Flow Boiling Burnout in a Hypervapotron Channel Under High Heat Flux and High Sub-Cooling Conditions

In this study, a subcooled flow boiling experiment was conducted to analyze the critical heat flux (CHF) of a hypervapotron (HV) channel based on the one-side high-heat load condition. The experimental loop used in this study was operated at high values of pressure (20 bar), flow rate (1.5 kg/s), and fluid temperature (150 °C) with a one-side joule heating system capable of loading a high heat of 14.8 MW/m 2 . We analyzed the effect of the system parameters on the CHF of the HV channel and determined that the CHF increased at high subcooling and flow rate. This can be attributed to the strengthening of forced convective heat transfer and rapid condensation of the vapor under the aforementioned conditions. Additionally, the CHF tended to increase with the increasing pressure, owing to the decreased bubble size under pressure ranges of 1 to 10 bar. Furthermore, we evaluated the prediction performance of the existing subcooled flow boiling correlations considering the CHF of HV. However, most correlations tended to underpredict as they were developed based on smooth channels. Therefore, we modified the Inasaka and Nariai CHF correlation and developed a novel HV CHF correlation using PYTHON and the artificial intelligence regression method. The mean absolute error and root mean square error of the proposed correlation are 10.68% and 11.99%, respectively, which are significantly lower than those of existing correlations. It is recommended that the newly developed CHF correlation be utilized at an inlet bulk temperature of 40–140 °C, a mass flow rate of 0.071–0.284 kg/s, and a pressure of 1–10 bar.