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Design Concepts for a New Guarded Hot Plate Apparatus for Use Over an Extended Temperature Range.


pdf icon Design Concepts for a New Guarded Hot Plate Apparatus for Use Over an Extended Temperature Range. (327 K)
Flynn, D. R.; Zarr, R. R.; Hahn, M. H.; Healy, W. M.

Insulation Materials: Testing and Applications, 4th Volume. ASTM STP 1426. 2002, ASTM International, West Conshohocken, PA, Desjarlais, A. O.; Zarr, R. R., Editor(s)(s), 98-115 pp, 2002.

Keywords:

insulation; heat transmission; conductive heat transfer; heat transfer; thermal conductivity; thermal insulation; thermal resistance

Abstract:

The National Institute of Standards and Technology is building a new guarded hot plate apparatus (GHP) for use at temperatures from 90 K to 900 K, with provision to conduct tests in various gases at controlled pressures from 0.013 Pa to 0.105 MPa ({approximately equal to} 1.04 atm). Important features of the design of the new NIST GHP include: enclosure of the entire apparatus in a vacuum chamber; solid metal hot plates and cold surface plates to provide highly isothermal surfaces in contact with the test specimens; an integral close-fitting edge guard to minimize the effects of edge heat losses or gains; connection guard blocks to minimize the effects of heat conduction along coolant lines, heater leads, thermometry wells, and sensor leads coming from the hot plate and the cold plates; provision of a system to provide a known clamping force between the specimens and the contacting hot and cold plate surfaces; provision of an accurate system for in-situ measurement of specimen thickness during a test and the use of three long-stem standard platinum resistance thermometers to measure the average temperature of the meter plate and the two cold plates.