Quenching of hot vertical wall with a falling liquid film is an important thermal-hydraulic process to ensure the safety of nuclear reactors during emergency after LOCA (Loss-Of-Coolant Accident). In this work, to develop a reliable model to predict the propagation velocity of the quench front, the temperature distribution of heat transfer surface during quenching was measured using a high-speed infrared camera. A silicon wafer, transparent to the infrared ray, was used as the hot wall, and the initial wall temperature, the wall thickness, the cooling liquid temperature, and the liquid flow rate were changed parametrically in the experiments. The main heat transfer mechanism from the wall to the liquid film near the quench front was found to be the nucleate boiling. The heat transfer coefficient profile derived from the measured temperature distribution was therefore correlated using widely accepted heat transfer correlations such as Zuber’s correlation for pool boiling CHF and Rohsenow’s correlation for the pool boiling HTC. The calculated quench velocity was in good agreement with the experimental data not only for the silicon wafer but also for a zirconium wall of different thermal properties.
OKAWA et al. (Wed,) studied this question.