要約

Boiling flow and heat transfer in porous media composed of spherical fuel elements have a significant influence on a reactor's efficiency and safety. In the present study, an experimental setup is designed and the boiling flow and heat transfer in porous media composed of regularly distributed spheres are investigated. The test sections mainly consisted of a polycarbonate plate for observation, an aluminum plate with densely distributed hemispheres, and a layer of glass spheres. The water flowing in the porous channels was heated by electrical power through the aluminum plate with hemispheres. Four types of spheres with diameters of 5, 6, 7, and 8 mm were involved. In the experimental parameter range, four flow regimes (bubbly, bubbly slug, slug, and slug annular) were observed to consider the effects of heat flux, mass flux, and particle diameter. The boiling heat transfer results showed that larger particles lead to a lower heat transfer coefficient and result in a higher wall superheat of the original nucleation boiling. Finally, a correlation between the boiling heat transfer coefficient and the measured data is proposed.