Visualizing The Thermal Performance Of Heat Pipes With Thermochromic Liquid Crystals


A novel and instructive technique has been developed to visualize the thermal performance characteristics of simple low temperature heat pipes and thermosyphons. Copper heat pipes with internal, annular mesh wicks and charged with Refrigerant-12 were externally coated with thermochromic liquid crystal (TLC) paints. The thermally sensitive TLC coating reversibly changes color upon heating and readily permits visual identification of transient and steady state isotherms during low temperature operation. The start-up and operational behaviors of the heat pipe as well as the presence of non-condensible gases can be visually identified through a spectrum of color changes. Each distinct color is indicative of an isothermal region on the heat pipe. The TLC thermal characterization technique can be used in the development and support of heat transfer models, performance evaluations and for identifying cooler, non-condensible gas regions within operating heat pipes. A brief seven-minute VHS video supplements this paper. The video dramatically illustrates a side-by-side comparison of a simple heat pipe with an equivalent solid copper rod and shows the thermal nature of an operating heat pipe. The effects of non-condensible gas migration to the condenser region of the heat pipe is also illustrated.

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Publication Title

Proceedings of the Intersociety Energy Conversion Engineering Conference



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Document Type

Article; Proceedings Paper

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Socpus ID

0025842823 (Scopus)

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