Simultaneous measurement of effective thermal conductivity and effective thermal diffusivity of Li2TiO3 pebble bed using transient hot-wire technique

Lithium-based ceramics in the form of pebble beds have been considered for tritium breeder material in the fusion reactor's breeder blanket. It is essential to study the thermal characteristics of these ceramic pebble beds subjected to fusion relevant conditions. Effective thermal conductivity (k), effective thermal diffusivity (alpha) and effective specific heat (c(p)) of a packed bed are some of the crucial parameters for the design of breeder blanket module. In the present study, the transient hot-wire technique was used to measure k, alpha and c(p) of lithium metatitanate (Li2TiO3) pebble bed fabricated at Institute for Plasma Research, India. Thermal properties of Li2TiO3 pebble bed (1 +/- 0.15 mm pebble diameter and similar to 63% packing fraction) are measured within the temperature range of 45 degrees C to 800 degrees C in stagnant helium gas environment. The filling gas pressure variation effect on the Li2TiO3 pebble bed's thermal properties for the pressure range of 0.105 MPa to 0.4 MPa has also been studied. Equations are suggested for k and alpha of Li2TiO3 pebble bed as a function of temperature at different pressure in the helium gas environment.

Automated summary

The thermal properties of lithium metatitanate pebble bed under fusion conditions, including effective thermal conductivity, effective thermal diffusivity, and effective specific heat, were studied. The transient hot-wire technique was used for measurement and the effect of filling gas pressure variation on thermal properties was also investigated. Equations for thermal conductivity and thermal diffusivity as functions of temperature at different pressures in helium gas environment were proposed.