The Thermal Conductivity of Beds of Spheres
The thermal conductivities (k) of beds of solid and hollow microspheres were measured using two radial heat flow techniques. One technique provided k-data at 300 K for beds with the void spaces between particles filled with argon, nitrogen, or helium from 5 kPa to 30 MPa. The other technique provided k-data with air at atmospheric pressure from 300 to 1000 K. The 300 K technique was used to study bed systems with high k-values that can be varied by changing the gas type and gas pressure. Such systems can be used to control the operating temperature of an irradiation capsule. The systems studied included beds of 500 µm dia solid Al203, the same Al203 spheres mixed with spheres of silica-alumina or with SiC shards, carbon spheres, and nickel spheres.* Both techniques were used to determine the k-value of beds of hollow spheres with solid shells of Al2O3, Al203,•7 w/o Cr203, and partially stabilized Zr02.** The hollow microspheres had diameters from 2100 to 3500 µm and wall thicknesses from 80 to 160 µm.
KeywordsNickel Convection Carbide Argon Helium
Unable to display preview. Download preview PDF.
- 1.R. E. Pawel, D. L. McElroy, F. J. Weaver, and R. S. Graves, High Temperature Thermal Conductivity of a Fibrous Alumina Ceramic, Paper to be published in Thermal Conductivity 19 ( October 1985, Tennessee Technological University).Google Scholar
- 2.J. P. Moore, R. J. Dippenaar, R. 0. A. Hall, and D. L. McElroy, Thermal Conductivity of Powders with U02 or Th02 Microspheres in Various Gases fromn 300 to 1300 K, 0RNL/TM-8196 (June 1982).Google Scholar
- 3.A. W. Longest, J. E. Corum, and K. R. Thorns, “Design and Fabrication of HFIR-MFE RB* Spectral Tailoring Irradiation Capsules,” Fusion Reactor Materials Semiannual Progress Report for Period Ending March 31, 1987, pp. 8–9, D0E/ER-0313/2 (September 1987).Google Scholar
- 4.A. T. Chapman, J. K. Cockran, J. M. Britt, and T. J. Hwang, Thin-Walled Hollow Ceramic Spheres from Slurries, Draft Report to 0RNL from Georgia Institute of Technology (86X-2204 3C) (January 19, 1987 ).Google Scholar
- 5.G. R. Cunnington and C. L. Tien, Heat Transfer in the Presence of a Gas, Thermal Conductivity 15, pp. 325–333 (1981).Google Scholar
- 6.D. W. Yarbrough, F. J. Weaver, R. S. Graves, and D. L. McElroy, Development of Advanced Thermal Insulation for Applicances Progress Report for the Period July 1984 through June 1985, 0RNL/C0N-199 (May 1986).Google Scholar
- 7.G. L. Copeland, D. L. McElroy, R. S. Graves, and F. J. Weaver, Insulations with Low Thermal Conductivity, Thermal Conductivity 18, pp.367–377, ed. byT. Ashworth and D. R. Smith (Plenum, 1985 ).Google Scholar
- 8.W. D. Turner, D. L. Elrod, and I. I. Siman-Tov, HEATING5 - An IBM 360 Heat Conduction Program, 0RNL/CSD/TM-15 (March 1977).Google Scholar
- 9.M. J. Shapiro, “An Experimental Investigation of the Thermal Conductivity of Thin-Wall Hollow Ceramic Spheres,” M.S. Thesis, Georgia Institute of Technology (March 1988).Google Scholar
- 10.S. H. Jury, D. L. McElroy, and J. P. Moore, “Pipe Insulation Testers,” Thermal Transmission Measurements of Insulation, ASTM STP 660, R. P. Tye, Ed., Americal Soceity for Testing and Materials, pp. 310–326 (1978).Google Scholar
- 11.R. J. Price, Properties of Silicon Carbide for Nuclear Fuel Particle Coatings, GA-A14061 (January 1977).Google Scholar
- 12.R. T. Parmley, and G. R. Cunnington, Jr., “Evacuated Load-Bearing High-Performance Insulation Study,” Lockheed Missiles and Space Company, Inc., NASA CR-135342 (December 1977).Google Scholar