EFFECT OF EXTERNAL-PRESSURE ON PARTICLE BED EFFECTIVE THERMAL-CONDUCTIVITY

Accurate prediction of the thermomechanical responses of particle beds in fusion blankets depends strongly on the availability of experiment al data on their thermal properties as a function of the blanket opera ting conditions. In this study, a series of experiments was conducted to measure the effective conductivity and interface conductance of sin ge-size aluminum, beryllium and lithium zirconate particle beds as a f unction of applied external load in the range 0-1.6 MPa. Experiments w ere carried out with both helium and air as cover gas over a range of pressure 30-760 Torr. In both aluminum and beryllium beds, as the appl ied load was increased to 1.5 MPa, the effective thermal conductivity increased by a factor of similar to 3-7 in an air cover gas, and a fac tor of similar to 2-3 in helium. With 1.2 mm lithium zirconate particl es and air as the cover gas, changes in the bed thermal conductivity w hen the applied load was varied in the range of 0-1.6 MPa were small a nd within the experimental error. The increase in the interface conduc tance values with applied external load shows variations similar to th ose of the thermal conductivity.