Experiment and model development of CHF with consideration of heater surface characteristics and fluid properties

Abstract

Downward-facing geometries have been considered in this study, and major parameters to be considered during severe accident progression have been included in the experiments performed: pressure, material, orientation, dimension and coolant. Multifactor effects were mainly observed. A heat transfer model has been developed as well to incorporate the physical behaviors observed. Especially, material, wettability and pressure effects have been considered. Dry patch formation and phenomena have been considered in the model, and a material effect term has been included to account for a heat dissipation under a dry patch. Data comparisons were done with the CHF data where wettability, pressure and orientation information were included. Pressure condition considered was up to 10 bar, and the orientations were from $15^\circ$ up to vertical positions. The predictability tended to be improved as the width scale increased, which may suggest potential applicability to large-scale facilities. Some parts of the experimental results were analyzed with the developed model.