Research Papers: Micro/Nanoscale Heat Transfer

Formation Mechanism and Characteristics of a Liquid Microlayer in Microchannel Boiling System

[+] Author and Article Information
Yaohua Zhang

Graduate School of Engineering, Yokohama National University, Tokiwadai, Hodogaya, Yokohama 240-8501, Japand08sb191@ynu.ac.jp

Yoshio Utaka

Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya, Yokohama 240-8501, Japanutaka@ynu.an.jp

Yuki Kashiwabara

 Tokyo Electric Power Company, 2-1377 Soga-cho, Chuo-ku 260-0822Chiba, Japankashiwabara1986@hotmail.co.jp

J. Heat Transfer 132(12), 122403 (Sep 20, 2010) (7 pages) doi:10.1115/1.4002365 History: Received October 23, 2009; Revised May 17, 2010; Published September 20, 2010; Online September 20, 2010

Experiments were performed using the laser extinction method to measure the thickness of the liquid film formed by growing flattened bubbles in a microchannel for gap sizes of 0.5 mm, 0.3 mm, and 0.15 mm. Water, ethanol, and toluene were used as test fluids. A high-speed camera was also used to simultaneously measure the bubble growth process. It was confirmed that the gap size and bubble forefront velocity determined the initial microlayer thickness. The variation trend of the microlayer thickness relative to the velocity of the interface was divided into two regions: region I, where the velocity is small and the thickness increases linearly with increasing velocity, and region II, where the thickness is almost constant or decreased slightly with increasing velocity. Furthermore, a nondimensional correlation for investigating the effects of test materials and gap sizes on microlayer thickness is presented. An analysis of the results showed that the boundaries of the two regions correspond to a Weber number of approximately 110, and in the region where the Weber number was smaller than 110, the thickness of the microlayer was thinner for the liquid whose value of ρ0.62ν0.42σ0.62 was relatively small. However, for the region where Weber number was larger than 110, the smaller the kinematic viscosity of the liquid, the thinner the microlayer became.

Copyright © 2010 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.



Grahic Jump Location
Figure 1

Schematic diagram of bubble

Grahic Jump Location
Figure 2

Experimental apparatus for measuring microlayer thickness

Grahic Jump Location
Figure 3

Error of microlayer thickness measurement due to variation in ambient temperature

Grahic Jump Location
Figure 4

Microlayer thicknesses versus local bubble forefront velocity for water, ethanol, and toluene

Grahic Jump Location
Figure 5

Relationship between microlayer thickness and ratio of I to I0

Grahic Jump Location
Figure 6

Microlayer thickness versus viscous boundary layer thickness

Grahic Jump Location
Figure 7

Effect of bubble forefront traveling distance

Grahic Jump Location
Figure 8

Nondimensional viscous microlayer thickness versus Weber number for all test liquids and gaps

Grahic Jump Location
Figure 9

Nondimensional microlayer thickness versus Weber number for water and toluene to examine the effect of gap sizes

Grahic Jump Location
Figure 10

Effect of fluid properties on initial microlayer thickness for s=0.5 mm, 0.3 mm, and 0.15 mm

Grahic Jump Location
Figure 11

Comparison between the prediction and the experiment




Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In