The scaling effect on the critical heat flux of a downward curved flow channel

The critical heat flux (CHF) on the reactor vessel external wall was measured using three test sections of a two-dimensional slice. The top region (inclination angle of 90 .deg) of the test section, which simulates the reactor vessel lower head for the in-vessel retention through external reactor vessel cooling (IVR-ERVC) strategy during severe accidents, was mainly considered in this study. The purpose of this study is to produce experimental data to assess the CHF limits on the external vessel wall and investigate the scaling effect on the CHF. Three test sections, with respective radius of curvature measurements of 0.15m, 0.25m and 0.5m, have been used. The width and gap size were 0.03 m and 0.03∼0.06m, respectively. The material of the test section was Type 304 stainless steel. The CHF results were acquired under the inlet subcooling of 2 and 10 K with the mass flux of 50 to 400 kg/m2s. In terms of the LOCA condition, the experimental results were compared with the results of large-scale experiments. To eliminate the inconsistency in the CHF relationship of the mass flux and exit quality conditions, the flow visualization technique was utilized, and the exit quality values for the experimental results were modified. A CHF correlation was developed with the data of this study and Jeong et al.'s work