Gravity injection experiments and direct-contact condensation regime map for passive high-pressure injection system

The gravity injection experiment in a passive high-pressure injection system with a pressurizer pressure balance line is conducted by using a small-scale test facility to identify the parameters having the effects on the gravity injection and the major condensation modes. It turns out that the larger the water subcooling is, the more the initiation of injection is delayed, and the sparger and the natural circulation of the hot water from the steam generator accelerate the gravity injection. The condensation modes identified through the experiments are divided into three modes: sonic jet, subsonic jet, steam cavity. The steam cavity is the unique mode of downward injection with the present geometry not previously observed in other experiments. The condensation regime map associated with the injection of steam into water through the steam pipe is constructed using Froude number and Jacob number