High heat transfer performance of foam freezing in phase change cold energy storage process

Phase change material (PCM) has high energy storage density, but the cold energy charging rate of PCM de-creases seriously with the increase of frozen thickness. The foam freezing produced by cold air flow can sharply increase the freezing rate. This research attempts to establish a theoretical model to quantify the heat transfer performance of foam freezing. The internal structure of the foam was obtained by experiment. The heat transfer process of single bubble was simulated by FLUENT, and analytical models for single bubble and foam were established. It was found that the tangent bubble array had the same heat transfer effect as the actual foam in freezing, and the bubble temperature variation obeyed the exponential distribution. The radius of more than 50% bubbles was about 2.5 mm, and the convective heat transfer coefficient in the bubble was 65 W/(m(2). K). The maximum completed heat transfer rate of foam freezing was 688 kW/m(3), when the air temperature was -20 degrees C. Foam freezing was compared with common ice storage structures, and was found had an order of magnitude higher than those structures in the heat transfer coefficient of unit volume.