Non-uniform melting in packed beds of fine ice slurry

The melting process of packed beds of ice slurry consisting of aqueous solution and ice particles with a mean diameter of 0.2 mm, so-called liquid ice, was studied. The packed ice layer was melted with aqueous solution sprayed on top of it directly and indirectly. Experiments of the melting process were done by changing the mass of ice, the inlet temperature and the flow rate. The time history of the outlet temperature of the bed was measured and the melting phenomenon was observed. During the melting, it was found that passages through the ice layer were formed and the aqueous solution sprayed on the top of the ice layer hardly permeated the ice layer, but flowed through the passages. Assuming that the flow rate of the solution through the passages was known, the melting process was analyzed. In the case of direct spraying, the effects on the outlet temperature and the formation of passage were clarified by changing the initial mass of ice, the flow rate and the inlet temperature. When the solution was sprayed on top of the ice layer directly (direct spraying), the outlet temperature was kept constant because the heat exchange was enhanced by the mixing effects of spraying. On the contrary, when an obstacle was placed on top of the ice layer (indirect spraying), the outlet temperature was higher than that in the case of direct spraying and was not kept constant.