| 摘要: |
| 复合相变蓄冷材料是近年来的研究热点，但对于其微观相变机理研究较少。本文以高潜热值的冰水相变为主，以质量分数为10%的丙三醇、20%的氯化铵作为成核剂和降温剂，添加质量分数为0%、3%、5%的聚乙二醇（PEG）后，采用分子动力学方法对其相变过程进行模拟，预测其相变温度并从成键与构象、键长与键角、径向分布函数、扩散系数和密度等参数进行分析。结果表明：机理方面：温度越低，分子动能越小，分子运动越平缓，羟基键长变小的概率增加，温度对于键角的影响较小，而对于键长的影响较大；相变方面：随着温度的降低，溶液体系的扩散系数降低，密度变大，溶液黏度增大，有序性增强，在10%丙三醇-20%氯化铵水溶液体系中，相变温度的拐点为255.2~256 K,与实验结果255.5 K非常接近。而在添加质量分数为3%、5%PEG聚合物后，预测溶液体系的相变温度分别为254.1~254.3 K、253.5~253.8 K，下降1.1~1.7 K、1.7~2.2 K。 |
| 关键词: 蓄冷剂 分子动力学 扩散系数 相变 聚合物 |
| DOI： |
| 投稿时间：2021-12-01 修订日期：2022-03-12
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| 基金项目:本文受河南省自然科学基金项目(162300410112)、河南 援疆资金、哈密市科技计划支持项目、新疆维吾尔自治区人才 专项课题支持。 |
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| Study on Phase Transition Mechanism of Polymer Composite Cold Thermal Energy Storage Agent Based on Molecular Dynamics Simulation |
| Chen Youliang,Sheng Wei,Wang Ruirui,Li Xueli,Hao Xiaoru,Zheng Haikun |
| (School of Mechanical and Power Engineering, Henan Polytechnic University;Hami Yuxin Energy Industry Research Institute) |
| Abstract: |
| Composite phase-change cold thermal energy storage materials have attracted significant attention in recent years; however, studies on their microscopic phase-change mechanism have garnered insignificant interest. In this study, the ice-water system with a high latent heat was mixed with polyethylene glycol (PEG) of mass fractions of 0%, 3%, and 5%, and using 10% glycerol and 20% ammonium chloride as the nucleating and cooling agents, respectively. The molecular dynamics method was used to simulate the phase transition process. The phase transition temperature was predicted and analyzed based on parameters such as the bonding and conformation, bond length, bond angle, radial distribution function, diffusion coefficient, and density. The results demonstrate that the lower the temperature, the lower the molecular kinetic energy, the smoother the molecular motion, and the greater the probability that the hydroxyl bond length will decrease. The temperature had a slight effect on the bond angle but a great impact on the bond length. With regard to the phase change, as the temperature decreased, the diffusion coefficient of the solution system decreased; the density increased; the solution viscosity increased; the orderliness increased. In the 10% glycerol-20% ammonium chloride aqueous system, the inflection point of the phase transition temperature was 255.2–256 K, which is very close to the experimental result of 255.5 K. After adding 3% and 5% PEG polymers, the phase transition temperature of the solution system was predicted to be 254.1–254.3 K and 253.5–253.8 K, demonstrating a decrease of 1.1–1.7 K and 1.7–2.2 K, respectively. |
| Key words: cold thermal energy storage material molecular dynamics diffusion coefficient phase change |
