ARTICLE:

• LOW THERMAL CONDUCTIVITY MEASUREMENTS WITH A GHP APPARATUS  download article

C. V. Madhusudana
School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney 2052 Australia

ABSTRACT

The guarded hot plate (GHP) apparatus is capable of accurate determination of the thermal conductivity of materials in the range 0.02 to 2 W/(mK). The current paper presents and discusses the results of measurements made on a number of materials using a GHP apparatus. The apparatus was constructed at the University of New South Wales according to British Standard, BS 874: Part 2: Section 2.1. The apparatus was first calibrated by making thermal conductivity measurements of a Standard Reference Material (SRM 1450c) and was found to be accurate to within 4% when compared with the certified data supplied by the National Institute of Standards and Technology. Subsequently, measurements were made on several materials with the following results:
For packed bed of glass beads with a void fraction of 0.306, the thermal conductivity ranged from 0.265 to 0.300 W/(mK) over the temperature range 288 to 312 K; with a void fraction of 0.369 the thermal conductivity ranged from 0.235 to 0.248 W/(mK) over the same temperature range. The results agreed excellently with the correlation of Imura-Tagekoshi. For packed bed of rice, the thermal conductivity ranged from 0.165 to 0.191 W/(mK) over the temperature range 286 to 317 K. The results agreed well with the theory of Krupiczka. For Tasmanian hardwood, which is a type of oak, the thermal conductivity ranged from 0.166 to 0.187 W/(mK) over the temperature range 318 to 331 K, compared to the average value of 0.17 W/(mK) for American oak.

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