A Technique for Measuring the Apparent Thermal Conductivity of Flat Insulations

Abstract

A technique for measuring the apparent thermal conductivity, λ _a , of flat insu lations (either batt or loose) is described. This technique consists of an elec trically heated flat Nichrome-screen wire sandwiched between a pair of samples. Results from a limited experimental test are described and compared with results from a pipe insulation tester. Thermal modeling of this system shows that accurate measurements with λ _a down to 0.01 W/m·K** and insula tion thicknesses below 0.089 m (3½ in.) should be straightforward. Measure ment of λ _a for material as thick as 0.305 m (12 in.) should also be possible with a lateral guard scheme to reduce heat flow along the screen wire heater.

Get full access to this article

View all access options for this article.

References

Donnelly, R.G. , Tennery, V.J. , McElroy, D.L. , and Kolb, J.O. , "Industrial Thermal Insulation: An Assessment," ORNL/TM-5283, Oak Ridge National Laboratory, Oak Ridge, Tennessee (March 1976).

Tye, R. P. (ed.), Thermal Conductivity, Vol. 1, Academic Press, New York (1969).

"Steady-State Thermal Transmission Properties by Means of the Guarded Hot Plate," ANSI/ASTM C-177, in 1980 Annual Book of ASTM Standards, Part 18, American Society for Testing and Materials, Philadelphia , pp. 20-53 (1980).

"Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter," ANSI/ASTM C-518-76, in 1980 Annual Book of ASTM Standards, Part 18, American Society for Testing and Materials, Philadelphia , pp. 222-253.

Pratt, A.W. , "Heat Transmission in Low Conductivity Materials," in Thermal Conductivity , Vol. 1, Tye, R. P. (ed.), Academic Press, New York (1969).

"Thermal Conductivity of Pipe Insulation," in 1977 Annual Book of ASTM Standards, Part 18, American Society for Testing and Materials, Philadelphia, pp. 97-102 (1977).

Jury, S.H. , McElroy, D.L. , and Moore, J.P. , "Pipe Insulation Testers," Thermal Transmission Measurement of Insulations, ASTM STP 660, R. P. Tye, ed., American Society for Testing and Materials, Philadelphia, pp. 310-326 (1978).

Moore, J.P. , McElroy, D.L. , and Jury, S.H. , "A Technique for Measuring the Apparent Thermal Conductivity of Flat Insulations," ORNL/TM-6494, Oak Ridge National Laboratory, Oak Ridge, Tennessee (October 1979).

Pelanne, C.M. , J. Therm. Insul, 1:48 ( 1977).

10.

Turner, W.D. , Elrod, D.C. , and Siman-Tov, I.I. , "HEATING5-An IBM 360 Heat Conduction Program," ORNL/CSD/TM-15, Oak Ridge National Laboratory, Oak Ridge, Tennessee (March 1977).