Performance characteristics of an apparatus based on the curve-fitting method for measuring thermal properties at cryogenic temperatures
✍ Scribed by M. Yoshiwa; A. Iwata
- Publisher
- Elsevier Science
- Year
- 1977
- Tongue
- English
- Weight
- 880 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0011-2275
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✦ Synopsis
This paper describes the performance characteristics of a new test apparatus and the measured results using the apparatus. It has been developed on the basis of Harmathy's curve-fitting method to measure, in a short time, the physical properties of the nonmetallic materials for a cryogenic storage tank. The apparatus has been used to measure the heat capacity, thermal conductivity, and thermal diffusivity of the materials at the same time in the temperature range of approximately-180°C to +50°C.
With this apparatus the thermal conductivity can be measured over a wide range of approximately O. 01 kcal m-1 h -1 o C-1 to 10 kcal m -1 h -1 o C-1 in the range of -180 ° C
to +50 ° C. The materials investigated were structural materials such as concrete, wood, frozen soil, and autoclaved lightweight concrete (AL C) and such insulation materials as calcium silicate, phenolic foam, and polyurethane foam.
Performance characteristics of an apparatus based on the curve-fitting method for measuring thermal properties at cryogenic temperatures M. Yoshiwa and A. Iwata
Due to the increasing interest in cryogenic engineering there has recently been a steady increase in data concerned with the physical properties of many different kinds of materials over a wide temperature range.
Physical properties have been measured by many workers in this field.t-3' 9-13 However, measurements on insulating materials such as phenolic foam, polyurethane foam, and so on have usually taken a long time, because of the steady state method adopted in JIS 4's and ASTM 6-~ has been used. Measurements carried out by authors using the steady state method, have taken about 50 hours 14 for a small specimen, 160 mm in diameter, at approximately -160°C and about 200 hours 14 for a large specimen, 2.5 m x 2.0 m x 0.2 m thick, which was kept at a temperature of between approximately -160°C on the cold surface and +30°C on the hot surface.
If the conventional steady state method is used to determine all values of specific heat, thermal conductivity and thermal diffusivity for a small specimen, it will take about 100 hours or more. To measure all these physical properties in the shortest time possible, the variable state method would appear to be the most reasonable.
A few papers 1~-22 have been published on the use of variable state methods to measure physical properties. One of these, the curve-fitting method 2° was developed by Harmathy in 1964 and has been used to measure the specific heat, the thermal conductivity, and the thermal diffusivity of concrete at high temperatures. 2° We have modified Harmathy's method and developed a new test apparatus for measuring physical properties at cryogenic temperatures.