Effective Thermal Conductivity Measurements of the Binary Pebble Beds by Hot Wire Method for the Breeding Blanket

This work presents the results of measurements of the effective thermal conductivity of Li₂O and Be pebble beds using a hot wire method¹. Also, preliminary results for a binary bed using Al₂O₃ pebbles are presented. The measured value for an Al₂O₃ single packing bed showed good agreement with Schulunder's correlation² and Hall-Martin's correlation³ with a contact area fraction of 5 × 10⁻⁵. The value of the contact area fraction in this study showed consistency with that reported by Dalle Donne et al.⁴. Results for the binary bed of Al₂O₃ (0.3 mm and 3 mm) pebbles showed good agreement with the same correlation using the same value of contact area fraction. The measured value of the effective thermal conductivity for an Li₂O bed using 1 mm pebbles agreed with the correlation using a value of 4.9 × 10⁻³ for the contact area fraction. The measured values of the effective thermal conductivity for 0.6 mm and 1mm Be pebble beds showed consistency with the correlation using 1 × 10⁻⁴ for the contact area fraction.