Abstract In this study, ice crystal growth in the freezing desalination process of binary water-NaCl system is investigated. The phase field method is used to conduct simulation and predict dendrite growth behaviour during the crystallization of sea ice. An experimental setup focusing on the directional crystallization of binary water-NaCl solutions on the horizontal wall is established to verify the e theoretical model. The results show that the crystal with single nucleus obtains obvious six-fold symmetry, while in the competitive crystallization of multiple crystal nuclei, spindle growth is inhibited. Brine channels and salt cells are formed in the directional crystallization, seawater consists of higher Mg2+and SO42− get more difficult in freezing desalination. The degree of subcooling significantly affects the salt cell concentration at the roots, the solid phase ratio, and the height of the planar crystal, while the heat flux significantly affects dendrite growth rate. The experimental average tip growth rate is 9.15 × 10−5 m/s, and the experimental average tip radius is 5.16 × 10−6 m. Peclet number of both simulation and experiment have the same order of magnitudes, with 0.1–0.2 and 0.3–0.6, respectively, which suggests the three-field coupling model established is reasonable for desalination simulation.

中文翻译：

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二元水-NaCl体系冷冻脱盐过程中的冰晶生长

摘要 本研究对水-NaCl二元体系冷冻脱盐过程中冰晶的生长进行了研究。相场法用于模拟和预测海冰结晶过程中的枝晶生长行为。建立了一个专注于水平壁上二元水-NaCl溶液定向结晶的实验装置，以验证e理论模型。结果表明，单核晶体获得明显的六重对称性，而在多晶核的竞争结晶中，纺锤体生长受到抑制。定向结晶中形成盐水通道和盐胞，由较高的Mg2+和SO42-组成的海水更难以冷冻脱盐。过冷度显着影响根部盐胞浓度、固相比和平面晶体的高度，而热通量显着影响枝晶生长速率。实验平均尖端生长速率为 9.15 × 10−5 m/s，实验平均尖端半径为 5.16 × 10−6 m。模拟和实验的 Peclet 数具有相同的数量级，分别为 0.1-0.2 和 0.3-0.6，表明建立的三场耦合模型对于海水淡化模拟是合理的。