Experimental simulation of high-temperature and high-pressure annular two-phase flow using an HFC134a-ethanol system; Characterization of disturbance wave flow

Zhang, H.*; Umehara, Yutaro*; Horiguchi, Naoki   ; Yoshida, Hiroyuki  ; Eto, Atsuro*; Mori, Shoji*

Nuclear power is a key low-carbon energy source for a carbon-neutral future. In boiling water reactors (BWRs), steam-water annular flow near fuel rods is crucial for reactor safety, but its high-temperature, high-pressure conditions (285C, 7 MPa) make direct measurement challenges. To address this, we used an HFC134a-ethanol system at lower conditions (40C, 0.7 MPa) to simulate BWR annular flow. Using a high-speed camera and the constant electric current method, we analyzed liquid-film characteristics, wave velocity and frequency. We also examined surface tension and interfacial shear stress effects. Furthermore, we proposed a new correlation for base film thickness.