ISSN Online: 2377-424X
ISBN CD: 1-56700-226-9
ISBN Online: 1-56700-225-0
International Heat Transfer Conference 13
LOW THERMAL CONDUCTIVITY MEASUREMENTS WITH A GHP APPARATUS
要約
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.
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.