Experimental investigation on minimum film boiling temperature during reflooding in multi-rectangular narrow channels

Determination of minimum film boiling temperature (T-min) is significant in the nuclear reactor safety analysis. T-min represents the start of quenching which is vital to mitigate the severity of the accident. In this paper, a bottom reflooding experiment is carried out to investigate T-min and quench velocity in multi-rectangular narrow channels. Effects of working conditions, including inlet subcooling, reflooding velocity, initial wall temperature, and system pressure on T-min and quench velocity, are analyzed in detail. It is found that T-min and quench velocity distinctly increases with the increase of subcooling, system pressure, and reflooding velocity. However, the effect of reflooding velocity on T-min and quench velocity is mild when the reflooding velocity is relatively high. T-min increases with the increase of initial wall temperature, while quench velocity drops. T-min at the upper position of the heating wall is lower than that at the lower position because the water subcooling changes when flowing along the heating channel. A prediction model of T-min during reflooding in rectangular narrow channel is proposed, and very good agreement is achieved comparing with experimental data with +/- 10% uncertainty. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This paper investigates the minimum film boiling temperature (T-min) and quench velocity in multi-rectangular narrow channels through a bottom reflooding experiment. The study analyzes the effects of working conditions on T-min and quench velocity, and proposes a prediction model for T-min during reflooding in rectangular narrow channels.