储能科学与技术 ›› 2019, Vol. 8 ›› Issue (5): 874-879.doi: 10.12028/j.issn.2095-4239.2019.0045

• 研究开发 • 上一篇    下一篇

正十四烷烃相变过程的分子动力学模拟

章学来1, 王绪哲1, 王继芬2, 徐笑锋1, 华维三1, 房满庭1   

  1. 1 上海海事大学蓄冷技术研究所, 上海 201306;
    2 上海第二工业大学应用化学系, 上海 201209
  • 收稿日期:2019-04-01 修回日期:2019-04-15 出版日期:2019-09-01 发布日期:2019-06-11
  • 通讯作者: 章学来(1964-),男,博士,教授,主要研究相变储能技术,E-mail:xlzhang@shmtu.edu.cn。
  • 作者简介:章学来(1964-),男,博士,教授,主要研究相变储能技术,E-mail:xlzhang@shmtu.edu.cn。
  • 基金资助:
    国家自然科学基金（51376115）。

Molecular dynamics simulation of phase transformation process of n-tetradecane

ZHANG Xuelai1, WANG Xuzhe1, WANG Jifen2, XU Xiaofeng1, HUA Weisan1, FANG Manting1   

  1. 1 Cold Storage Technology Institute, Shanghai Maritime University, Shanghai 201306, China;
    2 Department of Applied Chemistry, Shanghai Second Polytechnic University, Shanghai 201209, China
  • Received:2019-04-01 Revised:2019-04-15 Online:2019-09-01 Published:2019-06-11

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摘要： 采用分子动力学模拟方法，应用COMPASS力场模拟正十四烷烃无定形体系结构。将体系在NPT系综下从270 K逐渐升温至290 K，分析了该温度区间中正十四烷烃分子的扩散性随着温度的变化情况，并得出了体系的相变温度在278.5 K，通过将模拟得出的密度值、相变温度值与实验比较，密度误差为0.8%，熔点误差为0.23%。通过对正十四烷烃分子链在相变前后的末端距分布情况以及径向分布函数的分析，发现正十四烷烃在固态时分子链构象随着温度的升高逐渐由直链趋向于弯曲状态，而液态时随着温度的升高分子链的构象逐渐由弯曲状态趋向于直链。原子周围1.11 Å（1 Å=0.1 nm，余同）处呈现其他分子或者原子的可能性是最大的，原子周围0.99 Å内没有其他原子。研究结果可以为后续研究其他添加剂对于该分子体系微观结构的改变进行对比，为寻找更高效实用的相变储能材料提供一定的引导。

关键词: 分子动力学, 正十四烷烃, 径向分布函数, 扩散性, 末端距

Abstract: The molecular dynamics simulation method was used to simulate the amorphous tetradecane hydrocarbon system with COMPASS force field. The system was gradually heated from 270K to 290K under the NPT ensemble. The temperature-dependent diffusion of n-tetradecane molecules in the temperature range was analyzed. The phase transition temperature of the system was obtained at 278.5K. The obtained density value and phase transition temperature value are compared with the experimental results. The density error is 0.8% and the melting point error is 0.23%. The distribution of the terminal distance and the radial distribution function of the n-tetradecane molecular chain before and after the phase transition are also analyzed. It is found that the molecular chain conformation of n-tetradecane in solid state gradually changes from linear to curved with increasing temperature, while the conformation of molecular chain in liquid state gradually changes from curved to linear as the temperature increases. The possibility of presenting other molecules or atoms at 1.11 Å around the atom is the largest, and there are no other atoms in the 0.99 Å around the atom.The research results can be used to compare the changes of the microstructure of other molecular additives in the subsequent research, and to provide certain guidance for finding more efficient and practical phase change energy storage materials.

Key words: molecular dynamics, n-tetradecane, radial distribution function, diffusivity, end-to-end distance

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