Abstract
Water in a vertical annulus is frozen from the inner cylinder wall. The outer cylinder wall is insulated. The water is initially kept at a uniform temperature. Experiments and numerical analysis of this freezing process were carried out under the various temperature conditions. In the experiments, the water was 150 mm high and the diameters of the inner and outer cylinders were 20 mm and 100 mm, respectively. In the present analysis, a boundary fixing method was used and the two-dimensional unsteady natural convection in the liquid phase with density inversion was calculated. The analytical results of the time-wise changes of the freezing front and the temperature distribution agreed well with the experimental results. The effects of the density inversion on the temperature distribution in the liquid phase were shown clearly by the analytical results. Furthermore a one-dimensional approximate analysis was carried out, where the appropriate heat-transfer coefficient on the freezing front was given. It was shown that the approximate analysis as well as the present analysis was able to obtain the time-wise changes of the frozen volume and the total thermal energy storage.
