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

An experimental study of the rewetting of a hot surface at atmospheric conditions using sub cooled liquid at various flowrates

N. Kastanidis, A. Nikoglou, E. Hinis and S. Simopoulos
Nuclear Engineering Department NTUA, 15780 Athens, GREECE
In this study several experiments have been carried out to investigate the effect of coolant flow-rate upon the rewetting mechanism of a vertical annular channel encircling a heated rod at atmospheric conditions. A specifically designed and constructed experimental facility has been used to simulate the two-phase water flow phenomena of the rewetting process at atmospheric conditions and different degrees of inlet sub-cooling. The facility is a two-loop water flow system with a real time computer interface for operational monitoring as well as control and data acquisition during experiments. The wet front propagation along a stainless steel cylindrical surface vertically positioned at top flow rewetting conditions has been examined in the flow-rate range of 0.5 to 1.0 L min-1, inlet water sub-cooled in the range of 0 to 50 °C with an initial surface temperature of the rod up to 550 °C at atmospheric conditions. The result presented in this study shows that the rewetting velocity increases with an increase in liquid flow-rate and sub-cooling and decreases with an increase of the initial surface temperature.