2021 Annual Meeting

Presentation information

Oral presentation

III. Fission Energy Engineering » 304-1 Thermal Hydraulics, Energy Conversion, Energy Transfer, Energy Storage

[1A07-11] Gas-liquid Two-phase Flow

Wed. Mar 17, 2021 2:45 PM - 4:15 PM Room A (Zoom room 1)

Chair: Ayako Ono (JAEA)

3:15 PM - 3:30 PM

[1A09] An Improved Mechanistic Model for Prediction of Bubble Lift-off Diameter in Subcooled Flow Boiling for Inclined Heating Surface

*M. A. Rafiq Akand1, Kei Kitahara1, Tatsuya Matsumoto1, Wei Liu1, Koji Morita1 (1. Kyushu Univ.)

Keywords:Mechanistic model, Lift-off diameter, Orientation angle, In-vessel retention, Critical heat flux

The accurate prediction capabilities of bubble lift-off diameter for the inclined heating surface is essential to evaluate the critical heat flux (CHF) following the net vapor generation point (NVG) in In-vessel retention (IVR) conditions. Almost all of the existing bubble lift-off models and correlations have been developed either upward-facing horizontal or vertical flow boiling conditions by ignoring or using a constant bubble sliding velocity with respect to the fluid velocity. Experimental research has been performed with a high-speed video camera system to investigate the bubble lift-off process for different channel inclination from downward-facing horizontal to the vertical position. An improved force-balanced model is proposed to predict the bubble lift-off diameter, where the bubble sliding velocity is calculated as a dynamic basis rather than a constant. The proposed model correctly follows the parametric trends of experimental data and shows good agreement with experimental data with a mean relative error of 10.12 %.