Measurements of Burnout Conditions for Flow of Boiling Water in Vertical Rod Clusters

The present report deals with the results of the first phase of an experimental investigation of burnout conditions for flow of boiling water in vertical round ducts. Data were obtained in the following ranges of variables. Pressure 2.4<p<42 ata; Inlet subcooling 18<Δtsub< 192 deg C; Steam quality 0.37<x<1.0; Heat flux 28<q/A<180 W/cm2; Mass velocity 144<m/F<1909 kg/m2/s; Heated length 1040<L<3120 mm; Duct diameter 3.94<d<9.93 mm; L/d-ratio 105<L/d<790. The results are presented in diagrams where for a certain geometry, the burnout steam qualities, xBO, were plotted against the pressure with the surface heat flux as parameter. The data have been correlated by curves. The scatter of the data around the curves is less than ± 5 per cent. In the ranges investigated the observed steam quality at burnout, xBO generally decreases with increasing heat flux; increases with increasing pressure and decreases with increasing mass velocity. The mass velocity effect has been explained on the basis of climbing film flow theory. Finally we have found that for engineering purposes the effects of inlet subcooling and channel length are negligible