In order to study the effects of bead-packed porous structure

balls of different materials such as aluminum

stainless steel and glass with different diameters of 5

8 and 11 mm are added into distilled water forming porous media. Since the supercooling degree of water is not a certain value

the experiments are repeated many times at the same cooling condition and analyzed with statistical methods. The results show that the distribution of the supercooling degree of distilled water in porous media is more concentrated than that of pure distilled water and the supercooling degree of water in porous media is smaller. The average supercooling degree of distilled water decreases with decreasing diameter of the same material balls on the whole. The larger the thermal conductivity of solid substrate is

the more concentrated the distribution of supercooling degree of distilled water in porous media and the smaller the average supercooling degree. In addition

the heterogeneous nucleation is more likely to occur when the thermal conductivity of the solid substrate is small. An annulus solid ice begins to grow slowly from the inside wall to the center region and the phase change time is longer than homogeneous nucleation. Once the crystal nucleus is formed

it will grow up instantly

forming the loose ice of homogeneous nucleation. Therefore

the heterogeneous nucleation should be avoided in engineering application.