Pressure Drops and Dryout Heat Fluxes of Packed Beds with Cylindrical Particles

Motivated by reducing the uncertainties in coolability analysis of a debris bed formed in severe accident of nuclear reactors, the pressure drops of single-/two-phase flow and dryout heat fluxes of the packed beds with non-spherical particles are investigated in the present study. Both adiabatic single-/two-phase flow tests and boiling tests are performed on a particulate porous bed packed with cylindrical particles separately, the pressure drops and dryout heat fluxes under different conditions are measured to identify and validate the debris coolability analysis models. The results show that for a particulate bed packed with non-spherical particles such as cylinders, the effective particle diameter can be represented by the equivalent diameter of the particles, which is the product of Sauter mean diameter and the shape factor. Given this diameter, the measured pressure drops and the dryout heat fluxes are comparable with the predictions of Reed model. Comparing with the cooling scheme of top-flooding case, the bottom injection improves the dryout heat flux significantly.