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Title: Height effect on nucleation-site activity and size-dependent bubble dynamics in microchannel convective boiling
Authors: Lee, Man
Cheung, Luthur Siu Lun
Lee, Yi-Kuen
Zohar, Yitshak
Keywords: Microchannel convective boiling
Heat sinks
Heat flux
Two-phase flow
Issue Date: 2005
Citation: Journal of Micromechanics and Microengineering, v. 15, no. 11, November 2005, p. 2121-2129
Abstract: Forced convection boiling in microchannels is studied experimentally under the uniform heat flux boundary condition. Several microchannel heat sinks with integrated temperature sensors, spanning two orders of magnitude in height 5–500 µm, have been fabricated with designed nucleation sites on the bottom surfaces. The microchannels are capped by a glass wafer to monitor bubble activity using video microscopy. Distributed micro heater elements on the device backside are used as the heat source, while the working liquid flow rate is adjusted using a syringe pump. The boiling curves of the device temperature as a function of the input power have been measured for various flow rates. The curves for increasing and decreasing heat flux exhibit a hysteresis loop, while the conditions corresponding to the onset of nucleate boiling and critical heat flux (CHF) are clearly distinguishable. The activity of nucleation sites as well as the ensuing bubble dynamics, from incipience to departure, is found to depend on the channel height. The critical size above which a nucleation site is active, along with three aspects of bubble dynamics, namely growth rate, departure size and release frequency, have been characterized experimentally and proper control parameters have been identified.
Rights: Journal of Micromechanics and Microengineering © copyright (2005) IOP Publishing Ltd. The Journal's web site is located at
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