Hot wire thermal conductivity measurements in high temperature refractories

Technical Report · Fri Jan 01 04:00:00 EST 1982

OSTI ID:6243727

Dils, R R; Allen, J D; Richmond, J C; McNeil, M B

In the hot wire thermal conductivity test, a wire embedded in the material to be tested is heated with constant power input, and the temperature is measured at short time intervals. The thermal conductivity is computed from the known power input to the wire and the measured rate of increase in the wire temperature after about 700 s of heating. A finite-difference computer simulation of the hot wire test was developed to evaluate the effects of several variables in the properties of the materials tested and in the test procedures on the measured thermal conductivity. Equations relating the radiant heat transfer in a material to its optical properties were developed and a radiant heat transfer component was developed for the finite-difference simulation. Equations were derived to compute the spectral optical properties of a test material from the measured spectral normal-hemispherical transmittance of a sample of the material of known thickness that is thin enough to have a measurable transmittance over the wavelength range of about 500 to 20,000 nm, and the spectral near-normal hemispherical reflectance of a sample of the material thick enough to be completely opaque, over the same wavelength range. The optical extinction coefficient, and the ratio of the scattering coefficient, to the absorption coefficient, of MinK 2000 and K3000 brick were evaluated from their measured spectral transmittances and reflectances, and used to compute the radiant heat transfer component in these materials. The hot wire test measures an average thermal conductivity for all directions away from the wire in a plane normal to the wire. Extensive tests were made of MinK 2000 and K3000, and the measured values are compared to the guarded hot plate thermal conductivity, which is unidirectional normal to the face of a brick. 67 references, 31 figures, 23 tables.

• Research Organization: National Bureau of Standards, Washington, DC (USA)
• DOE Contract Number: AT01-81CS40442
• OSTI ID: 6243727
• Report Number(s): DOE/CS/40442-T1; ON: DE85004516
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
COMPUTERIZED SIMULATION
DATA
ENERGY TRANSFER
EQUATIONS
EXPERIMENTAL DATA
FINITE DIFFERENCE METHOD
HEAT TRANSFER
INFORMATION
ITERATIVE METHODS
MEASURING METHODS
NUMERICAL DATA
NUMERICAL SOLUTION
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIANT HEAT TRANSFER
REFRACTORIES
SIMULATION
THERMAL CONDUCTIVITY
THERMODYNAMIC PROPERTIES