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

R. Muwanga, Ibrahim Hassan

Research output: Contribution to journalArticle

34 Citations (Scopus)


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
Issue number7
Publication statusPublished - 1 Jul 2006



  • Experimental method
  • Heat transfer
  • Liquid crystal
  • Microchannel

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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