Thermal Conductivity Measurement with Silica-Coated Hot Wire for Li4SiO4 Pebble Bed

Abstract The effective thermal conductivity of a Li4SiO4 pebble bed was measured by the hot wire method. The bare and silica-coated Nichrome heaters were used as the hot wires. At 975 K, effective thermal conductivity was not measured correctly by the bare hot wire. This is due to the fact that the electrical signal of a bare thermocouple is distorted due to the electrical conductivity of Li4SiO4. Using a silica-coated hot wire, effective thermal conductivity can be measured at temperatures ranging from room temperature to 975 K. The effect of the coating layer on the measured effective thermal conductivity was estimated to be small and corresponded to the experimental data. The hot wire method with silica coating can be applied to other ceramic breeder materials. KEYWORDS: fusionblanketceramic breederLi4SiO4 pebble bedthermal conductivityhot wire methodsilica coatingelectrical conductivity