Measurement of heat transfer coefficient profile during quenching of a vertical hot wall with a falling liquid film

In the safety analysis of LWRs, spatial distribution of the heat transfer coefficient (HTC) in the vicinity of the rewetting front is of importance in order to predict the rewetting velocity of high-temperature fuel rods after the onset of reflooding during a loss-of-coolant accident. Many models are available for the HTC profile in literature, but they have not been validated sufficiently mainly due to the lack of experimental data. In the present study, transient of the wall temperature distribution during the wetting process of a high-temperature vertical plate with a falling liquid film was measured using a high-speed infra-red camera. The measured temperature data were substituted to the heat conduction equation to derive the HTC profile. It was confirmed that the wetting velocity measured in this work can be reproduced within the error of 10% if the calculated HTC profile is used. This indicates that the experimental data obtained in this work can be used as the base to develop a high-performance correlation for the HTC profile near the wetting front.