Phase change material (PCM) has high energy storage density, but the freezing rate decreases with the increase of frozen thickness. Foam freezing can sharply increase the freezing rate. In this research, the effects of bubble radius and convective heat transfer coefficient on freezing process were discussed. It was found that with the decrease of bubble radius and the increase of convective heat transfer coefficient, the shape of instantaneous freezing rate curve changed from linear dominant to C-type and then to L-type. With the increase of convective heat transfer coefficient, the opening direction of C-type curve of foam outlet temperature changed reversely, and the curves all intersected a specific area. The convective heat transfer coefficient was near the critical point of natural convection and light forced convection.
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