National Technical University of Athens
School of Mechanical Engineering
Nuclear Engineering Department

The 15th International Topical Meeting on Nuclear Reactor Thermalhydraulics, NURETH-15 Pisa, Italy, May 12-15, 2013

A study on the rewetting of a hot surface, using low pressure, subcooled liquid

S. Chatzidakis1,2, A. Nikoglou1, E. Hinis1 and S. Simopoulos1
1 National Technical University of Athens, Zografos Campus Athens, Greece
2 Institute of Nuclear Technology & Radiation Protection, National Centre for Scientific Research Demokritos, Athens, Greece
This study presents the experimental work carried out to simulate the rewetting behavior of a vertical annular channel with a heated rod at top flow rewetting conditions. A specifically designed and built experimental facility has been used to simulate the two-phase water flow phenomena at atmospheric conditions and low pressures at different degrees of inlet sub-cooling. Experiments have been conducted at atmospheric and steam conditions up to 3 bar with inlet sub-cooling in the range of 0-50°C. The initial surface temperature of the rod varies from 200 to 550 °C while the liquid flow-rate is steady and equals to 10-3 m3min-1. The main objective of this study is to identify the effect of low pressure steam environment in combination with inlet sub-cooling on the rewetting process. It appears that the rewetting velocity increases with an increase in pressure and inlet sub-cooling and decreases with an increase in the initial surface temperature. In addition, this study proposes a new rewetting correlation and discusses the effect introduced by the channel diameter on the rewetting phenomena.