Abstract:

There are many factors which affect supercooling of water. Under the same experimental conditions, supercooling degree of water is not a fixed value. The presence of bead-packed porous structure influences the supercooling of water. Experiments to test supercooling of distilled water and different ball diameters of bead-packed porous structure were conducted thirty two times. And experiments about characteristics of cold storage of distilled water and different ball diameters of bead-packed porous structure were also conducted. Experimental results of supercooling were analyzed using statistical methods, and a CCD camera and a thermal imager were used for observing the phenomenon of supercooling. The average supercooling degree of distilled water under the condition of cooling with large temperature difference was lower than that under the condition of stepped slow cooling. The smaller the ball diameter in bead-packed porous structure, the smaller the average and peak supercooling degree, but there was a special circumstance when ball diameter was 11 mm. The average supercooling degree and the peak value of bead-packed porous structure with 11 mm ball diameter were smaller than that with 8 mm ball diameter. In addition, the presence of a porous solid base greatly reduced storage phase transition time.

Key words: porous media, crystallization, degree of supercooling, phase change, distribution

摘要：

影响水过冷度的因素很多, 同样实验条件下水的过冷度并非一个定值, 多孔球层的存在对水的过冷度产生一定影响。对蒸馏水和不同球径的多孔球层介质进行了32次过冷度测定实验, 并对蒸馏水和多孔球层介质的蓄冷特性进行了实验研究。过冷度实验结果采用统计方法进行分析, 并用CCD相机和热像仪对过冷现象进行观察。结果表明:大温差降温条件下水的平均过冷度要小于阶梯缓慢降温条件下水的过冷度;多孔球层球径越小, 平均和峰值过冷度越小, 但直径为11 mm出现特例, 其平均过冷度比8 mm直径多孔球层要小, 峰值也比8 mm的小;多孔球层固体基底的存在大大缩短了蓄冷相变时间。

关键词: 多孔介质, 结晶, 过冷度, 相变, 分布