Experimental Results of Pebble Bed Thermal-Hydraulic Characteristics

Abstract

The purpose of this paper is to present the results of the experimental investigation of the thermal-hydraulic characteristics for two types of test sections: thin annular pebble beds (i.e., spheres dumped in thin annular slots) and pebble beds placed between cylinders. The experimental results of heat transfer from the spheres and from a cylinder, as well as hydraulic drag for both types of test sections, are presented in this paper. The results of the thin annular pebble bed experiments demonstrate that the maximum heat transfer and hydraulic drag is at the annular slot with the relative width K equal to 1.07 and 1.75 of the sphere diameter. The heat transfer in the internal layers at these values of K is equal to the heat transfer in the internal layers of large (unlimited) rhombic packing. The results of the experimental investigation of pebble beds between cylinders demonstrate that the randomly arranged pebble bed is preferable to the regular rhombic structure from the viewpoints of design simplicity, heat transfer from the cylinder, and drag coefficient.