skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Apparent thermal conductivity measurements by an unguarded technique

Abstract

An unguarded longitudinal heat-flow apparatus for measuring the apparent thermal conductivity (lambda/sub a) of insulations was tested with mean specimen temperatures from 300 to 330/sup 0/K on samples up to 0.91 m wide, 1.52 m long, and 0.15 m thick. Heat flow is provided by a horizontal electrically heated Nichrome screen sandwiched between test samples that are bounded by temperature controlled copper plates and 9 cm of mineral fiber insulation. A determinate error analysis shows lambda/sub a/ measurement uncertainty to be less than +- 1.7% for insulating materials as thin as 3 cm. Three-dimensional thermal modeling indicates negligible error in lambda/sub a/ due to edge loss for insulations up to 7.62 cm thick when the temperature difference across the sample is measured at the sceen center. System repeatability and reproducibility were determined to be +- 0.2%. Differences of lambda/sub a/ results from the screen tester and results from the National Bureau of Standards were 0.1% for a 10-kg/m/sup 3/ Calibration Transfer Standard and 0.9% for 127-kg/m/sup 3/ fibrous glass board (SRM 1450b). Measurements on fiberglass and rock wool batt insulations showed the dependence of lambda/sub a/ on density, temperature, temperature difference, plate emittance, and heat flow direction. Results obtained formore » lambda/sub a/ as a function of density at 24/sup 0/C differed by less than 2% from values obtained with a guarded hot plate. These results demonstrate that this simple technique has the accuracy and sensitivity needed for useful lambda/sub a/ measurements on thermal insulating materials.« less

Authors:
; ;
Publication Date:
Research Org.:
Oak Ridge National Lab., TN (USA)
OSTI Identifier:
5727072
Report Number(s):
CONF-8310163-4
ON: DE84001964
DOE Contract Number:  
W-7405-ENG-26
Resource Type:
Conference
Resource Relation:
Conference: 18. international thermal conductivity conference, Rapid City, SD, USA, 3 Oct 1983
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 36 MATERIALS SCIENCE; 47 OTHER INSTRUMENTATION; THERMAL CONDUCTIVITY; MEASURING INSTRUMENTS; THERMAL INSULATION; ACCURACY; PHYSICAL PROPERTIES; THERMODYNAMIC PROPERTIES; 420500* - Engineering- Materials Testing; 360603 - Materials- Properties; 440300 - Miscellaneous Instruments- (-1989)

Citation Formats

Graves, R S, Yarbrough, D W, and McElroy, D L. Apparent thermal conductivity measurements by an unguarded technique. United States: N. p., 1983. Web.
Graves, R S, Yarbrough, D W, & McElroy, D L. Apparent thermal conductivity measurements by an unguarded technique. United States.
Graves, R S, Yarbrough, D W, and McElroy, D L. 1983. "Apparent thermal conductivity measurements by an unguarded technique". United States.
@article{osti_5727072,
title = {Apparent thermal conductivity measurements by an unguarded technique},
author = {Graves, R S and Yarbrough, D W and McElroy, D L},
abstractNote = {An unguarded longitudinal heat-flow apparatus for measuring the apparent thermal conductivity (lambda/sub a) of insulations was tested with mean specimen temperatures from 300 to 330/sup 0/K on samples up to 0.91 m wide, 1.52 m long, and 0.15 m thick. Heat flow is provided by a horizontal electrically heated Nichrome screen sandwiched between test samples that are bounded by temperature controlled copper plates and 9 cm of mineral fiber insulation. A determinate error analysis shows lambda/sub a/ measurement uncertainty to be less than +- 1.7% for insulating materials as thin as 3 cm. Three-dimensional thermal modeling indicates negligible error in lambda/sub a/ due to edge loss for insulations up to 7.62 cm thick when the temperature difference across the sample is measured at the sceen center. System repeatability and reproducibility were determined to be +- 0.2%. Differences of lambda/sub a/ results from the screen tester and results from the National Bureau of Standards were 0.1% for a 10-kg/m/sup 3/ Calibration Transfer Standard and 0.9% for 127-kg/m/sup 3/ fibrous glass board (SRM 1450b). Measurements on fiberglass and rock wool batt insulations showed the dependence of lambda/sub a/ on density, temperature, temperature difference, plate emittance, and heat flow direction. Results obtained for lambda/sub a/ as a function of density at 24/sup 0/C differed by less than 2% from values obtained with a guarded hot plate. These results demonstrate that this simple technique has the accuracy and sensitivity needed for useful lambda/sub a/ measurements on thermal insulating materials.},
doi = {},
url = {https://www.osti.gov/biblio/5727072}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1983},
month = {Sat Jan 01 00:00:00 EST 1983}
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share: