Local heat transfer measurements in microchannels using liquid crystal thermography: Methodology development and validation

R. Muwanga, Ibrahim Hassan

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Microchannel heat transfer governs the performance of the microchannel heat sink, which is a recent technology aimed at managing the stringent thermal requirements of today's high-end electronics. The microencapsulated form of liquid crystals has been well established for use in surface temperature mapping, while limited studies are available on the use of the un-encapsulated form. This latter form is advantageous since it offers the potential for high spatial resolution, which is necessary for microgeometries. A technique for using un-encapsulated thermochromic liquid crystals (TLCs) in order to measure the local heat transfer coefficient in microchannel geometries is shown in the present study. Measurements were made in a closed loop facility combined with a microscopic imaging system and automated data acquisition. A localized TLC calibration was used to account for a non-uniform coating and variation of lighting conditions. Three test section configurations were investigated with each subsequent configuration arising due to a shortfall in the previous. Two of these configurations are comprised of single wall heated rectangular channels, while the third is a circular tube channel. Validation results are also presented; overall, the methods developed and utilized in this study have been shown to provide the local heat transfer coefficient in microchannels.

Original languageEnglish
Pages (from-to)617-626
Number of pages10
JournalJournal of Heat Transfer
Volume128
Issue number7
DOIs
Publication statusPublished - Jul 2006
Externally publishedYes

Fingerprint

microchannels
Microchannels
Liquid Crystals
heat transfer
liquid crystals
methodology
Liquid crystals
Heat transfer
heat transfer coefficients
Heat transfer coefficients
configurations
circular tubes
heat sinks
Heat sinks
Imaging systems
illuminating
surface temperature
data acquisition
Data acquisition
Electronic equipment

Keywords

  • Experimental method
  • Heat transfer
  • Liquid crystal
  • Microchannel

ASJC Scopus subject areas

  • Mechanical Engineering
  • Physical and Theoretical Chemistry
  • Fluid Flow and Transfer Processes

Cite this

Local heat transfer measurements in microchannels using liquid crystal thermography : Methodology development and validation. / Muwanga, R.; Hassan, Ibrahim.

In: Journal of Heat Transfer, Vol. 128, No. 7, 07.2006, p. 617-626.

Research output: Contribution to journalArticle

@article{15643be2f595412fb26f58aee7671930,
title = "Local heat transfer measurements in microchannels using liquid crystal thermography: Methodology development and validation",
abstract = "Microchannel heat transfer governs the performance of the microchannel heat sink, which is a recent technology aimed at managing the stringent thermal requirements of today's high-end electronics. The microencapsulated form of liquid crystals has been well established for use in surface temperature mapping, while limited studies are available on the use of the un-encapsulated form. This latter form is advantageous since it offers the potential for high spatial resolution, which is necessary for microgeometries. A technique for using un-encapsulated thermochromic liquid crystals (TLCs) in order to measure the local heat transfer coefficient in microchannel geometries is shown in the present study. Measurements were made in a closed loop facility combined with a microscopic imaging system and automated data acquisition. A localized TLC calibration was used to account for a non-uniform coating and variation of lighting conditions. Three test section configurations were investigated with each subsequent configuration arising due to a shortfall in the previous. Two of these configurations are comprised of single wall heated rectangular channels, while the third is a circular tube channel. Validation results are also presented; overall, the methods developed and utilized in this study have been shown to provide the local heat transfer coefficient in microchannels.",
keywords = "Experimental method, Heat transfer, Liquid crystal, Microchannel",
author = "R. Muwanga and Ibrahim Hassan",
year = "2006",
month = "7",
doi = "10.1115/1.2193541",
language = "English",
volume = "128",
pages = "617--626",
journal = "Journal of Heat Transfer",
issn = "0022-1481",
publisher = "American Society of Mechanical Engineers(ASME)",
number = "7",

}

TY - JOUR

T1 - Local heat transfer measurements in microchannels using liquid crystal thermography

T2 - Methodology development and validation

AU - Muwanga, R.

AU - Hassan, Ibrahim

PY - 2006/7

Y1 - 2006/7

N2 - Microchannel heat transfer governs the performance of the microchannel heat sink, which is a recent technology aimed at managing the stringent thermal requirements of today's high-end electronics. The microencapsulated form of liquid crystals has been well established for use in surface temperature mapping, while limited studies are available on the use of the un-encapsulated form. This latter form is advantageous since it offers the potential for high spatial resolution, which is necessary for microgeometries. A technique for using un-encapsulated thermochromic liquid crystals (TLCs) in order to measure the local heat transfer coefficient in microchannel geometries is shown in the present study. Measurements were made in a closed loop facility combined with a microscopic imaging system and automated data acquisition. A localized TLC calibration was used to account for a non-uniform coating and variation of lighting conditions. Three test section configurations were investigated with each subsequent configuration arising due to a shortfall in the previous. Two of these configurations are comprised of single wall heated rectangular channels, while the third is a circular tube channel. Validation results are also presented; overall, the methods developed and utilized in this study have been shown to provide the local heat transfer coefficient in microchannels.

AB - Microchannel heat transfer governs the performance of the microchannel heat sink, which is a recent technology aimed at managing the stringent thermal requirements of today's high-end electronics. The microencapsulated form of liquid crystals has been well established for use in surface temperature mapping, while limited studies are available on the use of the un-encapsulated form. This latter form is advantageous since it offers the potential for high spatial resolution, which is necessary for microgeometries. A technique for using un-encapsulated thermochromic liquid crystals (TLCs) in order to measure the local heat transfer coefficient in microchannel geometries is shown in the present study. Measurements were made in a closed loop facility combined with a microscopic imaging system and automated data acquisition. A localized TLC calibration was used to account for a non-uniform coating and variation of lighting conditions. Three test section configurations were investigated with each subsequent configuration arising due to a shortfall in the previous. Two of these configurations are comprised of single wall heated rectangular channels, while the third is a circular tube channel. Validation results are also presented; overall, the methods developed and utilized in this study have been shown to provide the local heat transfer coefficient in microchannels.

KW - Experimental method

KW - Heat transfer

KW - Liquid crystal

KW - Microchannel

UR - http://www.scopus.com/inward/record.url?scp=33746677947&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33746677947&partnerID=8YFLogxK

U2 - 10.1115/1.2193541

DO - 10.1115/1.2193541

M3 - Article

AN - SCOPUS:33746677947

VL - 128

SP - 617

EP - 626

JO - Journal of Heat Transfer

JF - Journal of Heat Transfer

SN - 0022-1481

IS - 7

ER -