statistics parameters, and to analyze the instantaneous velocity distribution, average velocity distribution and fluctuated energy spectrum, etc. The results show that, the elastic unstable flow is induced by the viscoelastic fluid, and which is stronger than the Dean flow in Newtonian fluid. 

For the microscaled convective heat transfer and boiling heat transfer, the experiments on the heat transfer of viscoelastic flow in the curved microchannel and boiling around a heated wire in the surfactant solution are carried out. 

The research of this study will provide the significant guidance for developing the novel microscaled heat transfer techniques, and establish the fundamental for seeking the efficient working fluids for heat removal in micro-power devices and micro-electronic chips.
 
About the speaker: 
Xiaobin Li (Ph.D., Associate Professor) received his Ph.D. in Engineering Thermophysics from Harbin Institute of Technology in 2012, and accomplished his post-doc research on microscaled flow in the University of Tokyo in 2015. His research interests are in the fields of fluid machinery, microscaled flow and heat transfer, and experimental fluid mechanics.