Freezing of saturated and superheated liquid in porous media

Abstract

Freezing of saturated and superheated liquid-porous media contained in a rectangular test cell has been studied experimentally. Water and different diameter glass beads constituted the liquid and porous media, respectively. The effects of different size glass beads, imposed temperature difference and liquid superheat were investigated. A one-dimensional conduction-based model was used to examine the importance of non-equilibrium effects. These effects were found to be unimportant for both water-aluminum balls and water-glass bead systems. For water initially at the freezing temperature, the model predictions agreed well with the experimental temperature and solidification front position data. When the superheat was sufficiently high to induce buoyancy driven convective flow, the local freezing rates varied with vertical location along the cooled wall. For low superheat, due to the density inversion of water, the rate of freezing at the top was higher than at the bottom ; however, for large superheat, the freezing rate near the bottom was higher as in freezing of ordinary liquids.