Experimental study of bubble behavior in a two-dimensional particle bed with high solid holdup

Cheng, S.*; Hirahara, Daisuke*; Tanaka, Yohei*; Gondai, Yoji*; Matsumoto, Tatsuya*; Morita, Koji*; Fukuda, Kenji*; Yamano, Hidemasa   ; Suzuki, Toru; Tobita, Yoshiharu

A series of experiments on bubble behavior in a particle bed was performed to clarify three-phase flow dynamics in debris bed, which is essential in heat-removal capability, under coolant boiling conditions. The current experiment was conducted in a 2D tank. Water was used as liquid phase, while bubbles were generated by injecting nitrogen gas from the bottom of the tank. Various experimental parameters were taken, including different particle bed height, various particle diameter, different particle type, and different nitrogen gas flow rate. By using digital image analysis method, three kinds of bubble rise behavior were observed under current experimental conditions and confirmed by the quantitative detailed analysis of bubble rise properties including bubble departure frequency and bubble departure size.