Liquid entrainment and off-take through the break at the top of a vessel

Abstract

In order to determine the bleed capacity of the safety depressurization system (SDS) of Advanced Power Reactor 1400 (APR1400) in the case of total loss of feed water (TLOFW), we performed an experimental study of liquid entrainment and liquid off-take from the swelled two-phase mixture surface in a vessel. A total of 220 experimental data on the entrainment and off-take are obtained using a test vessel with a height of 2.0 m and an inner diameter of 0.3 m and a top break with a diameter of 0.05 m. Two-phase mixture levels are measured by an ultrasonic sensor within ±1.77% with respect to the visual level data. Droplet entrainment data are obtained with and without the top break and are compared with the existing pool entrainment data. The present droplet entrainment data have higher values than the existing pool entrainment data due to (a) the pulling toward the break of the liquid deentrained on the top wall of the vessel and (b) gas acceleration in the vicinity of the break. In the present experiment, droplet entrainment, E fg, strongly depends upon j g * / h * and is proportional to the seventh power of j g * / h * in the same way as the off-take data. The empirical correlation for the onset of off-take is developed in terms of the Froude number ( Fr g) at the break and the non-dimensional inception height ( h b/ d). This correlation shows agreement with the present experimental data within ±15%. The present off-take quality data show agreement with Schrock's off-take quality correlation with the rms error of 15.8%.