0

Full Content is available to subscribers

Subscribe/Learn More  >

No New Physics in Single-Phase Fluid Flow and Heat Transfer in Mini- and Micro-Channels: Is It a Conclusion?

[+] Author Affiliations
Wen-Quan Tao, Ya-Ling He, Gui-Hua Tang, Zhuo Li

Xi’an Jiaotong University, Xi’an, China

Paper No. MNHT2008-52007, pp. 639-648; 10 pages
doi:10.1115/MNHT2008-52007
From:
  • ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer
  • ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer, Parts A and B
  • Tainan, Taiwan, June 6–9, 2008
  • Conference Sponsors: Nanotechnology Institute
  • ISBN: 0-7918-4292-4 | eISBN: 0-7918-3813-7
  • Copyright © 2008 by ASME

abstract

First the flow friction characteristics of nitrogen and helium in stainless steel microtubes, glass microtubes, square glass microchannels, and rectangular silicon microchannels are tested. The data in glass microtubes with diameters from 50 to 201 microns and in square glass channels with characteristic diameters from 52 to 100 microns show that the friction factors are in good agreement with the conventional predictions. The friction factors in stainless-steel tubes with diameters from 119 to 300 microns are much higher than the conventional ones. The results for two of the four silicon microchannels with characteristic diameters from 26–60 microns are in good agreement while those of the other two channels are larger. This discrepancy is resulted from the large relative surface roughness. Smaller friction factors in glass microtubes with diameters from 10 to 20 microns are obtained due to the rarefaction effect. Second the flow friction experimental data for deionized water flow in glass microtubes with diameters from 50 to 530 microns show that friction factors and transition Reynolds numbers are in good agreement with the conventional predictions. However, the friction factors in stainless steel microtubes with diameters from 50–1570 microns are much higher than the conventional predictions. This discrepancy is attributed to the large surface relative roughness or denser roughness distribution. Numerical simulations considering electroviscous effect are carried out. The simulation results show that the electroviscous effect does not play a significant role in the friction factor for channel dimensions of the order of microns though it does affect the velocity profile and hence it could be neglected in engineering applications for channel dimensions of the order of microns. Third the measured local Nusselt number distribution of deionized water along the axial direction of the stainless steel tubes of 373–1570 microns with uniform heat flux do not accord with the conventional results when Reynolds number is low and the relative thickness of the tube wall is high. Numerical study reveals that the large ratio of wall thickness to tube diameter at low Reynolds number causes significant axial heat conduction in the tube wall, leading to a non-linear streamwise distribution of the fluid temperature. The axial wall heat conduction effect is gradually weakened with the increase of Reynolds number and the decrease of the relative tube wall thickness. In conclusion, the conventional fluid flow and heat transfer theories should still be applied for single-phase flow in smooth microchannels. Nevertheless, micro-channels do raise some issues to be paid special attention to when being applied.

Copyright © 2008 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

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 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