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 con ductivity of Li2O and Be pebble beds using a hot wire method(1). Also, prel iminary results for a binary bed using Al2O3 pebbles are presented. The mea sured value for an Al2O3 single packing bed showed good agreement with Schu lunder's correlation(2) and Hall-Martin's correlation(3) with a contact are a fraction of 5 x 10(-5). The value of the contact area fraction in this st udy 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 agreemen t with the same correlation using the same value of contact area fraction. The measured value of the effective thermal conductivity for an Li2O bed us ing 1 mm pebbles agreed with the correlation using a value of 4.9 x 10(-3) for the contact area fraction. The measured values of the effective thermal conductivity for 0.6 mm and 1 mm Be pebble beds showed consistency with th e correlation using 1 x 10(-4) for the contact area fraction.