Some preliminary results of post-dryout heat transfer measurements at low qualities and pressures up to 20 bar

Steady state data have been obtained on post-dryout heat transfer for flow in a tube of inside diameter 10 mm and length 920 mm. The experiments covered mass velocities up to 200 kg/m2s at 10 and 20 bar and up to 1000 kg/m2s at 2 and 5 bar. Inlet qualities were close to zero and the equilibrium quality at exit ranged up to 60%. The tube was prevented from rewetting by massive copper hot patches, brazed to it at each end. Surface temperature measurements were made along the length of the tube. An in-stream thermocouple inserted into the flow at exit from the tube provided a measure of vapor temperature at this location. Typical sets of data are presented and the trends discussed. These new data extend the range of the available database against which the combined effects of the heat transfer and hydraulic models in reactor safety codes can be assessed. Comparisons are made with predictions obtained using the TRAC-PF1/MOD1 computer code and the reflood code BERTHA