Thermal Conductivity of Saturated Liquid Toluene by Use of Anodized Tantalum Hot Wires at High Temperatures

• Published in: Journal of research of the National Institute of Standards and Technology Vol. 105; no. 2; pp. 255 - 264
• Main Authors: Perkins, R A, Ramires, M L, Nieto de Castro, C A
• Format: Journal Article
• Language: English
• Published: United States Superintendent of Documents 01.03.2000; National Institute of Standards (NIST); [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology
• Subjects: anodized tantalum wire; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; instruments & instrumentation; liquid; OTHER INSTRUMENTATION; physics; thermal conductivity; thermal radiation; toluene; transient hot-wire; liquid; thermal conductivity; toluene; transient hot-wire; anodized tantalum wire; thermal radiation
• ISSN: 1044-677X; 2165-7254
• DOI: 10.6028/jres.105.029

Absolute measurements of the thermal conductivity of a distilled and dried sample of toluene near saturation are reported. The transient hot-wire technique with an anodized tantalum hot wire was used. The thermal conductivities were measured at temperatures from 300 K to 550 K at different applied power levels to assess the uncertainty with which it is possible to measure liquid thermal conductivity over wide temperature ranges with an anodized tantalum wire. The wire resistance versus temperature was monitored throughout the measurements to study the stability of the wire calibration. The relative expanded uncertainty of the resulting data at the level of 2 standard deviations (coverage factor k = 2) is 0.5 % up to 480 K and 1.5 % between 480 K and 550 K, and is limited by drift in the wire calibration at temperatures above 450 K. Significant thermal-radiation effects are observed at the highest temperatures. The radiation-corrected results agree well with data from transient hot-wire measurements with bare platinum hot wires as well as with data derived from thermal diffusivities obtained using light-scattering techniques.