Abstract:

In the dynamic ice storage of supercooled water, the ice adhesion on the low temperature heat exchange surface is the main threat to the stable operation of the system. Studies have shown that the interfacial region of ice and heat exchange surface has a quasi-liquid layer whose thickness is the main factor affecting the adhesion strength. The wall charging may increase the thickness of the quasi-liquid layer of ice and reduce the adhesion strength. Therefore, the molecular dynamics simulation of the equilibrium and stripping of the adhering ice on the copper wall was carried out under different wall charging conditions at the same water molecular system temperature (T=255 K), and the thickness of the quasi-liquid layer of adhering ice and adhesion strength was obtained. The results show that, compared with the case where the wall is uncharged, when the wall charge density Q_static=±0.1123 e/nm² and remains constant, the thickness of the quasi-liquid layer changes little, and the adhesion strength of ice increases due to the enhanced Coulomb interaction between the wall surface and water molecules. When the copper wall is charged with pulse Q_period=±0.1123 e/nm², the thickness of the quasi-liquid layer of ice increases significantly, and the adhesion strength decreases by 31.9% within the range that can be reduced. Therefore, wall pulse charging is an effective way to reduce the strength of ice adhesion.

Key words: molecular simulation, quasi-liquid layer, ice adhesion, wall charge, interface area, order parameters

摘要：

在过冷水式动态冰蓄冷中，低温换热表面上的冰黏附是系统稳定运行的主要威胁。研究表明，冰和换热表面的界面区域具有一层准液体层，其厚度是影响黏附强度的主要因素。壁面荷电可能增加冰的准液体层厚度，达到降低黏附强度的作用。因此，在同一水分子体系温度（T=255 K）的不同壁面荷电条件下，进行了铜壁面上黏附冰的平衡和脱附的分子动力学模拟，得到了黏附冰的准液体层厚度以及黏附强度。结果表明，相较于壁面不带电荷的工况，壁面电荷密度Q_static=±0.1123 e/nm²且保持不变时，准液体层的厚度变化很小，冰的黏附强度由于壁面与水分子之间的库仑相互作用增强而增大；当铜壁面采用脉冲荷电Q_period=±0.1123 e/nm²时，冰的准液体层厚度显著增加，黏附强度在可减小范围内减小31.9%。因此，壁面脉冲荷电是一种有效的降低冰黏附强度的方式。

关键词: 分子模拟, 准液体层, 冰黏附, 壁面电荷, 界面区域, 序参量