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

Kerntechnik 68 (2001) 1-2


E.P.Hinis and S.E. Simopoulos
Nuclear Engineering Section
Mechanical Engineering Department
National Technical University of Athens

Several water experiments have been carried out to investigate the physical mechanisms relevant to the rewetting phenomena either at atmospheric conditions or in a steam environment. Yet, there seems to be a scarcity of experimental data for the low pressure range from 2 to 7 bar with parameters the liquid film flowrate and the subcooling. An experimental facility to simulate two-phase low-pressure water flow phenomena has been designed, constructed and employed to investigate the rewetting process of hot surfaces in a water-steam environment at pressures in the above range, as well as at atmospheric conditions; the facility is on-line interfaced to computers which control its operation and undertake all the data acquisition tasks. Furthermore, a numerical method to experimentally evaluate the wet front position along the rod was introduced. The present paper describes the experimental work aimed at studying the wet front propagation along a stainless steel fuel rod, in a top-flooding environment in the pressure range 1-7 bar, wall temperatures up to 550°C and at a liquid flowrate of 10-3m3min-1 at both saturated steam conditions and in atmospheric environment with water subcooling in the range 0-75K. The experimental results fitted well to an existing dimensionless rewetting correlation, together with world available vapour environment rewetting data extending its validity down to the pressure of 1 bar. Furthermore, the effect of the inlet water subcooling was introduced in to this correlation.

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