0
Research Papers: Micro/Nanoscale Heat Transfer

Condensation in Microchannels: Detailed Comparisons of Annular Laminar Flow Theory With Measurements

[+] Author and Article Information
Hua Sheng Wang

School of Engineering and Materials Science,
Queen Mary University of London,
Mile End Road,
London E1 4NS, UK
e-mail: h.s.wang@qmul.ac.uk

John W. Rose

School of Engineering and Materials Science,
Queen Mary University of London,
Mile End Road,
London E1 4NS, UK
e-mail: j.w.rose@qmul.ac.uk

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received July 1, 2016; final manuscript received January 25, 2017; published online April 4, 2017. Assoc. Editor: Amitabh Narain.

J. Heat Transfer 139(7), 072403 (Apr 04, 2017) (6 pages) Paper No: HT-16-1434; doi: 10.1115/1.4036082 History: Received July 01, 2016; Revised January 25, 2017

A relatively simple theory of annular laminar film condensation in microchannels, based on the Nusselt approximations for the condensate film and a theoretically based approximation for the vapor shear stress, has no empirical input and gives the local heat transfer coefficient and local quality for given vapor mass flux and vapor–surface temperature difference distribution along the channel. As well as streamwise vapor shear stress and gravity, the theory includes transverse (to the flow direction) surface tension-driven motion of the condensate film and gives a differential equation for the local (transverse and streamwise) condensate film thickness. As well as four transverse direction boundary conditions due to condensate surface curvature, a streamwise boundary condition is required as in the Nusselt theory. When the vapor is saturated or superheated at inlet, this is provided by the fact that the film thickness is zero around the channel perimeter at the position of onset on condensation. Most experimental investigations have been conducted with quality less than one at inlet and only approximate comparisons, discussed in earlier papers, can be made. The present paper is devoted to comparisons between theory and measurements in investigations where local heat flux and channel surface temperature were measured and the vapor at inlet was superheated. Measured and calculated heat transfer coefficients and their dependence on distance along the channel and on local quality are in surprisingly good agreement and suggest that the mode of condensation is, in fact, annular and laminar, at least where the quality is high.

FIGURES IN THIS ARTICLE
<>
Copyright © 2017 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Dependence of vapor–surface temperature difference on distance along channel from the position of onset of condensation. G = 248 kg/m2 s [1113].

Grahic Jump Location
Fig. 2

Comparison between theory and experimental data of Kim et al. [1113]. Dependence of heat transfer coefficient on distance along channel from onset of condensation.

Grahic Jump Location
Fig. 3

Comparison between theory and experimental data of Kim et al. [1113]. Dependence of heat transfer coefficient on quality.

Grahic Jump Location
Fig. 4

Experimental data of Kim et al. [1113]. Vapor–surface temperature difference versus distance along channel. G = 186 kg/m2 s. Separate curve fits for each coolant flow rate.

Grahic Jump Location
Fig. 5

Comparison between theory and experimental data of Kim et al. [1113]. α versus z. Separate coolant flow rate tests distinguished.

Grahic Jump Location
Fig. 6

Comparison between theory and experimental data of Kim et al. [1113]. α versus (1 − χ). Separate coolant flow rate tests distinguished.

Grahic Jump Location
Fig. 7

Comparison of theory and experimental data of Koyama et al. [14]. α versus z.

Grahic Jump Location
Fig. 8

Comparison of theory and experimental data of Koyama et al. [14]. α versus (1 − χ).

Tables

Errata

Discussions

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