[3G08-10] Gas-liquid Two-phase Flow

[3G08] Bubble Lift-off Size in Subcooled Flow Boiling for Inclined Heating Surface.

*Md Abdur Rafiq Akand¹, Kei Kitahara¹, Tatsuya Matsumoto², Wei Liu³, Koji Morita⁴ (1. Student, Kyushu Univ., 2. Asst. Professor, Kyushu Univ., 3. Assoc. Professor, Kyushu Univ., 4. Professor, Kyushu Univ.)

Keywords:Lift-off diameter, Orientation angle, Subcooled boiling, High-speed digital camera, Flow visualization.

In the case of interfacial heat transfer, void fraction prediction, and interfacial area transport equation, bubble lift-off diameter is more significant than the departure diameter, though a minimal study was conducted on the bubble lift-off process. An experimental facility has been designed with a high-speed video camera system to investigate the bubble lift-off process for different inclination angles of heating surface from downward-facing horizontal to vertical position. The impact of channel orientation, heat flux, mass flux, and inlet subcooling on bubble lift-off size are thoroughly investigated with the current experimental facility. An increasing trend of bubble lift-off diameter was identified for increasing of heat flux and decreasing of mass flux as well as the inlet subcooling. A significant effect of the channel orientation angle on the bubble lift-off diameter was found and the maximum lift-off diameter was achieved in the downward-facing horizontal position of heating surface whereas the minimum one was at the vertical condition.