DocumentCode :
2248406
Title :
Size and shape effects on two-phase flow instabilities in microchannels
Author :
Lee, Minhung ; Wong, Y.Y. ; Wong, Man ; Zohar, Yitshak
Author_Institution :
Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
fYear :
2002
fDate :
24-24 Jan. 2002
Firstpage :
28
Lastpage :
31
Abstract :
An integrated microchannel heat sink consisting of shallow, trapezoidal microchannels has been fabricated using standard micromachining techniques to highlight the effects of the micrometer sized channel shape on the evolving flow patterns and, consequently, on the thermal response of the system. An integrated heater provides the local heat source, while an array of temperature microsensors is used for temperature distribution measurements. DI water, serving as the working fluid, is pressurized through the microchannels for forced heat convection. Temperature plateaus are observed in the boiling curves, corresponding to the latent heat of phase change of the working fluid from liquid to vapor phase. The evolving two-phase flow patterns have been recorded and analyzed using high-speed camera. Bubble formation, growth and detachment at specific nucleation sites have been observed. Annular flow mode has been found to be unstable in trapezoidal channels. Instead, a highly unsteady transition region from upstream vapor phase to downstream liquid phase flow is developed, and the average location of this region depends on the input power.
Keywords :
biomedical engineering; micro-optics; microactuators; microassembling; microfluidics; micromechanical devices; micropumps; microsensors; microvalves; microwave technology; scanning probe microscopy; CAD; MEMS technology; RF applications; acoustics; actuators; biomedical MEMS; bonding; high aspect ratio structures; inertial sensors; liquid handling; magnetic sensors; materials; mechanical sensors; microassembly; microfluidic MEMS; microscopy probes; molds; optical MEMS; packaging; physical sensors; power MEMS; probe cards; pumps; valves; wireless applications; Acoustic sensors; Biosensors; Magnetic materials; Magnetic sensors; Mechanical sensors; Microfluidics; Micromechanical devices; Optical microscopy; Optical sensors; Probes;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Micro Electro Mechanical Systems, 2002. The Fifteenth IEEE International Conference on
Conference_Location :
Las Vegas, NV, USA
ISSN :
1084-6999
Print_ISBN :
0-7803-7185-2
Type :
conf
DOI :
10.1109/MEMSYS.2002.984071
Filename :
984071
Link To Document :
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